This year none of my trees are bearing fruit. Apple, crab apple, and mock plum. The plums are a source of food for my wintering Robins. I have noticed a lack of bees. There are only a hand full of bumble bees. We have many flowers including wild flowers. I use no pesticides. There was no frost at the time of flowering.
Anoka County Minnesota
Apple trees, including crabapples, tend to bear fruit heavily one year and very little to no fruit on alternate years. Your plum tree is a bit fussy. Here is information on plums. If you don't have two trees, that could be the problem. Otherwise, please read through our publication for clues: http://www.extension.umn.edu/Garden/yard-garden/fruit/integrated-pest-management-for-home-stone-frui...
Barbara: I have 15 to 20 trees which have apples and plums. I have lived here for 5 years and always have some fruit. It may vary year to year, but, this year none have produced.
I am sorry but I have no more suggestions for you.