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Weekly Vegetable Update 6/4/2020

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. Many growers have reported asparagus beetle pressure. 
  • Potatoes have mostly emerged. Potato beetles have been spotted in most parts of the state and are beginning to lay eggs. Alfalfa fields are being cut, so anticipate potato leafhopper movement as well. 
  • Cucumbers: are mostly in the ground, and we've heard a few reports of cucumber beetles. 
  • Zucchini and summer squash: are starting to produce their first fruit. These fruit will likely stay small, and you may want to consider harvesting them to allow the plant more energy for flowering and later fruit. Check out our recent 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 now in the field for most of the state.
  • Cole crops are at various development stages depending on succession planting. We heard more reports of bolting this week, and flea beetles are out in full force. 
  • Dry beans are mostly planted at this point. Potato leafhoppers love beans, so keep an eye out, especially during this time of alfalfa harvest (more info below). 
  • Lettuce and leafy greens harvest remains in full swing

Problems in the field

Peppers with 2,4-D damage. Image: Annie Klodd


We've heard more reports of bolting in Brassicas. 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 followed by high heat, you may see more bolting this year in a variety of vegetables.

Herbicide drift

We've seen more herbicide drift symptoms in both fruit and vegetable crops this week. 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. 

Insect forecast

Can you spot the leafhopper? Photo: Natalie Hoidal
Potato leafhoppers are showing up in potatoes and beans. Potato leafhoppers tend to feed on alfalfa when they first arrive in Minnesota, and once the alfalfa fields are cut, they migrate into other crops. Alfalfa harvest has been ongoing for the last couple of weeks, and we're starting to see leafhoppers in vegetables. Scout carefully. These insects are tiny and hard to see, and their damage is difficult to detect at first. More info on leafhoppers.

Aster leafhoppers have also shown up on carrots. If you have carrots resistant to aster yellows, this is of limited concern. UW Extension has an in-depth overview of scouting and determining thresholds for Aster leafhopper in carrots on page 16 of their commercial growers guide.

Cucumber beetles are out and feeding on young plants. Scout cucumber beetles regularly: they can transfer bacterial wilt when your plants are young. From Veg EdgeThe action threshold for first true-leaf plants is when SCB populations exceed 2 or more beetles/plant on 25% of the plants.Once plants are at the 2nd or 3rd true-leaf stage, monitoring efforts should shift from monitoring beetles to checking the defoliation level.
Diamondback moth larvae on broccoli. Photo: NH

Potato beetles are emerging and starting to lay eggs.

Caterpillars in Cole Crops have shown up. The majority of current sightings are of Diamondback Moth larvae, though I have seen some Imported Cabbage Worm moths flying around as well. In the early season before cupping has begun, the threshold for spraying Diamondback Moths is 50% of plants infested with at least 5 larvae. Most fields are no where near this point.

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

Great Lakes Vegetable Producers Networkjoin us during your lunch break on Wednesdays for a 30 minute discussion about vegetables. Next week's topic (June 10th, 11:30am) will be about the do's and don'ts for sending samples and reading results. All previous episodes can be downloaded as podcasts. 

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