May 7, 2021
Michigan chestnut tree development impacted by big temperature swings

Significant geographic temperature variation has driven abnormally large differences in tree development this spring.


Michigan’s 2020-2021 winter recap

December and January were very mild with much below average snowfall for most of the state. Feb. 4-21 were more typical with cold and snowy conditions. Winter injury was mild on high and warm sites. Temperatures in late March were above average before returning to more typical temperatures in April. Above-average temperatures in late March accounted for most of the spring growing degree day (GDD) accumulation, which is currently above the five-year average for most growing regions across the state. Trees in southern Michigan suffered some frost and freeze damage from the early warm up in March that pushed bud development and were followed by more seasonally appropriate cold temperatures.

Watch the most recent agricultural weather forecast from Michigan State University state climatologist Jeff Andresen.

May 3, 2021, weather summary for major chestnut producing regions of Michigan
Location GDD 50 F (March 1-May 3) GDD 50 F (March 1-May 3) 5-year average Rainfall (inches) April 1-May 3 Historical rainfall (inches) average April 1-May 3
Deerfield/Blissfield 244 148 2.23 3.61
Benton Harbor (SWMREC) 236 159 1.22 4.11
Berrien Springs 238 151 1.57 3.52
Lawton 236 147 1.36 3.89
South central  
Hickory Corners 233 130 1.09 4.17
Kalamazoo 239 139 1.58 4.41
East central  
Flint 235 127 1.52 3.84
East Lansing (MSU Hort) 223 128 1.53 3.56
West central  
Ludington 149 73 2.16 3.19
Petoskey 106 20 2.65 4.00
Traverse City (NWMHRC) 102 60 2.87 2.58
Northport 68 28 1.61 1.72
Williamsburg 119 41 0.98 2.86
Hawks 93 40 1.98 3.00

Crop development


Observed cultivars are at the budswell stage.

Chestnut branch up close.
Colossal near Traverse City, Michigan, on April 30, 2021. Photo by Rob Sirrine, MSU Extension.

West central

All observed cultivars are at the bud swell stage.


Observed cultivars are at bud swell or bud break.

South central

Observed cultivars are at bud swell or bud break. Freeze damage is visible in some cultivars.

Pictures of eight chestnut cultivars.
Bud stage and cross section off (A) Colossal, (B) Marsol, (C) Maraval and (D) Marigoul on April 30, 2021, in south central Michigan. Photos: Mario Mandujano/ MSU


Most growers using granular fertilizers are planning to apply them soon. As a reminder, for nutrient management considerations, please reference pages 5-7 of the 2021 Michigan Chestnut Management Guide or the Nutrient Management section of the Michigan State University Extension Chestnuts website. Also, MSU recommends submitting soil samples each spring around the same time. Please refer to lab sampling and submission instructions prior to sending in samples.

Soil testing labs

Comprehensive soil health testing labs


Black stem borer, also known as ambrosia beetle, are emerging and can damage young orchards. Refer to the MSU Extension article, “Black stem borer: An opportunistic pest of young fruit trees under stress” for more information on biology, monitoring and management.


Existing chestnut blight infections (caused by Cryphonectria parasitica) can be observed at this time. To learn more about chestnut blight, visit the pest management section of the MSU Extension Chestnuts website.

Rust-colored spots on chestnut bark.
Cryphonectria parasitica (the fungus that causes chestnut blight) produces the small but visible rust-colored stromata that contain the spore producing structures seen in this picture of chestnut bark. Photo: Erin Lizotte/MSU Extension

Stay connected

For more information on chestnut production, visit MSU Extension Chestnuts and sign up to receive our newsletter. Also, join us for the 2021 Chestnut Chat Series every Wednesday at 12 p.m. May 5 through Sept. 8, 2021. This series of interactive Zoom meetings will allow easy communication between producers and MSU faculty. These informal weekly sessions will include crop and pest updates from Rob Sirrine and Erin Lizotte. In addition, MSU faculty will drop in to address timely issues and provide research project updates. Bring your field notes too! We want to hear what’s going on in your orchard.

This material is based upon work supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, under Agreement No. 2017-70006-27175. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

Be sure to check out our other specialty agriculture brands

produceprocessingsm Organic Grower

75 Applewood Drive, Suite A
P.O. Box 128
Sparta, MI 49345
Get one year of National Nut Grower in both print and digital editions.

Interested in reading the print edition of National Nut Grower?

Subscribe Today »