Southwest Michigan fruit regional report – June 24, 2014

Strawberry harvest is winding down. Cherry harvest has begun.

Fortune plum showing bacterial spot symptoms. Photo credit: Bill Shane, MSU Extension

Fortune plum showing bacterial spot symptoms. Photo credit: Bill Shane, MSU Extension


The weather last week was warm with highs in the upper 70s and 80s. Overnight lows were in the mid to upper 60s. Lows dropped into the 40s over the weekend. Wide spread rain fell across the region Wednesday, June 18, Saturday, June 21, and Monday, June 23. Rainfall totals varied from a third of an inch to over 3 inches, with 50 to 60 mph winds on Monday evening in advance of the rain. Soils are moist, but will dry out quickly. Currently the ET and rainfall has been relatively equal. Soils were warm with temperatures in the 60s. This coming week will be similar to last week; warm and wet. High temperatures will be in the 80s and lows in the 60s. Rain is in the forecast for most of the week. Last week we picked up about 200 growing degree days (GDD) base 42, about 28 per day, and 150 base 50, about 21 a day. GDD accumulations lag a little behind our long term average, but similar to 2013, 2011 and 2009. See the growing degree days for the last five years at Bainbridge in northern Berrien County. We seem to be about three or four days behind our long term average.

Southwest Michigan GDD summary from Jan. 1 through June 22, 2014


GDD 42 F

GDD 45 F

GDD 50 F

Benton Harbor (SWMREC)




Fennville (TNRC)




Average for the region




Tree fruit

Hand thinning of apples, peaches and pears is still underway. San Jose scale crawlers were detected late last week in central Berrien County.

Apricots are over an inch in diameter with hard pits and foliage looks good.

Peach fruit are 1.25 to 1.5 inches in diameter, with pit hardening a week off. Redhaven harvest for Central Berrien County is predicted to begin approximately Aug. 3, based on a GDD model developed at Michigan State University.

Oriental fruit moth catch still continues to decline with the end of the first generation. Both greater peach tree borer and lesser peach tree borer adults have been flying for three weeks. Borers require trunk sprays or pheromone disruption. Bacterial spot symptoms are becoming easier to see on leaves of susceptible varieties. The wind storm of Monday, June 23 will likely spread this disease to fruit. Peach fruit are most susceptible to bacterial spot infection from shuck split to pit hardening. Peach fruit with susceptibility to rusty spot disease should be protected from shuck split to pit hardening. Controlling this disease in nearby apples should help to manage rusty spot because they are caused by the same pathogen.

In cherries, plum curculio egg laying is ending. Growers also need to protect against cherry leaf spot. Birds are actively feeding in sweet cherry orchards.

Sweet cherry harvest of early season varieties started in southern Berrien County last week. Fruit cracking up until the rain of Monday evening was minimal. The smell of grapes is common near sweet cherry orchards from grower use of methyl anthranilate to repel birds. Growers need to protect against cherry leaf spot. Sweet cherry fruit is always susceptible to brown rot and growers are reminded that Michigan State University Extension has found that brown rot resistance to FRAC code 11 fungicides (strobilurins) in the area.

Tart cherries range from amber to red—quite a wide range of color. Cherry leaf spot lesions are easy to find in some orchards with some leaves already dropping. Growers should be continuing to apply sprays to control cherry leaf spot. Ethephon sprays to facilitate mechanical harvest are applied after all the fruit have colored to yellow.

In plums, Japanese plums are 1 to 1.25 inches in diameter, and European plums are 0.875 to 1 inch. Bacterial spot fruit symptoms are beginning to show in Japanese plum. Fruit drop is continuing in some varieties. Black knot, plum curculio and American plum borer are the primary pest concerns.

Apple fruit range from 1.5 to 2 inches in diameter. Deer feeding has increased now that young fawns are old enough to allow them and their mothers to move about. Apple scab primary ascospore season is effectively over. Fire blight symptoms on terminal shoot growth are becoming easier to see, mainly in older orchards with a perennial problem. The wind and rains of June 23 will likely spread this disease further.

The North Carolina model for sooty blotch and fly speck diseases indicates we have received approximately 180 hours of the 250 or more hours of wetness needed for symptoms, so symptoms may be about one week off. Oriental fruit moth, and more recently codling moth, catches have declined. Spotted tentiform leafminer numbers are declining, with new mines in leaves expected soon. Obliquebanded leafroller egg hatch is expected to begin approximately July 1 for Central Berrien County.

More trees girdled by mice or rabbits are beginning to exhibit symptoms. Tree growth looks poor from a distance with yellow leaves as the trees exhaust the reserves stored in the bark and wood of the shoots. The roots are still able to supply water, but at a reduced rate. Eventually the trees will collapse as the roots starve or the top of the tree runs out of water. In many cases there are many new shoots coming up from the rootstock.

Pear fruit are 1 inch or more in diameter. The crop is fair to adequate. Primary scab season is essentially over. Fire blight strikes are generally rare. Growers continue to tear out watersprouts as a way to remove protective habitats for pear psylla. Pear psylla can be found in all stages of development.

Small fruit

Fruit have moved rapidly in the summer weather. Growers should be irrigating shallow rooted berry crops. Spotted wing drosophila (SWD) adults have been trapped in the region over the past week. From a total of 85 traps checked from 23 fields, 5 male and 21 female SWD were found. The captures were widely distributed across Southwest Michigan from Berrien, Van Buren, Allegan and Ottawa counties. A total of 11 flies were caught in Berrien and Van Buren counties.

Grapes are moving through shatter. Berries are sizing rapidly.

Southwest Michigan GDD Summary for grapes, from April 1 to June 22, 2014


GDD 50 F

Benton Harbor (SWMREC)




Fennville (TNRC)


Average for the region


Most growers have applied post bloom sprays to control black rot, phomopsis, powdery mildew and downy mildew. Rose chafer numbers have peaked and are declining. Grape berry moth larvae are feeding in clusters. Michigan State University Extension recommends that growers target the second and third generations of grape berry moth. Tumid galls and red swelling on the leaves, stems or tendrils have been reported, and larvae exited a sample brought to for identification. This is a spotty problem that seldom requires treatment.

Blueberry fruit are sizing rapidly. The warm, moist conditions are good for plant growth and growth looks strong. Post bloom pesticide applications are focused on preventing fruit rots and leaf spots. Brown fruit rot has been reported in some areas but the cause is uncertain. The crop is variable with more fruit in the northern growing areas and close to Lake Michigan.

Strawberry harvest has moved quickly. Fruit quality has been excellent. With the emergence of spotted wing drosophila in the region this past week, growers need to protect fruit.

In brambles, floricanes have green fruit. Some growers report that bloom of the primocanes of some fall bearing berries has begun.

Upcoming meetings

The next weekly and final Monday fruit IPM meeting for this season is June 30 at Fruit Acres Farms, at 3452 Friday Rd, Coloma, MI at 5 p.m. Two Michigan restricted use pesticide (RUP) applicator recertification credits will be given for these meetings.

A Twilight Pre-Harvest Blueberry Meeting is scheduled next Wednesday, July 2 at the Olive Township Hall from 6-8 p.m. The meeting is a repeat of last week’s meeting near South Haven. There will be two RUP credits available at this meeting. For more information see 2014 Blueberry pre-harvest meetings.

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