East Michigan fruit update – May 1, 2018

Bob Tritten, Michigan State University Extension - May 01, 2018

Spring is finally upon us, pushing green tissue development in most fruit crops. With rain predicted late in the week, apple growers are covering today and tomorrow for their first possible apple scab infection period.

Weather

With warmer daytime temperatures in the last week, degree days have nearly doubled for most of our Enviroweather stations. Most fruit crops are finally seeing the start of green tissue development. That being said, this morning was our first warm night/morning, with this change and warm rain predicted for later this week, the pace of fruit crop development should pick up considerably.

This being said, our season is still between 12 and 14 days behind normal. Based on the short and medium-term weather forecast, I predict that we will be at pink in apples a week from now and then see bloom around May 18. We could have a very short or quick bloom period this season.

With the warmer days and windy conditions, our soils have dried considerably over the last week. A good amount of planting was finally accomplished over the weekend and this week. Many growers have been applying herbicides to tree fruit crops.

As I have been writing in my last few reports, there has been some flower bud damage from winter cold temperatures in peaches and sweet cherries; and this week I am starting to see a touch of damage in a few varieties of apples. I continue to encourage peach and sweet cherry growers to hold off the start of pruning until the extent of possible damage can be accessed more fully.

Lastly, most of our honeybee hives do not have any activity in them thus far this spring. It appears that our honeybees have had a tough winter.

East Michigan Growing Degree Day Totals for March 1^st to April 30^th, 2018
Location	GDD42	GDD45	GDD50
Commerce (Oakland County)	125	91	47
Deerfield (Monroe County)	160	116	62
Emmett (St Clair County)	105	76	40
Flint (Genesee County)	143	105	57
Freeland (Saginaw County)	118	84	44
Lapeer (Lapeer County)	120	88	47
Pigeon (Huron County)	88	64	35
Romeo (Macomb County)	129	93	50

Tree fruits

Apples are at ½-inch green in the south and green tip to ¼-inch green in the north. Most growers have a nice crop of flower buds this season, however I am starting to see a few varieties that have a small portion of their flower buds that are only pushing out leaves and no flowers. High numbers (60 to 90) of redbanded leafroller, adults are being caught in traps this week. More average numbers (80m to 100) of spotted tentiform leafminer adults are being caught in traps. I catch just a few apple scab spores after last week’s wetting event. That wetting event did not turn into an infection period. While a few of our local Enviroweather weather stations have recorded an apple scab infection period this season, there wasn’t any green tissue at the time of infection, so growers did have not needed to cover for apple scab yet this season. Rain that is predicted for this Wednesday and Thursday will most likely be our first apple scab infection period. Many growers are applying copper ahead of this rain event. Most growers have finished with pruning apples.

Pear bud scales are separated to flower buds exposed. The last few days I am seeing numerous pear psylla adults flying.

Peaches are at swollen bud to calyx green. Michigan State University Extension encourages growers to hold off the beginning of pruning of peaches until flower buds become more visible to determine any possible crop loss from cold this winter.

Sweet cherries are at side green to a few being at early green tip. As was discussed in the Weather section of this report, there has been some flower bud damage in sweet cherries this winter. I am also encouraging growers to hold off any further pruning in sweet cherries until crop load can be determined more fully.

Tart cherries are at side green to a few being at early green tip.

Plums are at bud swell to side color for European types and Japanese varieties are at green tip to tight cluster.

Small fruits

Strawberries look much different this week than last week, as many leaves have emerged from the crown over the last week. Not many of these emerging leaves have started to enlarge as of yet. I am not seeing any flower trusses emerging from the crown yet. I am encouraging growers to make a light application of nitrogen to encourage more leaf growth in what looks like will be a late harvest season for strawberries this year.

Raspberry canes are just starting to emerge from the soil in both summer and fall bearing raspberries. Summer raspberry canes remain dormant.

Blueberries are at bud swell to bud break, with no green tissue showing yet. Pruning continues in blueberries.

Grapes are at dormant to early bud swell. Pruning continues in grapes.

This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).