Welcome back to our fifth report of 2025 Notes from the Field! As a reminder, this year’s Notes from the Field will follow Ben Kraus with Gwenyn Hill Farm (Waukesha). The goal of this newsletter is to hear from the grower’s perspective and foster connection between fruit growers. We’ll be focusing our discussions on phenology/fruit development and integrated pest management. This week we will hear about Ben’s plans during fruit set and dive into plum curculio and codling moth management.

I met with Ben on Monday, June 2nd to check how things are shaking out as we move through fruit set. As a reminder, Gwenyn Hill has a 4-acre block of tree fruit and berries that sits along a north-facing slope, and ~150 table grape vines bordered by saskatoons and rhubarb across the road. Weather over the past two weeks (May 19 – June 2) has been moderate, with a few scattered precipitation events. According to NEWA, Gwenyn Hill had an average high temperature of 64.5℉, average low temperature of 47.1℉, and a total of 1.37” of precipitation (NEWA – Colgate, WI). All tree fruit are into fruit set, while grapes are between 2-3 leaves separated (EL9) and 5-6 leaves separated (EL12-13). As for berries, Ribes spp. are in the green fruiting stage and day neutral strawberries are just beginning to show some color.

Note: Gwenyn Hill is impacted by the “lake effect” from Lake Michigan and is slightly behind in terms of phenology, compared to other southern WI locations.

Earlier this spring, Ben planted a raspberry trial between trees in the lower half of the orchard. The trial involves 16 different raspberry varieties arranged by color gradient from blonde to black, and includes summer (floricane) and everbearing (primocane) varieties. Everbearing varieties may be productive this year, while summer bearing varieties will begin producing in year two. This fall, Ben plans to install a trellis system and drip irrigation.

Plum curculio (PC) oviposition (egg laying) damage has officially been observed in the plums at Gwenyn Hill. Nearly every developing plum fruitlet has a small, crescent-shaped wound or scar which is indicative of plum curculio injury. Plum curculio also impacts apples, though we did not observe much injury. Ben was able to capture an excellent photo of a plum curculio during a round of scouting this week and kindly shared it with me (see below). Plum curculio is a weevil that emerges right around petal fall, and continues emergence until 308 degree-days (base 50℉) have accumulated from petal fall. This serves as an important reminder to keep track of your petal fall timing to determine a start date for counting degree days. Ben plans to apply Pyganic (pyrethrins) to the plums and use Surround (kaolin) with Venerate (Burkholderia spp.) throughout the rest of the orchard to help control PC. Once 308 degree-days have passed, typically PC cease movement into the orchard and no longer require control.

Ben was able to hang codling moth COMBO MESO mating disruption, and pheromone monitoring traps about two weeks ago. The COMBO MESO mating disruption lures disrupt both male and female mating behavior. This week, a total of two cumulative codling moths were captured, one in each trap. Ben will use Cyd-X Virus (Cydia pomonella granulovirus) once 250 degree days (base 50℉) has accumulated from the trap biofix date. As a reminder, a biofix occurs when an influx of ~5+ moths are cumulatively captured across traps, or captured on consecutive days (sustained capture).

Note: Several factors determine the threshold for biofix, including size and elevation within the orchard, type of pheromone lure used, and if mating disruption is used.

That’s all for this week’s Notes from the Field. I wanted to point growers to a new Extension resource for commercial production called Ask an Agriculture Question. Growers can navigate to this page and submit their question which will be forwarded to the appropriate UW Extension specialist. Make sure to include a photo and description in your submission.

Good luck and best wishes to all WI Fruit Growers!

This article series is NOT intended to be prescriptive for other orchards. It is simply an opportunity for our readership to hear from other growers about their experiences growing fruit crops in Wisconsin. 

Growing the same crop does not always justify the same practices. Management decisions at your farm should be tailored to your operation and consider location, regional climate, disease and pest history of your vineyard, and your varieties. 

The mention of a product is NOT an endorsement. Always follow the instructions on product labels and consult weather stations (ex. NEWA) in your area for current weather forecast and disease and pest prediction models.

This article was posted in Notes from the Field and tagged Ben Kraus, Josie Dillon, Notes from the Field.