Thomas J. Koske | 5/14/2005 1:25:34 AM
Several diseases and insect pest problems can cause gardens to wilt and develop damage, but, after a saturating summer rain, we should expect many plants to wilt and then scald out. Scalded plants will look like "cooked spinach on the tomato vine." Especially prone to this are fully grown (or nearly so) peppers and tomatoes.
The scalded crop root systems are sitting in a low oxygen mud. The rainwater has displaced the soil atmosphere. In this saturated condition, the roots do not work well; they do not take up soil moisture as well. When a high evaporation demand (transpiration) is placed on the plants from bright sunshine after the rain, they show drought stress even though their "feet" are in watery mud.
As long as it is cloudy and humid, the plants hold turgidity and stay up. As soon as the sun shines strongly, the plants can't keep up with transpiration because of inefficient root activity. This physiological wilt then slows transpiration. Without this transpiration from leaf surfaces, leaves overheat and burn up/scald and may die. Then to add insult to injury, that lack of foliage cover from wilting sunburns the fruit.
What To Do
Pick what you can after the plants show a scald followed by bright sun. Fruit will probably sunburn the next day or sooner. Badly scalded plants are usually lost, because leaves burn up. Remove lost plants and plan for your next garden.
Next time, build high rows and improve soil drainage with drain furrows that move surface water away.
The LSU AgCenter and the LSU College of Agriculture