WSU Extension

Hortsense

Apple : Phytophthora fruit rot
(revision date: 5/20/2014)


Biology
Phytophthora fruit rot is caused by a soilborne fungus which can also be found in and carried by irrigation water. Infection occurs when water contacts fruit on low-hanging limbs or when overhead watering is used. Firm tan spots approximately 1" or more in diameter develop on infected fruit. If the infection moves up into the wood, a dieback of one-year-old wood resembling fire blight can occur. This fungus can also infect pears. Phytophthora fruit rot occurs sporadically and is of minor importance.
Management Options

Non-Chemical Management
  • Avoid overhead watering.
  • Reduce time fruit is wet from irrigation to less than one hour (this includes actual irrigation time as well as drying time).
  • Do not get water on fruit within 10 days of harvest.
Select non-chemical management options as your first choice!

Chemical Management

None recommended

Images
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Caption: Phytophthora fruit rot
Photo by: G.G. Grove