West Michigan tree fruit update – July 11, 2017

Changing lures for the next generation of codling moth is recommended.

It is becoming easier to assess apple fruit crop load now that June drop has occurred. Apples are mostly in the 30-millimeter stage. Fruit set is extremely variable across the general Grand Rapids, Michigan, region. Sweet cherry harvest is going quickly with most finishing up this week. Fruit size in sweets has been great and cracking has been minimal despite rain events.

Codling moth adults in traps are very low as we are in between generations. All first generation eggs should be hatched now. A regional biofix was set for May 15 (250 GDD50) and 874 growing degree-days (GDD) base 50 have been accumulated.

Traps numbers could start to increase in high pressure blocks in the next seven to 10 days. Change out lures for second generation this week. Cover sprays are less crucial for codling moth in low pressure blocks.

Apple maggot adults started flying in sandy sites last week. There have been a marked increase in apple maggot in the general Grand Rapids area over the last two or three years and all blocks should be trapping for it.

Traps should be in place in known hot spots and along orchard edges near wooded areas with alternate hosts present. You only know what’s happening with apple maggot if you are trapping for it correctly. Red spheres with essence lures are the best for apple maggot.

Obliquebanded leafroller adult flight is complete for the first generation. Nearly all eggs should be hatched at this time. Larvae are in the third to fourth instar. A regional biofix was set for June 8 (1,017 GDD42) with 848 GDD accumulated since then.

There could be a few eggs left to hatch for the first generation and problem blocks should maintain cover sprays. Change out lures in the next week or so to accurately capture the next flight.

We are approaching peak egg hatch for second generation oriental fruit moth and cover sprays are very important in tree fruits over threshold. A regional biofix was set for April 28 (307 GDD45) with 1,457 GDD accumulated since then.

Continue to monitor traps for adult activity and relative oriental fruit moth pressure. Michigan State University Extension advises scouting for terminal collapse and fruit feeding.

Be on the lookout for tarnished plant bug activity in peaches. Pay attention to orchard edges, especially near mowed hay fields.

Japanese beetle adults started to be found around July 1 and feeding damage is increasing. They are paired up and mating. Continue to monitor and manage as needed.

Traps for spotted wing Drosophila are starting to show a marked increase and larvae can be found in tart and sweet cherry where not managed well. Cover sprays in susceptible fruits are crucial as crops come near their harvest window.

New scales of San Jose scale have formed their waxy covering and management will be difficult. Second generation flight could begin in 10 to 14 days in high pressure areas.

All stages of European red mite continue to be found. Predator mites are also present. The threshold for July is five mites per leaf.

Green apple aphids continue to expand quickly in some blocks. Some beneficials can be found, but seem to be lower in numbers than expected or not at all present. Reports of woolly apple aphids continue.

It’s time to start thinking about summer disease management in apples—we have had enough hours of wetting for most Grand Rapids area Enviroweather stations that fungicides need to be added to the tank.

We experienced very high pressure from sooty blotch and fly speck in 2016, mostly due to the heavy rainfall amounts in September and October and the lack of good fungicide residues. Don’t get behind early in the management of this complex disease. 

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