Author: Natalie Hoidal, UMN Extension educator, local foods and vegetable crops
I could probably start every single one of these with something like "What a week!". This week was no exception. We had plenty of excitement: summer crops beginning to mature, some rain, and lots of farm tours and events. We also had some weird weather: Cotton and Hibbing got down to 33 and 34 degrees just a week or so after reaching nearly 100 degrees. We also learned that the best way to bring rain to a farm that's had almost none all year is to host a field day - it down poured during the entirety of our field day last night at Shepherd Moon and Big River Farms. But, folks made the best of it and had a great time regardless.
Crop updates
- Garlic: Garlic harvest is here! Despite some spotty aster yellows symptoms popping up around the state over the last couple of weeks, most people's garlic is looking healthy, and yields have been relatively high. Some of you may still be a week or so away from optimal harvest time - two clues that you're ready to harvest are: 1. about half of the leaves have dried out or turned a yellowish brown, and 2. if you harvest a few bulbs and cut them in half, the cloves should fill the skins with no air pockets. Many growers like to wash their garlic immediately at harvest; regardless of washing, garlic should be cured for 3-4 weeks until the necks dry out. For more detailed post-harvest information, see our postharvest handling page.
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| Freshly harvested garlic. Photo: terski, Pixabay |
- Tomatoes: This is an exciting week for tomatoes as well - many farms are getting their first week of sufficient tomato production to fill CSA boxes and farmers market stands. The hot, dry summer has been favorable for tomatoes, and the plants I've seen are mostly looking really healthy. I'll repeat the same advice from last week here - we tend to see the most blossom end rot in the first flush of tomatoes. Remove any tomatoes with BER symptoms as soon as you see them, as they will not grow out of it to form marketable fruits. Early BER symptoms do not mean you'll have it all season.
- Cucurbits: Cucumbers and zucchini / summer squash are coming into peak production. I've had less complaints about cucumber beetles over the last couple of weeks, but I suspect they are still causing problems for some of you. Now that many of us have had slightly more consistent rainfall for the past 2-3 weeks, make sure you're ramping up your scouting to look for diseases like powdery mildew, anthracnose, and angular leaf spot in your cucurbits. Continue to keep an eye out for squash vine borer and squash bugs, as this is the best time to manage them.
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| Keep scouting for squash vine borer adults and eggs. Photo: Squash vine borer larvae and damage, Jim Jasinski, Ohio State University Extension, Bugwood.org |
- Peppers: Peppers are sizing up nicely, and should start to turn color in a couple of weeks.
- Cole crops: Most of what I have to say this week is the same as last week - consider planting a trap crop with any final fall Brassica plantings. Cabbage caterpillars are active, as expected, so continue to monitor to make sure they are not reaching economic thresholds. I'm seeing more healthy, uniform broccoli heads this week compared to last week's curdy / uneven heads, which is a result of a couple of weeks of more moderate weather for final maturation.
- Potatoes: Based on our trials ~30 miles north of the Twin Cities, potato beetles are beginning to pupate, and a few second generation adults have emerged. If you're seeing high populations at this point in the season, preventative products like neem and Bt may be less effective. A number of studies show that foliar applied Beauvaria bassiana can successfully reduce the number of second generation of adult beetles - the fungus infects the larvae, and when they crawl into the soil to pupate, the cool humid soil environment allows the fungus to proliferate, which kills the pupae. Despite the hot weather, potato leafhopper populations remain low.
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| Beauvaria bassiana effects on larvae (larvae shown are not potato beetles). Photo: Louis Tedders, USDA Agricultural Research Service, Bugwood.org |
- Carrots:
I've heard from a couple of people that their carrots are just a little off this year. No major issues like diseases, just slower growth and nubby carrots. Like most things this year, the weather is likely the main cause of problems.
- Sweet corn: The very first sweet corn is showing up at markets this week, but most of us are still a couple of weeks out. How do people get corn to market so early? There are a couple of growers who grow sweet corn in high tunnels - this is an expensive use of high tunnel space, but they've deemed that extra week or two of being the only ones with corn to be worth it. Others start it really early indoors and transplant, but as noted last week, this doesn't always work out well. Either way, sweet corn season is right around the corner. While most of the sweet corn insect pests are not doing much damage yet, take a look at Marissa's article so you know what to look out for in the coming weeks.
Vegetable weather report
Temperatures should remain moderate for a couple of days before creeping up into the 90's again this weekend. Much of the state is receiving a fairly heavy rainfall as I write this, but the next 7 days are projected to be dry (i.e. basically no rain at all). Climate models continue to predict that the rest of July will be warmer and drier than usual, so while these last couple of weeks have given (some of) us a bit of reprieve, we should expect to keep irrigating and managing excessive heat.
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| 7 day precipitation forecast, weather.gov |
Problems in the field and things to anticipate this week
Air quality alerts
Tomato fertility
Summer cover crop opportunities
- Sorghum Sudangrass: Great for adding organic matter to the soil and suppressing weeds
- Phacelia: Attracts many pollinators
- Cowpea: A legume that establishes well in hot, dry conditions
- Sunflowers: Good for pollinators, can provide a side-benefit of some fall agritourism if the stand is large enough. Photographers love sunflower fields for fall senior photos.
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| Cowpea & Sorghum Sudangrass cover crop mix. Photo: Edwin Remsberg and USDA-SARE |
Educational opportunities
The Vegetable Beet: join us during your lunch break on Wednesdays for a
30 minute discussion about vegetables. Next week's topic will be about distinguishing virus symptoms from other physiological issues, and what to do when you identify viral symptoms in your crops.
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 requests for diagnostic help here.
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