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Showing posts from June, 2023

Japanese Beetle Emergence Underway

Bill Hutchinson, Professor, Department of Entomology Throughout much of southern Minnesota, Japanese Beetle (JB) emergence is underway. It will be several weeks before adult feeding damage becomes a concern for fruit crops, so growers have time to prepare and review pest management strategies. Adult beetles, with an appetite for >300 host plants –including several fruit crops, sweet corn, linden trees and roses, to name a few -- and their unique ability to aggregate and create a “feeding frenzy” quickly gets the attention of growers. However, most crops can tolerate high levels of defoliation.   Photo:  Whitney Cranshaw, Colorado State University, Graduate students in Entomology studied JB feeding behavior in detail the past two years.  In wine grapes, Dr. Dominique Ebbenga found that our common ‘Frontenac’ wine grape could easily tolerate 25-30% defoliation without a yield loss or quality loss. Adam Toninato, working in fall raspberries, found that ‘Heritage’ could to

Weather impacts on spotted-wing drosophila

Eric Burkness, Mary Rogers and Bill Hutchison, Departments of Horticultural Science and Entomology Spotted wing drosophila flies investigating a raspberry. Photo:Hannah Burrack, North Carolina State University, In a typical growing season, spotted wing drosophila (SWD) trap catch begins at approximately 755 degree days (DD), using a 50 ° F base temperature, as the flies begin seeking out and attacking a wide range of wild and cultivated small fruit that begins to ripen in mid to late June. In 2023, we have already surpassed 755 DD at both the Rosemount and St. Paul experiment stations in MN with DDs through June 22 nd of 920 and 928, respectively. As of June 22, we still have not detected SWD in either of those trapping locations .  Previous research has shown that SWD mating, and egg lay, will be reduced and may cease when temperatures exceed 86 ° F and as temperatures increase eggs that are laid may not hatch. Despite the adverse weather conditions, SWD infestations

Weekly vegetable update 6/28/2023

Authors: Natalie Hoidal , Shane Bugeja , Marissa Schuh Most growers got some much needed rain this week, but continued air quality issues has made field work challenging. Due a variety of challenges growers have faced this spring, this update includes some notes about pivoting late in the season, including crops that can still be planted if succession plans have gone awry, and marketing opportunities with schools if buyers have backed out or changed their terms. There are also a couple of new (for this season) pests to add to your radar including aster leafhoppers, Japanese beetles, and birds. Crop updates Cucurbits: Melon and early planted winter squash are starting to vine out, and early zucchini and summer squash plants are starting to produce. Squash vine borer reports continue to roll in. We’ve heard some reports of poor pollination, and some confusion about flowering and pollination in these crops. Row covers are an excellent strategy for keeping insects out of cucurbit planting

Weekly Vegetable Update 6/22/2023

Authors: Natalie Hoidal , Marissa Schuh , Shane Bugeja We'll spare you a note about air quality, heat, and drought -- you all know it's rough out there. Read on for notes about crop growth progress and common issues, as well as information about pests to look out for, holding lettuce, lambsquarters, and solarization. Crop updates Brassicas: We’ve heard some concern from growers that their brassica crops are not producing heads. It’s a bit early to be concerned - the growing season started late, and while it feels late in the season due to the heat, it’s still early enough that we’re not too concerned that heads are not forming. We’re also reaching the point in the season where cabbage caterpillars are reaching thresholds for treatment. Treatment thresholds for Minnesota are… For broccoli: Plants in transplant through first curd stage Imported cabbageworm, cabbage looper - 40% of plants with larvae. Diamondback moth - 20% of plants with larvae  Plant in first curd to final harve

Weekly vegetable update 6/15/2023

Authors: Natalie Hoidal , Shane Bugeja , Claire LaCanne , Anthony Adams , Quincy Sadowski , This has been a difficult week for farming with unhealthy air quality impacting most of the state for the last few days, and drought conditions getting worse, particularly in East Central MN. Air quality conditions are expected to improve over the next couple of days. In this week’s update, we discuss ozone damage symptoms, whether or not to use shade cloth in high tunnels, and a variety of crop updates. Crop updates Garlic: Garlic is producing scapes this week. Growers in Southern MN are likely already harvesting, and garlic in Aitkin county looked like it would be producing full scapes within days. Some reminders about garlic scape harvest: Accidentally removing even one leaf can reduce bulb size, so cutting by hand vs. mowing them off is usually worth the extra effort Snap the scapes by hand about 1 inch above the top leaf Remember to keep irrigating for a week or two after scape harvest, as

Should you acidify your high tunnel irrigation water?

Over time, high tunnels tend to accumulate salts, which can drive up the alkalinity and pH of the soil. Acidifying irrigation water is one way to address this problem, and it can be done with varying degrees of investment and technology. Understanding the problem When we apply fertilizer, compost, and manure to our soil, we are often adding salts. Calcium, magnesium, potassium, sodium, and ammonium are all examples of salts that we commonly add to agricultural soils. Typically, acidic rain water washes these salts out of the soil to keep things balanced. However, in tunnels where we lack access to rain, this washing out process does not happen. Further, sometimes the groundwater we use to irrigate in tunnels is also rich in salts. When salts build up in the soil, the alkalinity of our soil also increases. Alkalinity refers to the ability of water to neutralize acids and bases, and thus maintain a stable pH. Over time, this can lead to an increase in the pH of soil in high tunnels. This

Weekly vegetable update 6/8/2023

Authors: Natalie Hoidal , Marissa Schuh , Anthony Adams , Emily Hansen Growers are still catching up from a late spring, and many farmers markets will open this weekend. We’re expecting hot, dry weather in the weeks to come along with air quality concerns. Our updates this week focus mostly on preparing plants and people for these conditions. Crop updates We reviewed some old vegetable updates from around this time in previous years, and many growers are still behind on a lot of crops relative to 2020 and 2021. Peppers seem to be getting hammered the worst of all vegetables by cutworms this year. There was some interesting discussion in a Wisconsin vegetable listserv about using toothpicks or skewers next to plants to prevent cutworms from doing the final cut. We can't refer to any research studies about this, but it seems like any easy strategy to try if you’re at the end of your rope with cutworms. Tomatoes are reaching the point where staking and pruning should begin. The weath