Blotchy ripening is most often found in greenhouses and damage to fruit may be significant. It can also be encountered in the field in fresh-market and processing tomato crops. The cause of this physiological disorder and its relationship to "gray wall" is not well understood. Blotchy ripening has been linked to potassium and/boron deficiency and to high nitrogen levels, which promote excessive growth. This syndrome has sometimes been attributed to infection by Tomato Mosaic Virus, but this does not seem to be the definitive cause. Weather plays a role in the development of blotchy ripening; the disorder is more prevalent when temperatures are very high. Affected fruit ripen unevenly, with hard, gray to yellow patches. The patches do not turn red, but remain gray or turn yellow. When fruit are cut, the vascular tissues may appear brown and rotted. Growers should provide balanced fertilization and, in greenhouses, avoid excessively high temperatures, if possible. Cultivars vary in susceptibility to this disorder.
MB Dicklow 11/2010