Answer: Wilting tomatoes that do not recover in the evening may beshowing signs of wilt diseases of the root system or nematode damage to the roots. You can examine the roots and stem for the diagnosis.
Dig up a declining plant and look for swollen areas on the roots (nematodes). Then split the stem lengthwise and look for a brown streak between the green "outer bark" and the cream colored stem interior (wilt diseases). The solution to both is to select varieties with a VFN after their name.
Sometimes we see plants with a VFN showing these symptoms. This is usually due to a mislabeled plant (not the variety you thought you were getting), or a strain of the disease that overcomes the plant's resistance. Now you will see for example V, F1, F2, N plants indicating they are resistant to two strains of the fusarium fungus.
Finally, too much rain can cause wilting if the soil does not drain adequately. Waterlogged soil prevents oxygen from getting to the root system and can result in root loss and subsequent wilting.
Hope this helps. Good luck with your garden!
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