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Weekly Fruit Update - June 23, 2021

Author: Annie Klodd, Extension Educator - Fruit and Vegetable Production

In this week's fruit update:

  • Strawberry season and preparing for renovation
  • Grapes: Give the sprayer a break
  • Apples: Insect pest trapping update
  • Raspberries and blueberries


Strawberry season is running full-throttle throughout Minnesota. It is nice to see so many social media posts by farms teaming with U-pick customers! It is common for farms to be "picked out" by mid-morning or noon (or even 9:00 am) thanks to high customer traffic. So if this is happening to you, you are not alone! 

Maintain regular irrigation as we hope for rain this week on Thursday and Friday.

At least one farm has reported reaching the end of their season. Their season was shortened due to the prolonged heat and drought in their area. If you are nearing the end of your season and are preparing for renovation, please see: Follow These Steps for Strawberry Renovation.

Despite the drought conditions, Dr. Jim Luby advises that it is still best to renovate directly after harvest commences, like usual.


Photo: Marquette grape clusters at pea-size, near Prior Lake, MN, 6/22/21. A. Klodd.

In a nutshell: The need to spray anything right now is really minimal. 

We have the dry weather to thank for the lack of disease we are seeing in our vineyards! This is a great year to give the sprayer a break and spread out the intervals between fungicide applications. Pathogens have a very hard time infecting leaves and clusters in the absence of rain. On the insect side of things, it's too early to spray for Japanese beetles, so keep the insecticides in the shed.

So this year is a good example of why it's important to get away from the "calendar spray" - rather than just spraying every 1-2 weeks based on a calendar, time your fungicide sprays based on the need. This year, the need is low. 

As mentioned in last week's update, 'tis the season for leaf removal while you are out in the vineyard tucking shoots. Removing 2-4 leaves per shoot from the fruiting zone increases sunlight exposure to the fruit and increases airflow through the canopy.

I saw one advertisement for foliar testing services this week. This is not an appropriate or useful time to take foliar samples for nutrient testing. The data cannot be interpreted or used unless the samples are taken at bloom or veraison, as those are the times that the benchmark nutrient levels correspond to. Nutrient levels fluctuate too much right now to be meaningful. 

One more note: Most varieties had good fruit set at the vineyards I visited in the last week. However, the extreme heat during bloom seems to have caused low fruit set (poor pollination) in La Crescent.


Insect trap counts this week in White Bear Lake and Preston yielded very low apple maggot (0-1/trap) and Japanese beetle catches. Since this is the very beginning of emergence for both of these insects, it is too early to spray for either. The action threshold for apple maggot is 5/trap if using pheromone lures, which we were, and 1/trap if using no lures. 

Codling moth: If an effective insecticide application was made around 250-350 degree days after biofix, codling moth populations should be minimal. If codling moth is active in your orchard, use pheromone traps to monitor population density and treat with effective insecticides if needed.

Raspberries and Blueberries

Primocane-bearing (fall) raspberries in a high tunnel at Twin Cities Berry Company, Farmington, MN

We are at the very beginning of summer-bearing raspberry season in Minnesota. One U-pick farm near Monticello reported the start of their season a few days ago, 4 days earlier than their personal average. 

The hot temperatures have caused some fall-bearing raspberries to begin blooming and forming fruit, particularly in high tunnels. On a personal note, my own open-field Crimson Treasure raspberries (which I am trialing along with 4 farms) began blooming 3 weeks ago. Why is that weird? Because it is a primocane-fruiting variety, and the breeder himself told me that is about a month ahead of schedule.

There is still not much to report with blueberries right now, as the season has not yet started and pest pressure is so low. We did check two SWD traps in White Bear Lake today, which were empty - no official SWD yet. 

I received two very similar questions from blueberry growers this week, about defoliated branches. Leaves dying and falling off was a result of leaf injury during the May 28 freeze event.


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