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Too much water can wilt tomatoes
The Coast Gardener Newspaper and Web Column - April 13, 2002

Too much of a good thing can be harmful at times. Even though we needed the rain, your tomato plants may suffer from the heavy amounts the Coast received this past week.

It is true that tomatoes do like water. Properly mulched tomato plants combined with adequate irrigation and fertilization during the growing season helps maximize your harvest. We usually associate wilt with a lack of water--not too much of it. Too much water, however, can actually wilt the plants also.

Poorly drained soils with little organic matter and high clay content can cause a slight wilting of the foliage at the tops of the plants. This is the first sign of "water wilt." Waterlogged soil conditions do not allow affected plants to survive for very long. Plant death can occur in less than a week under these stressful conditions.

Too much carbon dioxide builds up in the soggy soil because roots quickly use up available oxygen. This lack of soil oxygen causes root death and plant wilt of tomatoes, peppers and other vegetables.

Sometimes tomato plants can recover from saturated conditions should soils dry out quickly, but roots are usually damaged so severely that investing in a new plant is the best way to go. Besides, even if the roots were to survive they would be susceptible to a number of soil borne diseases such as Pythium and Phytophthora root rot.

Another problem associated with rainy weather is "cracking." Cracks frequently develop on the stem end of fruit that is undergoing rapid growth. Cracks may radiate away from the stem end or form in concentric bands around the stem end. Wet weather that follows dry weather promotes the occurrence of these growth cracks. Some tomato cultivars are more susceptible to cracking than others.

Rainy periods also promote a condition called leaf roll. This condition occurs when lower leaves roll upward until the edges touch and become thick and leathery. Excessive fertilizer and pruning can also contribute to this problem. No serious consequences are observed, as plant growth and yield is not greatly affected.

These archived gardening columns were written by Chance McDavid, former Harrison County Extension Agent.