East Michigan fruit update – May 9, 2017

Frosty conditions for the last four mornings have concerned some fruit growers. Cold temperatures over the last week have dramatically slowed growth of fruit crops as well as insect development.

Weather

Cold temperatures over the last four mornings have been a concern for the region, with a few fruit growers seeing low morning temperatures in the 26- to 27-degree range and most seeing low temperatures in the 29- to 32-degree range. For some, the coldest morning was Monday, May 8, and for others it was this morning, May 9. As of yesterday afternoon I have already seen some flower/fruitlet damage or loss in apples in low-laying areas. I did not see any crop loss in stone fruits in areas north of I-96.

Cold temperatures have stalled development of fruit crops to a standstill over the last week. Most of the region accumulated less than 10 degree-days base 50 over the last week; I have never seen such little growth. Most days in spring we accumulate more degree-days in one day than we saw for the entire last week. Thus, our season has dropped back to being just a few days ahead of normal to being a few days behind normal.

While pollinators were active for a few short windows in the last week, how well our tree fruit crops have been pollinated is still questionable. Very windy conditions over the last two weeks have also been a concern. Combine these two factors with the frost and freeze events over the last four mornings, and apple growers are going to make the possibility of early thinning decisions a very difficult one. Michigan State University Extension suggests growers hold off early thinning for a few days for apples to be 8 millimeters or so to better assess fruit load.

Most of our region received rain over the last week, adding to an already wet spring. However, precipitation totals vary widely over the region, ranging from only a few tenths of an inch to just over 2 inches. Most growers finished planting tree and small fruit crops, but some are still holding off for soils to dry.

East Michigan growing degree day totals for March 1 to May 8, 2017

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

387

288

166

Deerfield (Monroe County)

502

382

228

Emmett (St Clair County)

350

258

147

Flint (Genesee County)

444

338

204

Freeland (Saginaw County)

360

270

164

Lapeer (Lapeer County)

412

314

192

Pigeon (Huron County)

295

213

125

Romeo (Macomb County)

394

293

169

Tree fruits

Apples are at late bloom to petal fall in the southern parts of the region and late full bloom to very early petal fall for most of the rest of the region, with the exception of growers close to Lakes Erie or Huron who are further behind. Later varieties, like Northern Spy, are at king to full bloom. For most growers, this has been a very long bloom period, maybe one of the longest growers can remember. Please refer to the weather section of this report for comments on pollination, cold temperatures and windy conditions as it relates to early thinning decisions.

New insect pests to report this week in apples include a very few green apple aphids and a few tarnished plant bug adults. Overall, insect pests have been at a standstill over the last week due to cold weather. Oriental fruit moth and redbanded leafroller trap catch continues at a slow pace. Obliquebanded leafroller larvae are on terminal leaves, with some leafrolling taking place. Small fruittree leafroller larvae are also being found. Spotted tentiform leafminer adult trap catch is on the decline for the first generation adult flight. Beneficials are being found, but in low numbers.

Apple scab leaf lesions started to be seen in a few apple blocks early to mid-last week. Most MSU Enviroweather stations had one apple scab wetting event this past week. Spore discharge continues with each rain event. With bloom continuing in apples, growers need to concerned about fire blight infections, especially where fire blight was a problem last season. The Enviroweather website has a great MaryBlyt tool to determine fire blight infection events. Also, be on the lookout for oozing fire blight cankers where it was a problem last season.

Pears are at petal to 6 millimeters in size. Pear psylla adults are flying.

Peaches remained mostly in the shuck for the last week. I have not seen any frost or freeze damage in peaches. Oriental fruit moth trap catch continues. Most growers have a good crop of peaches this season.

Sweet cherries have been in the shuck for the last week, with a slight bit of bloom remaining in many varieties. A few early varieties are at shuck split.

Tart cherries are at late bloom to being in the shuck.

Plums are in the shuck for European types and Japanese types out of the shuck to 7 millimeters in size. Some Japanese varieties have little to no crop on them this season.

Small fruits

Grapes are at bud burst for Concord and European varieties, just about the same as last week.

Strawberry growth has been at a standstill for the last week, with early bloom at the ends of rows and field edges. Flower trusses and new leaves are emerging from the crown. Most growers have frost protected three to four times the past few days, some starting just after midnight on Sunday night/Monday morning.

Raspberry leaves are emerging from the bud with flower bud emergence just starting for summer fruiting types, with tip dieback on many varieties. New canes are emerging from the ground in fall raspberries; the longest canes are 4 to 6 inches long.

Blueberries, also at a standstill, are at early bloom for early varieties with most varieties at late pink bud. Overall, we are around 10 percent bloom. Flower buds on many early flowering varieties have turned a deep shade of pink over the last week due to cold temperatures. I have not found any signs of mummy berry mummies on the ground.

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