Final weekly vegetable update

Final weekly vegetable update - 9/17/2020

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

Crop report

This will be the last weekly vegetable report of the season. Thanks to all of you who followed along and submitted photos and questions! After a week that felt like late fall, we're returning to fairly "normal" fall temperatures for a couple of weeks. Light frosts and cold weather have ended or substantially slowed harvest of summer crops, and fall crop harvest, field cleaning, and curing and storage season is fully underway. There is no rain in the forecast for most of the state this week, which is ideal for harvest, clean up, and bed prep.

Cucurbits: Farmers are harvesting the last of the melons, and winter squash and pumpkin harvest is entering full swing. It seems like the demand for pumpkins is creeping earlier and earlier each year. At this point, with Halloween only two weeks away, treating powdery mildew and other foliar pathogens is not worth it. There seems to be a wide range of practices around curing among Minnesota farmers - many farmers are curing pumpkins in the field, others move them out of the field. We've seen a few pumpkin and squash problems show up in the final stretch, including viruses (mostly Squash Mosaic Virus), and some fungal pathogens on the skin that have yet to be formally diagnosed.
Tomatoes and peppers: A few growers are still eking out some final peppers, but for the most part pepper season is over. I've seen a few frost damaged peppers at farmers markets. High tunnel tomatoes are at various stages - these last few weeks of production are when early season management decisions start to show. Tomatoes that have had adequate fertility and disease prevention are still doing well and producing abundantly. You'll likely notice some purpling of the leaves in unheated tunnels - this is related to the cold, since phosphorus becomes less mobile in cold weather.
Cole crops: Fall radish harvest has started - is there anything better than a freshly picked watermelon radish on a cold fall morning? Fall broccoli and cabbage are sizing up. I continue to get occasional reports of flea beetle problems and black rot, but disease pressure remains lower than most years. There is no rain in the forecast for most of the state, which is a good sign for disease prevention.
Sweet corn: Sweet corn harvest is wrapping up for most growers. Corn earworm flights have decreased around the state.
Carrots and beets: We are reaching peak carrot and beet harvest. I've heard from a few growers that aster yellows symptoms are worse than they had originally thought. Since carrot foliage is lacy to begin with, it can be tricky to notice damage or estimate the extent of damage until harvest. Aster leafhoppers do not overwinter, and aster yellows do not survive composting, so if you compost your infected carrots, that should *mostly* get rid of the problem for next year. However, aster yellows has a very wide host range, so consider scouting your field margins for any perennial plants that look like they have symptoms. More info on aster yellows.
Potatoes: As always, be vigilant with throwing out bruised or scraped potatoes to avoid soft rot contamination of your storage area. If you've seen soft rot in earlier plantings, allow your potatoes to fully mature in the field before harvesting. Check out this article from last year about post-harvest handling for potatoes.
Garlic: Get ready for planting season! Now is a great time to prep your beds. Garlic should be planted 1-2 weeks after the first killing frost. In Northern MN planting is typically done the 3rd to 4th week of September, and in Southern MN it's done in the first or second week of October. Make sure you have your seed in order and that you've reviewed the Growing Garlic in Minnesota guide.

Next week I'll be writing a guide to curing and storing fall vegetables. Reach out with any questions you have and I'll be sure to include them!

A newly establishing cowpea and millet cover crop in a Falcon Heights high tunnel. Photo NH

Plant a fall cover crop

It's not too late to plant many fall cover crops! See the Midwest Cover Crop Council's Decision Making Tool to see which cover crops are still suitable for planting in your county. The window for most winter-killed cover crops has passed for much of the state, but there's still plenty of time for winter wheat, winter rye, winter camelina, and a few others. Crops in the yellow zone can still be planted, but keep in mind that you may not accumulate as much biomass as you might hope, and there is a risk of freeze damage.