MSU Extension

Weather

The drought continues across the eastern part of Michigan. There was a widespread rain event last Friday morning, July 1, but it only brought an average of a third of an inch of precipitation for most fruit growers, and a few received less than a tenth. This was not enough precipitation to reverse our extremely dry soil conditions.

Soils remain very dry across the entire region. Some growers have not had a significant rain event for the last four weeks, but for most it has been over seven weeks without rain. Most of the region is short 2 to 3 inches of rain since mid May. I am seeing newly planted tree and small fruit plantings showing wilting, and some trees have died as a result of a lack of rainfall. Growers continue to devote a great deal of time to irrigation activities.

Fruit size for tart cherries and summer red raspberries has been affected by the drought, and blueberry size of ripening fruit is being reduced as well. I am surprised to see apple sizing continues to move along, but not at its typical pace.

Our season remains about five to seven days ahead of normal in terms of fruit crop growth stages and degree-day totals, except for farms along the shore of Lakes Erie and Huron where the season is a few days behind normal.

Tree fruits

Apples are mostly 1.75-2 inches in diameter across the entire region, which is unusual to see the same size over such a large area. Most summers I see larger fruit size in the southern part of our region, but not this season. Hand-thinning of apples continues for some growers, while others are done. Honeycrisp leaf modeling is being seen in many blocks.

Woolly apple aphids continue to be the question on growers’ minds these past two weeks. Woolly populations continue to build, mostly on tree trunks and at pruning scars, but more and more are being seen on terminals. The window of control is nearing an end for this pest. I can’t answer the question as to why woolly populations have been building these last few seasons, but pest populations generally go through cycles with very high populations. I have never seen as many woolly apple aphids as I am seeing right now.

Apple curculio adults have been seen in a few apple blocks and are a new pest to report this week; they are most likely emerging from larvae feeding on June drops. Japanese beetle adults are another new pest to report this week, but their numbers are low. Potato leafhopper adults were seen last week in strawberries, but this week I am starting to see some in apple blocks. Their numbers are low, but will need to be watched closely over the next few weeks.

Green apple aphid numbers remain very high in many apple blocks; they are being found on fruit in some blocks as well. Predators are working to reduce their numbers, but these need to be watched closely as I don’t like to see them on fruit at this time of the season. White apple leafhopper numbers are starting to build in many apple blocks. With continued hot and dry weather, European red mite adults remain at or above threshold levels in more apple blocks in the past week. San Jose scale crawlers have settled down now and have a waxy layer over them this week, so the crawler control window is now closed. Twospotted spider mites are being found in a few apple blocks. Obliquebanded leafroller adult trap catch is starting to decline.

Codling moth trap catch continues to be very high in many blocks, although trap catch is much lower in pheromone disrupted blocks. I have not had any apple maggot catch. Beneficial numbers continue to build; there are no new predators to report this week. Lady beetle populations are quickly building.

Fire blight strikes continue to be found, mostly in low numbers. However, I have had two reports today, July 5, of very high numbers of new strikes being seen in new plantings over this past July 4 weekend. I will be visiting both farms today and tomorrow to confirm if it is fire blight. Powdery mildew is being found, as are cedar apple rust and silver leaf symptoms.

Pears are mostly 1.5-1.625 inches in diameter. Pear fruit size does not appear to be affected by the drought. Pear psylla numbers are high on suckers.

Peaches are 1.625-1.75 inches in diameter for most growers. Harvest of a few early peach varieties continues. Hand-thinning continues. Rose chafer adults have been causing some cat facing to peaches.

Sweet cherry harvest is underway across the region. Cherry fruit fly adult catch has been seen in a few sweet cherry blocks starting late last week. Growers with more than a week to go with harvest might need an insecticide application to control this pest. Growers should be checking their traps every few days for this pest.

Despite dry soils, fruit size has been fairly good this season. I am concerned about the possibility of fruit cracking if and when we get rain. Bird feeding has been heavy in most blocks, mostly related to our lack of rain. I have not had any catches of spotted wing Drosophila in sweet cherry yet this season, although I expect to see first catch any day now.

Tart cherry harvest continues across the region; demand for tart cherries has been very good this season. Smaller fruit size has been at issue at many farms this past week or so, most likely from the drought. Cherry fruit fly adult catch has been seen in tart cherries at a few farms; growers with more than a week to go with harvest might need an insecticide application to control this pest. I have not had any catch of spotted wing Drosophila in tart cherry yet this season, although I expect to see first catch any day now. As with sweet cherries, bird feeding is an issue in tarts this season.

Plums have not sized much in the past week, European types are at 22 to 24 millimeters in diameter and Japanese types are approaching 1.375 inches in diameter. The crop load is variable for both types, especially in some Japanese varieties, as they have little to no crop.

Small fruits

Grapes continue to put on good growth. Concord fruit are almost at berry touch and European varieties are at buckshot. Japanese beetle adults are another new pest to report this week, but their numbers are low. Rose chafer numbers continue to build. I am seeing a few small grape berry moth larvae feeding in Concord grape.

Strawberry harvest has wrapped up for the region. Most growers report having a longer than normal harvest season. Renovation should begin as soon as possible. Most growers have started the process. Michigan State University Extension strongly encourage growers to water well as soon as the renovation process is complete; with the drought this season, this is more important than in most seasons where we have normal rainfall. I am seeing a few potato leafhoppers in new plantings. Growers need to watch for curled leaves, although this can be somewhat confusing as some of the same symptoms can be seen with drought stress. New berries are runnering well.

Raspberry harvest continues for summer red raspberry varieties. Small berry size is a problem at many farms due to drought. Fall red raspberry canes are much shorter this season than most years, and are much shorter than last season’s unusually long canes. This week, I am seeing some fall red raspberry fields with about one-third of the canes with a flower bud at the tip of the cane. I have always referred to these canes as “bud berries” that are forming on the shorter lateral canes. These are not a part of the fall crop, but can still be harvested. These berries will also need to be protected from spotted wing Drosophila. I have not had any catch of spotted wing Drosophila in raspberries yet this season, although I expect to see first catch any day now.

Blueberries are 10 to 15 millimeters in diameter, they have not sized well in the past week, mostly due to drought. Harvest of Bluetta is almost complete. Most varieties have no color in them yet.

Saskatoon harvest is underway.