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Weekly Vegetable Update August 27, 2026

Authors: Natalie Hoidal & Marissa Schuh Fall is in the air, and our classic fall vegetable problems are coming along with the cooler nights. While portions of the state entered extreme drought this week, we still have enough humidity and cool morning for dew – which drives the development and movement of many pathogens. We are out of the window where we have effective management available for disease problems, as many diseases are quite advanced, and disease management (even with pesticides) is preventative. Make notes of what problems are where on the farm, and make notes that will help you remember to trial helpful varieties and different cultural practices next year. Hedging your bets about fall frost dates We’re reaching the point where in a “normal” year, we would be about one month (northern MN) to one and a half months (southern MN) away from the first frost. You can look at fall frost date probabilities for your area here . Many growers start topping tomatoes around this ...
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As the growing season winds down, let us know what you thought of Fruit and Vegetable News! This helps us both figure out what to include in the newsletter in the future and advocate for fruit and vegetable research and extension. Found information of pests helpful? Let us know! Noticed something on your farm that you wished we wrote about? Let us know! Critique or compliment, we appreciate you sharing your thoughts. Fill out the survey below, or access it here : 

Fruit update - August 27, 2026

  Article written by Madeline Wimmer , UMN Extension Fruit Production Educator. Apples  Apple sales are starting at the farmers market in southern Minnesota Variety highlight: First Kiss, and dealing with fruit drop Article: How to Determine Apple Ripeness: Starch, Firmness, and Brix Testing Grapes Table grape harvesting tips Variety highlights: Reliance and Mars Help us grow the Fruit Update series! What’s working? What do YOU want more of? This is our annual request for your support of the UMN Fruit Update series and other articles by taking our short evaluation to let us know what you’ve enjoyed and what you want to see more of in the future!  Take our quick survey: UMN Fruit and Veg News Annual Eval You can also take the survey directly through our newsletter article: Share you thoughts on this newsletter  Our newsletter is only a success because of readers like you, and we greatly appreciate your feedback!  Apples  Apple sales are starting at the farme...

How to Determine Apple Ripeness: Starch, Firmness, and Brix Testing

Article originally written by Cindy Tong, UMN Postharvest Specialist, in 2018 and updated by Madeline Wimmer, UMN Extension Fruit Production Educator in 2026. As fall approaches and apples continue to ripen, what is the best way to determine when to harvest? It all depends on whether they will be sold more immediately for fresh market, or stored for a longer period.  The starch-iodine test chart with a ripeness scale of 1-8, as indicated by decreasing starch staining as the apple ripens. This image from Cornell’s starch-iodine index is based on the McIntosh variety. Overview There are several ways to determine apple ripeness. This involves changes in…  1) …peel background color from green to yellow. 2) …peel “overcolor” from green to yellow or red.  3) … fruit firmness from rock hard to being able to bite into easily (it shouldn’t break your teeth!). Fruit firmness can be measured using a tool called a penetrometer.  4) … preferred flavor, which varies from person-to...

Apples: Reflections on spring frost during bloom in 2026

  Article written by Madeline Wimmer , UMN Extension Fruit Production Educator, based on discussions by David Bedford, UMN fruit breeder and researcher.  Each year, the Minnesota Apple Growers Association hosts a summer tour at a commercial apple orchard location in Minnesota for growers to come together and learn during the growing season. This year, the summer tour gathered in early August at Fall Harvest Orchard. The University of Minnesota’s apple research, breeding, and education team hosted part of the program within the orchard to discuss a number of topics including dogwood borer, red star rust, and season trends.  Image: David Bedford discusses the topic of spring frost in 2026 at this year’s summer tour.   David Bedford, UMN researcher and plant breeder, talked about spring frost during bloom. While Minnesota has historically escaped much damage from spring frost episodes due to delayed bloom times compared to other Midwest regions, the UMN Horticultural R...

Corn Earworm Adult Flights Increase In Minnesota

Authors: Dr. Yucheng Wang, University of Minnesota, Postdoc Researcher, Dr. Fei Yang, University of Minnesota, Extension corn entomologist Corn earworm (CEW), Helicoverpa zea, adult activity has increased sharply across several areas of Minnesota since last week (The week of August 10th, 2026), indicating that a major moth flight is underway in parts of the state. CEW adults are primarily nocturnal, with flight activity beginning around dusk. Females preferentially lay most of their eggs directly on fresh, green corn silks. After hatching, larvae initially feed on silks before moving down the silk channel to the tip of the ear, where they feed on developing kernels (Figure 1). CEW generally cannot overwinter in the Upper Midwest, with its northern overwintering limit generally estimated near the 40th parallel. Most CEW moths found in Minnesota migrate from southern states during the growing season. Minnesota typically experiences two major periods of CEW migration. An earlier, generall...

Weekly Vegetable Update - August 20, 2026

Authors: Natalie Hoidal & Marissa Schuh We were off last week visiting farms, schools, and co-ops in north central Minnesota last week, and wow, it is dry! Much of the state is in severe drought , and while some pockets of the state got rain over the weekend, that isn’t enough to make a dent in the deficit many areas are in (though it was enough to split tomatoes and melons). As we reach fall, insect pests and diseases really become the star of the show. Tomato and potato growers - Late blight is in the region Late blight was confirmed last week in Southwest Michigan. Will this disease reach Minnesota? It's hard to say, but with time left in the growing season, it's worth knowing what to look for. This disease is easiest to spot when humidity is high, and leaves in the center of a dense canopy are often the first to get infected. Leaf spots are a brown-gray, sometimes described as greasy. You may see white spores on the underside of the leaf. As spots grow, they turn dar...

Fruit Update - August 20, 2026

  Article written by Madeline Wimmer , UMN Extension Fruit Production Educator. Apples  Growth stage update: Nearing harvest season for early-season apples Article: Organic apple orchard practices highlight in SW Michigan: Third Leaf Farm Grapes Article: Measuring fruit ripeness Article: Occasional insect pests that attack damaged grapes in Minnesota vineyards Blueberries Nutrition: Iron deficiency Apples Growth stage update: Nearing harvest season for early-season apples  Images: Outer-canopy apples are gaining color for these cultivars grown on central leader, freestanding trees. Top images, left to right: Gala, Honeycrisp, McIntosh. Bottom images, left to right: KinderKrisp, First Kiss, Wealthy.   Not all of these cultivars are early ripening. This week, we’ve been receiving some cooler nights and mornings, which is beneficial for Minnesota apple production as cooler temperatures during the night can impact fruit anthocyanins and help improve apple color. This is ...