Apple Fruit Set
For the week of May 19, apples are currently at about 10-11 mm for most varieties this far north. The season is moving quickly and with this growth, some growers have started their first chemical thinning application for the season. I was a bit concerned about biennial bearing/alternate bearing and it doesn’t seem to be too big of a concern this year. Most growers seem pleased with the fruit set thus far.
Weather
The simple truth is—we could really use some more rain in Northern Illinois. So far, we’re still running below average for precipitation. During the week of May 11, temperatures dipped into the 40s °F at night and climbed into the 70s °F during the day, with a particularly chilly low of 34 °F on Friday, May 16.
We didn’t see any measurable rain until the week of May 19, when some much-needed showers finally arrived. However, the rain came hand-in-hand with continued cool temperatures, often staying in the 40s °F. These types of conditions look to last into Memorial Day weekend.
This timing is important, as many warm-season crops like tomatoes and peppers are typically planted after May 15. For growers who planted in the lead-up to Memorial Day, the rain was certainly welcome—but the cooler-than-ideal temperatures were less so.
From an apple tree perspective, this weather has limited the choice of chemical thinners as some will not perform as well with these temperatures. Further, growers may find that additional thinning applications may be needed sooner than later based on the weather we’ve encountered to start and end the month.
Notching Update
In last month’s newsletter, I shared a project at Valley Orchard where grower Raoul Bergersen was notching trees to encourage the development of additional laterals. A follow-up visit a month later on May 22nd showed mixed results. While some trees have begun to show growth, many notches remain inactive, and no tree exhibited growth from all notches. On average, trees with 8–10 cuts produced just 1–2 emerging laterals. However, it may still be too early to draw conclusions—I’ll provide another update next month.
Tart Cherry Fruit Set Challenges
I’ve been receiving some reports of poor tart cherry fruit crop load this upcoming season. Typically, this crop is reliable for northern Illinois orchards. One likely cause dates back to cherry leaf spot issues in the summer of 2024. Significant defoliation last year may have reduced the trees’ energy reserves, increasing their vulnerability to winter injury and resulting in fewer flower buds and fruit for summer 2025. If you're seeing low yields this year, it's important to prioritize cherry leaf spot management this season. Taking action this season can help restore tree health and improve crop potential for 2026.
Farmers Markets
Farmers markets across Northern Illinois kicked off at the beginning of May. While it’s still early in the season, two standout crops so far have been rhubarb and asparagus—both doing okay this year. Rain would have benefited both these crops. These spring favorites typically wrap up by mid-June, giving us a harvest window of about 6 to 8 weeks.
In addition to rhubarb and asparagus, many growers have been offering cool season produce like lettuce, kale, carrots, microgreens, and more. May is also a great time to pick up extra transplants, as many vendors bring surplus seedlings to market for home gardeners.