Field Notes 04-04-24

An early April storm system brought a return of winter weather with accumulating snow to Wisconsin. Snowfall totals April 2-3 were widely variable and peaked at 14.2 inches in La Crosse, while southeastern locations near Milwaukee reported 0.5-3.5 inches of rain and snow mixed. Following a historically warm winter without significant snow coverage, this week’s precipitation was much needed and helped to restore soil moisture deficits ahead of the early planting window expected this month. According to the Wisconsin State Climatology Office, the December to February meteorological winter was the warmest since record-keeping began in 1895. The state three-month average temperature of 28.3°F was more than 2.0°F above the 2001-2002 previous record and nearly 10.0°F warmer than the winter normal average of 18.5°F. Meanwhile, much of the state received less than half of its normal snowfall through the end of February and 62% of the state is currently abnormally dry (D0) or in moderate (D1) to severe (D2) drought.

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For the 2024 growing season, a new Insect Pest Text Alert service will soon be available to Wisconsin crop producers and agricultural professionals. Developed by the Dr. Emily Bick Lab at UW-Madison, in collaboration with UW-Extension and DATCP, this service is designed to deliver concise, timely field and forage crop pest notifications and updates through text messaging.

Whether it is an influx of black cutworm moths, advanced warning of true armyworm activity, or a reminder to begin scouting for corn rootworm beetles, the real-time text alerts will help optimize pest scouting and decision-making. As part of our new service, subscribers will receive:

• Scouting alerts based on field survey observations
• Pest updates throughout the growing season
• Useful resources for scouting and management

Text messaging will begin in late April or May, and we expect to provide up to 15 short updates throughout the season.

If you would like to receive our insect pest alerts directly to your cell phone, please click the “Sign Up Now” button below.

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^{Winter cutworm larva | T. Schilder DATCP}

Plant and insect phenology are well ahead of last year and the 30-year normal pace in Wisconsin this spring, despite the early April snowstorm. In fact, growing degree-day (gdd) accumulations are adequate for the start of a few early-season insect events, such as eastern tent caterpillar egg hatch and common asparagus beetle emergence, while the first recorded black cutworm moths of 2024 were collected in survey traps on March 31.

A comparison of gdds from January 1-April 3 in the table below shows accumulations currently range from 129 gdds at Dubuque (the warmest location) to 18 gdds at Bayfield (the coldest location). Madison has so far accumulated 87 gdds. On the same date last year, Dubuque had accumulated only 32 degree-days while Bayfield and most northern areas were still at zero gdds. The 30-year normal accumulation for April 3 in Dubuque is 65 gdds and 16 gdds near Bayfield.

Recall that gdds accrue slowly in spring when nightly temperatures often fall below freezing. Most of Wisconsin accumulates just 1-3 heat units per day in early April (see column four in table). Using a daily accumulation of 1-3 gdds, our estimates indicate that plant and insect phenology is approximately 18-36 calendar days ahead of 2023 and about 2-24 calendar days ahead of the 30-year normals, depending on location. Of course, nearly all insect development is on hold until the snow melts and mild temperatures return next week.

Growing degree days for 24 Wisconsin locations are provided on the DATCP GDDs page and will be updated each Monday and Thursday through September.

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^{Swede midge survey trap | K. Hamilton DATCP}

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