MSU Extension

Weather and growth stages

All tree fruits have been sizing quickly with the warmer than normal weather that has settled in recently. The exception is sweet cherries, which seem to overall have a problem with size this season, perhaps due to the cool weather during fruit set.

Apples continue to size nicely and fruit finish is excellent at this time. Predicted harvest dates for apples are now available on the Michigan State University Enviro-weather website in the fruit tools section. At this time, harvest dates appear to be very similar or slightly above the 2015 season.

Peaches continue to grow fast with hand thinning wrapping up. The crop in the general Grand Rapids, Michigan, area appears to be set very well.

Sweet cherry harvest began in the Grand Rapids, Michigan, area late last week with the major push of harvest this week and next. All growers are commenting that fruit size is not what they would like this year, which indicates it must be a weather-driven problem affecting the whole region.

There continues to be higher bird pressure this season in cherries. All species of birds are being reported, and many growers report the cedar waxwings seem to be higher in number this season; they have been low since the 2012 no-crop year.

Growing degree-day (GDD) totals for the Sparta Enviro-weather station are 1,556 GDD base 42, 1,216 GDD base 45 and 934 GDD base 50. On average, degree-day totals put this area eight days ahead of normal average accumulations.

Diseases

Fire blight continues to be reported and overall it is not widespread in the area. Where it is bad, it looks really bad. Trees are beginning to set terminal buds and it looks as if fire blight is starting to ease up. Keep an eye to the weather for any storms that could rip or tear foliage and get the blight moving again, at least until we get into mid-July.

MSU Extension advises growers and scouts to continue to be on the lookout for primary apple scab infections as fruits and leaves are still susceptible to secondary infections. Once leaves and fruit toughen up in the summer months (July and August), further scab infections should be reduced in blocks with active infections.

Insects

Codling moth adult flight continues and is declining as expected for first generation. Most blocks should be just past peak egg hatch. A regional biofix was set for May 23 (302 GDD50) and 630 GDD50 have been accumulated since that date. Cover sprays continue to be very important with controls maintained for another two weeks to cover for all possible eggs to still be hatched.

All stages of European red mite are being found. A few beneficial mites are also found, but they seem to be in low numbers overall to help with high European red mite populations. Continue to monitor more closely as petal fall miticides lose effectiveness. The July threshold is five mites per leaf.

Obliquebanded leafroller adult flight should be past its peak and trap numbers will slowly decline over the next two to three weeks. Early egg hatch should be underway and high pressure blocks need cover sprays for obliquebanded leafroller soon. A regional biofix was set for June 12 (1,132 GDD42) and 405 GDD42 have been accumulated since that date. Consider early egg hatch timing (right now) for high pressure blocks. Peak egg hatch is estimated for around July 3. Low pressure blocks can scout for larvae and spray accordingly, most likely seven to 10 days away.

Apple maggot adult flight has not been reported in the Grand Rapids, Michigan, area, but traps should be in place in known hot spots and along orchard edges near wooded areas with alternate hosts present. Numbers have been creeping higher each year. You only know what’s happening with apple maggot if you are trapping for it correctly.

San Jose scale crawlers found in the last week or so have settled down on new growth and are forming new waxy coatings. Cover sprays will not be very effective now. Continue monitoring for new scales in high pressure blocks on shoots and fruits.

Oriental fruit moth second generation flight is underway with adult number increasing each week. A regional biofix was set for May 6 (308 GDD45), and 987 GDD45 have been added since then. The Enviro-weather’s oriental fruit moth model indicates second generation larvae will be at 10 percent hatch around July 3 or 4, and that’s the time to target them again in stone fruits and perhaps apples with very high trap numbers (more than 60 per trap per week).

Various species of aphids can be found in all tree fruits, and numbers seem to be building now each week. There are syrphid fly larvae and lady bug larvae present in some populations. Continue monitoring for all aphid species in all tree fruits as well as beneficials that attack them.

Dogwood borer adult flight began last week in low numbers. Target trunks at peak adult flight, typically the first week of July in the Grand Rapids, Michigan, area.

Spotted wing Drosophila adult flight continues in low numbers and mainly in strawberry sites. None reported in sweet cherries yet. Traps with lures should be in place in susceptible crops.

No reports yet of brown marmorated stinkbug adults or nymphs in the Grand Rapids, Michigan, area.    

The first Japanese beetle adults are now being found in the Grand Rapids, Michigan, area and they are starting to pair up. Continue monitoring and applying cover sprays when you see them in couples.