Authors: Marissa Schuh and Natalie Hoidal
Looking ahead the next two weeks, we are looking at warm (daytime highs in the 80s) and dry (good for harvest!) weather. We are maybe five weeks away from the first frost in the metro area, but we are wrapping up our updates now as we are reaching the end of the time where we can take meaningful action to deal with problems this season. Feel free to reach out to us (contact info above) if you have any questions about things you are seeing on your farm.
Cover crop time
Across Minnesota, the windows for planting cover crops are quickly closing in. While there are a few crops you can plant into October (winter rye, winter wheat, winter camelina), many cover crops are reaching the point in the season where they will not reliably germinate and establish before winter. If you're hoping to squeeze in a legume cover crop still this fall, some options include vetch, pea, and lentils. Use the Midwest Cover Crops Council tool to generate a planting calendar for your county, and check out our vegetable cover crop website for seeding rates and pros & cons of various cover crop options.
Planning for next year
For growers applying manure to fields this fall, remember a few basic best practices:
Crop Updates
In general the warm, dry weather in the forecast means favorable conditions for harvest and fall disease management.
Cole crops: Harvest continues. We are seeing a few leaf spotting disease show up now that the difference between daytime and nighttime temperatures mean prolong periods of dew – which give plant diseases the moisture they need to infect leaves and move around.
By far the most common foliar disease of brassicas is alternaria. This causes numerous, small brown spots, oftentimes surrounded by yellow leaf tissue. It can also make its way into the heads of broccoli and cauliflower, causing mushy, brown beads. See this article for more pictures and management information.
We also got a report of brassica powdery mildew, a disease we don’t often hear about. If you’ve seen powdery mildew in your vine crops or cut flowers, this is very similar, just a different variety of powdery mildew that infects brassicas. It appears as white, powder-like spores on the leaf. Resistant varieties exist in many crops if you are having major issues with this disease.
Garlic: Now is a good time to start preparing beds for garlic planting to allow residues from your previous crop or cover crop to break down. It's also a great time to get a soil test (turnaround time is about 2 weeks right now) so that you have time to amend your soil. About ⅓ - ½ of your garlic’s nitrogen should be applied in the fall. Now is also a great time to review the new Growing Garlic in Minnesota guide.
Onions: Take care to avoid harvesting before onions are fully mature; the necks should be as dry as possible before topping. Harvesting too early can lead to soft rot. More on onion soft rot.
Peppers: Harvest is ongoing. We are getting more and more pictures of phytophthora from growers, familiarize yourself with this disease so you can start working on preventing this disease from moving around if it ever shows up on your farm.
Vine crops: It’s looking like our fall weather will be ideal for field curing squash and pumpkins. Pumpkins and squash cure well outdoors when the weather is warm and we have 7-10 days without rain. Cut ripe pumpkins and squash from the rest of the plant and let it lay in the soil for 7-10 days until any nicks or cuts have scabbed over. Squash is done curing when it can no longer be punctured with a fingernail. Remember to wipe pumpkins and squash clean to remove soil before storing or displaying at your farm stand.
Seeing fruit with spots or scabs? Refresh yourself on common causes here.
Tomatoes: Tomatoes continue to go downhill after a wet season promoted all sorts of diseases. Clean up fields well, and consider doing something to chop up crop residues. The smaller those pieces are, especially if they get incorporated into the soil, the more quickly they will break down and reduce disease populations in your fields.
Looking ahead the next two weeks, we are looking at warm (daytime highs in the 80s) and dry (good for harvest!) weather. We are maybe five weeks away from the first frost in the metro area, but we are wrapping up our updates now as we are reaching the end of the time where we can take meaningful action to deal with problems this season. Feel free to reach out to us (contact info above) if you have any questions about things you are seeing on your farm.
Cover crop time
Across Minnesota, the windows for planting cover crops are quickly closing in. While there are a few crops you can plant into October (winter rye, winter wheat, winter camelina), many cover crops are reaching the point in the season where they will not reliably germinate and establish before winter. If you're hoping to squeeze in a legume cover crop still this fall, some options include vetch, pea, and lentils. Use the Midwest Cover Crops Council tool to generate a planting calendar for your county, and check out our vegetable cover crop website for seeding rates and pros & cons of various cover crop options.
Planning for next year
- Fall is a great time to invest in some bed prep for spring! Despite the drought periods we’ve seen over the last few years, our climate is generally becoming wetter in the spring, which can delay field work. By prepping some beds now and using cover crops in between, you can save yourself some labor in the spring and the cover crops can help to absorb early spring moisture while outcompeting weeds. Check out this video highlighting a research project where we tested this practice: https://www.youtube.com/watch?v=IXrJrOKDmII&t=3
- As you wrap up field work for the fall, consider getting your soil tested. Our team is available to work with you to understand your soil test results and make management recommendations for the coming year.
- In addition to testing your soil, make sure to take stock of nitrogen credits from this year's practices. If you have a cover crop in the field, take some time to estimate your biomass so that you can figure out how much nitrogen to account for next spring. The following video walks viewers through this process: https://blog-fruit-vegetable-ipm.extension.umn.edu/2022/09/final-weekly-vegetable-update-of-2022.html
For growers applying manure to fields this fall, remember a few basic best practices:
- Wait until soil temperatures drop to 50 degrees F to avoid losses due to nitrification
- Incorporate your manure into the soil to prevent volatilization.
- Test your manure if possible. At the very least, make applications based on a soil test, and consider testing your soil again in the spring.
- Pay attention to food safety. Applying manure in the fall is a better practice from a food safety perspective than applying it in the spring, because you're allowing more time for pathogens to break down.
Crop Updates
In general the warm, dry weather in the forecast means favorable conditions for harvest and fall disease management.
Cole crops: Harvest continues. We are seeing a few leaf spotting disease show up now that the difference between daytime and nighttime temperatures mean prolong periods of dew – which give plant diseases the moisture they need to infect leaves and move around.
By far the most common foliar disease of brassicas is alternaria. This causes numerous, small brown spots, oftentimes surrounded by yellow leaf tissue. It can also make its way into the heads of broccoli and cauliflower, causing mushy, brown beads. See this article for more pictures and management information.
Alternaria spots start small, but can become enlarged and turn yellow, or fall out leaving behind a hole. Photo: Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org
We also got a report of brassica powdery mildew, a disease we don’t often hear about. If you’ve seen powdery mildew in your vine crops or cut flowers, this is very similar, just a different variety of powdery mildew that infects brassicas. It appears as white, powder-like spores on the leaf. Resistant varieties exist in many crops if you are having major issues with this disease.
Garlic: Now is a good time to start preparing beds for garlic planting to allow residues from your previous crop or cover crop to break down. It's also a great time to get a soil test (turnaround time is about 2 weeks right now) so that you have time to amend your soil. About ⅓ - ½ of your garlic’s nitrogen should be applied in the fall. Now is also a great time to review the new Growing Garlic in Minnesota guide.
Onions: Take care to avoid harvesting before onions are fully mature; the necks should be as dry as possible before topping. Harvesting too early can lead to soft rot. More on onion soft rot.
Peppers: Harvest is ongoing. We are getting more and more pictures of phytophthora from growers, familiarize yourself with this disease so you can start working on preventing this disease from moving around if it ever shows up on your farm.
Vine crops: It’s looking like our fall weather will be ideal for field curing squash and pumpkins. Pumpkins and squash cure well outdoors when the weather is warm and we have 7-10 days without rain. Cut ripe pumpkins and squash from the rest of the plant and let it lay in the soil for 7-10 days until any nicks or cuts have scabbed over. Squash is done curing when it can no longer be punctured with a fingernail. Remember to wipe pumpkins and squash clean to remove soil before storing or displaying at your farm stand.
Seeing fruit with spots or scabs? Refresh yourself on common causes here.
Tomatoes: Tomatoes continue to go downhill after a wet season promoted all sorts of diseases. Clean up fields well, and consider doing something to chop up crop residues. The smaller those pieces are, especially if they get incorporated into the soil, the more quickly they will break down and reduce disease populations in your fields.
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