I have 2 female papaya trees. One is 10 ft. tall and the other is 8ft. tall. They are both robust healthy trees and flower continuously. I just recently planted a third "male" papaya tree and have been using it's flowers to hand pollenate the females, However the trees have not been setting fruit, instead the petals fall off the flowers and the tiny white undeveloped fruits sit on the tree for a week not even trying to grow, and then just fall off. I have have been nurturing these trees with compost, Azomite trace minerals, and supplemental amounts of 666 NPK fertilizer plus epsom salts for magnesium deficiency. The trees are neither over or under watered as they seem to have been growing vigorously with rich green foliage. Could it be that they are just not sturdy enough to fruit yet? The trees are 11 months old but were in 1 gallon pots for the first 3. Help would be greatly appreciated!