A. Diseases characterized by rotting of the fruit
(a) Uninjured ripe fruits showing slightly sunken water- soaked, circular spots becoming darker than the surrounding tissue. Older spots show concentric markings, centers sometimes tannish, with dark specks; in wet weather often colored pinkish by spore masses.................................................................Anthracnose
(b) Grayish-green or brown, water-soaked spots with smooth margins, often covering half of fruit surface; most common with fruit contacting the soil but not limited too. Spots commonly showing concentric bands of darker brown.
....................................................................Buck-eye rot
(c) Shrinking of tissue at the blossom end of fruit, causing a dark, flattened or sunken, leathery-appearing spot, sometimes including half the fruit. A physiological disorder not a disease.
............................................................Blossom end rot
B. Diseases characterized by cracking, spotting or malformation of fruits, but by no rot (secondary infections may be present).
Cracking is often the result of changes in watering and quick growth. Some varieties are more susceptible to cracking.
- cracking
- catfacing
- sunscalding
- zippering
- puffiness
- yellow shoulder
- rain check
Fruit can be malformed due to variety, less than optimal temperatures during early formation, insect damage, too much nitrogen and poor or uneven seed set. This condition may also be related or called catfacing
Fruits with whitish patches surrounded by yellow are due to sunscald. Green shouldered tomatoes are more susceptible. If a fruit starts out in the sun it should be okay, however if once shaded should fruit become exposed to direct sun, scalding will occur. Centers of sunscalds may split open.
Zippering is when small longitudinal scars form with smaller transverse scars giving the appearance of a zipper. In cooler weather, parts of the flower may adhere to the developing fruit and result in zippering. Some varieties are more susceptible to this than others.
Puffy fruit are often misshappen and are hollow on the inside. Puffiness can be related to nutritional problems (high nitrogen or low potassium), poor pollination, poor seed set, low or high temperatures during development or low light levels. Ensure adequete growing conditons and nutrition to prevent this problem.
Yellow shoulder is suspected to be caused by a possible combination of high temperature and direct light exposures. Green shouldered fruit seem to be more susceptible but susceptibility varies considerably between varieties.
Rain checked fruit often have small scars on the shoulders of affected fruits. It is not know what causes rain check. Rain check often appears on mature green developing fruit following periods of dry weather followed by rain. Glossy fruit as opposed to dull skin fruit tend to have less raincheck. Plants with good foliage cover often have less rain check.
Many other factors can cause malformed or damaged fruits such as;
nutritional disorders, pollution (ozone, CO damage), and herbicides exposures.