MSU Extension

Weather

Drought continues at most fruit farms in the eastern part of Michigan, although some temporary relief came with rain late last week and over the weekend. Most farms received between 0.7 and 1.5 inches of rain in several widely scattered rain events from Thursday, July 7, to yesterday, July 11. A few farms received over 3 inches of rain in one, four-hour event last Thursday. High winds and widely scattered reports of marble- to baseball-sized hail were also reported.

Soils remain very dry across most of the region. Last week’s rains were not enough to reverse our extremely dry soil conditions. Some growers have not had a significant rain event for the last five weeks, but for most fruit farms it has been eight weeks without good rainfall. Most of the region is short 3 to 4 inches of rain since mid-May. Newly planted tree and small fruits continue to show signs of wilting and some trees have died as a result of lack of rainfall. Growers continue to devote a great deal of time to irrigation activities.

This week, fruit size is being reduced for all of our fruit crops due to the drought, new this week is apples as well.

With the heat of the last week, our growing degree-day (GDD) totals have slowly gained, thus we are now a full week ahead of normal, except for farms along the shore of Lakes Erie and Huron, where the season is a few days behind normal. In terms of the fruit crop growth stages and beginning of harvest, we are about five days ahead of normal.

Tree fruits

Apples are mostly 2 inches in diameter for growers across the entire region, which is unusual to see the same fruit size over such a large area. Most summers I will see larger fruit size in the southern part of our region, but not this season. Interestingly, yesterday I was at one of the “lucky few” fruit farms that received 3.15 inches of rain in the last week, and their fruit size was notably one to two sizes larger than other farms where rainfall is short. Hand-thinning of apples continues for a few growers, while most are done. Honeycrisp leaf modeling is very common this season.

Apple maggot trap catch is a new pest to report this week. It was caught yesterday on yellow sticky board traps. None have been caught on red sphere traps yet this season. A second new pest to report in apples and other tree fruits is eastern tent caterpillar larvae, but they are in very low numbers. This is a bit early to see this pest. European red mite adults remain at or above threshold levels in more apple blocks in the past week, with bronzing of leaves starting to be seen. Woolly apple aphid populations are slowly declining in blocks where an insecticide application was made specifically to control this pest. However, their population continues to build in untreated blocks.

With continued hot weather, Japanese beetle adults are in greater numbers. Potato leafhopper and white apple leafhopper numbers are slowly building in many apple blocks. Green apple aphid numbers have dropped off in the past week where predator numbers have built. Twospotted spider mites were found in a few apple blocks. Obliquebanded leafroller, codling moth and oriental fruit moth trap catches continue to decline. Beneficial numbers continue to build, especially lacewings, velvet mites and flower thrips this week.

Over the last week, many apple growers found fire blight strikes in very high numbers in new plantings; this started over the July 4 weekend. This is trauma blight that infected the new leaves and shoots. The infection most likely came nine to 12 days earlier from strong wind events. Black rot is a new disease to report this week, found as spots on leaves. Powdery mildew continues to be found, as does cedar apple rust and silver leaf symptoms.

Pears are mostly 1.5 to 1.625 inches in diameter. Pear fruit size is starting to be affected by the drought. Pear psylla numbers are high on suckers.

Peaches are 1.75 to 2 inches in diameter for most growers. Harvest of a few early peach varieties continues. Hand-thinning continues at a few farms, most are done. Rose chafer adults are causing some cat facing to peaches.

Sweet cherry harvest continues at some farms and is finished at others. I was pleasantly surprised not to see fruit cracking was not more extensive at farms that had good amounts of rain over the last week. Spotted wing Drosophila (SWD) trap catch was seen in a few sweet cherry blocks last week, but their numbers are just starting to build and should not be a threat to sweet cherry blocks that will finish harvest in the next few days. Cherry fruit fly adult catch continues at a few sweet cherry blocks. Growers with more than a week to go with harvest might need an insecticide application to control this pest. Bird feeding has been heavy in most blocks, mostly related to our lack of rain.

Tart cherry harvest continues across the region, and demand for tart cherries has been very good this season. Smaller fruit size has been an issue at many farms this past week or so, most likely from the drought. SWD trap catch was seen in tart cherry as well in the last week, although trap catch is very low. Cherry fruit fly adult catch has been seen in tart cherries as well at a few farms. Growers with more than a week to go with harvest might need an insecticide application to control this pest. As with sweet cherries, bird feeding is an issue in tart cherries this season.

Plums have sized in the past week, despite the drought. European types are 1 inch in diameter, Japanese types are starting to color and early varieties are approaching 1.75 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

Grape growth has slowed this week. Concord fruit are nearing berry touch and European varieties are just beyond buckshot-sized fruit. Japanese beetle adults are increasing in numbers in grapes. Rose chafer numbers continue to build. I am seeing a few grape berry moth larvae feeding in Concord grapes.

Strawberry renovation continues. Due to dry soils, some growers need to put irrigation pipe back into the field and irrigate well in order to do a good job of sub-soiling and tilling between the rows. This is quite unusual. I also 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. New berries are runnering well.

We had one report of SWD trap catch last week in one strawberry field in southeast Michigan, caught just as harvest was ending. This pest may be a problem in strawberries in the future as SWD populations continue to build, particularly in late harvest seasons. This will need more monitoring next season. I am seeing a few potato leafhoppers in new plantings. Growers should watch for curled leaves, although this can be somewhat confusing as some of the same symptoms can be seen with drought stress.

Raspberry harvest continues for summer red raspberry varieties, although small berries are a problem at many farms due to drought. One grower reported SWD trap catch early last week, but none have been seen this week in our statewide trapping network. The growers’ numbers were very low and in my opinion do not merit an insecticide application to control it. Look for a complete SWD report on Friday published on the Michigan State University Extension Fruit & Nuts News website for results for this week from our statewide trapping network.

Fall red raspberry canes are much shorter this season than most years, and are much shorter than last season’s unusually long canes. For the past two weeks, I saw most fall red raspberry fields with about one-third to one-half of the canes with flower buds and fruitlets forming 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 part of the fall crop, but can still be harvested.

Blueberry harvest started at a few farms over the last few days, other farms are waiting a few days for berries to ripen more. I was surprised to see how quickly some fields ripened this season, most likely due to drought. While fruit size is fair to good for this first picking, I am concerned that later ripening fruits are not sizing well, again, due to drought.

Saskatoon harvest is complete.