June 17, AppleTalk Call Summary

AppleTalk Conference Call Summary
Tuesday, June 17th, 2014, 8:00 – 9:00 a.m.
Presenter: John Aue, Threshold IPM.
Moderator: Peter Werts, IPM Institute of North America; questions or comments, pwerts@ipminstitute.org

June 17th call download: Click here

Black rot
Managing tree stress in orchards with blocks of dead trees is critical to preventing additional black rot infections. Although rainfall may seem adequate a sod layer or heavy weed competition in the drip line may result in additional drought stress. Weeds can outcompete trees for the uptake of moisture and nutrients early in the summer, during times of rapid growth. As the season progresses weed competition becomes less significant as they turn to seed. Moisture requirements are also reduced in mid-late July for trees as shoot development ceases. Herbicide applications or mowing can reduce competition at this crucial time. A foliar application of nutrients may appropriate if a deficiency is suspected. Stress prevention needs to continue throughout the season, this includes irrigating and thinning fruit. At this time, removing dead scaffolds and trees will not protect healthy trees, plan to remove inoculum during the off season.

Fire blight
Symptoms, i.e., shepard’s crook, amber ooze, of shoot blight will begin showing during shoot development. If shoot blight is suspected, pruning out infected tissue one foot below any symptoms will help prevent further spread. Cuttings do not need to be removed from orchard since fire blight bacteria need living tissue to survive. Streptomycin, applied before or after rains, is an effective control for trees that are still in bloom or applied within 24 hours of a damaging wind or hail event.

Utilizing technology
Sensor technology, i.e., light meters and soil tensiometer, can be utilized to manage and prevent tree stress by allowing a more tactical approach to fertilizer, irrigation and pesticide applications.

New foliar disease: Marssonina blotch
Marssonina blotch is a new leaf disease present in Asia, Europe and portions of North America. Last year it was discovered in Bayfield, Wisconsin. It is a warmer weather disease with a similar biology to apple scab. Symptoms include dark spot on leaves, yellowing of leaf surface and early defoliation. Continuing fungicide programs through the summer may provide adequate control. Additional resources below.

Rainfast characteristics of codling moth insecticides
Heavy rains over the past few days and a volatile five-day forecast presents challenging conditions for codling moth management. When timing an application, or reapplication, it is important to compare the rainfast characteristics of insecticides with the forecast and storm totals. Reapplying is necessary to maintain a toxic dose of pesticide on the fruit surface for ingestion by codling moth larvae. Note: no material can be exposed to two inches of rain and effectively control codling moth. A reapplication may be necessary if heavy rainfall was experienced with consistently high trap counts. Applying insecticides a higher rate may provide extended protection from rain and a longer reapplication interval. Granulosis virus does not offer this trait and is more effective when applied more frequently, at lower rates. Additional information below.

Apple curculio
Apple curculio is a weevil, similar in appearance to plum curculio (PC). Damage resulting from apple curculio (AC) is rounder and deeper than that of PC. Localized, yet significant pressure in orchards has been observed in recent years. AC persists in orchards latter in the season than PC. Monitor for this pest as it has potential to become a serious problem.

Apple maggot
Apple maggot monitoring can begin in hotspots or blocks with late summer verities, i.e., Redfree, or locations with wild hosts present. Monitoring earlier then traditionally recommended, July 1st, is suggested as apple maggot were noticed emerging in some orchards in mid-June of 2012.

San Jose scale
San Jose scale may begin emerging in the crawler stage this week. Apply monitoring tape to scaffold branches in blocks with history of damage.

Additional articles and resources
Rainfast characteristics of insecticides on fruit for 2014. John Wise, Michigan State University Extension, Department of Entomology.

Marssonina blotch
Apple Blotch fungal characterization- full article (KoreaMed Synapse)
Biological Characterization of Marssonina coronaria Associated with Apple Blotch Disease
Epidemiology of Marssonina blotch (Marssonina coronaria) of apple in India _ and SANJEEV SHARMA _ Indian Phytopathology
European and Mediterranean Plant Protection Organization (EPPO)