East Michigan fruit update – May 15, 2018

Apples are in bloom across the region. Apple growers across the southern two triers of counties have had a very long wetting event, making for tough conditions for apple scab and fire blight management.

Weather

The stationary cold front parked over the region just north of the Ohio border since late last week has brought good amounts of rain to the region. Rainfall totals over the last week have varied widely for the region, but generally the further southern areas of the region received more rain, as high as 3 inches. The Deerfield and Emmett Michigan State University Enviroweather stations are experiencing a 91-hour wetting event that is ongoing at this writing. This has been a challenging time for apple scab and fire blight management.

Continued warm temperatures have moved our season forward to a point where we are about four to six days behind normal in terms of growing degree-day (GDD) totals, and about seven days behind normal when I look at growth stages. We had a quick bloom period in tart cherries this past week, and the same could happen in apples this week.

Some growers have been able to do some planting in the past week, while most others have soils that are too wet for planting and other fieldwork. Most growers have completed planting.

Bee activity has varied widely as more of our fruit crops have been in bloom. Many honey bee hives did not overwinter well and have been replaced this spring. In my travels yesterday, May 14, I was surprised not to see more honey bees working in apples. On the other hand, I did find a good number of honey bees working in pears. There seems to be a good population of bumble bees this season.

East Michigan GDD totals for March 1 to May 14, 2018

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

375

305

203

Deerfield (Monroe County)

437

352

238

Emmett (St Clair County)

351

285

194

Flint (Genesee County)

420

344

237

Freeland (Saginaw County)

364

293

195

Lapeer (Lapeer County)

362

295

202

Pigeon (Huron County)

306

246

165

Romeo (Macomb County)

394

321

219

Tree fruits

Apples are in bloom over most of the region. More specifically, for growers in the south, the early bloomers are at petal fall and Gala are at full bloom. Apples to the north are a few days behind this, with many varieties at king bloom and a few at full bloom. Most growers had a nice crop of flower buds coming along this season; a few weeks will be needed to determine pollination and fruit set.

First catch of oriental fruit moth adults in traps was reported last week, more growers reported first catch this week. Just a few growers had high enough numbers for biofix for this pest. Good numbers (70 to 100) of redbanded leafroller adults continue to be caught in traps for the third week in a row, and late last week and yesterday I found a good number of redbanded leafroller larvae feeding in apple flower clusters. It is a bit unusual to see this feeding so early, and where apples are not in bloom a pink spray may be needed to control this early season feeding injury. Where apples are in bloom, growers will need to get on their petal fall spray quickly to control them.

A lone tarnished plant bug was seen yesterday in one apple block; this is the only new pest to report for this week. High numbers (300 to 500) of spotted tentiform leafminer adults continue to be caught in traps for the second week.

With all of the rain of the past week, growers have been very busy controlling apple scab. Most of the region had between two and four wetting events in the past week, and almost all areas had at least one infection event, many with two infection periods. A few of our weather stations are in a 91-hour wetting event at this time, which is one of the longest wetting events I can remember. I had high catches of apple scab spores after all four of the rains at my trapping location in the past week.

With wet conditions and warmer temperatures, EIP numbers for fire blight infection are now critical. The fire blight prediction tool for blossoms is showing numbers above or over the 80-cutoff number. Remember, apple blossoms that open after a streptomycin application are not protected.

Pears are at full bloom. High numbers of pear psylla adults are being found in some blocks.

Peaches are at petal fall to post bloom for most varieties. Most growers in the southern areas of the region had a good crop of blossoms, so normal pruning is taking place for these growers. For peach growers to the north, the crop is extremely variable. Good sites had a full crop of bloom and marginal and poorer sites had just a few flowers. Pruning can begin in these areas as well, but the extent of the pruning will need to be adjusted to the crop load. It will be hard for the pruning crews to adjust from tree to tree as there is so much variability. Trees with a short crop will need to have less pruning done, maintaining as many fruits as possible.

Sweet cherries are in the shuck in the south and petal fall to the north. I see much less winter damage in sweet cherries than I am seeing in peaches. So, most growers can continue with normal pruning of sweet cherries when weather conditions are dry.

Tart cherries are at late full bloom to being in the shuck in the south, and to the north at early petal fall. Tart cherries moved through bloom very quickly this season. I hope there was enough good pollination weather for bees to work. There is a fair amount of fine wood or branch death in tart cherries at many farms this year. Most of this deadwood is the result of not controlling leaf spot last season combined with winter injury.

Plums are at petal fall for European types and Japanese varieties are in the shuck.

Small fruits

Strawberry flower trusses continue to emerge from the crown, with a few early varieties at 10 percent bloom. Leaves have started to enlarge at most farms. This being said, strawberries generally do not have their normal “look” or vigor for mid-May. Be on the lookout for strawberry clipper injury as blossoms open and young fruitlets form. It looks like we will have a late strawberry harvest this season.

Raspberry canes continue to emerge from the soil in both summer and fall bearing raspberries, with the longest canes being between 3” and 5” in height. Flower trusses are now visible on early flowering summer bearing floricanes. Cane dieback is now plainly visible on some varieties of summer raspberries, caused by cold temperatures this winter. These dead tips will need to be pruned back to living tissue over the next few weeks.

Blueberry flowers are at late pink bud for early flowering varieties, with most varieties at early pink bud. Leaves at late green tip to shoot expansion. Pruning has wrapped up in blueberries.

Saskatoon bloom ended last Thursday for most varieties.

Grapes are at 1 to 3 inches of early shoot growth. Pruning is wrapped up in grapes at most farms.

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