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Weekly Vegetable Update 6/25/2020

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

Like last week, this week was mostly hot and dry. This was great for holding off diseases, but many growers experienced drought stress, and insects continue to thrive in these conditions. 
Flowering melons, NH
  • Asparagus has reached the fern stage for most growers at this point. Invest some time in weed management this week as the fern canopies start to fill in. 
  • Garlic: Most of you have removed scapes by now, and garlic is beginning to invest in bulbs. You may notice your leaves are turning yellow - this is likely a response to heat and drought stress. 
  • Potato beetles are out in full force; larvae in Marine on St. Croix were already at the 4th instar (larval stage) last week, at which point they become quite difficult to manage with insecticides. I am still seeing A LOT of potato leafhoppers. 
  • Cucurbits: are vining and flowering. At this point it's too late for second applications of fertilizer. Now we cross our fingers and hope for good pollination weather. I've seen a  few cases of fungal diseases in cucumbers this year, but not many. 
  • Tomatoes and peppers are setting fruit, both in the field and high tunnel! Tomato disease season seems to have begun - keep scouting regularly. 
  • Cole crops are being harvested - many farms will have their first (or even second) broccoli crop this week. Diamondback moths are still present, and we're seeing imported cabbage worm moths sporadically. 

Problems in the field

Wind and heat damage

Stressed peppers, Grower Submitted
We've seen photos from a few growers around the state of peppers that seem generally beat up. There are no obvious insect, disease, or nutrient issues; we even sent a sample to the disease clinic just in case we were missing something and it came back negative. Our best guess at this point is that with the high heat and some very windy days, they experienced some heat and wind stress. This is especially exacerbated if plants are being grown on black plastic.

Pollination in cucurbits

Cucumber beetles have been an issue this year, and now that cucumbers and melons have begun to flower, it's critical to take extra care to protect pollinators as you manage beetles. Cucurbits rely on bumblebees and squash bees for pollination and fruit set. With a few storms and hot days in the forecast, pollinator activity may already be reduced.
Stunted peas, NH

Stunted peas

I first noticed this in my garden, and then heard reports of stunted peas from growers in Wisconsin.
 Pea plants seem to be flowering really early when the plants are only about a foot tall, and setting very few pods before the plant has really had a chance to develop. If this is happening in your field, check the stems for lesions. In most cases, the culprit seems to be Fusarium root rot. 

Insect and disease forecast


I am starting to see more tomato diseases, including early blight. Otherwise, disease pressure is generally better than in previous years. Keep an eye on cucumbers - downy mildew has shown up in other states, but so far we have no reports from MN. 


Fourlined plant bug: I saw quite a bit of damage from fourlined plant bugs this week, particularly in herbs.

I keep catching substantial numbers of potato leafhoppers when I go out to scout in potato and bean fields. They are small and hard to see, but they can do a lot of damage. (More info on leafhoppers).

Cabbage caterpillars: I am still seeing plenty of diamondback moth larvae, but I saw a whole bunch of imported cabbage worm eggs this week.

Potato beetles in Marine on St. Croix had already reached their final larval instar stage late last week. After the first and second instar, pesticide treatments become less effective. I have truly never seen potato beetles in such abundance. 

Leafhoppers and potato beetles, NH

Educational opportunities

Great Lakes Vegetable Producers Networkjoin us during your lunch break on Wednesdays for a 30 minute discussion about vegetables. All previous episodes can be downloaded as podcasts. Next week's episode will be about Boron! 

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