West central Michigan tree fruit regional report – July 14, 2015
Sweet cherry harvest is well underway in west central Michigan.
Sweet cherry harvest is well underway and will come to an end in a week to 10 days. Fruit quality has been very good for sweets this year. Early peaches will begin soon. Watch the pre-harvest intervals of spray materials you are using for these early ripening fruits.
Tree fruit diseases
We are hearing and seeing some apple scab show up in some blocks. It’s not widespread, but it serves a reminder to scout closely for scab now that you have reduced fungicide rates. If there was some primary scab present, it begins to really show up once you switch to summer fungicide rates.
In blocks with active fire blight, it should begin to slow down its spread now that tree growth is slowing. If we were to get a hail storm or high winds, I would only be concerned for blight in blocks with heavy infections present. All clean blocks would not need fire blight covers if a trauma blight situation occurs.
You should have had at least one application on for summer diseases in apples.
Tree fruit insects
Codling moth adult flight in high pressure blocks has declined. Egg hatch is about 90 percent now and should come to an end early next week. Adult flight in average or moderate pressure blocks is declining. Egg hatch should be about 70 percent and should come to an end in about 10 days. Adult flight in low pressure blocks with mating disruption continues to be low as expected, but some scouts report a slight increase in adult trap numbers over the last 10 days. Egg hatch should end in about seven to 10 days.
For codling moth, you should make your spray decisions based on trap numbers that occurred 10 to 14 days ago. If those numbers 10 days ago were above threshold, then eggs potentially are hatching now and cover sprays are still needed.
European red mites have begun to build in some blocks. Threshold is five mites per leaf for July. Michigan State University Extension advises growers to monitor for beneficials – one per leaf indicates wait a week and count again.
Obliquebanded leafroller adult flight should be declining. Some blocks are still reporting very high adult flight which is a bit surprising. A regional biofix was set for June 12 (1,036 GDD42). GDD since biofix is 775. It is expected that we are about 75 percent through egg hatch with hatch coming to an end about seven days from now.
Oriental fruit moth second generation adults are flying steadily, but have not yet reached a peak. A regional biofix was set for May 6 (256 GDD45). GDD since biofix is 1,275. Expect second generation flight to increase over the next week or so before beginning to decline again. We are most likely at 25 percent egg hatch and will reach a peak egg hatch in seven to 10 days. Cover sprays are needed in stone fruits to prevent shoot and fruit feeding damage. Unless you are trapping very high numbers – over 40 moths per trap – controls are not needed in apples for second generation, but perhaps will be needed for third generation in late summer.
Japanese beetles started to be found in the last week. When you start seeing them in your crops pairing up, controls are needed.
Some initial spotted wing Drosophila flight was reported in various Michigan locations. Not an issue for apples, but monitoring should be done in soft fruits like cherries, peaches, plums and berries.
Some overwintered brown marmorated stink bug adults are becoming active. None have been trapped in the Grand Rapids, Michigan, area.