Vegetable Update - June 4, 2026

UNIVERSITY OF MINNESOTA EXTENSION - www.extension.umn.edu

Parts of the state have received rain over the last week, but most of the state is abnormally dry, with a few areas of southeast and north central Minnesota in moderate drought. There is a chance of rain and storms across the state in the next week. Planting and field prep continues around the state.

Herbicide drift

We have gotten our first reports of herbicide drift of the year - we always do around this time. This is a common time for field crop growers to apply a variety of herbicides, each one has its own potential to drift and produces their own unique drift symptoms.

On the prevention side, have conversations with neighbors and put your farm on Driftwatch.
 

What are some potential indicators that your crops have been drifted on?

• Drift damage often forms a gradient – with the most severe damage on the field edge.
• Drift damage isn't spotty in the field, it tends to be fairly consistent in affected areas (this is in contrast with some of our plant viruses, which can affect a plant here or there, or in a row where an infected tray was transplanted).
• Drift can impact vegetables, but also neighboring vegetation. Checking in on plants in field borders and trees to see if they have damage that mirrors what you are seeing in the field.

What do different herbicides look like? Depends on the chemistry, the plant that has been exposed, and the amount of exposure. Generally, tomatoes are the most sensitive vegetable we grow, and are the vegetable most likely to show symptoms.

Dicamba is available for soybean growers again this year. This chemistry with high drift potential wasn’t available last year, but is back this year.  There are Minnesota state level restrictions around the product. This herbicide is a synthetic form of a plant hormone that is involved with plant growth, so susceptible plants that are exposed have twisted, distorted growth. This herbicide has the potential to move over far distances, so the source of the drift may not be an immediate neighbor.

A tomato plant 5 days after dicamba exposure. Note the twisting stem and leaves. Photo: J. Arana, Purdue University.

2,4-D is a type of product that has application scenarios in both field crop and lawn settings. This chemistry is also a synthetic plant hormone, so it causes distorted new growth. Susceptible plants that have been exposed this herbicides often have twisted and distorted leaves and stems, as well as stunted growth.

Tomato leaflets with twisted and distortion after 2,4-d exposure. Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org

Glyphosate is also used in field crops this time of year. This chemistry interacts with the plant differently, so the damage looks different. Glyphosate drift appears as bleaching in the bottom portion of new growth.

The bleaching at the base of the youngest leaflets is characteristic of glyphosate injury. Photo: Brenda Kennedy, University of Kentucky, Bugwood.org

There are other herbicides being used in field crops this time of year that cause other symptoms. Use the above distribution clues, and feel free to reach out if you want to get an opinion on what you are seeing.

Ultimately, only a lab can confirm by doing residue analysis. The sample has to be collected soon after the drift event, as the herbicide can degrade and may not be able to be detected in lab tests after a certain point. The Minnesota Department of Agriculture will perform investigations and do lab testing, you can learn more about that process on their website. 

Armyworms and cutworms are out

We’ve gotten reports of damage from both cutworms and armyworms from high tunnels in the Southern half of the state this year. We’ve had lots of conducive weather for the moths of these caterpillars to move north, and the eggs these moths have laid over the last 2 months have now hatched. The damage has ranged from the snipped transplants we expect from cutworm, to armyworms and cutworms feeding extensively on foliage, stems, and even fruit in some high tunnel tomatoes. To manage these guys effectively, you have to catch them when they’re small, once they start cutting or doing major defoliation, yield loss has already occurred and getting any spray to work is tricky.

Crop reports

Asparagus: Harvest is good, with some farms reporting having more asparagus coming out of their fields than they have markets for.

Cole Crops: Flea beetles and caterpillars are out. As with the cutworms above, the smaller the caterpillars are, the easier they will be to control. Bt is effective on small caterpillars, targeted to preserve beneficial insects, and OMRI-listed.

Garlic: We are entering the time of year where aster leafhoppers can get moved to Minnesota with weather fronts. This matters because this insect is the vector for aster yellows (which can also impact carrots, celery, and lettuce).  Michigan State collects and processes aster leafhoppers for aster yellows, generally the leafhoppers they’ve caught have had low levels of Aster Yellows. This disease is super dynamic, how much aster yellows we see in a given year comes down to luck – do we have a flush of aster leafhoppers carrying a lot of aster yellows? Just one drop can cause a big problem. Research in Michigan suggests that the biggest time period for aster yellows risk is mid-season, so at least we often don’t have garlic and lettuce out at this time.

Greens: We’ve heard reports of bolting in spinach and other spring greens, as well as sun scald. All greens planted at this stage should be varieties specifically selected for heat tolerance and summer planting. 

Tomatoes: We got multiple reports of cutworms in tomatoes and peppers this week. These heat loving crops are growing quickly with the warmer weather, and it’s already time to prune tomatoes. We’ll do a more comprehensive pruning review next week. For now, it’s better to prune early and often via waiting and pruning a bunch of foliage at once. At a minimum, try to keep foliage about a foot off the ground to help prevent foliar disease spread.