For all the joy and satisfaction that growing tomatoes can give a gardener, the frustration and aggravation can be equally as great! Several issues can plague the tomato grower. Here are a few non-disease problems:
Blossom drop can occur when nighttime temperatures are below 55°F. Rain can also hinder pollination and so can high humidity. Shaking the plant can encourage better fruit set by helping to release the pollen for pollination.
No fruit developing on the plant can be caused by too much nitrogen fertilization. In addition to no fruit development, plants that have had too much nitrogen fertilization will appear very large and dark green.
Leaf curling is caused by an excessive amount of rain.
Blossom-end rot appears as a black leathery scar on the blossom end of the fruit. This is the end opposite where the tomato attaches to the vine. The most common cause of blossom-end rot is an inconsistency in soil moisture that leads to a calcium deficiency in the developing fruit. This is often times seen when we go from periods of really wet weather to periods of hot, dry weather. Correct by maintaining uniform soil moisture through mulching and irrigating. Mulching helps to retain moisture within the soil, it cools the soil and reduces the competition for water with weeds.
Fruit cracks usually occur during hot rainy periods (above 90°F), especially when preceded by a long dry period. Fruits exposed to the sun are most susceptible.
Sunscald first appears as a yellow or white patch on the side of the fruit facing the sun. The spot may blister and dry, forming a paper-like surface. Poor foliage cover allows exposure to sun such as on pruned, staked tomatoes, sprawling plants, or unhealthy plants. Caging offers the best protection.
Blotchy ripening, the uneven development of color, may be due to temperatures below 60°F, root stress from compacted or soggy soil, or low levels of potassium in the soil. The fruits can still be used, simply cut away the poorly-colored areas.
Submitted by Amanda Sears, Agent for Horticulture, Madison Co. Cooperative Extension Service