Managing Wildlife Damage In Maturing Sweet Corn

Wildlife damage is an aggravation to the hard working farmer.  Many of the most effective control measures are illegal.  Some growers consider wildlife damage a cost of doing business and try to ignore the problem.

Before you begin a control program, try to budget out just how much crop loss you are sustaining.  For bird control, if a shellcracker costs the same as the profit from a dozen ears of sweet corn, is it worth it for the peace of mind of having tried something?   Should the grower try to recoup the loss by other means such as raising the price per dozen a bit?  Good wildlife damage data, in volume or dollars, should be forwarded to the Massachusetts Farm Bureau Federation.  Good data helps prepare a case for long term legislative solutions.  The Farm Bureau is located at 466 Chestnut St., Ashland, MA 01721-2299.  The Bureau's telephone number is  508-881-4766.

Blackbirds and raccoons can also cause major damage in sweet corn.   The following techniques are suggestions for reducing wildlife damage, and are fairly immediate in their action and nature.

Bird Control
Birds invade sweet corn fields about three days before picking. Time any control techniques from then until harvest is complete.  Good insect control will reduce the corn's attraction to birds.  Birds eat insects, which is good, but they also like succulent grains of sweet corn and apparently can't tell the difference.  The corn worm complex and sap beetles tend to open the tips and make it easier for birds to feed.

Successive harvests from successive plantings also complicate the problem because animals form habits.  A method that some growers say works is to rotary mow or disc the interior blocks of the previously harvested fields.  Birds like to feed on the ground because it is easier than clinging to an ear, but they prefer perching nearby for protection and rest.  If birds begin perching in the unharvested fields, they then drop down and feed on the newer crop. 

The only chemical method available to farmers now is the use of Avitroltm.  To purchase and use this material the grower must be certified to handle restricted use pesticides and also have a permit from the State Pesticide Board. Training from USDA Animal Damage Control is required to obtain a permit.  The training can be  offered on an individual basis. Call Laura Henze (413-253-2403)  for details.  Permits must be renewed annually, but previous training secessions will be credited. Avitroltm is manufactured by the Avitrol Corporation and can be obtained through some agriculture pesticide channels.  Suggested techniques are to apply it in weed free fields so the birds will find the bait.  Pre-bait with ordinary cracked corn and then apply the Avitrol purchased as a cracked corn bait. Only a small portion of the Avitrol bait is treated with active ingredient.  Birds ingesting Avitroltm give off distress signals before dying, frightening others away. 

Exploders are gas fired cannons placed in the field at random, elevated on 55 gallon drums with alternating discharge timings.  These can be quite affective.  Cannons are available from some agriculture supply sources.  The South Amherst USDA, APHIS, Animal Damage Control office have a few for loan.  The telephone number is 413-253-2403.  Do check with your farm neighbors and the local police to let them know what you are going to do.

Eye-spot balloons and reflective mylar ribbons are effective and fairly economical for small fields.  Many growers are now using these silent deterrents and the general feeling is that with variety and timing of use these methods are somewhat affective. Growers report that the following methods make balloons more effective: use at least 8 balloons per acre,  place them in the field several days before harvest, and leave the previous block standing, without balloons, to allow birds to feed in older corn.  Check with your local farm store for a supply.

Shellcrackers are 12 gauge shotgun special loads that fire a projectile that explodes many yards out into the air.  Use a single shot, inexpensive shotgun as the loads are very corrosive. Firing a few rounds early and late in the day will unsettle birds.  Firing a few live rounds is also "unsettling".  Shellcrackers are available from a few sources. We are told that with a charge card a quick turn around order can be obtained for Reed-Joseph International Company, 1-800-647-5554.  This method is quick interactive with wildlife and can be satisfying on a short term basis.

There are some longer term controls such as favorable damage control legislation, bird traps, interacting with US and Massachusetts Wildlife Control personnel.  Next winter would be an appropriate time to investigate the longer term control techniques.

Raccoon Control
Experiences show that not every raccoon surrounding an area will learn to feed on a particular sweet corn field.  Often removing a few animals that frequent the field will reduce the damage to a tolerable level.

Raccoons invade sweet corn fields about a day before the grower plans to harvest.  Pre-harvest trapping is recommended.  Animals committing or about to commit food crop depredation can be destroyed.  The farm owner or full time employee can kill by shooting crop damaging species that are protected by State laws.

Trapping:  Pre-harvest live trapping and then destroying the animals cannot be over emphasized and appears to be the most efficient method  of managing raccoon damage. Live traps are available from farm supply stores.  Bait the trap with sardines packed in oil (oil-packed dry slower, thus the aroma lasts longer).  Trapped animals can not be relocated legally  because of the possibility of spreading rabies.  Shoot the trapped animal with a .22 caliber short.  Wash the trap immediately to remove an animal tissue or scent.  If shooting is not possible, then drown in a drum or tank.  Bury the dead animals to recycle them.

Use of Dogs:  Local hunting clubs may have members who would like to train their dogs during the sweet corn season.  Hunting during the legal taking season is a longer term option in some cases.  Raccoons soon learn the range of chained dogs in the field.  Move the chain frequently.

Electric Fencing:  This method is adequate for smaller fields and in some other situations.  Two wires must be used with one about six inches above the ground and another twelve to fifteen.  The area must be weed free to not short out the shocking affect.  A twelve volt battery, six volt battery or AC electricity can power the fence. 

The Massachusetts Wildlife Service has specially licensed some professional hunters of crop-destroying species.  Some growers have paid for these services and are satisfied with the results.  The Massachusetts Farm Bureau can put you into contact with such a local hunter or you  can call the Massachusetts Fish and Game Headquarters for information and advise.  The Mass. Fish & Game Headquarters is located in Westboro at 508-366-4479 or 792-7270.

1996 Vegetable Integrated Crop Management Fact Sheet Series. 
Prepared by R. Alden Miller and Ruth Hazzard