Santa Rosa plum problem

Asked June 26, 2019, 7:53 PM EDT

Help- I’m having problems with my Santa Rosa plum tree. Many are hard, misshapen - see the pictures. We’ve had fruit off for three or four years, no issues. Not this year though, and I can’t figure out what the issue is online- maybe someone can help? Thanks

Multnomah County Oregon plums sunburn abiotic issues

1 Response

Thank you for the nice images of your damaged plums. The don't have a disease. Instead, they are sunburned. This most likely occurred during one or more of our recent hot, bright days.

The clues to diagnosis are that the damage is on the highest point on each fruit, a place not covered by leafy growth.

The remedy is to remove all the damaged fruits because the damage can't be undone.

Further, I suggest you thin the fruits so that, as the fruits enlarge, the accumulated weight does not break the branch.

To thin, remove all the damaged and off-color fruits first because they won't develop further.
Next, remove all the small fruits. Keep only the biggest fruits but be certain to allow 5 to 6 inches between adjacent fruits.

Next year, plan to remove the excess fruits when they are the size of medium-size olives. The benefit of thinning early in fruit development is that you'll harvest an abundant crop of large, high-quality fruits. See this information: https://extension.oregonstate.edu/news/thin-now-higher-quality-tree-fruits