Shriveled immature fruit on Italian Plum #734107 - Ask Extension


Shriveled immature fruit on Italian Plum #734107

Asked November 17, 2020, 8:12 PM EST

We have an Italian Plum that is 10-12 years old. It had been producing well then a few years ago the immature fruit became to shrivel and drop before ripening. Fruit, often heavy yield, will initially look normal, well formed and filling out nicely. Leaves also look normal. Then before ripening, fruit shrivels and eventually fruit looks like a purple pit and falls off. This began 3 years ago or so and lost all the fruit several years. This year it happened again, but we did get some fruits that ripened and looked normal while approx half were effected. The tree is pruned each fall and we have been spraying with dormant spray 3 times during dormancy, alternating between a copper spray and sulfur spray. We had not sprayed for many years but after problems began we started the spraying regimen. For 2 years it didn’t seem to help at all, but wondering if this was how we saw some improvement season 2020. Is there something more or different we should be doing?

Multnomah County Oregon

Expert Response

Lacking images of the affected fruit, my best guess is that the plums are affected by Brown Rot of Stone Fruit, a common fungus disease in the northwest of peaches, plums and nectarines.

Several sprays are required to decrease the likelihood of the disease. Even then, environmental conditions vary from year to year. Thus, few fruits will be affected some years whereas many fruits are damaged other years. In other words, growing stone fruits hereabouts may be a frustrating exercise.

Timing the sprays is critical. "Apply fungicides during the bloom period at early popcorn, full bloom, and/or petal fall to control the blossom blight phase."

Several products are available for use by home gardeners, among them the following; follow label directions as to dilution rate:
- Bonide Captan 50 WP
- Bravo Weather Stik
- Infuse Systemic Disease Control

According to our official disease management resource, "Fixed-copper products are registered but due to low level of control are not recommended."

Professional pest control companies have more product choices than do home gardeners, plus they have the the necessary equipment to apply a thorough spray.

Jean R. Natter Replied November 18, 2020, 10:21 PM EST

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