Skip to main content

Minnesota Vegetable Update 5/28

Author: Natalie Hoidal, UMN Extension Educator, Local Foods and Vegetable Production

If you're seeing interesting things in your fields, insects and diseases, or just want to share photos, we'd love to hear from you! As always, don't hesitate to reach out with questions and pictures. We're still here for technical assistance over the phone, via text, or via email.

Vegetable questions go to me (Natalie):
Fruit questions go to Annie:
Food safety questions go to Annalisa:

Crop report

So, the weather predictions from last week were totally off. This week has been soggy and wet, and many of you have not been able to get in to the fields. Here's to hoping the next 7 days or so of dry weather in the forecast are accurate! The first succession of most crops are now in the field.
  • Asparagus harvest continues. 
  • Potatoes are coming up. We had our first report of Colorado Potato Beetles, but in many parts of the state they have not yet emerged. Do not spray the first generation of adults.  
  • Cucumbers: Cucumbers are mostly in the ground, and many growers are seeing some transplant shock.  Check out our latest What's Killing my Kale episode for a discussion about setting cucurbits up for success, and some insight about the flowering and fruiting issues we saw across the state last year. 
  • Tomatoes and peppers are mostly in, though many farms are having to wait due to the wet weather. If you're holding transplants longer than expected, see our article from a couple of weeks ago about holding transplants. 
  • Cole crops are at various development stages depending on succession planting. Flea beetles are showing up this week. We've also heard about some bolting already in cauliflower. 
  • Lettuce harvest is in full swing
Pepper plants waiting to be transplanted following this week's heavy rainfall. Photo: Natalie Hoidal

Problems in the field


With so much water and humidity this week, it's time to start thinking about diseases. We've seen miscellaneous reports of diseases in crops ranging from cucumbers to lettuce to broccoli. Some of these diseases were most likely seedborn, so make sure you're doing hot water treatments where applicable and scouting transplants. We are here to help you diagnose diseases, but we will often recommend that you send a sample to the disease clinic for a formal diagnosis, since they are able to look at your plants under a microscope and conduct genetic testing. Lina Rodriguez from Iowa State made an excellent video recently about how to collect a sample for diagnosis. 

Purple leaves

Purple pepper leaves. Photo: Natalie HOidal
We continue to see purple leaves, particularly in tomatoes and peppers. In early spring when the weather is cool, phosphorus is less mobile due to decreased microbial activity. This can result in a phosphorus deficiency in plants, which is expressed as purple leaves. Do not worry, and do not apply more phosphorus! As the weather warms, phosphorus will become more available and plants should recover. 


We've heard one report of very early cauliflower starting to bolt already. For an in-depth discussion of bolting in spring vegetables, see Ben Phillips and Ron Goldy's recent article from MSU. Due to the cool spring weather, you may see more bolting this year in a variety of vegetables.

Herbicide drift

We've seen some potential herbicide drift symptoms in both fruit and vegetable crops. See Annie's article in this week's newsletter about damage symptoms in berries. Drift can look different in different vegetables, but this fact sheet from Wisconsin does a pretty good job of showing the typical symptoms from a wide variety of herbicides. If you suspect you've experienced drift on your farm, contact MDA immediately. Also, consider signing up for DriftWatch so that applicators in your area know about your farm and can take extra precaution. 

Pest forecast


You may be tired of hearing about cabbage maggot and seedcorn maggot by now, but we are still at peak emergence for both insects this week. With plant growth delayed by cold weather, take extra care to scout and protect your crops if necessary. These insects will not be in every field, but if they are present, now is when they are active. Both insects are attracted to yellow. By placing yellow pails filled with water in your fields, you can keep an eye on populations. 

Flea beetle damage in arugula
Photo: Natalie Hoidal

Cutworms are very active in Southern MN. See the most recent cutworm trapping network report for more information. 

Flea beetles

Flea beetles are one of the most consistent insect pests, yet they remain one of the trickiest to manage for organic growers. We are starting to see flea beetles emerge around the state. Due to the cold weather, your crops may be slower growing than usual, and they are most susceptible to damage when they are young. See our previous post about flea beetle management. 

Educational opportunities

What's Killing my Kale podcast: we're uploading new episodes every couple of weeks! The most recent episode is about setting up your cucurbit plantings for success.

Great Lakes Vegetable Producers Networkjoin us during your lunch break on Wednesdays for a 30 minute discussion about vegetables. Next week's topic (June 3rd, 11:30am) will be about nutrient management for high tunnel tomatoes with David Van Eeckhout (The Good Acre) and Judson Reed (Cornell). 

Print Friendly and PDF