About six stands out of the over 1000 stands of tomatoes were discovered to show some signs of leaf curling as shown in the picture. Please what could be responsible for this condition and how can it be cured or prevented. Thanks
Leaf curling can be worrisome. High winds, blowing dust and low humidity can damage the leaves and stems on tomato plants. Heat and low moisture can cause the edges of the tomato leaves to die back, then twist and curl. Hot dry weather may also cause a symptom called physiological leaf roll.
Physiological leaf roll, which on some tomato cultivars is normal and not harmful. It can also be a temporary condition caused by weather conditions or by an inconsistent supply of moisture. Lack of other symptoms (yellowing, parallel veination, lack of vigour, stunting, etc.) distinguishes it from its lookalikes. Here are a few websites which provide more information: https://aggie-horticulture.tamu.edu/vegetable/files/2010/10/E-626-What-Makes-Tomato-Leaves-Twist-or-Curl.pdf
Other conditions may be drought stress, spider mites, herbicide injury and some viral diseases. The Missouri Botanical Garden website has an excellent article on leaf curling lookalike conditions: http://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/visual-guides/tomato-foliage-problems.aspx