East Michigan fruit update – May 29, 2018

The next few days will be key for apple thinning. With ragtag bloom still remaining in some apple varieties, the risk of fire blight infection remains high.

Weather

The flip-flop weather of spring continues with the unusual warm weather of the past week. We had one of the coldest April’s on record, and now it appears we may have one of the warmest May’s on record. With the heat of the last week, all fruit crops grew at a very rapid pace.

With continued warm temperatures, our season has yet again moved forward this past week to a point where we are now between three and seven days ahead of normal in terms of growing degree-day (GDD) totals. For crop stages, we are still behind normal, but the degree being behind is really crop specific. For example, strawberries are still in bloom, most years by this time of the season we have thimble-sized fruit to even having a few berries on the ends of rows that are ripe. How this wide swing of temperatures will impact harvest windows of fruit crops later in the summer is yet to be seen.

Hot temperatures and windy conditions have dried soils quickly over the past week. In in the southern tier of counties that had excessive rain just two weeks ago, wet holes are still damp, but most of their soils are on the dry side. For growers to the north, newly planted tree and small fruit crops are starting to show signs of water stress. Even established strawberries need a good watering.

There were some narrow bands of thunderstorms that moved over the region Saturday and Sunday evenings, May 26 and 27. Most folks who received these storms received close to 0.5 inch of rainfall. As a result, there were a few areas that had a wetting event for apple scab and fire blight management.

East Michigan GDD totals for March 1 to May 28, 2018

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

704

591

422

Deerfield (Monroe County)

783

656

472

Emmett (St Clair County)

655

548

392

Flint (Genesee County)

757

639

465

Freeland (Saginaw County)

683

570

405

Lapeer (Lapeer County)

694

584

420

Pigeon (Huron County)

594

494

348

Romeo (Macomb County)

741

626

456

Tree fruits

Apples are mostly in the range of 7 to 9 millimeters in diameter, with Idared and Zestar being 10 to 14 millimeters in size. The next few days are a critical time for thinning in apples, as temperatures will be more favorable for thinners and most fruit will be close to 10 millimeters in size. The need for thinning varies greatly between varieties and site. Growers will need to do a close inspection of every variety and block to determine the need for and the rates of thinners to use this season.

There are several new insect pests to report in apples this week, including plum curculio adults and feeding injury, rosy apple aphids on leaves, white apple leafhopper adults and European red mite adults. A few tarnished plant bugs continue to be found. Oriental fruit moth and codling moth adult trap catch remains low for most growers, with the exception of just a few growers that traditionally have much higher catches. Redbanded leafroller and spotted tentiform leafminer trap catch has dropped off to near zero in the last week, and growers who applied an insecticide are no longer finding leafroller larvae feeding in fruit clusters.

I found my first apple scab lesions on leaves yesterday morning, May 28. A few growers had an apple scab infection period from thunderstorms on either Saturday or Sunday evening. I continue to catch apple scab spores with each wetting event, but the numbers of spores continue to decline. There is a fair amount of ragtag bloom that is open in some apple varieties. Fire blight control has been a major issue across the region over the last week, with very high EIP numbers predicted in the Maryblight model if the right weather conditions exist.

Pears are 8 to 13 millimeters in diameter. All stages of pear psylla are being found in some blocks.

Peaches are out of the shuck for most varieties and fruit is mostly between 6 to 8 millimeters in size. I am finding a few green peach aphids as of yesterday and continue to find a few green fruitworms in peaches.

Sweet cherries are mostly between 9 and 12 millimeters in diameter. I continue to find a few black cherry aphids in sweet cherries.

Tart cherries are 8 to 10 millimeters. Some blocks have seen a good amount of fruit drop in the past week.

Plums are still at shuck split for European types and Japanese varieties are 6 to 10 millimeters in diameter. Some Japanese varieties have a very light crop on them, most likely due to poor pollination.

Small fruits

Strawberry bloom is still present in most varieties, with some fruit set just starting to take place. No thimble-sized berries were seen yesterday in my travels. It was unusual to see this long of a bloom period in strawberries. It looks like we will have a late strawberry harvest this season. A few spittle bugs were found yesterday. I have not seen any strawberry clipper injury on blossoms or young fruitlets. Be on the lookout for strawberry clipper and tarnished plant bugs. Most growers have applied a second or third fungicide as strawberries remain in bloom. Weather condition have also been favorable for angular leafspot infection.

Raspberries put on a great amount of growth in the past week, with the longest canes reaching 20 to 24 inches in length, and a good number of new canes continue to emerge from the soil. Bloom is now open in many varieties of summer raspberries.

Blueberries are at late bloom to petal fall.

Saskatoon fruit are 6 to 7 millimeters in diameter. I have not seen any apple curculio feeding injury yet this season.

Grapes also put on a good deal of new growth in the past week. The longest canes are 10 to 16 inches in length, with flower clusters at the per bloom stage. 

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