West central Michigan tree fruit update – May 10, 2022

Warm weather has rapidly advanced bud development this week, and some fruit trees will be in bloom by the end of the week.

Apple, peach, cherry and pear branches.
Figure 1. Stage of tree phenology for apple, peach, cherry and pear in Oceana County on May 9, 2022. Photo by Emily Lavely, MSU Extension.

Weather update

Warm weather is here this week and bud development is rapidly changing across west central Michigan (Figure 1). Based on the Michigan State University Hart Enviroweather station for May 10, current growing degree day (GDD) accumulation is 260.9 GDD42 and 102.7 GDD50 (Figure 2). Across the region, GDD accumulation is now similar to the five-year average (Table 1).

Warm weather will continue through the week with a slight cool down over the weekend. Highs will be in the 70s and 80s with lows in the 50s and 60s. Rain showers may occur on Tuesday and Wednesday this week. Rainy weather is also forecasted for this weekend. Temperatures will cool back down next week to be in the 60s and 70s.

There has been very little rain in the region over the past week. Soil has dried out enough for growers to be in the field, but there is adequate moisture to support nutrient uptake. Soil temperatures are also increasing, and at soil depth of 4 inches, the Hart Enviroweather station has recorded soil temperatures in the 50s and low 60s this week.

At soil temperatures above 45 degrees Fahrenheit, new roots are initiated, and roots become more active. Fruit trees use carbohydrate and nutrient reserves to support early season growth, but roots will also begin to take up nutrients from the soil. Growers are encouraged to apply nutrients over the next few weeks, particularly nitrogen, to support early season canopy development and fruit growth according to tree age and bearing stage.

Table 1. Current and five-year average GDD summary from Jan. 1- May 9. Numerical integration was used for degree day calculations.


2022 GDD base 42 F

5-year average GDD base 42 F

2022 GDD base 50 F

5-year average GDD base 50 F




































New Era**





*Averages were calculated using data from 2020-2021.
**Averages were calculated using data from 2018-2021.

GDD graph
Figure 2. Cumulative and forecasted degree days for base 42 F and base 50 F for the Hart Enviroweather station.

Weather data was gathered from MSU Enviroweather

More information and reports on normal weather conditions and departures from normal can be found on the NOAA Climate Prediction Center websiteNOAA U.S. Climate Normals websiteNOAA Climate Normals Quick Access Page (which may be searched by region) and Midwest Regional Climate Center website.

Crop update

Warm daytime and nighttime temperatures have advanced tree growth and flower development rapidly. Growers in the region have been finishing up tree trimming, brush cleanup, tree planting, and trellis system installation where needed. Bumblebee and honeybee hives have also continued to arrive in the region ahead of bloom for cherry, apple, peach, and pear. Plums and apricots are already in bloom this week, and many bees were seen foraging for pollen. As bloom gets closer, growers should consider how to protect and support native and commercial bees. Be sure to avoid capsulated insecticides during bloom, which can harm bees. If an insecticide is needed, use reduced risk insecticides such as Sivanto.

Apple varieties in the west central region range from half inch green to pink. Early varieties such as Zestar and Idared are at first pink. Later varieties such as Gala and Honeycrisp are at tight cluster. Hart is at 260.9 GDD42 and 107.2 GDD50. There are many fruit buds this year, and a heavy crop is expected for 2022. Consider thinning fruit early, starting with blossom thinning. Thinning early can be particularly important for varieties, such as Honeycrisp, that initiate flower bud development for the following season shortly after bloom.

For more information on thinning strategies for Honeycrisp in 2022, check out this article from Michigan State University Extension specialist Anna Wallis, “Honeycrisp crop management for 2022.”

Tart and sweet cherry buds range from bud burst to bloom. Weather is forecasted to be warm and dry over the next week which should support bee activity and good pollination. While good pollination conditions are expected, sweet cherry growers should consider applying ReTain to cherry blocks to enhance fruit set and yield. For more information about using ReTain, read this article by MSU Extension specialist Nikki Rothwell, “ReTain use to increase sweet cherry yields.”

Peach buds range from calyx red to first bloom.

Pear varieties range from blossom bud exposure to tight cluster.

Pest and disease update

In the west central region, greater insect activity is expected this week due to the warmer weather. Consider your scouting reports and block history to target hot spots for early season pests in the orchard according to bud stage.

Early season pests

On May 9, the Trevor Nichols Research Center in Fennville, Michigan, trapped the common apple pests red banded leafroller and spotted tentiform leafminer. Oriental fruit moth (average of 2.3 per trap) was also captured for the first time.

European red mite is in the egg stage. Scout for viable eggs that are bright red. If eggs are pale or clear, they are not viable. A miticide or oil may be used to manage mites at tight cluster. Hatch will begin during the pink stage and will continue through bloom.

San Jose scale is present in some orchards in the region. Targeted sprays or oils can be used for infested trees to manage scale and target adults.

Rosy apple aphid is a common pest in our region. Scout for eggs on the bark of apple trees. For early apple varieties that may already be at pink, check for colonies in fruit clusters and treat blocks as needed.

Black stem borer first flight for females is predicted to occur after two consecutive days above 68 F. For stone fruits, this typically occurs just before or during bloom. For apple, first flight typically occurs between half-inch green and pink. For the west central region, first flight is predicted to be about May 11.

Obliquebanded leafroller is predicted to have sustained catch on May 16 due to the rapid accumulation of GDD and warmer weather this week. Scout problem blocks in the coming weeks to determine if a spray is needed.

Redbanded leafroller adult fight is low in number in the region. Continue to monitor this minor tree fruit pest.

Oriental fruit moth biofix one is estimated to have occurred on May 9; however, trapped oriental fruit moth have not been reported in our region. First egg lay is predicted to be on May 12. Be sure to scout orchards and deploy mating disruption products prior to pink.

Apple scab

RIMPro forecast is predicting that emerging tissue in apple is at slight risk for an apple scab infection on May 11 and 12 (Figure 3). Warmer weather means that the scab fungus, Venturia inequalis, is more active and can infect leaf tissue quickly. With rapid tree growth in our region, it is important to protect new growth with adequate fungicide coverage. Coverage will also be important for pear blocks in the region for pear scab (Venturia pirina).

Rimpro graph
Figure 3. RIMPro forecast for Hart, Michigan.

Powdery mildew

Warm temperatures and high humidity this week may result in powdery mildew infection. Powdery mildew is caused by the fungus Podosphaera leucotricha. It affects apples and pears and causes infections on the underside of the leaf that lead to chlorotic patches or spots on the upper side of the leaf.

It is important to manage powdery mildew because infected blossoms can cause poor fruit set or stunted and russetted fruit. Note that sterol inhibitors, strobilurins, and succinate dehydrogenase inhibitors control powdery mildew. Captan, Scala, Vangard, and EBDC fungicides will not control powdery mildew. Spray for powdery mildew from tight cluster or bloom through midsummer.

Cherry leaf spot

Consider starting cherry leaf spot management once bract leaves emerge prior to bloom. Cherry leaf spot is caused by the fungus, Blumeriella jaapii. This fungus overwinters on the ground in diseased leaves. Fungal ascospores are released in spring during prolonged wetting events. In 2020, MSU plant pathologist George Sundin reported that spores can infect as soon as bract leaves emerge. Spores infect through open stomata, and stomates on bract leaves were shown to be open when they emerged from buds. Bract leaves are beginning to unfold in Oceana County, so an initial cherry leaf spot application may be needed depending on the orchard location. Disease pressure was high in 2021 in west central Michigan, and maintaining coverage of new tissue will be critical this season.

Fire blight

There was high fire blight pressure in west central Michigan in 2021, and it will be important for growers to manage fire blight as blossom blight and shoot blight this year, particularly in young, high-density plantings. Warmer temperatures this week may lead to more bacteria growth in cankers over the next few weeks, so keep blossoms protected once they open.

For pest and disease management recommendations, please refer to the Michigan Fruit Management Guide (E-154) for product guidelines.

For more information about regional reports, please visit the Michigan State University Extension website.

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