Weekly Minnesota Vegetable Update

Now that the growing season has started, I'll be posting weekly vegetable updates with a crop report, problems or interesting things we're seeing in fields, a pest forecast, and educational opportunities. Since we are not able to travel to farms due to COVID-19, we have a little less insight this year than we typically would. 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): hoida016@umn.edu
Fruit questions go to Annie: kloddann@umn.edu
Food safety questions go to Annalisa: hultb006@umn.edu

Crop report

The big news this week was frost. We seem to have moved through it, with much warmer weather predicted for next week. After a rainy weekend, we should have a warm, dry week ahead, just in time for transplanting. 

• Asparagus suffered frost damage around the state. If your spears are mushy, remove them now to prevent secondary infection. Expect re-growth to be a bit slower following a frost. 
• Transplants of all kinds (even under row cover) experienced frost damage this week. 
• Many carrots and beets suffered some frost damage last week. If these crops have already emerged, you'll be able to tell pretty easily whether you need to re-seed. 
• Garlic - The time has pretty much passed for your spring fertilizer application. If you haven't done it yet, do it now and do not wait any longer! More info on garlic management. 
• Cole crops are going in. Keep an eye out for cabbage maggot for the next couple of weeks. Especially with the recent cold snap, your brassicas may be slower growing, making them more susceptible to cabbage maggots (and flea beetles too when they show up). 
• Potatoes are mostly planted at this point, but there's still time to plant if you haven't done so.
• Peas are establishing well, and most seem to have weathered the freeze just fine. 

For crops that you have yet to transplant, check out our recent article about maintaining healthy transplants until you're ready to plant. 

Photo: Christina Elías. Row cover was our friend last week; here's some photo evidence that it's possible to cut and lay row cover while maintaining 6' distance! 

Problems in the field

Beyond frost damage, we received very few reports of vegetable problems this week. 

Photo: Erik Heimark

Limited Phosphorus uptake

Are you seeing reddish / purple leaf margins on some of your early season crops? A grower submitted this photo of peas exhibiting phosphorus deficiency, but his soil test showed very high levels of phosphorus. Cool weather can prevent phosphorus uptake in plants, even if it's present in the soil. If you're seeing these symptoms, do not add more phosphorus! As the soil warms and microbes become more active, phosphorus will become more available. NRCS has a nice basic overview of P uptake if you'd like to read more.

Weeds!
Weeds are always a  problem, but this year we're seeing more growers expanding into previously un-planted areas like hay fields or fallow fields. If you're planting in a new field, see our recent article about tips for planting in a new field to prevent excessive weed pressure.

Pest forecast

The cold weather slowed down cabbage and seedcorn maggot emergence last week, but anticipate them in the week or two to come. Cabbage maggot should emerge in the lower 1/3 of the state this week, and seedcorn maggot should emerge in the lower 1/2. With plant growth delayed by cold weather, take extra care to scout and protect your crops if necessary. Both insects are attracted to yellow. By placing yellow pails filled with water in your fields, you can keep an eye on populations. The degree day models tell us when emergence is occurring, but population levels will vary, so scouting on your farm can help inform your management decisions. More info on cabbage maggot and seedcorn maggot.

Cucumber beetles and flea beetles cannot be predicted with Degree Day models, but anticipate seeing them soon. 

Our colleagues in Michigan spotted Alternaria leaf spot in cole crops already, likely coming in from transplants. Make sure you're scouting your transplants and only planting the healthiest plants! 

Black cut worms are showing up across the state, especially in the West. Cutworms are rarely an economically significant pest in fruits or vegetables, but we hear sporadic reports of them in early season vegetable transplants. 

Educational opportunities

What's Killing my Kale podcast: we're uploading new episodes every couple of weeks!

Great Lakes Vegetable Producers Network: join us during your lunch break on Wednesdays for a 30 minute discussion about vegetables. Next week's topic (May 20th, 11:30am) will be about early season weed management