Northwest Michigan fruit update – April 7, 2020

Most perennial crops are still dormant, and the cooler than normal temperatures later in the week will minimize crop development.

San Jose scale on apple spur
San Jose scale on apple spur at the Northwest Michigan Horticulture Research Center on April 5, 2020. Photo by Emily Pochubay, MSU Extension.

At the Northwest Michigan Horticulture Research Center, our normal day-to-day operations have been disrupted but we are finding ways to finish pruning, tie tops, clean brush, etc. in a safe way. We are developing online scouting information, central posting and sign in/out forms for our staff to access. Additionally, part of our “coming to work” protocol requires each of the station staff to fill out a self-assessment survey for symptoms of illness before coming into work; if we are symptom-less, we can head to the station to carryout activities. To ensure the safety of Northwest Michigan Horticulture Research Center staff, we have been in regular communication via phone and email about who will be coming to the station, for what purpose and when. We are also hosting a weekly staff meeting to discuss the coming week’s activities. Based on our discussions with growers in the area, many of you are also modifying operations to accommodate the “new normal.”

We have also heard some good news. Growers with farm markets have reported that recent sales since late March have been higher than usual for this time of year. On the Michigan State University Extension internal fruit team call this morning, MSU Extension educators shared similar stories from their respective areas in the state. It was heartwarming to hear that farm markets are being supported by their local communities during these difficult times.

Weather report

The seven-to-10-day forecast is calling for a shift in temperatures away from the warmer spring temperatures we have had across the region to cooler daytime conditions. A Canadian air mass will be moving south into the state and by Thursday, April 9, we will have significantly cooler temperatures. The temperatures are predicted to be abnormally cooler as we head into the weekend and into the beginning of next week; temperatures may be 10 degrees cooler than normal.

As the cold air mass moves into Michigan, the southern part of the state may experience some severe weather on Tuesday evening, April 7, that may result in hail and high winds. We also may have high levels of rainfall, but these will be short lived and overall precipitation will be minimal across the state.

Crop report

Many of the crops are still in the dormant stage. However, sweet cherry buds are swelling and early varieties at the research station are starting to show some side green. Growers are still finishing up pruning and bucking brush. Tree planting has begun further south, but little planting has started here in the north.

Pest report

Dormant season scouting has started. Over the last several years, we have noted San Jose scale populations have been building in sweet cherries. More recently, we have observed upticks of this new-old apple pest in the area’s apples. Coming off of a milder winter, it is likely that a higher percentage of San Jose scale survived the winter. At the station, it is not difficult to find San Jose scale in our apples blocks and we will likely need a dormant application to keep this pest in check (see photo). This spray would also help with the few European red mite eggs we have found overwintering on spurs.

Current cold conditions are not good for applying oils; cooler temperatures will also slow bud development, meaning there is still time to wait to make this application when weather is warmer and more favorable. For more tips on dormant applications, review “Dormant oil for tree fruit pest management in 2015” from our colleague Amy Irish-Brown. It would also be a good idea to sign up for the free tree fruit webinar on April 15 on spring sprayer set up and configuring your air-assist spraying, presented by Jason Deveau of the Ontario Ministry of Agriculture, Food, and Rural Affairs.

Cooler weather will buy more time for dormant applications for diseases, and it is a good time to start strategizing. Reflecting on diseases, a few memories stand out. Last season was especially challenging for cherry leaf spot as green tissue was exposed during prolonged periods of cool and wet weather and became infected. Furthermore, MSU’s George Sundin’s latest resistance screening work for cherry leaf spot is suggesting that the SDHI fungicides will not be as effective moving forward as they have been in the past.

In apples, fire blight was also problematic and growers that had challenges should be considering what their fire blight approach will look like for 2020. With a slowdown in development, there will also be time to get on peach leaf curl sprays before that 100 growing degree day (GDD) base 42 mark; cooler, wet weather during peach bud development are favorable for this fungal disease.

A good time to get your disease management questions answered would be next week on the April 16 and 17 tree fruit webinar series, which is when Sundin will join us.

Weeds are germinating. Growth will slow in the cooler weather, which will give growers more time to decide their approach for weed management this year. MSU weed specialists will discuss orchard weed management on April 20 as part of our tree fruit webinar series. Just in case you missed it last week, growers that plan to use paraquat or Gramoxone this season should review the new label and training requirements associated with this herbicide.

Farm workers are arriving or returning to farms, and getting everyone up to speed on Worker Protection Standards (WPS) would be a good activity for rainy or slower days. There are WPS training videos available for workers and handler/applicators in both English and Spanish. Please review the pesticide safety training requirements for details on who needs to be trained and who can train those that need training.

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