Santa Rosa Plum Stops Bearing
Question from Debbie:
8 years ago we planted a Santa Rosa plum (Sunset 23, Pacific Palisades). for the first few years it had 3 or 4 plums – delicious! The tree kept growing(like crazy), but my gardener has pruned it hard in Dec or Jan for the past 3 years, and now we have plenty of flowers in Feb/March, but no fruit. Should I tell him to stop? The new small Santa Rosa next to it set fruit. Used fertilizer spikes. 2nd year for apricot tree, 150 fruits!
Answer from Pat:
I am very sorry to hear about what happened to your plum tree. Plum trees come in two types, Japanese and European. The European plums need very little pruning. The Japanese types take heavy pruning. Santa Rosa is a Japanese type of plum. The fact you got plenty of flowers though no fruit shows your gardener did not over-prune the tree, but the lack of fruit probably came from lack of a pollinator.
Santa Rosa plums are self-fruitful, but they still need to have the pollen transferred from the male part of the flower to the female part in order to bear fruit. Your problem most likely resulted from lack of bees to do this pollination. Rain and cold temperatures sometimes keep bees in their hives. Spraying with chemicals when there are flowers open can kill bees. Bees pollinate the flowers on a self-fruitful tree by going from flower to flower all over the tree. Cross pollination occurs when the bees visit various trees and mix the pollen from tree to tree. Some plum varieties need cross pollination but Santa Rosa does not. Next year if you see no bees, get a sable brush and go from flower to flower swirling the brush inside individual flowers here and there all over the tree. You should then get fruit! Do the job in the morning after the dew has dried but while the pollen is still fresh and keep it up for several days doing some flowers every day. The more flowers you pollinate the more fruit you will get.
Fertilizer spikes are not the best fertilizer for fruit trees. A better choice is to fertilize all over the ground under the tree when flower buds swell with a balanced organic fertilizer recommended for deciduous fruit trees or follow the suggestions in my organic book.