What's Growing in the Garden

[trc65]

Does anyone have any experience using preen garden herbicide? Although it's not considered organic it's nothing but corn gluten which apparently is effective as a pre merge herbicide. I've got a crabgrass problem, I can do a pretty good job of controlling it by tilling until about half way through the growing season. Eventually the plants get too large to do much tilling and more crabgrass sprouts to make a seed crop for next year. I'm hoping to do a thorough tilling and weeding after everything is well established then incorporate preen into the soil. Any thoughts would be appreciated.

Your rationale for using it is sound, but I've never used the corn gluten meal. Reading a little, it sounds like good soil moisture before application and a good rainfall/watering immediately after application are important. Don't delay after tilling. I'd want to get the CGM on within a day of tilling as crabgrass will germinate quickly with warm temps and moisture.

If you can get cheap corn gluten meal from a mill, I'd do that. I believe that was how it was discovered, somebody had extra CGM and tossed it on the garden to get rid of it.

 

[sprucegum]

Your rationale for using it is sound, but I've never used the corn gluten meal. Reading a little, it sounds like good soil moisture before application and a good rainfall/watering immediately after application are important. Don't delay after tilling. I'd want to get the CGM on within a day of tilling as crabgrass will germinate quickly with warm temps and moisture.

If you can get cheap corn gluten meal from a mill, I'd do that. I believe that was how it was discovered, somebody had extra CGM and tossed it on the garden to get rid of it.

Apparently the best time to apply it is before the soil gets above 50⁰ of course it will stop the seeds that I want to grow from germinating. I'm definitely going to try it on peas, they usually come up before the soil I very warm. Probably would also work well on anything that I start indoors.

 

[DLJeffs]

I remember doing some research on crab grass back when I was working for Chevron Chemical (we packaged all the Ortho brand of products). The more you chop up crab grass, the more it grows. So tilling it might not be a good control method because you just make more sprouts from all the chipped up pieces.

 

[trc65]

I remember doing some research on crab grass back when I was working for Chevron Chemical (we packaged all the Ortho brand of products). The more you chop up crab grass, the more it grows. So tilling it might not be a good control method because you just make more sprouts from all the chipped up pieces.

While that is true, I think Dave's proposed method may be the best option in the absence of conventional herbicides.

Crabgrass starts germinating at ~50° soil temp and as Dave mentioned, that is also the temp around which corn is germinating, so can't use gluten meal before the crop has reached a certain stage of growth.

By tilling it, you are killing a portion of the CG, and if the soil is dry, a higher percentage will die from root dessication. Certainly, some of it will re-root, but the Corn gluten meal will inhibit new root formation, so control should be higher than tilling alone. Tilling will bring fresh weed seed to the germination zone, but the Corn gluten meal will help prevent growth.

The important thing that tilling does mid season is disrupts the growth of the weeds(with a percentage killed) while allowing the crop to grow unimpeded. This allows the corn to "get ahead" of the weeds and gain a competitive advantage for light, moisture, nutrients and space. Sweet corn growth alone won't control the weeds, but it will shift the advantage and along with the corn gluten meal will hopefully keep weed growth to a minimum.

The other concept in weed-crop interactions is a minimum weed free period. If the crop can attain a certain size before the weeds do, yield will not be compromised as weeds will still be present but won't have the size to gain an advantage over the crop.

In some crops, for example potatoes, if the ground is kept weed free for approx 8 weeks after emergence, the crop itself will control weeds by shading the soil surface and preventing nearly all weed growth for the rest of the season.

 

[sprucegum]

While that is true, I think Dave's proposed method may be the best option in the absence of conventional herbicides.

Crabgrass starts germinating at ~50° soil temp and as Dave mentioned, that is also the temp around which corn is germinating, so can't use gluten meal before the crop has reached a certain stage of growth.

By tilling it, you are killing a portion of the CG, and if the soil is dry, a higher percentage will die from root dessication. Certainly, some of it will re-root, but the Corn gluten meal will inhibit new root formation, so control should be higher than tilling alone. Tilling will bring fresh weed seed to the germination zone, but the Corn gluten meal will help prevent growth.

The important thing that tilling does mid season is disrupts the growth of the weeds(with a percentage killed) while allowing the crop to grow unimpeded. This allows the corn to "get ahead" of the weeds and gain a competitive advantage for light, moisture, nutrients and space. Sweet corn growth alone won't control the weeds, but it will shift the advantage and along with the corn gluten meal will hopefully keep weed growth to a minimum.

The other concept in weed-crop interactions is a minimum weed free period. If the crop can attain a certain size before the weeds do, yield will not be compromised as weeds will still be present but won't have the size to gain an advantage over the crop.

In some crops, for example potatoes, if the ground is kept weed free for approx 8 weeks after emergence, the crop itself will control weeds by shading the soil surface and preventing nearly all weed growth for the rest of the season.

My little patch of sweet corn did exceptionally well last year. I kept the grass under control untill the corn
was about knee high and like you said the corn
was able to win the battle after that. I'm not against conventional herbicide but on a small scale with a big diversity of crops I don't see a lot of good options.

 

[trc65]

One herbicide that I use a lot of in the garden is s-metolachlor. It is labeled on almost everything. However, there is a different rate for almost everything too.

Several things against using it though on small areas. I think it is only available in 2.5 gallon containers. Use rate ranges from 0.5 to 2 pints per acre, but rates are different for each type of crop. For a small patch of sweet corn 15'x30' the chemical needed would be less than 10 ml.

Most people don't have experience calculating and measuring small amounts, let alone calibrating sprayers and accurately applying over small areas. Because of that I seldom talk here about using specific herbicides on food crops.

If someone here does have that kind of experience, I'd be happy provide some guidance and provide links to some resources.

 

[sprucegum]

One herbicide that I use a lot of in the garden is s-metolachlor. It is labeled on almost everything. However, there is a different rate for almost everything too.

Several things against using it though on small areas. I think it is only available in 2.5 gallon containers. Use rate ranges from 0.5 to 2 pints per acre, but rates are different for each type of crop. For a small patch of sweet corn 15'x30' the chemical needed would be less than 10 ml.

Most people don't have experience calculating and measuring small amounts, let alone calibrating sprayers and accurately applying over small areas. Because of that I seldom talk here about using specific herbicides on food crops.

If someone here does have that kind of experience, I'd be happy provide some guidance and provide links to some resources.

Probably not a viable option for my small diversified garden. I will probably have to keep battling the weeds. I use black plastic mulch for my squash, the crabgrass seeds germinate and die under the plastic. I rotate the squash usually with beans and corn, that helps quite a bit hopefully the corn gluten will help also. I don't think I can eliminate the problem but perhaps I can manage it better.

 

[trc65]

Probably not a viable option for my small diversified garden. I will probably have to keep battling the weeds. I use black plastic mulch for my squash, the crabgrass seeds germinate and die under the plastic. I rotate the squash usually with beans and corn, that helps quite a bit hopefully the corn gluten will help also. I don't think I can eliminate the problem but perhaps I can manage it better.

One thing that you can do to combat the grasses is use one of the post emergence grass killers. Can't use it on the corn, but these products are labeled on nearly every other non grass vegetable. They are easy to use as there is no soil activity so application is forgiving and they are low toxicity to non target organisms.

I use clethodim which you can usually find for around $60 per gallon. Use rate is around an ounce per gallon of mix plus about 2 oz of crop oil concentrate.

If you are interested, I'll provide some specifics and guidance.

 

[sprucegum]

One thing that you can do to combat the grasses is use one of the post emergence grass killers. Can't use it on the corn, but these products are labeled on nearly every other non grass vegetable. They are easy to use as there is no soil activity so application is forgiving and they are low toxicity to non target organisms.

I use clethodim which you can usually find for around $60 per gallon. Use rate is around an ounce per gallon of mix plus about 2 oz of crop oil concentrate.

If you are interested, I'll provide some specifics and guidance.

I've been looking at some of those, depending on which one you buy they are packaged in home garden size containers. I may not even grow corn this year, my son and grandson have planted a large amount to sell for the past 2 years. They are pretty busy and I end up picking for them pretty often. They with never miss what we use.

 

[trc65]

I've been looking at some of those, depending on which one you buy they are packaged in home garden size containers. I may not even grow corn this year, my son and grandson have planted a large amount to sell for the past 2 years. They are pretty busy and I end up picking for them pretty often. They with never miss what we use.

That's even better. If they are packaged for home garden, they probably have the crop oil concentrate included. What I have is clethodim, but sethoxydim is another in the same family. Traditionally clethodim has been cheaper, but they both work the same. They are also useful if you have grasses invading ornamental/flower beds.

 

[djg]

Talking about weeds, I've got a small 3-sided raised bed (on a slope) that I want to finish backfilling (6"-8") NOW. It's full of weeds.

What's the best way to deal with them now?

Whack them and spray and then cover?

Spray and let die off and then cover?

Just cover and deal with sprouts in the Spring?

 

[trc65]

If they are annual weeds, I'd just cover them, that will kill them. If perennial, it might kill them, but depending on the weed, might grow through. If you've got some perennial you are worried about I'd hit them with glyphosate, wait a week to 10 days and then cover.

If all conditions are perfect now and you want to get this done, just add the soil. You will get a flush of weeds again anyway, and if perennials have grown, hit the whole thing with glyphosate.

 

[sprucegum]

The last Delacata squash from 2025, it still hard as a rock. We have plenty more frozen slices for roasting, they are nearly as good as fresh.

 

[djg]

If they are annual weeds, I'd just cover them, that will kill them. If perennial, it might kill them, but depending on the weed, might grow through. If you've got some perennial you are worried about I'd hit them with glyphosate, wait a week to 10 days and then cover.

If all conditions are perfect now and you want to get this done, just add the soil. You will get a flush of weeds again anyway, and if perennials have grown, hit the whole thing with glyphosate.

This is one that I have particular trouble without spraying (too close to plants). That's why I'd like to address them now if I can before I plant this Spring. I only know the names of a couple of weeds and I'm sure identification is as difficult as woods. Is there a "Weeds of Illinois" book lol.

 

[Mr. Peet]

This is one that I have particular trouble without spraying (too close to plants). That's why I'd like to address them now if I can before I plant this Spring. I only know the names of a couple of weeds and I'm sure identification is as difficult as woods. Is there a "Weeds of Illinois" book lol.

View attachment 285126

Creeping Charlie?

 

[2feathers Creative Making]

We called that horse mint. If the stem is square and it blooms blue/purple . I suspect the spread is like mint with the stem rooting everywhere it touches the ground.

 

[trc65]

There are several weeds that all look somewhat similar to your picture, but are easily distinguished by a few characteristics once you know what to look at. Henbit, creeping charlie(ground ivy) and purple dead nettle are the three most common and if you Google how to tell the difference between the three, you will get pictures and descriptions. Don't worry about the source you find, I've noticed that nearly every site I found uses the same pictures that were stolen from an University Extension Publication.

Most of these type weeds are in the mint family with square stems. Some will have mint aroma when leaves are crushed, and others won't.

As to wood ID books, the cheapest and probably most used is "Weeds of the North Central States"



You can find copies of this at many online used books stores for ~$10 or less. Be aware, this book is all high quality B&W line drawings with descriptions. It was the standard used in all weed science courses throughout the NC region. There are a few weed ID books out there with color pics (Nebraska Weeds is one), but don't know if they are in print anymore and even a used copy will be above $75.

 

[trc65]

BTW, I think what you have is purple dead nettle. A winter annual that blooms early in the spring, and the same weed that you commonly see on field edges before spring tillage starts. The one that turns whole edges of fields purple.

 

[trc65]

Here is a picture of purple dead nettle on the left and henbit on the right. Purple dead nettle will also get a purple tinge on leaf tips near the top of the plant as it matures.



Another pic showing the three.

 

[djg]

BTW, I think what you have is purple dead nettle. A winter annual that blooms early in the spring, and the same weed that you commonly see on field edges before spring tillage starts. The one that turns whole edges of fields purple.

Since it's an annual, I can just cover it up with soil (ca 6") and it should die? (raised bed)