Plant Cover Crops

Learning about the benefits of planting cover crops.

Killing Annual Ryegrass in the Spring

Cover Crops: Buy One Year, Get Another Year Free

Surprise! That's what our reaction was to the volunteer annual ryegrass growing in our fields nearly 18 months after they were sown.
Surprise! That’s what our reaction was to the volunteer annual ryegrass growing in our fields nearly 18 months after they were sown.

Almost two years to the day I posted an article about Killing Tall Annual Ryegrass.

The problem of a wet and chilly 2011 has resurfaced an ugly head to be a wet and COLD spring of 2013. But over the past week or so temperatures have warmed into the 70’s and 80’s with cover crop annual ryegrass and winter cereal rye having grown tall in some areas of the Midwest. Producers need to kill their cover crops as soon as possible to comply with RMA regulations.

What about the surprise cover crops?

In a previous post I wrote about dormant seed in cover crop species on our home farm.

I showed how radishes were present in soybean fields and how annual ryegrass was coming up even after there was residual herbicide and burndown herbicide applied.

Now here we are in the spring and we have a few new surprises.  Fall 2011 planted annual ryegrass and even fall planted winter cereal rye are now growing in the spring of 2013.  These cover crops were fully terminated in the spring and summer of 2012; there was effective weed control.  So dormant seed has germinated and now grown a full 15-18 months after it was seeded.  So yes, cover crops can become weeds.

(But remember, cover crops also suppress weeds.)

So what does this matter?

We have the benefit of a “thin” cover crop and we did not have to pay seed cost or application cost for the second year.  In our farming situation it is not a big deal.  We terminated all of our cover crops and weeds with a “hot” chemical mix.  It is a mix similar to what we used in our no-till fields prior to glyphosate coming on the market.  However, if we were growing wheat or oats or barley for grain and straw it could be a problem.  Thankfully there are now chemicals to use in cereal crops to eliminate annual ryegrass.  I hear reports that Jamie Scott from northern Indiana has seen excellent results with this practice.

We have less winter annual weeds where we have the “volunteer” cover crops and I’m confident our soil health is better where we have the cover crops.

What do we do now?

We enjoy the benefit that we have from the cover crop (even though it is a sparse stand) and we watch to make sure we do not have any cover crops coming back before harvest. The cover crops are now dead and a residual herbicide is applied.  Now we wait to plant the corn and soybeans and scout for any additional dormant seed to germinate and grow.  A clean harvest is important to all producers.  Our goal is to use the information from our own farm to make sure that farmers understand the rewards that cover crops bring and also the risk that comes with the reward.  The risk is not huge and it is manageable, but it is risk none-the-less.

 

This volunteer annual ryegrass was terminated before heading out but it was jointed and would have made a great forage plant.
This volunteer annual ryegrass was terminated before heading out but it was jointed and would have made a great forage crop.

 

 

 

 

 

 

 

 

Volunteer Winter Cereal Rye was also growing in the old plot area. The cover crop was terminated well before the corn will be planted.
Volunteer Winter Cereal Rye was also growing in the old plot area. The cover crop was terminated well before the corn will be planted.

 

Can Cover Crops Become Weeds?

In a previous post I wrote that cover crops can suppress weeds.  And many farmers are planting them with that primary benefit in mind.

But, can cover crops become weeds?

Unfortunately, the answer is “yes, they can.”  Obviously we never want this to happen on our farm.  And with good management practices, we can lessen the possibility that it will.

Two species that require precise management are annual ryegrass and radishes. Both annual ryegrass  and radishes benefit the soil tremendously and have been shown to increase profit per acre, but both must be carefully managed as well. Specifically, there must be a comprehensive plan for terminating annual ryegrass. If you are not absolutely clear on how you are going to do this, you should not plant it. Likewise, with cover crop radishes, you need to be absolutely clear on what you are buying and when the seed should be planted.

It only takes a few annual ryegrass plants that produce seed to create a weed problem - especially if wheat is in the rotation.
It only takes a few annual ryegrass plants that produce seed to create a weed problem – especially if wheat is in the rotation.

This is why Hans Kok, from the Indiana Conservation Cropping Systems Initiative often tells farmers that are trying cover crops for the first time to start with a few acres of oats and radishes as a cover crop.  His thinking is that because both oats and radishes die over the winter that farmers will not have to worry about terminating the cover crop in the spring.  And I agree with Hans on this.

However, cover crops are becoming more popular and many producers are convinced that they are excellent at killing weeds and cover crops.  While Ag Chemical companies have shied away from making too many recommendations on killing cover crops, farmers are confident in their abilities to “figure it out” and make cover crops work on their farm.  Why use “boring” oats and radish?  Let’s use Annual Ryegrass!

Don’t get me wrong, Annual Ryegrass is a fabulous cover crop with tremendous value as a cover crop and forage.  But, it does take more management than many other cover crops.  Annual Ryegrass provides high reward with some additional risk.  On our home farm we sprayed our soybeans three times to make sure all annual ryegrass was killed.

Planting Radishes too early or planting the wrong Radish can create a problem with seed production on the radishes...and you don't want that!
Planting Radishes too early or planting the wrong Radish can create a problem with seed production on the radishes…and you don’t want that!

I’d love to hear your “formula” for annual ryegrass control. Have you noticed any difference with terminating annual ryegrass on different soil types? Different temperatures? Different additives? Different times of the day?

 

Terminating Cover Crops – Use Residual Herbicide

Terminating cover crops is part of the “stepped-up management” that using cover crops requires.  Over the past month I shot videos about killing annual ryegrass, killing crimson clover, and about the difference of killing cereal rye and annual ryegrass.  In each of the videos I examined the importance of killing the cover crop…and killing it dead.  Overall, most of the cover crop fields that I have seen had a very good burn down.  In more than a couple of instances it was obvious that the applicator missed a few (if not many) spots or strips.

Terminating Cover Crop Radishes

In the cover crop plots where Radishes were in the mix we now have plenty of Radishes in the corn!

But burndown is not all that we need to be concerned about.  In 2011 I saw photos from fields in Michigan that almost made my heart stop!

A corn field in southern Michigan had radishes that were taller than the knee high corn. And a field of soybeans had large radishes in it at harvest time.  Thankfully the corn field yield was not affected, but areas of the soybean field could not be be harvested.  At $12-13/bu soybeans that was an expensive lesson.

Applying glyphosate once a season without using a residual herbicide does not provide adequate weed control. These radishes germinated after the spring glyphosate application.

So how did these situations happen?  In both instances the producers used glyphosate for their burndown and did not  use (or had not yet used) residual herbicide.  Of course the radishes were not the only “weed” in the field, but it was the focus of the growers!

Terminating Cover Crops at Robison Farms

At Robison Farms in Central Indiana we have two issues going on in our fields this spring of 2012:

#1) Radishes are coming in the corn and soybeans, even though we did apply a residual herbicide!

#2) There are more annual ryegrass escapes than I’d ever like to see. We actually had very good burndown and we used residual herbicide too.  Note that these are NOT the only “weeds” that we have growing in the fields.  I cannot remember a year when we’ve seen so many winter annuals and broadleaf weeds survive residual herbicide.

My brother Don has been scouting our fields and he reports seeing ragweed, morning glory, cocklebur, Queen Anne’s lace,  and a variety of other broadleaf weeds across our 300 plus acres.  The weeds aren’t thick, but there are too many of them. So we’ve concluded that it is not “just the cover crops” that are escaping.

So what is the advice here?  Make a commitment to scout your fields for weeds, whether they be “cover crop species escapes” or other weed pressure.

  • Excellent weed control is vital for top profits in cash crops.
  • Use residual herbicide in corn and soybean fields.
  • Scout fields looking for escapes and other weed issues.
  • Terminate all escapes before they produce viable seed.
  • Realize that cover crop radishes do have hard seed and you most certainly will see radishes in the spring.
  • Oilseed crops (brassicas like radishes, turnips, rape, canola, kale, mustards) can stay viable in the soil for years. Scout each year in fields where you have had these brassicas.
  • Scout for brassicas later in the season as well.  This should not be an issue but don’t take a risk of losing acres of soybeans.  The soybean field in Michigan had no residual herbicide applied but the radishes that caused the problems came up later in the season (probably late July or early August gauging from their size at harvest).
  • In some years like 2012 (even if you did not use cover crops), you will have more weed pressure than other years.  Eliminating all weed pressure is important!
The casual drive-by look at this plot looks like we achieved a great kill on this annual ryegrass cover crop. The corn looks great, the grass looks brown and dead, but...
...in more than one area I found annual ryegrass "escapes" that are heading out or nearly heading out. These plants need to be sprayed right away so they will not produce viable seed.

 

Killing Cover Crop Annual Ryegrass – How Are We Doing?

This Annual Ryegrass plant was almost killed. But almost is NOT good enough!

Over the winter of 2011-12 I did nearly 55 cover crop meetings across the Midwest.  And one of the “hottest” topics was how to kill annual ryegrass in the spring. This topic is almost like the Tim Tebow of the cover crop world. Some have no problems managing it and some hate it (cannot get it killed).

During the meetings I suggested that farmers read a really good article on Ag Web that I was asked to help write along with Mike Plumer, Dan Towery, and a few others.   In the article Mike Plumer and Dan Towery both give excellent advice on killing annual ryegrass.  I have also written quite a bit on the blog about killing tall annual ryegrass.  The one theme we make sure producers know is that they need to kill the annual ryegrass dead!

At this point many farmers swear that they have no problems and others just swear!

I have done a couple of videos that I hope help in this matter.  They are pretty representative from what I have seen this spring across the Eastern Corn Belt.  The first video was taken before spraying, the second taken after spraying was done. A third video shows the difference between killing annual ryegrass versus killing cereal rye.

One of my key points is that we be ready to spray again if we see green.  Don’t assume that if you see green that the initial herbicide application will eventually work.

Please forgive the wind noise on the second and third videos. I used the mic but it was very windy.

 

Annual ryegrass on the left and cereal rye on the right. Look at the massive amount of cover on the annual ryegrass!
This green leaf tells us that the plant is not entirely dead. While we may have a 99% kill this plant will end up producing seed if it is not terminated.

Formula for Killing Tall Annual Ryegrass

These varieties of Annual Ryegrass were already knee high on April 28th in Lexington, KY in the U-K Annual Ryegrass trial. On that date there were already some seed heads starting to be visible.

It’s May 7, 2011. I received five phone calls yesterday from farmers that have wet fields…flooded fields, and knee high annual ryegrass and winter rye.  The question from all five can be summed up as “I wanted to kill my cover crop earlier but it was too cold, now it’s too wet; this stuff is growing like crazy…what should I do now?”

Again, I will tell you that I am NOT a chemical expert.  However, I get to rub shoulders with guys that do lots of spraying that have had very, very good success killing ryegrass over the past few years.  One of the gentlemen that I trust (because I’ve seen his very good work) is Chris Nuest, who works for CFS at Winamac.  He has done the spraying at Four L Farms where we saw a total of four escapes on ARg last season (on 200+ acres).  Chris told me today that he will use the following formula to kill his taller annual ryegrass on his farm.  These rates are per acre…he uses Round-up(R) at a 2 QT rate and Basis(R) at the 0.5 oz. rate along with a non-ionic surfactant, AMS, and a pH reducer.

His other recommendation was to maybe look at Basis(R) + Balance(R) Pro with Round-up(R)  at full rates (again with AMS, and pH reducer).  Here is another helpful site from Purdue.

Like I said, Chris has an excellent track record of killing annual ryegrass.  E-mail me at dave@plantcovercrops.com if you want to contact Chris.

This field of annual ryegrass in north eastern Indiana is needing to be killed pretty soon! This photo was taken May 5, 2011. The field is still too wet to cross with equipment.

To quote a friend of mine…”the rain is falling, but the sky is not!”