Notes from the Field: A Grower’s Perspective – Chris McGuire Chat #2
I had my second chat with Chris on May 13…
With most varieties past petal fall and younger trees displaying a few straggler flowers, removing any final blooms on newly planted trees becomes a priority.
At Blue Roof Orchard, NEWA’s apple scab model shows all ascospores released at this site, and RIMPRO shows only a tiny fraction as unreleased – therefore, Chris is not concerned about apple scab at this stage. The threat of blossom blight has ceased but scouting for shoot blight is still necessary as shoots continue to grow. The focus also shifts to combating cedar apple rust (CAR), often a larger challenge in organic orchards compared to conventional orchards. With the recent rain and wind events throughout the state, it has been difficult to find a window of opportunity to apply any pesticides. However, when looking at the apple disease models in NEWA, disease risks have been low to moderate in many locations across Wisconsin. I suspect that this is due to the lack of persistent rain events (i.e., minimal prolonged wetness) and quick drying off periods following the rain. Last Friday Chris applied Regalia, a key component in their organic pest management strategy, along with EcoSwing, potassium bicarbonate (Carb-o-nator), and potassium silicate (Sil-Matrix).
Organic practices present unique challenges, from the reduced tools for chemical thinning to managing pests like plum curculio.
The threat of plum curculio looms, and Chris anticipates that they are laying eggs currently. There are limited organic insecticide options for managing plum curculio, however, Chris has found that the deterrent properties of Surround appear to offer some benefits; he has made 3 applications this season so far and anticipates additional sprays as the insects continue to be active. After all the blooms are off the trees, he plans an application of Pyganic insecticide for plum curculio. Chris has also set up mating disruption for codling moth which may also make its way into orchards soon.
Chris evaluates micronutrient deficiencies in the orchard through summer leaf tissue testing and corrects these deficiencies through targeted foliar sprays in the Spring. This season he applied copper, zinc, and iron. Synthetic nutrients are reserved for documented deficiencies, adhering to organic principles. Branch training is also a focus in the orchard on 1st and 2nd year trees – keeping branches horizontal promotes fruit bud formation. With the last few seasons of drier weather, orchard irrigation has become critical for all growers. Chris is setting up drip irrigation for these younger trees to support their establishment.
Some fruits have already reached 8-12 mm in diameter, the ideal size for dropping. Fruitlet thinning, employing ProTone (OMRI approved plant hormone that promotes fruit drop), is underway to optimize fruit set. Chris is also working now to get ahead of the weeds using Homeplate herbicide. This herbicide acts as a burndown, and it is not systemic and is primarily effective against young seedlings. Additionally, he is pulling many of the winter annuals that have flowers and will soon drop seed on top of the mulch in the orchard rows. Weed seeds that are on top of the mulch are a particular concern because they can germinate and grow readily, whereas seeds under the mulch will not emerge as their access to sunlight is blocked. Perennial weeds are always a concern in mulched systems, and it is key to manage them in the seedling stage while they are still small and vulnerable.
That’s all for now! Check out the notes from my next chat with Chris in two weeks on May 31. If you missed my previous chat with Chris, check it out here.
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.
Additional reading for topics discussed in this article:
- https://fruit.wisc.edu/2022/06/28/mating-disruption-in-apple/
- https://fruit.wisc.edu/2018/06/15/codling-moth-management/
- Plum Curculio UW Fact Sheet – https://d31n3wj3oi4lt9.cloudfront.net/wp-content/uploads/sites/36/2018/06/A4160-Plum-Curculio.pdf
- https://hort.extension.wisc.edu/articles/cedar-apple-rust/