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Plum, Prune (Fresh)
Disease
Armillaria root rot
Bacterial canker
Black knot
Brown rot
Crown gall
Cytospora canker
Plum pockets
Russeting
Shothole (Coryneum blight)
Silver leaf
Virus diseases
Insect
Aphids
Apple-and-thorn skeletonizer
Brown marmorated stink bug
Earwigs
Fruittree leafroller
Leafhoppers
Pacific flatheaded borer
Peach twig borer
Peachtree borer
Pear slug
Scale insects
Shothole borer
Spider mites
Spotted wing Drosophila (SWD)
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Caption: Fruit russeting on plum
Photo by: R.S. Byther
Plum, Prune (Fresh) : Russeting
(revision date: 9/12/2016)
Use Integrated Pest Management (IPM) for successful plant problem management.
Biology
Russeting of plum can be caused by several factors. Rain during the period of full bloom, mechanical rubbing against other fruit or branches caused by wind, or other injury of the (russet scab) fruit surface can result in russet symptoms. High winds following full bloom and copper fungicide applications are other causes of russeting on French prunes. Affected fruit initially show shiny areas on the surface where normal wax is lacking. The shiny area develops into a brown, corky or scabby area just before fruit harvest. Affected fruit may be misshapen. Thrips may cause similar russeting symptoms on all stone fruits.
Management Options
Non-Chemical Management
Avoid overhead watering during bloom and petal fall.
Select non-chemical management options as your first choice!
Chemical Management
IMPORTANT:
Visit Home and Garden Fact Sheets for more information on using pesticides
Though no fungal or other microorganisms have been associated with russet scab, fungicides applied during the bloom period control the problem. A yeast has been associated with russet on pome fruit. Russeting caused by wind or thrips would not be managed with fungicide applications. Homeowners should not make foliar applications to trees over 10 ft tall. Consult a commercial pesticide applicator for treatment of trees and shrubs over 10 ft. tall.
Listed below are examples of pesticides that are legal in Washington. Always read and follow all label directions.
Bonide Fung-onil Multi-Purpose Fungicide Conc
Active ingredient: chlorothalonil | EPA reg no: 60063-9-4
GardenTech Daconil Fungicide Conc
Active ingredient: chlorothalonil | EPA reg no: 67572-82-71004
Ortho Max Garden Disease Control Conc
Active ingredient: chlorothalonil | EPA reg no: 239-2522
This list may not include all products registered for this use.
Images
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Caption: Fruit russeting on plum
Photo by: R.S. Byther