Vegetable Bedding Plants Pest Management
Printable Tables 
Scouting Guidelines and Biological Control Options for Vegetable Bedding Plants and Transplants
Insecticides and Miticides for Vegetable Bedding Plants Grown in Greenhouses
Fungicides for Vegetable Bedding Plants Grown in Greenhouses
Organic Pest Management for Vegetable Beding Plants Grown in Greenhouses
Plant Growth Regulators for Vegetable Bedding Plants Grown in Greenhouses
Introduction
Vegetable bedding plants are commonly grown in the Northeast as part of the spring sales mix. Although vegetable bedding plants may only be in the greenhouse for a short period of time, it is important to produce a high quality pest-free transplant. This can pose a challenge. A review of pesticide labels indicates that there are no growth regulators and only a limited number of insecticides and fungicides labeled for greenhouse-grown vegetable bedding plants. Most pesticides labeled for ornamental bedding plants are not labeled for vegetable bedding plants.
Integrated pest management (IPM) offers a practical way to effectively manage pests on vegetable bedding plants. Through the use of sound cultural practices, monitoring techniques, accurate problem identification, and timely implementation and evaluation of appropriate management strategies, growers can improve vegetable bedding plant production while minimizing their reliance on routine pesticide applications. IPM utilizes many different management options; cultural, physical, mechanical, biological and chemical. Routine crop inspection alerts growers to developing pest and cultural problems while they are still minor and can be easily managed. Early detection and intervention is the foundation of an IPM program.
To begin, obtain up-to-date cultural information and schedules for producing vegetable bedding plants. Consult with your seed supplier or review the references listed at the end of this fact sheet for information specific to the crops you will be growing. Pay particular attention to the scheduling times, light, temperature and nutritional requirements needed to grow healthy transplants.
Links to the main topics in the fact sheet are below:
Managing Plant Height
Disease Management
Fungicides and Bactericides Table
Specific Diseases
General Pest Management (Scouting and decision making)
Insecticides and Miticides Table
Biological Control for Insects and Mites
Scouting Guidelines and Biological Control Options Table
Specific Insects and Mites
Managing Plant Height
A review of pesticide labels indicates that Sumagic (uniconazole-P) (12 hr. REI) is the only growth regulator labeled for use on a limited group of vegetable transplants (tomato, pepper, ornamental pepper, eggplant, tomatillo, ground cherry and pepino). See supplemental label. As with any plant growth regulator, it is recommended to test growth regulator treatments on small crop samples and starting with a low rate before full-scale implementation. The maximum cumulative amount of Sumagic applied must not exceed 10 ppm with coverage of 2 quarts per 100 sq. feet. This means that total amount used inswquential applications can only add up to 10 ppm spray (example, 1 application at 10 ppm or two applications at 5 ppm or 4 applications at 2.5 ppm). The last spray must be no later than two weeks after the two to four leaf stage of development. Experiments have shown that sequential applications produce the best results and that the earlier that the plants receive the Sumagic spray, the greater effect it will have on the final height of the transplants.
Since very few growth regulators are registered for vegetable bedding plants, plant height is often managed by adjusting temperature, water and fertilizer levels, or by physically brushing the plants. Research has shown that mechanical stress reduces stem elongation and maintains plant height. For example, brushing transplants twice daily for 18 days using about 40 strokes back and forth with a cardboard tube suspended from an irrigation boom can result in as much as a 30% reduction in stem elongation. Growers have also successfully used a wand made of plastic plumbing pipe or a flat piece of polystyrene foam. Vegetable plants such as tomatoes, eggplants and cucumbers have responded to this method of height control. Note that this technique has damaged some tender plant species such as peppers and could also enhance the spread of disease.
Water stress is another tool growers can use to manage plant height. Maintaining plants on the dry side limits cell expansion and plant growth. This method requires close attention to avoid permanent damage such as leaf burn or even plant death. One technique is to irrigate the growing mix thoroughly and then allow it to dry to the point where plants wilt before irrigating thoroughly again. Growth is restricted during the period when the growing medium is very dry. Once watered, the plants rapidly resume growth. This technique is used by experienced tomato growers.
Vegetable transplants are responsive to DIF (difference between day and night temperature), as well. Stem elongation or stretch can be controlled by manipulating this difference between day and night temperature. Plants grown with cooler day than night temperatures will be shorter than those grown with warmer day than night temperatures. The longer that the cool day temperatures can be maintained during the day, the greater the effect of DIF on stem elongation. This is especially true when cloud cover and low levels of light, favor stretching. The most important hours for height control are the first 2 to 3 hours following sunrise. For many plants, lowering the temperature during the first 2 to 3 daylight hours will reduce plant height as much as lowering the temperature throughout the entire day. Using this technique, growers can reduce plant height as much as 50-70%. Allow the air temperature to dip to 50o - 55oF for 2-3 hours at dawn, and then keep normal day/night temperatures of 60o - 70oF. Most growers find it most efficient to start lowering the day temperature for one-half to one hour prior to sunrise. Vegetable bedding plants will vary in their responsiveness to DIF; tomatoes show a large response whereas squash show little or no response.
Withholding nutrients can also be used to prevent stretching. Low phosphorus fertilization has been shown to be effective for controlling vegetable bedding plant growth. Tomatoes are especially sensitive. If carefully managed, a mild to moderate phosphorus (P) deficiency may result in a desirable reduction in growth and no foliar symptoms of P deficiency. A grower wishing to try this method of plant growth control should use a low P soilless growth medium, preferably custom blended. The mix should contain 1 lb./cu. yd. of potassium nitrate as a starter charge. Do not use a starter charge containing P. Begin fertilizing twice a week right after transplanting with 20-0-20 for 2 or 3 weeks and then finish with a NPK fertilizer such as 20-10-20 or 15-16-17. Rates should be 150 - 200 ppm N. For crops sown before mid-March the low P fertilization period may have to be longer. If this is the case, careful observation of the crop will be needed if fertilization with 20-0-20 is extended beyond three weeks so as to avoid too much growth reduction or P deficiency symptoms.
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Disease Management
Diseases of vegetable bedding plants include Botrytis blight, damping-off, tospoviruses such as tomato spotted wilt virus and impatiens necrotic spot virus and bacterial leaf spots. To control diseases effectively, it is important to identify them properly. When diseases are not successfully managed, it is often because the cause was not accurately identified. Symptoms caused by poor cultural practices can also mimic disease symptoms. Fungicides cannot correct problems caused by high soluble salts, poor aeration or a nutrient imbalance. An integrated approach to disease management involves the use of resistant cultivars, sanitation, sound cultural practices and the proper use of the correct pesticide.
Resistant cultivars
Seed catalogues often feature disease resistant and tolerant varieties of vegetables. Utilize resistant varieties where feasible, but take some time to research the diseases that are giving the most trouble to find other strategies to incorporate into the disease management plan.
Sanitation
Pest management on vegetable bedding plants begins with a clean, weed-free, disinfected greenhouse. Before growing the crop, the greenhouse should be cleared of plant debris, weeds, flats and tools. Empty benches, potting tables, storage shelves, tools and cell packs should be washed and disinfected with a sanitizing agent. After the greenhouse has been sanitized, care must be taken to avoid recontamination with pathogens. Purchase seed from reliable sources. If possible, purchase seed that has been disinfested by chemical and/or heat treatment by the seed company. Potting media is easily reinfested by dirty hose nozzles or tools and unsanitary growing conditions. The floor of the greenhouse is a good source for diseases. Use a hook to keep the hose nozzles off the floor. Grow transplants off the ground in a well-ventilated greenhouse. To prevent root rot diseases, avoid overwatering and overfertilizing. Water early in the day to help prevent foliar diseases.
Use separate greenhouses for vegetable seedlings and ornamental bedding plants. Separate greenhouses: 1) will protect vegetable seedlings from any insect pests that may migrate from ornamentals and plants that are held over 2) will protect vegetable seedlings from tospoviruses such as impatiens necrotic spot virus (INSV)/ tomato spotted wilt virus (TSWV) and 3) will make it easier to treat the vegetable seedlings if pesticides are needed.
Techniques to reduce high humidity
High relative humidity is one of the major contributing factors to diseases such as Botrytis blight, a common fungal disease of greenhouse crops. Warm air holds more moisture than cool air. During warm days, the greenhouse air is more humid. As the air cools in the evening, the moisture-holding capacity drops until the dew point is reached. Water then begins to condense on surfaces. Humidity can be reduced by exhausting the moist air and replacing it with cooler outside air that is drier. Activate the exhaust fans for a few minutes, and then heat the greenhouse to raise the air temperature. Then, exhaust the humid air. The cooler, outside air will lower the humidity as it is warmed in the greenhouse. A relay may be needed to lock out the furnace or boiler until the fan shuts off so the flue gases are not drawn back into the greenhouse. This will help to prevent air pollution damage to sensitive seedlings. Heat and vent two or three times per hour in the evening after the sun goes down and early in the morning at sunrise.
Using Horizontal Air Flow (HAF) can also reduce condensation. HAF fans keep the air moving in the greenhouse, helping to minimize temperature differential and cold spots where condensation occurs. Air that is moving is continually mixed. The mixed air along the surface does not cool below the dewpoint, and therefore does not condense on plant surfaces.
In addition, cultural practices can be used to reduce humidity within the plant canopy. These include proper watering practices and spacing of plants. Since most vegetable bedding plants are grown in flats that are spaced flat to flat, reducing humidity within the canopy is difficult. Proper planting dates, plant nutrition, watering practices and height management techniques help to prevent lush, overgrown, crowded plants thereby reducing humidity within the canopy.
Handwatering and overhead irrigation systems are the primary methods of watering vegetable bedding plants. Always water in the morning to reduce the length of time the leaves stay wet after irrigating and to prevent foliar diseases. Rising temperatures during the day will evaporate water from the foliage, so the leaves stay dry. Avoid watering late in the day or when water will sit on leaf surfaces for long periods of time.
Seed Treatments
Seed treatments are useful for many vegetable crops for preventing root diseases, as well as certain diseases carried on or within the seed. There are two general types of seed treatment: eradicative and protective. Eradicative seed treatments use hot water or chlorine to kill disease-causing agents on or within the seed. They are useful in controlling certain seed-borne diseases such as bacterial leaf spot on pepper and bacterial canker on tomato. Protective seed treatments use fungicides on the seed surface to protect the seed against decay and soil-borne organisms such as damping off. For more information regarding seed treatments, contact your seed sales representative, Extension vegetable specialist or plant pathologist.
Fungicides
Fungicides can provide excellent management of some diseases, but for others they may be ineffective. In general, to control root diseases, broad-spectrum fungicides should be applied as a drench on a preventative basis. Read directions for application on pesticide labels. An application of additional water may be necessary. For foliage diseases, obtain thorough spray coverage, and treat when disease is first evident. Table 1 provides a listing of fungicides labeled for vegetable bedding plants.
Biofungicides
Biofungicides are fungicides that contain living organisms such as fungi, bacteria or actinomycetes and can work in a number of ways. Growers need to be aware of their mode of action and how to most effectively use biofungicides to suppress plant diseases. Storage conditions, soil and air temperatures, and use of other chemicals effects their efficacy. Biofungicides should be used as a preventative in conjunction with a regular monitoring program where root health and crop quality is evaluated. They will not cure diseased plants. The following products are commercially available for use on vegetable bedding plants. Trichoderma harzianum (Rootshield and TopShield) are formulations of a selected strain of a common soil saprophytic fungus. Streptomyces griseovirdis K61 (Mycostop) is a powdered formulation of dried spores and mycelia of the soil actinomycete. Trichoderma virens GL-21 (SoilGard 12G) is a granular formulation of a common soil sapropytic fungus. Ampelomyces quisqualis M-10 (AQ10 Biofungicide) is a water-dispersible granule formulation of a fungus that parasitizes powdery mildew. See Table 1 for information on labeled crops and diseases for these biofungicides.
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| Fungicide | Targeted Pest | Labeled Crops | Comments |
|---|---|---|---|
| Basic Copper Sulfate (Cuprofix Ultra 40 D Disperss) 12 hr. REI Group M1 |
Angular leaf spot, downy mildew, Alternaria blight, anthracnose, bacterial blight, bacterial spot (depending upon the crop) |
Many including cucumbers, eggplant, peppers, tomatoes and others |
Preventative, contact fungicide. Crops grown in the greenhouse may be more sensitive to copper injury so the user should determine plant sensitivity. Observe for 7 to 10 days for symptoms of injury. |
|
Bacillus pumilus (Sonata) |
Downy mildew, powdery mildew on many different crops (see label). early blight, late blight on certain fruiting vegetables |
Many including cole crops, cucurbits, fruiting, leafy vegetables |
Broad spectrum, preventative biological fungicide. Begin applications when conditions in the greenhouse favor disease development. |
|
Bacillus subtilis(Cease) |
Fungal and bacterial leaf spots, powdery mildew, botrytis blight, downy mildew (see label) |
Many including cole crops, cucurbits, fruiting vegetables, leafy vegetables, bulb vegetables |
Broad spectrum, preventative biological fungicide. Begin applications when conditions in the greenhouse favor disease development. thorough coverage is essential. |
| Bacillus subtilis (Companion Liquid Biological Fungicide) 4 hr. REI NC Organic product |
Camping off fungi, root rots (Fusarium, Pythium, Phytophthora, rhizoctonia), Botrytis, leaf spots, (fungal and bacterial), powdery mildew | Many including cole crops, cucurbits, fruiting vegetables, leafy vegetables, bulb vegetables | Preventative biological fungicide for control and suppression of soil and foliar diseases. Activtes ISR (induced systemic resistance). |
| Copper Hydroxice (Champ Dry Prill, Champ Formula 2 flowable) (Champ WG) Organic product (Kocide products) Group M1 |
Leaf spots, Anthracnose, Bacterial spots and other diseases (see label) | See labels for specific crops. | Protectant, contact fungicide. See labels for specific usage instructions. Several Kocide products are available. |
| Copper soap (Camelot O) 4 hr. REI Group M1 |
Leaf spots (many), powdery mildew, downy mildew, early blight, late blight and others (depending upon crop) | Cole crops, lettuce, onion, tomato, eggplant, pepper | Works by contact. See label for specific usage instructions and plant safety precautions. |
| Copper salts of fatty and rosin acids (Camelot) 12 hr. REI group M1 |
Bacterial leaf spots, fungal leaf spots and blights, downy mildew, powdery mildew and others (see label for specifics) | Greenhouse vegetables (see label for specific crops) | Works by contact. See label for specific usage instructions and plant safety precautions. |
| Dichloran (Botran 75-W) 12 hr. REI Group 14 |
Botrytis, White Mold (Sclerotinia) | Cucumbers, leaf lettuce and tomatoes | Preventative, contact fungicide. Seedling or newly set transplants of tomatoes may be injured by drenching. |
| Fenhexamid (Decree 50WDG) 12 hr. REI Group 17 |
Botrytis | Fruiting vegetables, tomatoes, cucumber and leafy greens (except spinach) | Preventative translaminar fungicide. Thorough coverage needed. do not make more than two consecutive applications. Do not apply in the field. |
| Hydrogen dioxide (Oxidate) 0 hr. REI 1 hr. REI (spray) Organic product N/A |
Downy mildew, powdery mildew, leaf spots and blights, root rots (see label) | Tomatoes, peppers, leafy and cole crops, cucurbits, bulb crops and others | Works by contact. Strong oxidizing agent. |
| Insecticidal soap Potassium salts of fatty acids (M-Pede) 12 hr. REI NC Organic product |
Powdery mildew | Greenhouse Cucumber | Works by contact. See label for usage instructions. |
| Kaolin (Surround WP) 4 hr. REI NC Organic product |
Powdery mildew | Cucurbit vegetables | Forms a mineral-based particle film resulting in a dry, white film. May be unsightly for retail sales. Uniform coverage important for effectiveness. |
|
Mancozeb |
Leafspot diseases |
Many vegetables including cucumbers, melons, onions, tomatoes and summer squash |
Broad spectrum protectant fungicide. |
| Maneb (Maneb 75 DF, Maneb 80WP) 24 hr. REI Group M3 |
Anthracnose, leaf spots, early blight, late blight | Tomatoes (greenhouse) | Protectant, contact fungicide. |
| Neem Oil (Trilogy) 4 hr. REI Organic product |
Alternaria, Anthracnose, Early blight, Botrytis, Leaf spots, Downy mildews, Powdery mildew | Many different vegetables (see label) | Broad spectrum, contact fungicide. See label for plant safety precautions. Plant injury may occur during humid conditions in the greenhouse. |
|
Pentachloro-nitrobenzene PCNB |
Root and stem rot, damping off (Rhizoctonia, solani) |
Vegetable bedding plants: limited to container-grown broccoli, Brussels sprouts, cabbage, cauliflower, peppers and tomatoes |
Protectant, contact fungicide. 400 and 75WP: Apply as a soil drench. |
| Petroleum Oil (SuffOil X) 4 hr. REI Organic product NC |
Powdery mildew | Vegetable crops (see label) | Works by contact. Thorough coverage of all plant parts is important. |
| Phosphorus Acid (Alude) 4 hr. REI Group 33 |
Downy mildew, Phytophthora spp., Pythium spp., Gummy stem blight | Vegetable transplants such as cole crops, curcurbits, fruiting vegetables, leafy vegetables, onions, okra | Systemic fungicide. See label for plant safety precautions. |
| Phosphorus Acid (Fosphite) 4 hr. REI Group 33 |
Downy mildew, powdery mildew, Phytophthora, Pythium, Fusarium, Rhizoctonia | Many vegetables (see label) | Systemic fungicide. Make applications prior to disease development in conjunction with good cultural practices. |
| Polyoxin D zinc salt (Vernda O) | Cucurbit vegetables: powdery mildew, gummy stem blight, Botrytis, Corynespora leaf spot, scab, early blight Fruiting vegetables: Powdery mildew, Botrytis sp., early blight, suppression of anthracnose |
Cucurbit vegetables, fruiting vegetables | Locally systemic fungicide. Active ingredient (Polyxin) is a natural antibiotic and fermentation product of a soil bacterium. Preventative and curative activity. |
|
Potassium bicarbonate |
Powdery Mildew and others (See labels for more information) Kaligreen is only labeled for powdery mildew |
Many vegetables including cabbage, cucumber, eggplant, broccoli, cauliflower, lettuce, peppers, tomatoes and squash |
Contact fungicide. Thorough coverage essential. Potassium bicarbonate disrupts the potassium ion balance in the fungus cell, causing the cell walls to collapse. |
| Propamocuarb HCl (Previcur Flex) 12 hr. REI Group F |
Root rot and damping off caused by Pythium, Phytophthora | Tomatoes, cucurbits, peppers, leaf lettuce | Systemic fungicide. Phytotoxicity may occur if applied directly to dry growing media, especially in intense sunlight. |
| Pyrimethanil (Scala SC) 12 hr. REI Group 9 |
Gray mold (Botrytis), Early blight (Alternaria) | Tomatoes | Preventative fungicide. Apply only in well ventilated greenhouses and ventilate for at least 2 hours after application. Phytotoxicity may occur in unventilated greenhouses with relative humidity above 80%. |
| Reynoutria sachalininsis (Regalia) 24 hr. REI Organic product |
Powdery mildew, downy mildew, gummy stem blight, bacterial blight, bacterial leaf spot, early and late blight (depends upon crop) | Edible crops such as cucurbits, peppers, leafy vegetable crops and tomato | Formulation of an extract from the Giant Knotweed. Use preventativley to increase natural defense system of plants. |
|
Streptomyces griseoviridis strain K 61 |
For control of seed rot, root and stem rot (Fusarium, Alternaria and Phomopsis) Suppression of Botrytis and root rots of Pythium, Phytophthora and Rhizoctonia |
Many including lettuce, cole crops, cucumbers, melons, peppers, tomatoes and others. |
Preventative biological fungicide. Contains a beneficial bacterium. Repeat applications may be needed. Use as a soil spray or drench. |
| Streptomycin lydicus (Actinovate SP) 1 hr. REI NC Organic product |
Suppression of soil borne fungi such as Fusarium, Rhizoctonia, Pythium, Phytophthora, and foliar diseases such as downy mildew, powdery mildew, Botrytis, Alternaria | All greenhouse vegetables | Preventative biological fungicide for suppression of root rot dieases and some foliar pathogens. |
| Streptomycin lydicus (Actino-Iron) 4 hr. REI NC Organic product |
Suppression of Fusarium, Pythium, Rhizoctonia, Phytopthora and others | Greenhouse vegetables | Preventative biological fungicide that suppresses certain diseases. Also contains iron and humic acid. |
|
Streptomycin sulfate |
Bacterial Spot |
Tomatoes and peppers |
Xylem mobile fungicide. Repeated applications can result in resistant bacteria. Do not apply through any irrigation system. |
| Sulfur (Microthiol Disperss) (Micro Sulf) 24 hr. REI Group M2 Organic products |
Powdery mildew | Microthiol Disperss: Crucifers, cucurbits, peppers and tomatoes Micro Sulf: Cole crops, cucumbers, eggplants, greens, peppers, tomatoes |
Contact fungicide. Crops grown in greenhouses may be more sensitive to sulfur injury, so the lowest label rate should be tried initiallly. Do not use within two weeks of oil spray treatment. |
| Thiophanate methyl (3336 WP) 12 hr. REI Group 1 |
Anthracnose, Gummy Stem Blight, Powdery Mildew, Target Spot, Botrytis Blight | Vegetable transplants such as beans and cucurbits |
Xylem mobile fungicide. Resistant populations of Botrytis are common in the greenhouse. High risk of resistance. |
|
Trichoderma harzianum |
Pythium, Rhizoctonia Fusarium, Cylindrocladium and Thielaviopsis |
Fruiting vegetables, leafy vegetables and cole crops |
Preventative biological fungicide. It will not cure diseased plants. Avoid applications of fungicides at least one week before or after application. (Foliar applications only for non-food crops) |
|
This information is supplied with the understanding that no discrimination is intended and no endorsement implied. Due to constantly changing regulations, we assume no liability for suggestions. If any information in these tables are inconsistent with the label, follow the label. Always follow label instructions regarding registered uses and note cautions. to avoid any phytoxocity problems, spot test first before widespread use. * Fungicides are grouped by their mode of action (MoA) and each MoA group is assigned a Fungicide Resistance Action Committee (FRAC) code. Most systemic fungicides (that are absorbed into plant tissues) are specific in their mode of action. Protectant fungicides are less likely to develop resistance problems as they have multi-site modes of action (M). To prevent the development of resistance, alternative applications among different FRAC codes and incorporate biological fungicides into your disease management plan. See www.frac.info/frac/indes.htm NC = Not classified Updated 1/11 L. Pundt, Universityof ConnecticutCooperative Extension and T. Smith, Universityof MassachusettsExtension Return to "Fungicides" paragraph, above Return to "Record Keeping and Decision Making" paragraph, below Return to Top |
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Specific Diseases
Botrytis blight (Photos)
Botrytis can cause leaf blight, cankers, damping off and root rot. Plants may be attacked at any stage, but the new tender growth, freshly injured tissues and dead tissues are most susceptible.
Symptoms: Botrytis blight produces characteristic gray fuzzy appearing spores on the surface of infected tissues. Air currents and splashing water can easily disseminate the spores. In general, germination of spores and infection is dependent on a film of moisture for 8 to 12 hours, relative humidity of 93% or greater and temperatures between 55o and 65oF. After infection, colonization of plant tissues can occur at temperatures up to 70oF.
Management: Management of environmental conditions such as temperature, humidity and duration of leaf wetness, sound cultural practices and fungicides will help prevent disease development.
- Control weeds and remove plant debris between crop cycles and during production. Dispose of diseased plants and debris in a plastic trash bag. Keep the bag closed while it is being carried through the greenhouse to help prevent spreading spores to uninfected plants.
- Reduce humidity and leaf wetness duration to prevent spore germination. See techniques for reducing relative humidity.
- Provide good air circulation and reduce humidity within the canopy. Proper planting dates, fertility, watering and height management will prevent overgrown plants, thereby reducing humidity within the canopy.
- Water in the morning, never late in the day. Rising temperatures during the day will cause water to evaporate from the foliage and dry the leaf surface.
- Avoid growing ornamental hanging baskets above vegetable bedding plants. Spent flowers dropping on plants below cause Botrytis infection.
Damping-off of Seedlings (Photos)
Damping-off is a common disease of germinating seeds and young seedlings. Several fungi are capable of causing damping-off including Rhizoctonia, Alternaria, Sclerotinia and the water molds, Phytophthora and Pythium. Soil-borne fungi generally do not produce air-borne spores but are easily transported from contaminated soil to pathogen-free soil by infected tools, hose ends, water-splash and hands. Young seedlings are most susceptible to damping-off. However, later in the crop cycle, the same pathogens may cause root and stem rot.
Symptoms: Symptoms of damping-off include seedlings failing to emerge or the wilting of seedlings, often with a stem lesion that appears water-soaked or dark, necrotic and sunken at the soil line. The fungus disease usually spreads radially from a central point of contamination. Therefore, plants often die in a circular pattern. Vegetable seeds that are germinated in poorly drained, cool soils are especially susceptible. Young plants that do emerge are weak and often wilt at or below the soil line. Cabbage, cauliflower, tomato and pepper seedlings may be girdled by brown or black sunken cankers. Stems of these plants may shrivel and become dark and woody (wirestem or collar rot). The plants may not collapse, but they may remain stunted or die after transplanting.
Management: Damping-off must be prevented because it is difficult to stop once symptoms occur. There are several strategies to prevent damping-off.
- Use only certified disease-free seed from reputable seed companies.
- Use fungicide-treated seed. Certain fungicides are labeled for damping-off for selected vegetable crops.
- Use pasteurized soil, compost-based or soilless mixes.
- Disinfect all flats, cold frames, pots and tools.
- Germinate seed under conditions that will ensure rapid emergence, such as the use of bottom heat.
- Avoid overwatering, excessive fertilizer, overcrowding, poor air circulation, careless handling, and planting too deeply.
- Provide adequate light for rapid growth.
- Promptly rogue out infected plants from flats.
Tospoviruses (Photos)
Tospoviruses are a group of viruses that include impatiens necrotic spot virus (INSV) and tomato spotted wilt virus (TSWV). They may infect hundreds of plant species including many vegetables such as tomatoes, peppers and eggplant. These viruses are primarily spread by the western flower thrips. It is not seedborne but is brought into the greenhouse on vegetatively propagated ornamental plants or seedlings that have been exposed to the virus. Once the thrips in the greenhouse become infected, they can transmit the virus to other crops and weeds.
Symptoms: Symptoms include stunting, foliar ringspots and black lesions on stems. Symptoms of INSV and TSWV vary depending upon the host.
Management: To manage tospoviruses, it is necessary to discard infected plant material, including weeds, and to manage thrips. Infected vegetable transplants planted into the garden or field will be stunted and not produce a harvestable crop. Since INSV and TSWV are not seed-borne, vegetable transplants may be kept free of INSV and TSWV if they are not brought into contact with other infested crops or thrips carrying the virus. Growers attempting to concentrate all their warm temperature crops in a single house run a risk of mixing INSV-free vegetable seed crops with leftover ornamental stock plants or new cuttings that may carry the virus. Pre-finished or vegetatively propagated ornamentals from another producer could be infested with thrips or infected with a virus. Therefore, vegetable bedding plants should always be grown in separate greenhouses.
Bacterial diseases
Bacterial diseases of vegetable bedding plants, such as bacterial leaf spot of peppers, bacterial speck and bacterial canker of tomatoes, and black rot on cole crops are introduced into a greenhouse through infected seed and transplants.
Bacterial leaf spot, Bacterial speck
Symptoms: Bacterial leaf spot is caused by Xanthomonas campestris pv. Vesicatoria and is found primarily on peppers although all above-ground parts of tomatoes and peppers are susceptible. Spots on leaves are irregular and water soaked or greasy in appearance. The dead tissue often dries and cracks. Severely spotted leaves will appear scorched and defoliation may occur. Foliar symptoms on pepper are similar to those on tomato. This disease is most prevalent during moderately high temperatures and long periods of leaf wetness.
Bacterial speck occurs on tomato but not pepper. The bacterium, Pseudomonas syringae pv. tomato, causes small black spots to develop resulting in chlorosis (yellowing), necrosis (dead tissue) and blighting of foliage.a fruit spot and blight of the foliage. Bacterial speck can usually be distinguished from bacterial spot by the size of the lesions; however, in some cases, the symptoms can look similar.
Bacterial canker
Bacterial canker of tomato is caused by Clavibacter michiganensis (formerly Corynebacterium michiganense). In New England, bacterial canker occurs less frequently than other tomato diseases but it is potentially more destructive. Peppers are another host of this highly contagious disease. The bacterium is seed-borne but may survive on plant debris in soil for at least one year. It can also survive in the greenhouse on wooden stakes and flats. Wilt, scorch of the foliage, canker, pith necrosis and fruit spot may occur singly or in combination depending on the circumstances. When the bacterium is carried in the seed, the vascular system becomes colonized, resulting in wilt, pith necrosis and external cankers.
Wilt initially occurs on one side of a leaf or one half of a plant because only a portion of the vascular system is blocked. Cankers and pith necrosis are a later stage of disease development. Cankers are dark and water-soaked in appearance and often exude bacteria which are easily spread to adjacent plants. Pith necrosis is first evident as a darkening of the center of the stem which soon becomes chambered or hollow. When leaf scorch occurs, the petioles usually bend downward while the leaf edges curl up. The margins of the leaves become brown with a yellow border to the inside. Scorching of the foliage often develops in the absence of wilt or stem canker.Transplants may not express symptoms until six to eight weeks after infection and initial symptoms expression is accelerated by environmental stress.
Black rot
Black rot, caused by the bacterium Xanthomonas campestris pv. campestris occurs throughout the world where cruciferous plants are grown. Cabbage, cauliflower and Chinese cabbage are often severely affected. The bacterium enters the leaves by colonizing the hydathodes (water pores) and moves from the leaf margins inward. Lesions may also begin at wounds. Diseased tissue is often V-shaped, flaccid, tan to yellow and with blackened veins. The blackened veins are diagnostic and are best seen by holding the leaf up to the sun. When the lesions reach the petiole and stem, the bacterium moves systemically through the plant, resulting in premature leaf drop. At this stage of disease, a cross-section of the stem will reveal a ring
Management: These bacteria can be introduced on infected seeds, infected transplants purchased from another operation, or in the field on crop residues. These bacteria can also survive on weeds in the same family as the host crop. The management of these bacterial diseases is similar and includes the following strategies:
- Buy certified seed from a reputable source.
- Use hot water-treated seed. Ideally, the seed should be custom-treated by the seed company. Seed companies may treat the seed upon request. There is a risk that germination percentages will be reduced if the seed crop is grown under stressful environmental conditions.
- Promptly remove infected plants and adjacent plants to prevent further infection and avoid unnecessary handling of plant material.
- Avoid overhead irrigation, splashing or periods of extended leaf wetness.
- Disinfect all benches, equipment, flats and stakes.
- Follow sound practices for weed and insect control.
Prevent bacterial leaf spot on peppers by choosing resistant varieties whenever possible. There are many resistant varieties of bell peppers available, but there are few choices for resistant specialty peppers.
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General Pest Management
Monitoring
A regular monitoring program is the basis of all pest management programs. Conduct a regular, weekly scouting program to detect problems early. This early detection and treatment will result in better pest control since plant canopies are smaller and better spray coverage can be achieved.
Yellow Sticky Cards
Use yellow sticky cards to trap and detect adult stages of fungus gnats, thrips and whiteflies. Place one to four cards per 1,000 square feet. The cards should be spaced equally throughout the greenhouse in a grid pattern with additional cards located near doorways and vents. Place some cards just above the plant canopy (to detect thrips and whiteflies) and some of the cards on the rim of the flats or pots to detect fungus gnats. Inspect and replace the cards weekly to keep track of population trends.
Plant Inspection
Plant inspection is needed to detect diseases, assess general plant health and to detect mites and aphids plus any hot spots of immature whiteflies. Randomly select plants at ten locations in an area of 1,000 square feet, examining plants on each side of the aisle. Start this pattern at a slightly different location each week, walking through the greenhouse in a zigzag pattern down the walkway. Examine the underside of leaves for insect pests and inspect root systems to determine whether they are healthy.
Key Plants and Indicator Plants
Focus on scouting key plants and indicator plants. Key plants are those plants or cultivars that have serious, persistent problems every year. For example, peppers and eggplants are prone to aphid infestations. Look for aphids on the young leaves and for shiny honeydew on the upper leaf surface. If grown near flowering plants, peppers and eggplant will also indicate an early thrips population. Look for distorted, young leaves with silvery flecked scars that are signs of thrips feeding damage.
Fava beans and certain cultivars of petunia are used as indicator plants to detect the presence of thrips carrying (INSV) and (TSWV). These plants will develop viral symptoms within one week if fed on by the infected thrips. The petunia cultivars 'Summer Madness', and 'Super Magic Coral' and several varieties of fava bean have been successfully used to detect INSV/TSWV. To use petunias and fava beans as indicator plants:
- Remove flowers from indicator plants to encourage feeding on foliage where symptoms can be observed.
- Place a blue non-sticky card in each pot at plant height. The blue card will attract thrips to the indicator plant. Blue plastic picnic plates work well.
- Place petunia plants throughout the greenhouse among the crop at a rate of one plant every 20-30 feet and fava bean plants at 12 pots per 1,000 sq. ft.
- Remove symptomatic leaves on petunia plants and continue to use the plants. The virus is not systemic in these plants. Thrips feeding injury leaves distinct white feeding scars on the foliage. Virus symptoms appear as a brown rim around the feeding scars.
- Remove entire plants of fava beans if symptoms are observed, because the virus is systemic in these plants. Viral symptoms appear as dark brown angular lesions on leaves or yellow to light green ring spots. Dark necrotic areas can also be seen on the stem. Fava beans have dark black spots on their stipules that should not be confused with viral symptoms. Replace with new plants, planting 1-2 bean seeds per 4"pot.
Record Keeping and Decision Making
Each time the crop is scouted, record the pest numbers, their location and the number of plants inspected. Records on pest numbers and locations will help you identify population trends. Population trends will also indicate if initial control measures were successful or if they need to be repeated. Once this information is collected each week, a pest management decision can then be made. Monitoring and record keeping will answer the following questions and help you make the necessary treatment decisions. Is the population decreasing, increasing or remaining stable over the growing season? Do you need to spray? Are insects migrating from weeds under the benches to your crops? Is the treatment from last week working? Table 1 and Table 2 provide a list of selected materials labeled for managing insects, mites and diseases on greenhouse-grown vegetable transplants. Follow label instructions before using the material on vegetable bedding plants. The product must be used only for crops for which the compound is registered.
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| Insecticide | Target Pests | Labeled Crops | Comments |
|---|---|---|---|
| Acetamiprid (Tristar 30 SG) 12 hr. REI Group 4A |
aphids, psyllids, mealybugs, leafhoppers, caterpillars, hard and soft scales, plant bugs, whiteflies, fungus gnat larvae, thrips, leaf eating beetles, leafminers | Vegetable transplants (See supplemental label) | Contact insecticide with translaminar activity. The addition of a surfactant may improve efficacy for certain pests (see supplemental label). |
|
Azadirachtin |
Aphids, beetles, weevils thrips, true bugs, caterpillars, leafhoppers, leafminers, whiteflies, fungus gnat larvae |
Many vegetables including bulb, cole, cucurbit, leafy and fruiting types (eggplant, tomato, peppers) (see specific labels. |
Insect growth regulator for immature stages of insects. Repeat applications needed. Repels insects and can be used as an antifeedant. |
| Azadirachtin (Azatrol) 4 hr. REI Organic product |
Beetles, weevils, thrips, thru bugs, leafhoppers, cutworms, loopers, fungus gnat larvae | ||
| Azadirachtin (AzaGuard) 4 hr. REI Organic product |
Leafminers, soft scales, mealybugs, thrips, aphids, fungus gnat larvae, whiteflies, caterpillars, beetles, weevils | ||
| Azadirachtin (Azahar) 4 hr. REI Organic product |
Beetles, weevils, thrips, true bugs, leafhoppers, whiteflies, aphids, leafrollers, cutworms, loopers, fungus gnat larvae | ||
| Azadirachtin (Azatin XL) 4 hr. REI |
Aphids, caterpillars, loopers, fungus gnat larvae, leafhoppers, leafminers, thrips, whiteflies | ||
| Azadirachtin (Molt X) 4 hr. REI |
Whiteflies, leafminers, soft scales, mealybugs, thrips, aphids, fungus gnat larvae, caterpillars, beetles, weevils | ||
| Azadirachtin (Ornazin 3% EC) 124 hr. REI |
Aphids caterpillars & loopers, cutworms, leafminers, leafhoppers, thrips, whiteflies, fungus gnat larvae, beetles, weevils | ||
| Azadirachtin (Neemix 4.5 EC) 12 hr. REI Organic product |
Aphids, beetles, caterpillars, fungus gnat larvae, leafhoppers, leafminers, thrips, whiteflies | ||
| Bacillus thuringiensis subsp. aizawai (Xen Tari) 4 hr. REI Group 11B Organic product |
Certain caterpillars (see label) | Brassica and fruiting vegetables in the greenhouse (see label) | Stomach poison that must be ingested to be active. Most effective against small, newly hatched larvae. Insects stop feeding and dies 1 to 5 days later. |
|
Bacillus thuringiensis subsp. kurstaki (DiPel Pro DF) |
Certain caterpillars (see label) |
Many vegetables including leafy, cole and fruiting types (see label) |
Stomach poison that must be ingested to be active. Most effective against small, newly hatched larvae. Insects stop feeding and dies 1 to 5 days later. |
|
Bacillus thuringiensis subsp. israelensis (Gnatrol WDG) |
Fungus gnat larvae |
Vegetable plants such as leafy and cole crops, cucumbers, peppers, tomatoes and eggplants |
Stomach poison that must be ingested to be active. Most effective against first instar larve. Apply as soil drench to control fungus gnat larvae. Larvae must ingest material to be killed. May be applied through drip or sprinker irrigation system. Do not combine with fungicides or fertilizers containing copper or chlorine. |
|
Beauveria bassiana |
Aphids, thrips, whiteflies, psyllids, mealybugs, leafhoppers, plant bugs (See labels for more information) |
Many vegetables including cole crops, greens, eggplant, peppers and squash. Do not use ES formulation on tomatoes. |
Contact insecticide. Active ingredient is an insect killing fungus. To be effective needs relative humidity greater than 70% and75F for 8 to 10 hours. Treat when insect populations are low. Repeated applications may be needed. |
| Bifenazate (Floramite SC) 12 hr. REI Group 25 |
Spider mtes | Greenhouse tomatoes. Varieites greater than one inch in diameter when mature. | Contact miticide. Active against all stages of the two-spotted spider mites. Not effective against rust mites or broad mites. Relatively inactive against beneficial predatory mites. |
| Buprofezin (Talus 40 SC Insect Growth Regulator) 12 hr. REI Group 16 |
Whteflies, mealybugs, leafhoppers | Greenhouse tomatoes | Insect growth regulator active against nymph stages. Thorough coverage of all plant parts is imprtant. Chitin synthesis inhibitor, suppresses oviposition of adults and reduces viability of eggs. Treated pests may remain alive for 3 to 7 days, but feeding damage is low. |
| Chlorfenapyr (Pylon) 12 hr. REI Group 13 |
Caterpillars (including hornworms), spider mites, broad mites, western flower thrips | Tomato, tomatillo, ground cherry, peppers, eggplants, pepinos. Do not use on tomato varieties with a diameter of less than one inch when mature. | Insecticide/miticide with contact and translaminar activity. Active on larvae and nymphs of spider mites and thrips. See label for resistant management guidelines. |
| Dinotefuran (Safari 20 SG) 12 hr. REI Group 4A |
Aphids, leafminers, mealybugs, thrips (suppression), whteflies (including sweet potato whiteflies - B and Q biotypes) | Many vegetable transplants grown in enclosed structures (see label) Do not apply to greenhouse grown vegetables. | Systemic insecticide. Do not make more than one application per crop. |
|
Etoxazole |
Spider mites |
Indoor grown tomatoes (see supplemental label) |
Miticide with contact and translaminar activity. Available in 2 oz. water soluble packets. Active on mite eggs and nymphs. Does not kill adults. |
|
Horticultural oil |
Aphids, leafminers, spider mites, thrips, whiteflies, leafhoppers |
Many vegetables (see labels for specific crops. |
Works by contact. Thorough coverage of all plant parts is important. Foliar injury may occur if applied during humid conditions. See labels for information on plant safety. All applications should be preceded by a phytotoxicity check to ensure that the material is safe for that particular plant variety. |
| Petroleum Oil (Saf-T-Side) 4 hr. REI NC Organic product |
Aphids, leafhoppers, leafminers, thrips, mites, whiteflies | Vegetable crops (see label) | |
| Petroleum Oil- White Minteral Oil (JMS Stylet Oil) 4 hr. REI (Organic JMS Stylet Oil) Organic product |
Leafhoppers, leafminers, mites, whiteflies | Vegetable crops (see label) | Works by contact. See label for information on plant safety. |
|
Imidacloprid |
Aphids, leafhoppers, leafminers, thrips (suppression), mealybugs, whiteflies, fungus gnat larvae |
Vegetable bedding plants intended for resale only |
Systemic insecticide. Many other generic products are available including (but not limited to) Imida E Pro 60 WSP, QualiPro Imidachloprid 2F |
| Imidacloprid (Marathon 60 WP) 12 hr. REI Group 4A |
Aphids, fungus gnat larvae, leafhoppers, leafminers, mealybugs, thrips (suppression), whiteflies | Vegetable bedding plants intended for resale only. | |
|
Insecticidal soap |
Aphids, mites, thrips, whiteflies, broad mites, leafminers, leafhoppers |
Many vegetables including bulb, cole, leafy, fruiting and cucurbit types |
Works by contact. Short residual activity. Thorough coverage is needed. Refer to label for information on plant safety. Can be tank mixed with other products to increase efficacy. |
| Iron phosphate (Sluggo Snail and Slug Bait) 0 hr. REI NC Organic product |
Slugs and snails | Many vegetables (see label) | Ingestion causes the slugs and snails to cease feeding, become less mobile and begin to die in 3 to 6 days. Best applied in the evening. Non-toxic to cats and dogs. |
|
Neem Oil |
Mites and insects (whiteflies, aphids, leafhoppers) |
Many vegetable transplants (see labels)
|
Works by contact. Thorough coverage of all plant parts is important. Refer to label for information on plant safety and precautions for use in the greenhouse.
|
|
Neem Oil |
Aphids, mites, mealybugs, whiteflies and thrips (suppression) |
||
|
Parasitic nematodes |
Fungus gnat larvae |
Greenhouse vegetables |
Available in packages. Remove screens and filters from fertilizer injector or sprayer. Nematodes are very sensitive to ultra violet light and desiccation. For soil dwelling pests such as fungus gnat larvae, drench on soil surface and then water in. Apply to moist growing media at temperatures between 50-85F. For western flower thrips (Nemasys), foliar application. Do not apply in direct sunlight. Lightly mist plants before application. Efficacy will be variable depending upong relative humidity, temperature, concentration, frequency of application and insect growth stage. |
|
Pyrethrins |
Aphid, caterpillars, adult fungus gnats, thrips, leafhoppers, whiteflies and others |
Many vegetables including bulb, leafy, cole, legume, fruiting and cucurbit types |
Contact insecticide. Provides rapid knockdown of pests. |
| Pyrethrins plus PBO (Pyrethrum TR aerosol) 12 hr. REI Group 3A |
Aphids, cabbage worms, adult fungus gnats, mealybugs, thrips, whiteflies and others | Many vegetables including bulb, leafy, cole, legume, fruiting and cucurbit types | Contact insecticide. See label for specific directions for placement and use for successful application. |
| Pyrethrins plus PBO (Pyreth-It Formula 2) 12 hr. REI Group 3A |
Aphids caterpillars, fungus gnat adults, leafhoppers, beetles, thrips, whiteflies and others | Many different vegetable crops (see label) | Contact insecticide. May be combined with other insecticides. |
| Pyrethrins plus PBO (Pyronyl Crop Spray) 12 hr. REI Group 3 and 27A |
Aphids, caterpillars, fungus gnats, leafhoppers, leafminers, mealybugs, plant bugs, thrips, whiteflies and others | Many different vegetables (see label) | Contact insecticide. |
| Pyriproxyfen (Distance Insect Growth Regulator) 12 hr. REI Group 7C |
Foliar spray for whiteflies (greenhouse & sweetpotato) and aphids (suppression) Apply as a sprench (growing media surface spray or drench) for fungus gnat and shore fly larvae |
See supplemental label for use on indoor-grown fruiting vegetables. Do not apply to tomato varieties less than one inch in diameter or to non-bell peppers. | insect growth regulator. See label for specific use instructions on rates and plant safety for use as a drench or sprench(soil surface spray) against fungus gnats or shore flies. Do not make more than 2 applications per season. |
| Soybean Oil (Golden Pest Spray Oil) 4 hr. REI NC Organic product |
Aphids, mites, leafminers, certain caterpillars, whiteflies, thrips and others | Vegetables such as cabbage, cauliflower, cucurbits, lettuce, melon, peppers, squash and tomatoes | Works by contact. See label for information on plant safety. |
| Spirotetramat (Kontos) 24 hr. REI Group 23 |
Aphids, leafhoppers, mealybugs, spider mites (suppression), whiteflies | Vegetable transplants (see label for specific types) | Systemic insecticide |
| Sucrose Octanoate Esters (SucraShield) 48 hr. REI NC Organic product |
Aphids, caterpillars, leafhoppers, mites, thrips, whiteflies | Many vegetables see label for specific types) | Contact insecticide with limited residual actiavity. Thorough coverage of all plant parts is needed. Sucrose octanoate esters are produced in the hairs of tobacco leaves. |
|
Thiamethoxam |
Fruiting vegetables: Aphids, flea beetles, leafhoppers, whteflies, stink bugs |
Foliar application to vegetable plants grown for resale to consumers |
Systemic insecticide. |
|
This information is supplied with the understanding that no discrimination is intended and no endorsement implied. Due to constantly changing regulations, we assume no liability for suggestions. If any information in these tables are inconsistent with the label, follow the label. Always follow the label instructions regarding registered uses and note cautions. To avoid any phytoxicity problems, spot test first before widespread use. Reistance Groups (number and letter) indicate products with a common mode of action based on the Insecticide Resisance Action Committee (IRAC) guidelines at http://www.irac-online.org/ . For multiple applications to one crop, select products from different resistant groups. NC=Not Classified Updated 1/11 |
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Biological Control for Insects and Mites
Biological control may be an option for aphids, mites, fungus gnats, thrips and whiteflies. Natural enemies are living organisms that need to be released when pest populations are low. They do not act as quickly as pesticides so cannot be used as a "rescue" treatment. Natural enemies (parasites, predators or pathogens) are best used early in the cropping cycle when plants are small, pest numbers are low and damage is not yet observed. A detailed plan of action is needed to insure success. Accurately identify the key pests in your production system. Natural enemies, especially parasites, are often very specific to a particular pest. Many insecticide residues can adversely affect natural enemies for up to 3 months after their application. Koppert Biological Systems has compiled a list of insecticides and their effects on natural enemies. This list is available from Koppert Biological Systems, Inc., 2856 South Main St., Ann Arbor, Michigan 48103 or through their website www.koppert.com. Become familiar with using insecticides that are compatible with natural enemies such as insecticidal soap, horticultural oil and neem-based materials, and have a sprayer dedicated for their use.
Start in a small trial area to become familiar with releasing, monitoring and evaluating the effectiveness of natural enemies. A separate greenhouse is best. With help from your supplier and university specialist, establish a schedule for introducing the natural enemies. Release rates and timing will vary depending upon the crop and its size, the degree of infestation, effectiveness and type of natural enemies, plus the time of year. Starting a biological control program will involve some trial and error, as release rates have not been scientifically evaluated for vegetable bedding plants. Vegetable bedding plants with only one or two key insect pests or with a longer production schedule may be logical candidates for biological control. Be sure that natural enemies are received from your supplier quickly (2-4 days), and that they are kept cool during shipment. Inspect natural enemies for viability and quality when they are received. Table 3 provides information on scouting for key pests and biological control options.
| Pest | How to Monitor | Where to Look | Biological Control Options |
|---|---|---|---|
|
Aphids |
Monitor weekly. Rely on plant inspection, not sticky cards. Look for small, 1/16 inch long aphids with two cornicles or "tailpipes" at the rear of their body. Identification to species is needed to determine which host specific aphid parasite to release when using biological controls. If uncertain, mixes of different species are available. |
Underside of leaves and along stems on tips of new growth on eggplant, pepper, tomatoes and many different leafy vegetables. Signs of aphid activity: shed white skins, shiny honeydew, presence of ants, curled new leaves, distorted growth. |
Aphidoletes aphidimyza |
|
Bacterial Leaf Spot |
Spots may be dark brown and water-soaked in appearance. Severe spotting can cause defoliation. Some strains cause leaf spot on tomatoes. |
Seed-borne disease. More prevalent during moderately high temperatures and long periods of high humidity and leaf wetness. |
Bacillus subtilus (Cease) (biofungicide) |
| Botrytis blight | Look for leaf blight and tan stem cankers. Botrytis blight produces characteristic gray fuzzy appearing spores on the surface of infected tissues during humid conditions. | In areas where plants are spaced close together and where condensation may occur. |
Bacillus subtilus (biofungicide) |
| Broad Mites | Look for symptoms of damage - leaf edges curling downward, twisted and distorted growth. Under a microscope, look on underside of leaves for mites and their eggs. | Near ornamental crops affected with broad mites. | Neoseiulus californicus (predatory mites) Neoseiulus cucumeris (predatory mites) |
| Cyclamen Mites | Look for symptoms of damage - inward curling of leaves, puckering and crinkling. Under a microscope, look within buds for mites and their eggs. | Near ornamental crops affected with cyclamen mites. | Neoseiulus californicus (predatory mites) Neoseiulus cucumeris (predatory mites) |
| Damping Off (Pythium root and stem rot) | Monitor seed flats of susceptibel plants. Inspect weekly. Visually examine roots for cortex that sloughs off leaving central core. | Inspect plants weekly for signs of disease: Wilted, stunted off-color plants with discolored root systems. Focus on areas where plants stay wet, or where there may be high populations of shore flies that may carry disease spores. High soluble salts/fertility increases susceptibility. | Bacillus subtilis (biofungicide) Trichoderma harzianum (biofungicide) Streptomyces griseoviridis (biofungicide) Stretomyces lydicus (biofungicide) |
| Damping Off (Rhizoctonia Root and Crown rot) | Monitor seed flats of susceptible plants including cole crops, peppers and tomatoes. Look for small, water-soaked spots on stems or leaves before seedling collapse. | Seed flats near walkways or near dust and debris. Overcrownded seedling flats are more susceptible to damping off. | Bacillus subtilis (biofungicide) Trichoderma harzianum (biofungicide) Streptomyces griseoviridis (biofungicide) Stretomyces lydicus (biofungicide) |
|
Fungus gnats |
Use sticky cards to monitor for adults. Place cards horizontally above soil surface. Potato chunks can be used to monitor for larvae. Check every two days. |
Favorable habitats include areas with standing pools of water, mud floors, spilled media and weeds. |
Bacillus thuringiensis israelensis (pathogen) |
| Powdery mildew | Scout weekly. Look for faint, white fungal threads and spores on leaves. | Scout near vents, or any location with a sharp change between day and night temperatures. | Bacillus subtilis (biofungicide) Streptomyces griseoviridis (biofungicide) Stretomyces lydicus (biofungicide) |
| Spider Mites (Two-spotted spider mites) |
Rely on plant inspection. Look for light flecking, speckling or discolored foliage and webbing if high populations have developed. | Look in hot dry locations in greenhouse (i.e. near furnace) or near entrance ways. | Feltiella acarisuga (predatory midge) Neoseiulus californicus (predatory mite) Phytoseilus persimilis (predatory mite) |
| Thrips (Western flower thrips) |
Rely on sticky cards (placed just above crop canopy) and foliage inspection of key plants for early detection and to evaluate treatments. Use petunia and fava bean plants to indicate early thrips feeding. | Inspect plants by tapping new growth over a white sheet of paper. Watch for curled, emerging leaves, distorted new growth on pepper. Look for white scarring and black fecal spots (size of pin point) on foliage of cucumber and eggplant. | Amblyseius swirskii (predatory mite) Chrysoperla spp. (green lacewing, predaor) Hypoaspis miles (predaory mite) Neoseiulus cucumeris (predatory mite) Orius insidiosus (pirate bug, predator) |
|
Tospovirus |
Symptoms will vary depending upon the host. On pepper, look for necrotic spots on the leaf. Ringspots (thumbprint-like marks) may also develop. Young plants may wilt with black lesions on the stem. On tomato, young leaves may develop small, dark brown spots. Use petunias and fava bean plants for early detection. |
Thrips populations may be highest at front and rear of the greenhouse. Use fava bean or petunia indicator plants to determine if thrips are carrying the virus. Symptomless weeds may also be a source of virus. |
None |
|
Whiteflies |
Rely on plant inspection to detect immature stages. Use sticky cards to monitor adults. |
Egg laying adults are found on the uppermost tender leaves of tomatoes, eggplant and assorted greens. Immature stages are stationary and are found on the undersides of leaves. |
Chrysoperla carnea (green lacewing, predator) |
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Specific Insect Pests and Mites
Common insect pests on vegetable bedding plants include aphids, whiteflies, fungus gnats, shore flies, thrips and two-spotted spider mites. The following are brief descriptions, life cycles and monitoring tips for the major pests. See Table 1 and Table 3 for additional scouting guidelines, registered pesticides and biological control options.
Aphids
Lifecycle: Several species of aphids can occur on vegetable transplants, but the most common are green peach and melon. Aphids are small, 1/16-inch in length, round, soft-bodied insects that vary in color from light green to pink or black. The green peach aphid is yellowish-green in summer; pink or yellowish in fall and spring. Winged forms are brown with a large dusky blotch on the abdomen. Melon aphids are greenish-yellow to very dark green with black mottling and short dark cornicles. Aphids feed by inserting their piercing sucking mouth parts into plant tissue and removing fluids.
In greenhouses, aphids are usually females which produce live young called nymphs. Each female can produce 50 or more nymphs. Nymphs mature to adulthood and begin reproducing in as little as 7 to 10 days. Adults are usually wingless, but some will produce wings when populations reach outbreak levels. Large numbers of aphids will stunt and deform plants. In addition, aphids produce a sticky digestive by-product called honeydew. Honeydew can cover leaves and flowers and provide a food source for a superficial black fungus known as sooty mold. Aphids are present on weeds and may enter the greenhouse through vents.
Monitoring: Detect an early aphid infestation by examining the foliage, along stems and new growth of key plants such as peppers and eggplants. Signs of aphid activity include shed white skins, shiny honeydew, presence of ants, curled new leaves and distorted growth. Yellow sticky cards can help detect entrance of winged aphids into the greenhouse from outdoors. Yellow cards will not, however, allow you to monitor aphids within the crop, as most of the aphids will be wingless.
Whiteflies (Photos)
Lifecycle: The silverleaf whitefly (Bemisia argentifolii) and greenhouse whitefly (Trialeurodes vaporariorum) may infest vegetable bedding plants. However, greenhouse whitefly is the most common species. Both adult and immature whiteflies have piercing sucking mouth parts, are able to remove fluids and produce honeydew that also results in sooty mold fungus. Winged adult whiteflies are 1/16-inch in length, and found on the undersides of the youngest, most tender leaves. Females may lay from 150 to 300 eggs, which hatch into first-instar nymphs in about a week. The crawlers move for a short distance before settling down to feed. After three molts, a pupal stage is formed from which adults emerge in about six days. Whiteflies complete their egg to adult cycle in 21 to 36 days depending on greenhouse temperatures.
Monitoring: To monitor whiteflies, check plants at ten locations in an area of 1000 square feet, examining plants on each side of the aisle. Look on the undersides of one or two leaves per plant, for nymphs, pupae, or adults. Yellow sticky traps can also be used to detect adult whiteflies once populations have reached higher densities. Begin treatments as soon as the first sign of infestation is noted.
Fungus Gnats and Shore Flies (Photo)
Lifecycles: The damp, moist environment in greenhouses favors both fungus gnats and shoreflies. Fungus gnat larvae are translucent, white and legless, about 1/4 inch long when mature, and have a shiny black head. The mosquito-like adult is about 1/8 inch long, with long legs, a pair of clear wings and long antennae. There is a distinct "Y" vein on each wing. Fungus gnats are weak fliers and are frequently observed resting on pot media or running over the foliage or other surfaces. The larvae feed on fungi and decaying organic matter, and often injure seedlings and plants. Larva feeding occurs on young, tender roots and in the stem at the base of the plant. This feeding injury provides an entry for disease pathogens. A female fungus gnat may lay up to 300 whitish eggs in clusters of 20 or more. The eggs are deposited on the surface or in the crevices of moist soil or potting media. Eggs hatch in about six days. Larvae feed for 12 to 14 days before changing into pupae. The pupal stage may last five to six days. Adults live up to ten days. The life cycle from egg to adult requires approximately four weeks depending on greenhouse temperatures.
Shore flies also occur in greenhouses and are often confused with fungus gnats. The adult shore fly is about 1/8 inch long and has a robust body, very short antennae, shorter legs and dark wings with about five light spots. Larvae are off-white and do not have distinct head capsules. Shore flies do not injure plants through direct feeding, but can carry root rot pathogens from diseased to healthy plants.
Monitoring: To monitor for fungus gnat larvae, place raw potato chunks (with peel removed) on the soil surface. Larvae are attracted to the potato chunks, under which they move and congregate. Check the potato chunks daily for larvae. Potato disks, cut one inch in diameter and half to one inch thick, work well. In addition, choose plants on each bench and inspect the soil surface and around the base of the plant including the stem just below the soil line. Record the location and the level of infestation. Badly infested containers of plants should be removed as they serve as a source of infestation.
Adult flies can be monitored with yellow sticky cards placed at the base of the plant at soil line. Weekly inspections of yellow sticky cards can detect the onset of an infestation, and continued recording of the number of adults per card per week can aid in evaluating the efficacy of control efforts.
Thrips
Lifecycle: The most injurious species is the western flower thrips (WFT). They often do considerable damage before they are discovered, because thrips are small, multiply rapidly and feed in plant buds in which they can remain undetected. WFT also vector tospoviruses. Feeding marks from the rasping mouthparts of thrips appear as white streaks on the leaves. Infested new growth may curl under, and leaves are often deformed. Adult WFT are about 1/16 inch long, with narrow bodies and fringed wings. Females are reddish brown and males are light tan to yellow. Immature stages are light yellow. Female thrips insert eggs (several hundred per female) into plant tissue and on flower surfaces. The tiny yellowish larvae molt twice and feed on plant fluids as they mature. Larvae drop off the plant into the soil and pass through two stages, after which adults emerge. The egg to adult cycle can be completed in 7 to 13 days depending on greenhouse temperature. During warmer temperatures development is more rapid than at cooler temperatures.
Monitoring: Early detection of a thrips infestation is critical for effective management for populations are lower and it is easier to obtain good coverage when plant canopies are small. Symptoms of their feeding are often not noticed until the damage has occurred. Yellow sticky cards, key plants and indicator plants provide an easy way to detect the onset of an infestation. Yellow sticky cards should be placed just above the crop canopy, and near doors, vents and over thrips-sensitive cultivars to monitor the movement of thrips. Recent research has shown the light-to medium-blue sticky cards catch more thrips than yellow ones. However, it is more practical to use yellow cards for general pest monitoring to attract fungus gnats, whiteflies and winged aphids. The number of thrips per card should be recorded and graphed weekly to monitor population levels and movement in or out of the greenhouse, and thus aid in control decisions. See section on key plants and indicator plants for more monitoring information.
Spider Mites
Lifecycle: Two-spotted spider mites can be found on vegetable bedding plants. Adult females are approximately 1/50-inch long, and slightly orange in color. All mobile stages are able to pierce plant tissue with their mouth-parts and remove plant fluids. Most spider mites are found on the underside of leaves. Feeding injury often gives the top leaf surfaces a mottled or speckled, dull appearance. Leaves then turn yellow and drop. Large populations produce visible webbing that can completely cover the leaves. Eggs are laid singly, up to 100 per female, during her 3- to 4-week life span. Eggs hatch into larvae in as few as 3 days. Following a brief larval stage, several nymphal stages occur before adults appear. Egg to adult cycle can be completed in 7-14 days depending on temperature. Hot and dry conditions favor spider mite development.
Monitoring: Checking for mites must be done by examining foliage for adult mites are not found on sticky cards. Mites often develop as localized infestations on particular groups of plants such as beans or tomatoes. Sample plants by turning over leaves and with a hands-free magnifier (Optivisor) or hand lens, check for the presence of spider mites.
References:
- Bartok J. and Koths J. 1986. Horizontal Air Flow. University of Connecticut, Cooperative Extension System Bulletin 85-14.
- Boucher T.J. 1996. Pepper IPM: Aphids. Grower - New England Vegetable and Small Fruit Newsletter. 96(5): 6-7.
- Boucher T.J. 1999. Resistant/Tolerant Vegetable Varieteis Are Worth A Try. Yankee Grower. 1(1):8.
- Casey, C. (ed) 2000. Integrated Pest Management for Bedding Plants. New York State IPM Program, Cornell Cooperative Extension Pub No. 407.
- Cox D. 1999. Can "Phosphorus Starvation" Control the Growth of Bedding Plants? Floral Notes, UMass Extension, Plant and Soil Sciences. 11(6):9-11.
- Daughtrey M. 1991. Spring disease control: your guarantee for profits. Grower Talks. 54(a):33-40.
- Elmer W. Biofungicides: How do they work? What's commercially available? Fact Sheet. Yankee Grower 1(4):4-5.
- Garson M. L. et al. 1999.Tips on Growing Bedding Plants, 4th Edition. Ohio Florists' Association Services Inc., Columbus, Ohio.
- Horst K.R. 1998. Knock out root and crown rot with fumigants or biologicals. Grower Talks. 62(10): 88-90.
- Lopes, P. and L Stack (ed.) 1999. New England Greenhouse Floriculture Recommendations: A Management Guide for Insects, Diseases, Weeds and Growth Regulators. New England Floriculture Inc., Pocassett, MA.
- Precheur, R.J. (ed.) 2000. Ohio Vegetable Production Guide. Bulletin 672-00, Producing Transplants. Ohio State University.
- Vavrina, C. 1994. Vegetable Transplants. p.351-362. In: E.J. Holcomb. Bedding Plants IV. Ball Publishing, Batavia, IL.
- Wick, Robert L. 1991. Diseases of Vegetable Crops: Bacterial Black Rot of Crucifers. The Plant Disease Diagnostic Laboratory, Department of Plant Pathology, University of Massachusetts.
- Wick, Robert L. 1991. Bacterial Canker of Tomato. The Plant Disease Diagnostic Laboratory, Department of Plant Pathology, University of Massachusetts.
- Wick, Robert L. 1991. Bacterial Spot and Speck of Tomato and Pepper. The Plant Disease Diagnostic Laboratory, Department of Plant Pathology, University of Massachusetts.
Acknowledgements
Financial support for the original publication was provided by a grant from the New England Greenhouse Conference. We also thank T. Jude Boucher, University of Connecticut Cooperative Extension System, Sharon Douglas, The Connecticut Agricultural Experiment Station, Ruth Hazzard and Robert Wick, University of Massachusetts Extension for reviewing the content of this publication. We also thank Patsy Evans, University of Connecticut Publications, for assistance in editing.
Prepared in January 2001
updated January 2011 by:
Extension Educator
University of Connecticut
Cooperative Extension System
Greenhouse Crops and Floriculture Program
University of Massachusetts Extension
