Allison Jonjak, Christelle Guédot, Jed Colquhoun, and Leslie Holland

As disease treatment windows close and we start counting insect number, continue degree day accumulation, and prepare to assess fruit set percentages, we wanted to give growers an update on the status of the 2021 pesticide trial program.

The first trial of the season tests a variety of pre-emerge herbicides, along with growth regulator hormones. Jed took the opportunity to teach me to measure and stake trial plots, and to familiarize me with the CO₂ backpack sprayer used to make applications at 20 gallons per acre in our treatment blocks. Walking speed and boom height are critical for even applications. We applied all the products at the same timing, at the Wisconsin Cranberry Research Station.

The next trial to be applied was the pre-bloom portion of a leafhopper control trial. We are screening 8 chemistries for control of the blunt-nosed leafhopper, as well as other leafhopper species present on cranberry marshes. Each product was applied pre-bloom in one plot to assess their efficacy at controlling leafhopper nymphs, and products will also be applied post-bloom in a second plot to screen insecticides that could control leafhopper adults. Finding a site for this trial involved lots of helpers—since BNLH are only present at some marshes, IPM scouts kept in constant contact to identify marshes that could host timely trials. Thanks to all involved!

Then a heat wave brought us suddenly quickly through bloom! Three fungicide trials were applied to marshes with a history of fruit rot pressure.

The Candidate Fungicide Trial screens 9 chemistries for protection against fruit rot. The Reduced Risk Candidate Fungicide Trial screens 6 products, including OMRI-certified and biological products, for protection against fruit rot. In each trial, each product was applied at 20% bloom and at 80% bloom.

The Use Patterns Trial is focusing on effectiveness of various application timings. Four fruit rot prevention tank mixes are tested in each of two timing plans – plan 1 is two applications made during bloom at 20% and 80% bloom, and plan 2 is with single application made during bloom at 50% bloom.

Degree Days have been accumulated to determine the egg hatch window for sparganothis fruitworm based on previous research (Steffan et al). The Wisconsin Cranberry Research Station has enough lepidopteran pressure to host this trial, in which we evaluate the effectiveness of Altacor sprays at 10% of egg hatch, 25% of egg hatch, and 40% of egg hatch, based the DD model benchmarks. The 10% egg hatch window arrived just as the fungicide trial window was closing, so these applications were made on the same day.

Still to be applied are the post-bloom portion of the post-emerge herbicide trial, the post-bloom portion of the leafhopper trial, the 40% egg hatch phase of the sparganothis/cranberry fruitworm trial, and the flea beetle trial, which will assess 6 products, including 3 unregistered products.

A hearty thanks to all operations who are hosting trials, or have offered to host trials this year! I look forward to sharing the results with everyone after we take the crop to yield.

This article was posted in Cranberry and tagged Allison Jonjak, Christelle Guédot, Cranberries, field trials, Fungicides, Herbicides, Insecticides, Jed Colquhoun, Leslie Holland, screening, trials.