Northwest Michigan fruit update – May 31, 2022
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EmailRain in the area was helpful with our dry conditions. Cherries are coming out of the shuck, and apple growers are working on thinning.
Weather report
We are in the middle of heat wave, but after the storms move through this evening, we will be back to more ‘normal’ conditions (Figure 3). There is some threat for severe weather overnight, but southwestern lower Michigan is at particular risk compared with us. There are predictions of high winds and hail for this evening, May 31. Overall, temperatures have been cooler than normal in the north with more rain this past week. Even with the cool temperatures this past week, we are still ahead of normal (Figure 4), but the northern part of the state remains cooler than other areas of the fruit growing regions. We are forecasted to have a hot and windy day today, May 31, with strong south to southwest winds that could reach up to 25 mph. This type of weather is good for bringing up insects on the storm fronts. By Thursday morning, there still could be some isolated showers. By Friday and into the weekend, we are predicting to see more seasonal temperatures and drier conditions through Saturday and by Sunday or Monday, we might see some more rain coming into the region. Conditions will be sunny. There is an active storm track through June, and greater than normal chances for precipitation. The longer-term forecast is still predicting warmer and wetter trends for the first half of June.
We have accumulated 613GDD base 42 and 333GDD base 50 for the NWMHRC. Our 33+-year average is 609.7GDD base 42 NS 307.5GDD base 50.
Crop report
The warm and cold temperatures have been a start and stop for crop development.
Pest update
With the recent quick warm weather, insect activity is likely to move along, but cooler weather will decrease activity this week.
Green Fruit Worm. We caught no green fruit worm this week.
San Jose Scale. We caught 26 male SJS this week. Activity will slow with the cool weather, and growers with a scale issue should be treating next week. Growers should consider Sivanto or Centaur to target SJS, and there is enough leaf area so now Movento could be used.
Lesser Peach Tree Borer. We caught our first LPTB moths this week. The numbers are very low, but growers that have had issues in the past should be aware that this pest is flying. Lorsban is not an insecticide for trunk sprays unless it is a NON-BEARING block.
American plum borer. We caught an average of 7 APB moths this week.
Black stem borer. We caught an average of one BSB again this week. Growers with BSB issues in past should be considering control strategies. Unfortunately, Lorsban is no longer an option, and Warrior is the best insecticide for BSB control.
Codling Moth. We caught our first codling moths this week. This pest prefers to fly on warmer nights, so likely, we caught them this past evening. With the weather cooling down, CM flight will decrease. Growers should monitor blocks as this pest is regional in its habits. If we catch CM next week, today will be our biofix date. We will keep growers posted.
Disease update
Cherry Leaf Spot. With the fruit coming out of the shuck, growers should be aware of cherry leaf spot. This disease is an issue with open leaves and open stomata, both of which are open at this time. The ascospores shoot up from the overwintering leaves into the fresh tissue, and the fungus invades through open stomata. Growers should cover up new tissue, but there is little rain in the forecast until June 5.
Powdery Mildew. This disease loves warm and dry weather. There may have been an early jump on mildew this year with the warm and dry weather. We have done some work on PM, and we have found that the optimal timing for control is first cover, and then growers can reduce their sprays for this disease. (Figure 4).
Apple scab. Apples at the NWMHRC are at petal fall, but there are some tag bloom in our Gala and Honeycrisp. The warm weather will continue the concern for blossom blight (Figure 6), and EIPs are in the 400+ for today, May 31. However, after today, conditions will cool and the fire blight model is predicting low EIPs.
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Fire blight. Apples at the NWMHRC are at petal fall, but there are some tag bloom in our Gala and Honeycrisp. The warm weather will continue the concern for blossom blight (Figure 6), and EIPs are in the 400+ for today, May 31. However, after today, conditions will cool and the fire blight model is predicting low EIPs.
