October 2009. Papaya leaves from Pohnpei, Federated States of Micronesia, with vein clearing and mosaic, but not ring spots. The symptoms are on the Solo Sunrise variety from Hawaii.
Members suggested a number of possibilities:
· NOT Papaya ring spot virus
· Broad mites - similar, but generally the leaves curve downwards
· Herbicides, particularly 2,4-D
· Boron deficiency
The symptoms of PRSV, in sequence, are as follows:
· Mosaic on younger leaves, dark green streaks on leaf petioles and upper stem
· Leaves may become distorted and eventually look like a monkey’s hand
· Fruit with tell-tale ring spots
· Growth will slows down
Do the plants grow out of the symptoms?
Similar symptoms were reported from Cambodia, and as neighbouring field were planted to cucurbits, it had been assumed that the plants were infected with PRSV. And it was thought that PRSV-P “probably” does not spread in seed.
Later, the Global Plant Clinic wrote that there might be another virus in the FSM plants. Recently, the Clinic has identified Moroccan watermelon mosaic virus from papaya from Congo. Symptoms are given in the following: http://www.bspp.org.uk/publications/new-disease-reports/ndr.php?id=015003.
Leaf symptoms ranged from yellow mosaic patterns to deformation and shoestrings as the disease progressed. Oily streaks in petioles and variations in shape and size of the ring spots on the fruits were also seen. Within the trunk, pink discoloration and tumor-like growths appeared; these eventually became brown and necrotic. In the final disease stage, plants resembled a pole with a tuft of small leaves at the apex and the internal trunk became fibrous.