Fruit and Vegetable News

Natalie Hoidal & Marissa Schuh After a cool, rainy week with some impressive storms, we finally have a few warm days ahead of us (and some really really hot weather in the forecast). This should give recently planted crops a chance to perk up and catch up. Potassium deficiency or salt stress? We received some photos of tomatoes growing in a high tunnel this week with yellow leaf edges and necrotic tips. Sounds like a potassium deficiency, right? But, the photos didn’t quite match a potassium deficiency. The edges of the yellow ring were too neat, and the tips more crispy than what you might expect from a potassium deficiency. We reviewed the soil tests and saw off the charts potassium (literally, the UMN soil lab caps reporting at 300 ppm). So what was the culprit? Soluble salts!   Salt stress in high tunnel tomatoes. Anonymous grower submitted photo.  We know from our study of 100 MN high tunnels that most high tunnels have more fertilizer than they need (fertilizer is l...

Madeline Wimmer-U MN Extension Fruit Production Extension Educator Apples : Growth stage: Apple fruits ranging from 25–40 mm wide Whole apple tree dieback June-bearing strawberries : Growth stage update: Fruit ripening and harvest Planning for field renovation and care during late-season dry spells Note on strawberry pest management resources Additional fruit crops: Growth stage highlights Pears, plums, and summer-bearing raspberries Serviceberries from budbreak to harvest Note to readers: This is the 9th fruit update of the season—can you believe it!? The newsletter will be on pause next week, with the next update planned for the following week. In the meantime, previous issues remain available for reference, along with the Midwest Fruit Pest Management Guide and the UMN Extension website for fruit farming and general fruit growing .  Madeline Wimmer  UMN Extension Fruit Production Educator Apples: Growth stage update: Apple fruits ranging from 25–40 mm wide Image: Zestar gr...

Originally written by Annie Klodd, former University of Minnesota Extension Educator, in April 2020. Updated for formatting by Madeline Wimmer in 2025. (Reviewed by: Dr. Bob Blanchette and Dr. Brett Arenz, UMN Department of Plant Pathology The Great Lakes Fruit Workers Group contributed research-based information to inform this article.) Apple tree with a canker suspected to be black rot.  Photo used by permission of the grower. A number of factors including diseases, herbicide damage, insect/animal activity, and winter injury can all contribute to trunk cankers on fruit trees. To complicate things further, these factors can interact. For example, winter injury can cause cracks in the trunk, which pathogens can then enter and infect the tree. Treatment of existing trunk cankers is not always possible, but identifying the cause will lead to determining management steps to prevent it from happening again. Diagnosing fruit tree trunk cankers  Because the causes of trunk can...

Madeline Wimmer- UMN Fruit Production Extension Educator Updated on June 16 to correct an error in the original text, which incorrectly referenced the Bocking 14 comfrey cultivar. Bocking 4 was the intended reference grown at Alternative Roots Farm in New Ulm, MN. Apples : Site specific strategies: Bocking series comfrey orchard ground cover Grapes : Growth update: Bloom Raspberries : Update on diseased canes in SE Minnesota Apples Site-specific strategies: Bocking series comfrey orchard ground cover Images: Flowering Bocking 4 comfrey at Alternative Roots Farm (left) and an apple tree row with Bocking 14 comfrey before it collapses into a mat (right; photo by John Knisley of Alternative Roots Farm , New Ulm, MN). Conventional herbicides are commonly used to manage grass and broadleaf plants under orchard understories in conventional vineyards, but these products also come with their own drawbacks and limitations, and are not allowed under USDA Organic production. A number of options e...

Natalie Hoidal & Marissa Schuh This spring has been pretty ideal for planting. Cooler weather with fairly consistent, gentle rains have allowed farmers to get crops in the ground, reduce transplant stress, and keep cool season crops like Brassicas happy. Looking ahead, the NOAA 3-month forecast has shifted from projecting an “average” summer, to a summer that is likely to be hotter and drier than usual. While many crops seem slightly slow to establish at this point, they’ll catch up quickly as the weather warms up in June. Crop updates Greens galore : Many farmers are starting their CSAs and farmers markets this week with an abundance of leafy greens. We’ve seen a few disease related lettuce questions including bottom rot and some mysterious leaf spots. Remember that when you’re seeing pathogens, you’re always welcome to reach out to us for help with identification and figuring out management strategies. Garlic is scaping, so here is your annual reminder about best practices for...

UMN Extension and Renewing the Countryside are hosting two field days this month, all about pruning and trellising in high tunnels. We'll meet at the high tunnel on the University of Minnesota's St. Paul campus, where we've set up tomatoes, peppers, and cucumbers with different types of trellises. You'll get to see the different systems, learn about the pros and cons of each, and get some hands-on experience with pruning each crop.  Systems we will feature include: nets, basketweave, single leader, double leader, and lower & lean.  Field days: Monday June 23, 10am - 12pm Saturday June 28, 10am - 12pm These events are free, but we ask that you register ahead of time so we can make sure to have enough snacks and supplies on hand.  Register at z.umn.edu/HTpruning o r with this QR code: Directions: Navigate to The Bee Lab (1634 Gortner Ave, St Paul, MN 55113). There is a field road 200 feet north of the bee lab heading East. Take this road until it ends, and the high ...

Madeline Wimmer- UMN Fruit Production Extension Educator Apples : Growth stage updates: Apples between 12–24 mm, rapid shoot growth Removing newly emerging water sprouts Apple scab update Grapes: Growth stage update: 6–8 leaves separated  Bloom: Petiole sampling for nutrient analysis Berry crops: Pest highlight: Spotted Wing Drosophila (SWD) About SWD Monitoring SWD adults and larvae Managing SWD Apples Growth stage updates: Fruitlets between 12–24 mm, rapid shoot growth Images: A step by step demonstration of hand removal of a newly emerging water sprout from a larger scaffold branch on a freestanding central leader trained apple tree. Image from Sekapp Orchard in Olmsted County, MN (Zone 5a) . By the time apple fruitlets begin to grow past 10 mm in circumference, a good amount of shoot growth has typically occurred. In SE Minnesota orchards, many fruits are between 12-24 mm depending on the location, variety, and other factors; vegetative shoots were around 7 inches long and stil...

Marissa Schuh A hot weekend shifted into a week of wildfire smoke over much of the state. Some areas got some soaking earlier this week, and there is some more rain in a forecast, a relief as much of greater Minnesota is abnormally dry or in D1 drought . Some beautiful early season produce is being harvested and heading to markets and CSA boxes. Wildfire smoke and plant health The effects of wildfire smoke on plants is poorly understood, and what we do understand is that it is complex. For example, while the smoke does block some sunlight, it also creates diffuse light, which can more easily penetrate the plant canopy than direct sunlight. If the smoke is high in ozone, this can damage plants, causing a variety of white and yellowing speckling on a wide range of vegetable crops. The impact of the smoke will also vary depending on how close or far you are from the source , we may see different things in parts of Northern Minnesota where there were local fires, compared to the metro and...

Madeline Wimmer, UMN Extension Educator- Fruit Production & Soon Li Teh, Extension Specialist and Assistant Professor in Grape Breeding and Enology Image: a plant nutritional pyramid showing from bottom to top those nutrients supplied by air and water: Carbon (C), Hydrogen (H), and Oxygen (O); primary macronutrients: Nitrogen (N), Phosphorous (P), and Potassium (K); secondary macronutrients: Calcium (Ca), Magnesium (Mg), and Sulfur (S); micronutrients: Molybdenum (Mo), Boron (B), Nickel (Ni), Copper (Cu), Zinc (Zn), Iron (Fe), Chlorine (Cl), and Manganese (Mn).  Graphic created by Madeline Wimmer, 2023. Plant nutritional analysis—also known as foliar/leaf/petiole testing—is the practice of analyzing nutrition within a plant to determine adequate, excess, or deficient nutrient levels. Oftentimes, this involves collecting a plant’s leaf, leaf with petiole, or only the petiole at a specific growth stage.  Plant nutritional analysis is a critical step in determining any poten...