West central Michigan tree fruit update – May 21, 2019

Stone fruit is in bloom, apples are at pink and early insect activity is picking up.

May 21, 2019 - Author: ,

Weather

Cool weather over the past week has continued to keep tree fruit in west central Michigan growing at a slow pace, but soils are finally starting to warm up a little bit and warmer weather in the next week will help push the region through bloom quickly. Cold night temperatures on May 20 brought some concerns of a freeze event, but wet ground and some cloud cover helped keep temperatures above 32 degrees Fahrenheit throughout most of the region and no major freeze event occurred.

Growers have noticed light damage (10% or less) in sweet cherries and tart cherries in a few spots around the region, likely from the night of April 28 when some Michigan State University Enviroweather stations in west central Michigan reported temperatures as low as 26 F in the pre-dawn hours. Peaches and apples do not appear to have been impacted.

Growing degree day (GDD) accumulations continue to add up slowly, with stations running between 299-376 GDD base 42, 210-268 GDD base 45 and 106-157 GDD base 50.

Station

GDD base 42 current

GDD base 45 current

GDD base 50 current

Benona / Shelby

305

220

117

Elbridge / Hart

329

237

127

Hart

317

226

117

Ludington

299

210

106

New Era

376

278

157

Shelby - East

320

232

123

The region is now well behind our five-year average and even 2014, which was considered to be an extremely late year by growers. Warmer weather forecasted to arrive in the second half of the week and going in to the weekend should help move things along a little bit more, but the region is likely to remain behind for at least the first half of the growing season. This likely means later harvest dates, particularly for sweet cherries and tart cherries.

Year

GDD base 42

GDD base 45

GDD base 50

2019

317

226

117

2018

421

327

201

2017

551

417

250

2016

473

355

203

2015

474

367

229

2014

368

275

155

Average of 5 years

457.4

348

207.5

Crops

Apples are at pink, with some king blooms opening up on early varieties including Zestar and Gingergold. An apple scab infection event occurred May19-20 throughout the region; spore discharge was extremely high with the rains that arrived over the weekend. The first apple scab lesions are now visible on bract leaves in unsprayed orchards from the heavy infection event that occurred back on May 8-9.

Keep an eye on fire blight as the week goes on and more flowers open up. Some early bloom lead to concern about fire blight in the first half of this week, but generally weather was too cold for concern and management was not necessary. This is likely to change by the end of the week as weather moves towards the low 70s and rain arrives. Keep an eye on the MSU Enviroweather fire blight model as we move in to full bloom on our prominent varieties.

Codling moth is not active yet. Oriental fruit moth started flying this week, and obliquebanded leafroller overwintering larvae have been active in blocks with a history over the past two weeks. Apple grain aphid and rosy apple aphid can now be found. Black stem borer is also active at this time, so growers with blocks that have a history should be monitoring for adults and damage to the trunks of young trees.

Tart cherries are in bloom. Bract leaf expansion has been rapid in the past several days and growers have been out covering new foliage to protect from cherry leaf spot. We had a cherry leaf spot infection event over the weekend, and in most area orchards this represented the first major infection event of the season as the only other event that occurred in early May was at a time when little to no foliage was present.

Growers concerned about European brown rot infections should be putting another cover during bloom to protect from this disease, the first should have gone out at the popcorn stage. Indar is the product of choice for this purpose. European brown rot tends to be an issue in tart cherry orchards that are close to the lake, as this disease is favored by cool, humid and wet conditions during bloom.

Sweet cherries are in full bloom. The time is now past for most growers to use ReTain as this product needs to be out between popcorn and about 10% bloom to have an effect. Growers will be putting out an application for American brown rot sometime in the next week in most orchards.

Peaches are in bloom. Oriental fruit moth has been captured in some traps in the area; biofix will end up being around May 20 in west central Michigan this year. Brown rot sprays will go out sometime in the next week in most peach orchards. Growers will be timing the first insecticide of the season in peaches at petal fall and should be mindful to avoid pyrethroids for managing oriental fruit moth due to concerns of resistance. Tarnished plant bug was also controlled very effectively with pyrethroids, so be mindful of this and try to put out material outside of the pyrethroid insecticide class that effectively controls both oriental fruit moth and tarnished plant bug.

Tags: agriculture, apples, cherries, msu extension, peaches, west central michigan tree fruit


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