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.
Members remarked on a number of the conditions as follows:
a) leaf miners (IMG_3553)
b) yellow leaves followed by necrosis, probably a nutritional problem (IMG_3540-IMG_3547, 3556). The symptoms of chlorosis (yellowing) of the older leaves while the growing points remain green is typical of nitrogen deficiency where the N is translocated from older to younger parts of the plant. Note that the yellowing is concentrated at the leaf margin and in the areas between the main veins and the tissues there subsequently died. That pattern of lesion development is often related to more general nutrient deficiency; it is not typical of any kind of disease caused by a pathogen. In this case it is likely that nitrogen is the main problem, but other nutrients such as potassium are probably also in short supply. The amount of fern regrowth on the site and fern debris on the soil surface suggests that the area may have been cropped previously and allowed to revert to fern for some time. Under those circumstances it is likely that there has been a lot of nutrient leaching leading to the current problem. A soil analysis would be useful, and some idea from the farmer about the use of te land previously.