Curling of Tomato Leaves and occasionally of other vegetables' leaves are symptoms of a physiological problem, not one caused by disease. Often the symptoms will progress up the plant. Since no pathogen is involved, there are no sprays which will control this problem. The best thing is to maintain soil moisture as uniformly as possible and avoid damaging the root systems by too vigorous cultivating. Even with leaves curling, the fruit usually develops normally, and other than the peculiar rolled leaves, nothing further occurs.
Squashes often fail to develop, turn yellow, and finally rot if unpollinated.
Both male and female flowers and bees or other pollinators need to be present to effect pollination. Plants which already bear large fruits or which have nutrient deficiencies often abort fruit and eventually cease producing flowers. Botrytis frequently infects aborted fruits, spent flowers, and occasionally even healthy fruit. Potato plants sometimes produce small green fruits resembling tomato fruits. These contain true seeds and look similar to small tomato seeds, as both are closely related.