Weekly Vegetable Update September 3, 2026
Authors: Natalie Hoidal & Marissa Schuh
It’s hot, it’s dry, it’s humid. Temperatures will take a turn to the cooler in the next week, and there’s chances of rain throughout the state. Our weekly crop-specific updates are winding down as we shift into harvest season, which means we’re starting to think more about fall and winter programming, and protecting soil over the winter.
What to do after storm damage
Some counties in Southern Minnesota experience some strong storms, with winds and hail being reported. This is a frustrating time for weather damage, as so many crops in the field are at or nearing the finish line.
Wait until things dry out, then assess damage level. We’ve written a lot in the last month about diseases that can hitchhike on people and equipment under wet conditions, and wounded plants will be extra vulnerable.
Give plants protection from plant disease that can flare up in wounded plants, something broad spectrum like copper is a good bet. Organic growers may also get some efficacy from products like Oxidate, Serenade, or Cease. If a crop was almost done for the season anyway, these measures may not pay for themselves. Pay attention to the re-entry and pre-harvest intervals to make sure these applications won’t delay harvest.
If there are damaged tomatoes, peppers, summer squash, and other unmarketable products, remove them from the plants so the plant can focus on the remaining, marketable fruit. In addition, these damaged fruits will continue to break down in the field, as well as in storage.
For pumpkins and winter squash, small scabs can heal over, take extra care when harvesting to make sure that stuff that is in the process of breaking down doesn’t end up in storage.
In spots where foliage was damaged, we may see an increased incidence of sunburn in things like peppers and pumpkins, as fruit that were previously shaded are exposed to direct sunlight.
In the early 2010's Extension hosted a very popular high tunnel conference every year. It ended when Extension educator Terry Nennich retired, and we're finally ready to bring it back!
Our plan is for this to be an annual one day event, with more intermediate to advanced topics for growers who have experience managing high tunnels. We recognize there are already so many conferences and events in the off-season in Minnesota, but there is a gap in more advanced learning opportunities for experienced farmers.
We’ve developed a super short 4 question survey to get your input on when and where you want this conference to happen, and topics we should include. Help us shape it
Have you spotted white mold?
 |
| White mold in high tunnel cucumbers. Photo: Dan Egel, Purdue University. |
 |
| Sclerotia on a head of cabbage. Photo: Marissa Schuh, UMN Extension. |
With drought in most of the state, some of the most tricky diseases have been on hold. Regardless, we know every growing season is different, and are trying to get a gauge on the disease white mold in the state for some potential research next summer.
You can share about frequency, patterns, and impacted crops in this survey.
Fall cover crops: seeding rates & what to seed now
What, when, & how
Cucumbers are slowing down, squash are ripening ahead of schedule, Brassicas are being harvested, and there are now open pockets in the fields. You can still plant some radishes, lettuce, and other greens, but the window for most things has passed. We’re looking at a warm winter, with limited snow cover. Traditionally snow has acted as a protective blanket, but less snow means bare soil may be extra vulnerable to erosion, either from dry windy conditions, or from rain. Cover crops are a great way to keep your fields protected throughout the winter and spring.
If you can plant now, a mixture of oats and peas, with or without berseem clover is a great fit. Oats establish quickly, providing weed suppression and organic matter, and the peas will come in more slowly, providing nitrogen while using the oats for support. Oats and peas die back over the winter, and usually break down pretty quickly in the spring, allowing you to get into your fields early to plant spring crops.
 |
| Oats & peas planted in rows with a Jang seeder. Photo: Lindsey Miller |
For fields that will continue producing for a while (e.g. tomatoes, later successions of winter squash, storage onions), consider a winter wheat or winter rye cover crop into October, possibly planted with vetch, which is a legume that provides nitrogen. Both rye and vetch are notoriously hard to kill in organic systems, but they provide excellent soil health benefits throughout the spring. They can work well in fields you won’t plant until later in the spring (e.g. fields that will be planted with tomatoes, cucumbers, and other heat loving crops next year).
 |
| Rye & vetch mixture planted in rows with a seeder in a high tunnel. Grower submitted photo.
|
We have two new videos all about how to plant cover crops. The first just came out yesterday, and is all about how to successfully seed cover crops at different scales. Check it out below, or at
How much to seed?
For the last two years, we’ve been working with Julie Grossman’s lab on a cover crop trial in high tunnels (we’re excited to share the results very soon!). One of the most common pieces of feedback from growers has been that our seeding rates are too low, despite us using really really high seeding rates compared to what’s recommended by seed companies and Extension programs. The economics are different on a vegetable farm than on a larger conventional farm: seed costs are relatively low when you’re seeding an acre or less (compared to farmers seeding hundreds of acres), and your labor costs are high, so it makes sense that growers want to seed a little extra for insurance to make it worth the labor. Most of the time, this is probably fine. Sometimes, it causes problems. Thomas Bjorkman of Cornell shared recently in a blog post about crucifer cover crops (i.e. cole crops like mustard, radish, etc.) that a high seeding rate can actually result in stunted plants. ““The optimal seeding rate is surprisingly low, typically around 6 pounds per acre. For gardeners, that is 2½ oz per 1000 square feet or one teaspoon per square yard.”
For recommended seeding rates, check out UMN Extension’s page on getting started with cover crops: scroll towards the end of the page where there is a drop-down drawer on recommended planting dates and seeding rates.
Oats: 30-50 lbs per acre
Peas: 30-90 lbs per acre
You’ll notice that this is quite a range. If you are broadcast seeding, go with the high end. If you are using a seeder or drilling, go with the lower end. Whichever method you use, if you’re mixing species, do about 50% of the rate you would do for a single species. So, if you’re broadcasting a mix of oats and peas, aim for 25 lbs of oats, and 45 lbs of peas per acre.
You made it to the end of the update, let us know if these updates are helpful
Filling out this survey helps us improve the newsletter, and should take only a few minutes. Scroll down, or you can access it directly at this link.
Comments
Post a Comment