Weekly vegetable update 6/1/2022

Author: Natalie Hoidal, UMN Extension educator, local foods and vegetable crops 

After an already tough spring, we had yet another week of severe weather that caused damage on farms across the state. The week ahead is looking moderate, with comfortable temperatures for catching up on planting. As crops slowly get established, insects are catching up quickly. In policy related news, the MN drought bill passed this week, and disaster loans are available for farmers who suffered storm related damages last month.

Crop updates

• Sweet corn and beans: Soils across the state are finally reaching temperatures that will allow for quick germination and growth. This is important, because when seeds sit in cold soil too long, they are more susceptible to insects like seedcorn maggot (which are active right now), and certain soilborne diseases.  
  

• Cucurbits: All of our Extension pumpkin trials were planted this week. We have a couple of variety trials going on, and our colleague Charlie Rohwer at the Southern Research and Outreach Center has an exciting trial where he's intercropping pumpkins with clover. You can follow that trial and others on Twitter at @SROCHort. A few other notes about cucurbits: 
• Remember that cucurbits (especially cucumbers) have very sensitive root systems and if you're transplanting later than you had intended to, they can sustain transplant damage. This is especially true if you use plastic pots, as the roots can get snagged as you remove them from trays if they are overgrown.
• Seedcorn maggots eat pumpkin / squash seeds that are direct seeded. Waiting until your soil is warm enough to plant can help prevent seedcorn maggot damage. The following photo was taken in Waseca today: 

Maggots (likely seedcorn maggots) eating a pumpkin seed. Photo: Charlie Rohwer

• Lettuce: It's been a great week for lettuce, and farmers market stands are starting to fill out with a wider variety of spring greens.
  

• Cole crops: Cole crops are sizing up nicely. Our black rot / Alternaria broccoli screening trials start today; 80 growers are planting a mix of 16 varieties to find varieties with some degree of disease tolerance. I've written about how the cold weather we've had this spring makes cole crops more susceptible to bolting when hot weather finally hits, so the week ahead with moderate temperatures is ideal. It's warm enough to allow them to keep growing, but likely not warm enough to trigger any bolting. In my own garden, my uncovered turnips are showing quite a bit of cabbage maggot damage this year; cabbage maggot pressure is expected to remain an issue for at least another week or two. 

 

Cabbage maggot damage to a turnip root. Photo: Natalie Hoidal

• Tomatoes and peppers: Most people (aside from perhaps the Iron Range growers) have their tomatoes and peppers out in the field. With the cold week ahead, expect slow growth, and potentially some minor cold damage, which plants should grow out of. With the cold wet spring, many growers have tomatoes and peppers that already have some disease pressure, particularly from gray mold and bacterial spot. Check out Marissa's article about how to handle these diseases once your plants leave the transplant house.
  

• Garlic: I'm seeing more and more "green garlic" being sold at farmers markets in the last couple of years. If it makes sense for you financially, this is a nice way to offer customers something interesting in addition to the abundance of greens and radishes in the spring, and a way to free up bed space if you're growing in a small space.

"Green garlic" Photo: Andrea Nguyen, Flickr

 

• Potatoes: Potatoes are beginning to emerge. The first alfalfa harvests are beginning this week, so anticipate some movement of potato leafhoppers. These insects are tiny and hard to spot, so they often go unnoticed, but they can cause substantial yield loss. If you're growing very close to an alfalfa field, watch your neighbors fields, and consider scouting with a sweep net soon after they cut their alfalfa.
  

Soil temperature report

If you read this blog regularly, you'll notice that I took the weather report out this week. With all of the storms and unpredictable we've been having, my quick weather summary was starting to feel less useful. If you'd like to see it included in future weeks, let me know and I'll put it back!

Soil temperatures warmed up considerably this week, and except for the very far northern parts of the state. While the week ahead will be fairly cool, soil temperatures are now at the point where it's safe to plant warm-season direct seeded crops like sweet corn, beans, etc.  The following tables provide a snapshot of soil temperatures across the state. For more detailed info, see https://app.gisdata.mn.gov/mda-soiltemp/

Soil temperatures from MDA stations, data collected to 6’’ depth

Station location	Nearest major town	Coldest soil temperature in the last 7 days (approx.)	Temperature on May 31, 2022 (approx).
Blue Earth	Albert Lea (Iowa border)	55 º F	64 º F
Russel	Marshall	54 º F	63 º F
Henderson	St. Peter / Belle Plaine	55 º F	66 º F
Hoffman	Alexandria	49 º F	60 º F

Soil temperatures from ND-managed stations in MN

Station location	Nearest major town	Approximate turf soil temp on May 31  (4’’)
Sabin	Fargo / Moorhead	60 º F
Mavie	Thief River Falls	56 º F
Fox	Roseau (Canada border)	57 º F

Problems in the field / things to do this week

Drought relief! Plus: Infrastructure destroyed in storms

The much awaited drought relief bill has passed! From MDA: Minnesota livestock farmers and specialty crop producers who incurred expenses due to last year’s drought can apply for up to $7,500 per farm in reimbursement through the Minnesota Department of Agriculture’s (MDA) 2021 Agricultural Drought Relief Program (ADRoP) when it opens in mid-June. All Minnesota counties except Goodhue, Rice, Wabasha, Winona are eligible. 

The application will only be open for 10-12 days (exact dates to be announced), so the Department of Agriculture is recommending that farmers take time now to gather receipts. Read more here.

 

Due to the recent severe weather, many farmers have experienced damage to high tunnels and other farm infrastructure. The Minnesota Rural Finance Authority Board has approved zero-interest loans for Minnesota farmers who suffered damage from the storms in May. Learn more about this program here. 

Tunnel damage after storms. Photo credit: Ted Carey, Kansas State University via eOrganic.

Irrigation water testing

I've written a few articles about this already this year, but as high tunnel crops start to take off, it's a good idea to test the pH and alkalinity of your irrigation water if you haven't already. Generally, we see that high tunnel crops perform very well for a couple of years, and then start to decline around years 4-5. You can learn more about this in our recent Vegetable Beet podcast episode "Tunnel trouble: increasing many things but not yield". This is often a water issue. High alkalinity water can deposit salts in your soils, and over time this drives up the pH of your high tunnel soils. One way to deal with this is to acidify your water. 

 

There are fancy ways to do this with injectors like Dosatrons, but I learned about a much simpler method that can work my own dad, who has been doing this for years (go figure!). Rather than using an injector, he simply fills a drum with water, adds his acid until the pH reaches around 6 (testing with paper strips), then uses a sprinkler pump to pull water from the drum into the irrigation system. This is obviously more daily work than having an automated system, but it can work well for folks who aren't ready to make the jump, or folks who aren't great with machines / technology. 

A low-tech way to acidify irrigation water. Photo: Natalie Hoidal

Connect with the fruit & vegetable team

If you're seeing interesting things in your fields, need help identifying problems, or just want to share photos, we'd love to hear from you! Growers can reach out directly to me any time at hoida016@umn.edu, and you can submit questions and diagnostic help below.