West central Michigan tree fruit update – July 27, 2021

Tart cherry harvest is over in west central Michigan, and peaches are sizing.

Weather report

It is summertime in west central Michigan. Growers have been enjoyed warm daytime temperatures in the mid-70s to low 80s degrees Fahrenheit for the past week. Daytime highs did hit 85 F yesterday, July 26. According to the Hart Enviroweather station, we have accumulated 2,183 growing degree days (GDD) base 42 and 1,394 GDD base 50. These accumulations are similar to northwest conditions where they have accumulated 2,204 GDD base 42 and 1,420 GDD base 50. The spread of accumulations between growing regions is less than in most years.

The region did receive some rainfall on July 23, and the Hart Enviroweather station recorded 2.08 inches of rain. According to Jeff Andresen, more rain is coming Thursday and perhaps some isolated rain showers on Saturday, July 31. Once the front moves through on Thursday, cooler conditions will prevail over the weekend. Next week, conditions should warm again. Andresen is predicting August to be warmer than normal.

Crop report

Tart cherry harvest is over in west central Michigan. On the Michigan State University Extension fruit team call, there were concerns about split pits in peaches. In addition to the split, growers are concerned about the insect pests that infest this damaged area. As mentioned in the 2021 predicted apple harvest dates article, apple harvest is expected to be earlier throughout the state as in past years, likely due to the early heat.

Pest and disease report

Diseases

Primary apple scab season is over for west central Michigan. If growers were successful in controlling primary scab, there should be little concern for fruit scab. However, if scab was able to get a toe hold on foliage, fruit must continue to be protected.

As many growers have finished harvest, we recommend trees keep their leaves into September to minimize chance of cherry leaf spot damage if we have a hard winter. Chlorothalonil or captan are good choices for a post-harvest application. If growers have been clean of leaf spot until now, these orchards may not need a post-harvest application. We rated our leaf spot efficacy trials, and even the UTC is surprisingly clean this season compared to past seasons, particularly those with wet springs that really jump start leaf spot infection early. This dry spring minimized early infections, and the weather reduced the amount of leaf spot we are seeing in orchards later into the season.

We have observed higher than normal levels of powdery mildew in both apple and cherry. This disease is favored by hot and dry conditions, both of which we have had this season. This disease often takes a back seat to leaf spot and apple scab, but this year, this disease is much more of a concern. There is a lot of mildew on new shoot growth in tart cherries, and as a result, powdery mildew makes the leaves brittle and are easily removed during the shaking process. Unfortunately, there is little growers can do to eradicate this disease once we can see mycelial growth on the leaves.

Insects

We are fortunate to have Kenna Schwass on board in the west central region to help scout for insect pests, and she will be scouting in peaches and apples for the remainder of the season.

We caught 22 peach tree borers in the past week at one peach orchard in Elbridge, and we caught another five borer moths in a New Era orchard. The trap was set at the west central station last week, and we caught 31 peach tree borers this past week. We have caught an average of four greater peach tree borer moths this week in three traps in peaches.

We observed variability in oriental fruit moth in our three traps: zero in New Era, 10 in Elbridge and one in west central station.

We caught seven oriental fruit moth this week in apple in a block in Elbridge and none at the orchard in New Era. Codling moth numbers were zero at our trap in Elbridge and one moth was found in the codling moth trap in New Era.

We found 16 San Jose scale males in Elbridge and 30 in New Era. Growers should be proactive in apple as this is the stage of this insect that can injure fruit.

We did not detect obliquebanded leaf roller in our traps in any apple traps this week.

We found five black stem borers in one trap in New Era and 11 black stem borers in the trap in Elbridge.

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