A network that helps people worldwide obtain rapid advice and information on crop protection, including the identification and management of plant pests.
PestNet is a network that helps people worldwide obtain rapid advice and information on crop protection, including the identification and management of plant pests. It started in 1999. Anyone with an interest in plant protection is welcome to join. PestNet is free and is moderated, ensuring that messages are confined to plant protection.
December 2004. Are the cucumber leaves, from plants growing in Pohnpei, Federated States of Micronesia, showing a nutrient deficinecy? Or it is possible that the symptoms are caused by soap spray? The farmer has used a commercial soap spray several times on the crop.
Boron deficiency was suggested because of the presence of the light brown edges of the leaves; however, there is no cupping or upward curling of leaves, which tends to be quite typical in situations where boron is decficient. It is likely that the excess of soap solution is a more probable reason for the problem.
However, it was also suggested that there may be two problems: nutritional and disease. The photo with several leaves (top, right) shows marginal necrosis that could well be the beginning of gummy stem blight, Didymella bryoniae. A photo (left, below) was sent; this was taken in FSM in 1984. Many of the varieties there seemed very susceptible to the disease at that time. If it looks like the problem, see SPC Diseases of Cultivated Crops in the Pacific Island Countries, page 61.