QUESTION
The client called about a 6-yr old plum tree that had fruit for 3 years but not for last 2 even though it bloomed well.
DIAGNOSIS / RECOMMENDATION
The problem was identified as a lack of a pollinator variety. Japanese plums require a different but related variety of plum for pollination, within 100 yds. There may have been one in past that since was removed.
ADDITIONAL INFORMATION
While European plum cultivars are self-fertile, most Japanese plums are self-sterile and do require a different variety in order to be pollinated (1, 2, 3). Picking the correct cultivar for plums can be a particular challenge since there are known pollen incompatibilities (2, 5). It also is important to properly fertilize and prune the plum trees in order to maintain good fruit production (3). Soil fertility can have a significant impact on the flowering and production of plums (6). Native bees also can be an important factor in pollination of plums, particularly in home gardens, since plums bloom earlier than other fruits (6).
RESOURCE LINKS
1 https://extension.umd.edu/resource/tree-fruit-pollination
2 https://extension.umaine.edu/fruit/growing-fruit-trees-in-maine/pollination-requirements/
3 https://www.pubs.ext.vt.edu/content/dam/pubs_ext_vt_edu/426/426-841/SPES-259.pdf
4 https://hgic.clemson.edu/factsheet/plum/
5 https://extension.umn.edu/fruit/growing-stone-fruits-home-garden#plums-682262
6 https://extension.umaine.edu/publications/2034e/
(All resource links live and accessed April 12, 2022)
By: Betsy Brown, Bedford Extension Master Gardener Volunteer; Help Desk Coordinator