West central Michigan tree fruit update – April 16, 2024

Warm weather has rapidly advanced bud development this week. Peaches are beginning to bloom in the region.

For decorative purposes.
Figure 1. Stage of tree phenology for apple, peach, pear, plum, sweet cherry and tart cherry in Oceana County on April 15, 2024. Photo by Emily Lavely, MSU Extension.

Temperatures have been very warm over the past few days and will gradually cool down as the weekend approaches in west central Michigan. For the Hart Enviroweather station, high temperatures over the next few days are forecasted for the mid-60s with a gradual decrease in temperatures by the weekend with high temperatures in the upper 40s on April 20 and 21. Low temperatures will be in the 40s and upper 30s with temperatures dipping down into the low 30s by the weekend.  

Bud development has changed rapidly over the past few days in tree fruit as we move closer to bloom (Figure 1). Based on the Hart Enviroweather station for April 15, current growing degree day (GDD) accumulation is 216 GDD42 and 76 GDD50 

Rain showers are forecasted for the next few days with the potential for about 1 inch of rain. At the Hart Enviroweather station, soil moisture content is 9.5% at 4 inches deep and 8.6% at 20 inches deep. Rain this week will support early growth as trees begin to bloom. Soil temperatures at 2 and 4 inches deep reached 64 and 60 degrees Fahrenheit on April 15, so roots are actively taking up water and nutrients needed for early season growth. Stored carbohydrates (primarily from coarse roots) and nutrients (stored in the trunk and branches) in the tree are also moving to actively growing tissue this time of year since there is not enough new leaf tissue to support tree growth yet.  

Weather data was gathered from Michigan State University Enviroweather.  

Watch a full weather update from Jeff Andresen, Michigan State University climatologist. 

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


Crop update 

Growers continue to plant trees, chop brush, prune trees and put on cover sprays this week. Note that fruitlet thinning of apple can start with pruning by removing excess fruit buds. Earlier thinning will improve fruit size and quality. Carbohydrate and nutrient resources available early in the season are divided between the number of fruit buds on the tree. By removing excess buds, more resources are available to remaining buds. 

Bud development advanced rapidly from last week (Figure 1). With warmer temperatures, there has been a lot of pollinator activity over the past few days. Commercial honey bee and bumble bee hives will arrive in orchards over the next few weeks for pollination of cherry and apple. Honey bees will forage at temperatures of 65 F or warmer. Bumble bees and solitary bees will forage at temperatures 5-10 degrees cooler than honey bees. As we approach bloom, implement practices that minimize pesticide exposure to bees by using reduced risk pesticides and spraying at times when pollinators are not active. Find tips and guidelines to minimize bee pesticide exposure in the following Michigan State University Extension article: Pollinator stewardship during fruit crop bloom 

Early apple varieties in the west central region are at open cluster or first pink such as Zestar and Idared. Gala and Honeycrisp are between half-inch green to tight cluster in Hart.  

Tart cherry buds are moving slowly but are at the swollen bud stage at the West Central Michigan Research and Extension Center. Early sweet cherry varieties are at bud burst in Hart.  

Peaches are at first bloom on early fresh market varieties. Venture peaches at the West Central Michigan Research and Extension Center changed from pink to first bloom on April 15, and full bloom will be right around the corner.  

Apricots were in full bloom over the weekend and are at petal fall. Early plums are in full bloom while later varieties, like Stanley plum, are at bud swell. Sprays for brown rot are warranted this week as trees are in bloom. 

Pear varieties range from blossom bud exposure to tight cluster. Bartlett pears at the West Central Michigan Research and Extension Center are at bud burst.  

Pest and disease update 

Insects are becoming more active in the west central region. The insect trapline at the Trevor Nichols Research Center captured 5.3 adult green fruitworm this week.  

An average of 65.3 redbanded leafroller and 366 spotted tentiform leafminer were also trapped on April 15 at the Trevor Nichols Research Center. With cool conditions this week, we expect insect pest activity to slow in west central Michigan. Oriental fruit moth was trapped at the Trevor Nichols Research Center for the first time on April 15. Michigan State University staff will continue monitoring oriental fruit moth to determine sustained catch and a biofix date. 

Warm temperatures have led to a lot of new green tissue in apple this week. Tissue is at high risk for apple scab infection this week with rain events forecasted for Wednesday and Thursday, April 17 and 18. A large spore release is expected with the next rain event as spores mature more quickly at higher temperatures as we have had over the past few days. After the last wetting event on April 11 – 12, 24 spores per rod were found in Oceana County. Pear trees are also at risk for pear scab infection this week. 

Some growers have applied copper in apple and pear to knock down bacterial populations of the fire blight pathogen, Erwinia amylovora. Dormant and delayed dormant sprays help manage fire blight primarily if fire blight was present the previous season. It will be important for west central growers to manage fire blight, particularly in young, high-density plantings.  

No bract leaves are present at this time, so no cherry leaf spot risk is predicted this week. 

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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