Frost Damage Possible in Mich. Fruit Until Mid-May
Published: Friday, May 15, 2026
The update is based on May 6 data.
Apricot trees have small fruit in central Berrien and Van Buren counties, with an average of 7 millimeters (mm). Controlling plum curculio now prevents unmarketable fruit later in the season. The first catches of plum curculio occurred two weeks ago in Berrien County.
This week is a control window for plum curculio with neonicotinoids and other insecticides.
Peaches and nectarines are sizing, with early cultivars approaching 8 mm and splitting from the shuck. Now is the time when fruit buds that were damaged by cold or not successfully pollinated will fall off. A good way to quickly check crop load is to first count the number of fruit on a limb. Then, brush your hand against the fruit and count how many fall off. The proportion that remains is the proportion of fruit that is likely set.
Brown rot pressure is expected to be low for the upcoming week, as temperatures will remain lower than necessary for disease progression. When weather favors infection, prioritize high-efficacy materials with rotation among FRAC groups and ensure applications are made ahead of rainfall events with strong coverage throughout the canopy.
Plum curculio continues to be caught in Berrien and Van Buren counties. There were no new catches at the Trevor Nichols Research Center in Allegan County this week. Cool temperatures have slowed down its movement. Check traps close to your orchard to get a better understanding of the insect pressure.
Selecting insecticides for plum curculio should prioritize rapid knockdown of immigrating adults combined with enough residual activity to protect newly exposed fruit during the oviposition window. Broad-spectrum materials with strong efficacy on plum curculio, such as Imidan 70 WP, Avaunt 30 WG, Voliam Flexi or Besiege, provide the most consistent control and are well suited for blocks with confirmed activity.
Pyrethroids including Warrior II, Mustang Maxx and Baythroid XL can be highly effective during warm periods of active movement due to their fast knockdown, though their shorter residual and impact on beneficials should be considered. Neonicotinoids like Assail 30 SG or Actara 25 WG offer additional activity but generally require higher rates or tank-mix support for reliable plum curculio control.
In all cases, choose products paired with tight application timing at petal fall, followed by additional coverage based on temperature-driven activity. Protection must be in place before egg laying begins to prevent irreversible fruit injury.
Plums are around 8 mm and sizing. Management should focus on maintaining a consistent protective program, timing insecticides with periods of pest activity and keeping fungicide coverage ahead of rain events to limit infection during early fruit development.
In cherries, tart cherries and sweet cherries are in shuck split in Berrien and Van Buren counties.
This stage marks a transition as the developing fruit emerge from the shuck and become increasingly susceptible to disease and insect injury. Warm, wet conditions during shuck split strongly favor brown rot infections, particularly as exposed fruit tissue and senescing floral parts create ideal infection sites.
Fungicide applications should therefore be timed ahead of rain events using effective materials with strong residual activity and excellent canopy penetration.
At the same time, shuck split signals the beginning of meaningful insect pressure as fruit become exposed and vulnerable to feeding and oviposition. Plum curculio, obliquebanded leafroller, green fruitworm and tarnished plant bug can all contribute to early fruit injury during this period.
Management should focus on a well-timed insecticide application targeting this transition, with products that provide both knockdown of active insects and residual protection as new fruit tissue develops.
Broad-spectrum materials such as Imidan 70 WP, Avaunt 30 WG, Voliam Flexi or Besiege offer strong control across multiple pests, while pyrethroids such as Warrior II or Mustang Maxx provide rapid knockdown during periods of active movement. Softer materials such as Surround WP or Entrust can be used in constrained systems but require tighter spray intervals and excellent coverage.
As with disease management, timing remains critical. Applications should closely align with pest activity and environmental conditions to prevent early-season injury that cannot be corrected later.
Most apple varieties are in petal fall and fruit set. Prolonged cool conditions during bloom have reduced pollinator activity and may have limited pollination efficiency in some orchards, particularly during periods of low bee flight and extended wetting.
Apple scab risk is still low over the next several days. While risk is low, maintaining adequate fungicide protection is important to stop the spread of disease during wetting events. Avoid copper beyond half-inch green to reduce the risk of fruit russeting. SDHI fungicides are excellent choices to control primary scab. The MSU Enviroweather apple scab model can be used to track infection periods and better time applications.
As fruitlets become exposed, plum curculio movement into orchards increases and oviposition injury can begin rapidly following warm evening temperatures. European apple sawfly, tarnished plant bug, green fruitworm and early obliquebanded leafroller activity may also contribute to feeding injury during this period. Protection
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