WSU Extension

Hortsense

Holly
 
Disease
Boron deficiency 
Green algae 
Phytophthora leaf & twig blight 
Red leaf spotting 
Insect
Brown soft scale 
Cottony camellia scale 
Holly bud moth 
Holly leafminer 
Lecanium scale 
Orange tortrix 



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Caption: Holly Phytophthora leaf and twig blight
Photo by: J.W. Pscheidt
  
Holly : Phytophthora leaf & twig blight
(revision date: 3/2/2015)


Biology
Leaf and twig blight of holly is caused by a different Phytophthora species than is associated with root rots. Symptoms first appear in the fall and winter during wet, cool weather. Leaves develop purple to black spots and may drop from the plant. Twigs develop cankers and die back. The disease begins on the lower portions of the plant and progresses upward through the winter. Disease development usually stops in the warm, dry weather of summer. Phytophthora leaf and twig blight is mainly a concern in nurseries and holly orchards.
Management Options


Non-Chemical Management
  • Space plantings and prune to provide good air circulation.
  • Avoid overhead watering.
Select non-chemical management options as your first choice!

Chemical Management

Make the first application before fall rains begin. Additional applications after harvest or severe winter storms may be useful. 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: Holly Phytophthora leaf and twig blight
Photo by: J.W. Pscheidt