Southwest Michigan fruit regional report – June 23, 2015

Rains have stopped strawberry harvest. Sweet cherry, raspberry and blueberry harvest is just beginning.

There is a good crop of Montmorency tart cherries in southwest Michigan. All photos: Mark Longstroth, MSU Extension
There is a good crop of Montmorency tart cherries in southwest Michigan. All photos: Mark Longstroth, MSU Extension


Last week was warm and humid. High temperatures were near 80 with low temperatures in the 50s, 60s and 70s. Heavy rains last Monday night, June 15, dropped 1-2 inches of rain overnight. These storms followed heavy rains earlier in the week and resulted in some flooding in fields with poor drainage and low lying areas near rivers. The rest of the week was cloudy with only a few scattered showers. The weekend was relatively dry.

Violent storms crossed the region yesterday, June 22. Storms in the early afternoon crossed northwest Van Buren County and moved across Allegan County to the northwest. A second line of thunderstorms moved across northern Van Buren, Allegan, Barry and Kalamazoo counties and tracked west, north of I-94. Rainfall totals from these storms were 2 inches or more. These heavy rains resulted in some flooding in the northern counties. There was no hail reported from these storms. Most other areas received little rain.

Weather for the upcoming week will be cooler with high temperatures in the 70s and lows near 60. Thunderstorms and showers are possible Wednesday night and Thursday, but heavy rain appears unlikely. Fair conditions are forecast over the weekend and early next week. Our rainfall totals since April 1 are generally just above 11 inches. Soils are wet, especially heavier soils with poor drainage or wet spots in fields. We are close to normal in terms of crop development and Growing Degree Day (GDD) accumulations. With the pleasant weather last week, we picked up about 23.5 GDD base 45 and 18.5 base 50 per day. We expect similar heat accumulations this week.

Southwest Michigan GDD summary from Jan. 1-June 21, 2015


GDD 42 F

GDD 45 F

GDD 50 F

Benton Harbor (SWMRC)




Lawton (Lawton)




Fennville (TNRC)




Average for the region




Accumulation last week




Tree fruit

Drier weather has helped reduce problems due to soggy soils. Obliquebanded leafroller egg hatch is underway in the region. San Jose crawler emergence is predicted to begin in southwest Michigan about June 13. Crawlers were detected last week in southeastern Michigan. Summer materials for San Jose control are often timed to control crawlers. See the “2015 Michigan Fruit Management Guide” from Michigan State University Extension for more information.

Apricot harvest of early varieties will start later this week.

Peaches are growing rapidly with harvest of early varieties such as Harbinger and PF1 expected to begin the first week of July in Berrien County. Redhaven harvest is predicted for Aug. 3 in central Berrien County. Some peach orchards under reduced input programs due to poor crop are showing pale green leaves, a symptom of nitrogen deficiency. Fungicide treatments for rusty spot should continue until pit hardening for varieties such as Loring, Bellaire and other peaches with showy bloom that tend to be more susceptible to this disease. Bacterial spot symptoms are slowly building up on leaves of susceptible varieties. Mycoshield, with 21-day pre-harvest interval (PHI) restriction, is the best tool now to keep bacterial spot from building up on foliage.

Oriental fruit moth adult catch from first generation flight is declining. Shoot tip flagging caused by burrowing oriental fruit moth larvae has been reported at several sites. Tarnished plant bugs continues to be a concern.

Sweet cherry harvest of the early season variety Cavalier has begun with Black Pearl soon to start. There is some fruit cracking due to rain, but it is not severe. Bird feeding is a problem in early ripening varieties. Cherry leaf spot lesions are just beginning to appear. Since cherry leaves always are susceptible to cherry leaf spot, growers need to maintain protectant fungicide coverage before rain events. Warm rains are good infection periods for brown rot as well, and sweet cherries are very susceptible to brown rot as the fruit ripens.

Tart cherries are mostly red except where foliage on the trees is scarce. Some growers have applied ethephon sprays to facilitate harvest. Winds on Monday, June 22, caused some damage to trees in some orchards and wind-whip to the fruit. Generally, damage to trees was not severe. Wind-whip will become more apparent in the next few days as harvest approaches. The tart cherry crop looks good and a heavy crop of fruit is visible from a distance in many orchards.

Cherry leaf spot symptoms and yellowing leaves are appearing. Cherry leaves are always susceptible to this disease and protection needs to be maintained throughout the season. Tart cherries are moderately tolerant to copper applications that can help reduce bacterial canker and cherry leaf spot in cherries. Growers need to avoid copper buildup on the leaves and reduce or discontinue copper use if there is no rain between sprays. Use MSU Enviro-weather’s cherry leaf spot model to help guide sprays and track infection periods. Cherry fruit flies have not been trapped at the Trevor Nichols Research Center trapline.

Japanese plums are 1 inch or more in diameter, depending on the variety. European plums are up to 1 inch in diameter. Fruit and leaf russet due to chemical phytotoxicity are common, including Captan-induced russet. Plum fruit and leaves are susceptible to bacterial leaf spot, but Mycoshield is not labeled for use on plums. Growers also need to protect current season’s growth against black knot until shoot growth ceases later in the season.

Apple fruits are sizing well. The largest fruits are approaching 2 inches in diameter for main season varieties. Hand-thinning is underway in many orchards to break up clusters of fruit. Secondary apple scab is common in some orchards and unsprayed trees are shedding infected leaves. Bright yellow cedar apple rust symptoms are also common in some orchards. New fire blight symptoms are showing up in young trees planted this spring, which bloomed later than mature trees. Recent humid weather is causing fire blight-infected tissue to ooze. Rainfall amounts and the duration of leaf wetness vary widely across the region.

Growers need to include fungicides to control sooty blotch and flyspeck in their cover sprays. According to the sooty blotch and fly speck model on MSU Enviro-weather, symptoms can be expected after 240 to 290 hours of wetness. Hours of wetness vary from 200 to 300 hours across the region. Codling moth egglaying and hatch is still underway for first generation. According to the codling moth model on MSU Enviro-weather, we are past peak egg laying and probably two weeks away from first emergence of the second generation.

Growers should be scouting for obliquebanded leafroller larvae. The obliquebanded leafroller model on MSU Enviro-weather indicates peak egg hatch is in the southern portions of the region. We expect to see oriental fruit moth larvae damage to fruit any time now. Green aphid populations are building on succulent leaf tissue.

Pear crop potential is generally good. Bartlett average up to 1.125 inches in diameter and Harrow Sweet are 0.875 inches in diameter. Growers are removing water sprouts from trees in order to discourage pear psylla populations. Pear psylla numbers are increasing.

Small fruit

Japanese beetles have begun to emerge. Only a couple spotted wing Drosophila (SWD) were trapped in Berrien County.

Grapes have buckshot-sized berries in Concord and Niagara, and bloom is ending in hybrid and vinifera wine grapes. During early fruit development, grape flower and fruit clusters are vulnerable to infection from powdery mildew, downy mildew, black rot and phomopsis, and latent infections of Botrytis. With frequent rains, many growers will still apply protectant and systemic fungicides with activity against all of these diseases. See “Protect grape clusters from all major grape diseases during early fruit development” for more information. Leaf infections of phomopsis and black rot are developing where early-season coverage was not achieved, and the first symptoms of downy mildew have appeared in unprotected clusters of vulnerable varieties.

First generation grape berry moth flight is over, and larvae are webbing in clusters. This early in the season, the loss of berries is compensated by later berry growth, and sprays for these larvae are not recommended in most cases. MSU Extension recommends most growers do not need to spray for grape berry moth until second generation egglaying. Wild grape bloom was around May 26 in Berrien County and June 1 in Van Buren County, varying somewhat from farm to farm. This date is used in MSU Enviro-weather’s grape berry moth model to time insecticide applications for the second and third generation egglaying. Second generation egglaying is predicted to occur in about two weeks during the first week of July.

Rose chafers are present in some vineyards in Berrien County. In wine grapes, scout during the coming weeks for potato leafhoppers, which arrive on storms and winds from the south. Look for grape leafhoppers in juice grapes. Usually, only severe outbreaks of these insects require treatment. Japanese beetles are emerging.

Blueberry fruit are sizing well with all the rain. Fruit on early varieties are coloring and harvest of early varieties will start this weekend in southern Berrien County. We are still catching cherry fruitworms and cranberry fruitworms for several weeks and these moths are laying eggs on green fruit. Most growers have applied insecticides to control these insects and fungicides to protect the green fruit from anthracnose fruit rots and stem blights such as phomopsis. Growers with vigorous growth from the base of the plants should direct fungicide on these new shoots to protect them from shoot diseases. No blueberry maggot flies have been trapped. A few SWD have been trapped in the region, but there is no need to protect green fruit.

Early ripening blueberry fruit
Early ripening blueberry fruit.

Strawberry harvest is ending for many growers. Fruit quality suffered due to heavy rains. Growers should prepare to renovate their fields. Strawberry renovation should be done as quickly as possible after the end of harvest. In June bearing matted row systems, the rows are narrowed after harvest using a rototiller or by herbicide sprays. Often, the field is mowed and broad spectrum contact herbicides are applied to kill unwanted weeds in the plant. Longer acting soil residual sprays are also applied to control more weeds during strawberry renovation. After field work is done, be sure the field has adequate moisture and irrigate if necessary. Be sure to protect leaves against potato leafhoppers and strawberry foliar diseases.

Raspberry fruit is developing rapidly. Black raspberries are coloring and black cap harvest will begin soon. Primocane blackberry bloom continues. Red summer raspberry harvest has begun in some farms. Japanese beetles can be a problem in raspberries. Grower need to time their controls with harvest. Raspberries are very attractive to SWD and growers should pay close attention to protecting against this pest. See “Spotted Wing Drosophila Management Recommendations for Michigan Raspberry and Blackberry Growers” for more information.

Upcoming meetings

Our final Monday fruit IPM meeting is June 29 at Fruit Acres Farms, 3452 Friday Rd, south of Coloma, MI 49038 at 5 p.m. Two Michigan pesticide applicator recertification credits will be given for these meetings.


Fruit growers who suffered plant loss due to severe winter cold the past two winters should contact the Farm Service Agency (FSA) to document the loss. See “Relief may be available for fruit, nut and ornamental growers with winter injury” for more information.

See also

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