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.
June 2007. Hawaii asked about malformed leaves on papaya: has anyone seen symptoms like those in the attached image? A client has about a dozen young papaya (0.5 to 1.5 meter tall) in his backyard and most are showing these symptoms on the youngest leaves. Is this a pathogen or something else was the question?
Mites – but none were found under the microscope, nor insects. However, Eriophyid mites are very small and feed in the growing point and on very young leaves. They will not be found on the expanded leaves and they are normally very hard to find even in the growing points. A miticide could be tried, although in a backyard this might not be desirable. The damage tends to be seasonal, so the problem may simply disappear as the plants get larger.
It was pointed out that there are also Tenuipalpid mites (not Eriophyid). Look for tiny active shiny mites.
There were other suggestions, mealybugs, virus and even Erwinia, a bacterium; however, mites were thought to be the most likely.