By Becky Wiepz and Dan Kielar
Continuing rain and heat means that fungal pressure will be high, especially in blocks where initial infection was high and inoculum has been continuously present.
Scale pests, both San Jose and Oyster Shell, are in some orchards. According the the NEWA model, orchards throughout Door and Kewaunee counties have reached the crawler stage of development so apply treatments accordingly.
Spotted Wing Drosophila has been caught throughout the county! Cherries are vulnerable when they begin to color so throughout the county fruit is in the low or medium risk categories.
| Date 6/27 | 2020 | 2021 | 2022 | 2023 | 2024 | 20-year avg. |
| Base 50 | 598.5 | 757.5 | 633 | 711 | 761 | 680 |
GDD50 continues to be approximately 3-5 days ahead of the 20-year average.
Apples
Hormonal thinners are no longer effective as most fruit has surpassed 30mm average in diameter. Hand thinning will no longer affect fruit size at harvest but will still open the canopy to reduce disease pressure and improve fruit color.
If using plant growth regulators to encourage return bloom, especially in Honeycrisp, your final application should be occurring shortly. This article from Amaya Atucha provides information on rate and timing of different chemicals.
Insects
First generation flight of Codling Moth continues to be very large this year. Treatments should be applied throughout the first generation flight. For more information on Codling Moth and it’s life cycle visit this article from the UW Fruit Team.
Stink Bugs, Tarnished Plant Bugs, and Borer numbers (other than Dogwood Borer, which are moving in large numbers) seem to be decreasing slightly, although they are still present.
A few Wooly Apple Aphids (WAA) and Rosy Apple Aphids have been found during scouting and WAA numbers seem to be increasing.
Apple Maggot traps were placed this week and we expect some to be caught soon.
Disease
Continue to monitor the forecast and NEWA’s Apple Scab Model to time your fungicide applications.
Powdery Mildew pressure continues to be high this year and can require different fungicides than those used to manage Apple Scab. Check the Midwest Fruit Pest Management Guide for chemical efficacy ratings.
Remember that fungicides are almost exclusively protective, so it’s important to protect new growth when active infection is present in the block.
Fireblight strikes may be appearing in orchards over the next few weeks, be sure to prune them out promptly to prevent spread within the tree. This article from Leslie Holland has more information on the latest recommendations for removing Fireblight strikes. Remember that Strep is not an effective tool for managing shoot blight.
Cherries
GDD continues to be ahead of last year and the twenty year average, so harvest appears to be slightly early throughout the region as cherries are currently turning blush colored, although the long bloom and heavy crop have resulted in uneven ripening in many blocks and even in individual trees.
Harvest is expected to start around July 6th for pick-your-own orchards in Southern Door County.
Now is the time for machine-harvested orchards to plan the rate and timing of their Ethephon applications. This article from Michigan State provides information on timing your application and how to adjust for temperature and cropload.
Insects
Spotted Wing Drosophila continues to be prolific throughout the county and most cherries are at risk and should be protected through harvest. Check the Midwest Fruit Pest Management Guide for chemical efficacy ratings and be sure to rotate your mode of action as much as possible while saving your shorter PHI chemicals for close to harvest.
Large populations of borers are currently in flight while leaf and fruit feeding are beginning to decrease.
No Cherry Fruit Flies have been caught in the county
Disease
Some blocks are starting to see Sour Cherry Yellows Virus so be sure to check if yellow leaves in your orchard are due to Cherry Leaf Spot or Sour Cherry Yellows before making your management decisions. Sour Cherry Yellows exhibits green to yellow mottling and interveinal chlorosis of the leaves while Cherry Leaf Spot starts as purple spots on the upper leaf surface that develop white sporulation underneath and eventually turn brown. When severe, Cherry Leaf Spot can lead to yellowing and leaf drop.
Powdery Mildew continues to be present in many blocks and may require different products to manage than your Cherry Leaf Spot program. The Midwest Fruit Pest Management Guide is a good resource to check product efficacy. For both Cherry Leaf Spot and Powdery Mildew, cover sprays should continue until terminal buds are set.
GRAPES
Grapes on the station are at buckshot stage. Fungicides applied from now until Berry Touch will help protect the vines from bunch rot through harvest.
Insect pressure continues to be high, and Japanese Beetles are expected to arrive soon. Scout your vineyard and choose a chemistry that is effective against the pests and damage you observe.