Winter Moth Update
Heather Faubert, URI Extension

The way to determine if a pre-bloom spray is needed is by inspecting your flower buds starting in about one week. You will need to dissect buds and see if there are winter moth caterpillars inside.
 

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For detailed information concerning the biology and management of Winter Moth, visit the following:
http://extension.umass.edu/landscape/fact-sheets/winter-moth-identification-management

http://extension.umass.edu/landscape/fact-sheets/winter-moth-overview
 

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ID/Disease Cycle: The first symptom of this disease is browning along the major leaf veins on newly emerging leaf clusters. The leaves wilt quickly and bend to resemble a shepherd's crook. A light gray powdery layer of spores develops at the leaf base. These spores go on to infect flowers and fruit. Infected green berries appear healthy but cutting them open reveals a white fungal growth inside. When berries start to ripen, infected berries appear pinkish tan and slightly ridged. They feel rubbery and contain a gray to black fungal mass inside. Infected berries eventually become faded, shrivel up, and fall to the ground. After the fruit skin has weathered off, the berries look like tiny black pumpkins.
The fungus overwinters in the mummified fruit on the ground. In early spring, trumpet-shaped mushroom cups produced on the mummies eject windborne spore that infect young shoots. Frost may increase susceptibility of blueberry shoots to infection.  Spores are produced on blighted shoots and are carried to flowers by wind, rain, and insects (bees), resulting in fruit infections. Mummies that fall to the ground provide inoculum for the disease in the following year. 
   
photo credits: 1) MSU Blueberry Facts 2) eXtension fact sheet 3) NC State Fruit Consortium
Damage: The fungus infects and invades the developing fruit rendering it unmarketable.

Management:
Monitoring: Consult scouting records from previous years to determine if build-up of this disease is indicated.  Monitor weather conditions to identify likely infection periods.  Scout fields beginning at budbreak for symptomatic tissue.  This timing often coincides with Fortsythia bloom.

Control strategies:
Cultural/Biological:

• Plant resistant varieties whenever possible. Those that are most resistant to the shoot blighting phase of the disease include Bluejay, Darrow, Duke, Elliot, and Toro. Cultivars that are consistently resistant to the fruit infection phase include Northsky, Reka, Northblue, Bluegold, Bluejay, Weymouth, and Patriot. Resistance to fruit infection appears to be unrelated to resistance to shoot blight, and weather factors can also affect cultivar response to the disease.
• Prune bushes to open the canopy to light, air, and spray penetration.
• Cultivate beneath plants in fall and again in early spring to disrupt overwintering inoculum.
• Apply a 3-4” layer of mulch material over the soil surface in early spring before mushroom cups emerge to create a physical barrier to spore release.

•  Apply recommended fungicides at budbreak if scouting and weather monitoring indicate risk of infection.
• Time fungicide applications closely to frost/freeze events that predispose tissue to infection.
• Repeat fungicide applications at recommended intervals if weather conditions are conducive to infection.
• Rotate fungicide materials from different FRAC groups to avoid promoting the development of resistant strains of this disease.

Summary Management Table:

Conventional	Organic (OMRI Listed	Cultural
Abound F, 6.2-15.4 oz (0 day phi; Note caution regarding spray near or with equipment also used in apples) Captec 4L, 0.75-1 qt (0 day phi) Indar 2F, 6 oz (30 day phi) PropiMax EC, 6 oz (30 day phi) Quash, 2.5 oz (7 day phi) Quilt Xcel, 14-21 oz (30 day phi) Switch, 11-14 oz (0 day phi)	⊗ Actinovate AG, 3-12 oz (0) ⊗ Double Nickel 55, 0.25-3 lb (0) ⊗ Serenade Max, 1-3 lb (0)	Use resistant varieties Prune for open canopy Cultivate beneath plants after harvest to disrupt inoculum Mulch in early spring to cover inoculum
Read labels thoroughly for application rates and restrictions (REI, PHI, etc.) * restricted use material ⊗ OMRI listed