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Ryegrass taking root in Arkansas

If Ford Baldwin's eyes weren't enough of a confirmation, then the many phone calls from farmers “hollering” about being covered up with ryegrass did the trick.

“I wasn't sure before — but now, after walking a bunch of fields? Yeah, ryegrass in the state is getting worse,” says the weed scientist with Practical Weed Consultants (and Delta Farm Press contributor). “I keep hearing producers complaining that they've got it where they've never had it before. I'm not sure what can be done about it at this late date. It's already heading out, and spraying Roundup all over the countryside to suppress it is not a good idea.”

Ryegrass is increasing everywhere tremendously, says Baldwin. Almost every time he goes out on a rice call, “producers complain about seeing so much more ryegrass. It seems every field I look across that hasn't been worked up this spring is solid ryegrass. And sometimes fields that have been worked up look bad, too.”

Ken Smith has been getting many similar calls. This afternoon, the Arkansas Extension weed scientist is on his way to see a ryegrass field.

“What we've been seeing is that Roundup used at burndown just isn't taking ryegrass out,” says Smith. “The weed will turn brown or orange and then will rejuvenate. Ryegrass has always been a little hard to kill, and now it seems, without a maximum dose of glyphosate it won't be killed.”

If the weed isn't taken out early, it becomes increasingly difficult to control later on. Smith believes the main problem this year — besides the increasing population — was the size of the ryegrass when burndowns began.

“The plants were just too large. Last fall and winter, the weather was conducive to getting ryegrass stands up and growing them to large sizes. Our winter was too warm. So now we've got clumps of ryegrass that won't die. We've sprayed them, they come back, and we spray them again.”

William Johnson, Pioneer field sales agronomist, says when Hoelon-resistant ryegrass showed up a few years ago, “we knew trouble was brewing. The ryegrass that has come since is much hardier than the stuff we were seeing say, six or seven years ago. The ryegrass problem is all over the state. I get report after report of it.”

So what can be done with the weed? At this stage of the growing season, not much.

Osprey has received a label for use on ryegrass. It should help some in wheat fields with Hoelon-resistant ryegrass.

“Osprey has good activity,” says Baldwin. “The thing that I keep in the back of my mind — and the experience by producers overseas has shown — is that if you use a herbicide in a big way for a few years, ryegrass will become resistant to it. We've got to be careful.”

Smith says he's already hearing “plenty” of reports of glyphosate-resistant ryegrass. “I'm a little skeptical that we have that problem. It's a long way from being confirmed. It could develop, though.”

Osprey has been effective against ryegrass in wheat, says Smith. A problem has developed though, with ryegrass germinating behind Osprey (which has no residual activity). That post-Osprey flush is now full-sized and seeding. That, says Smith, is a “major aggravation” since a lot of wheat was sprayed with Osprey back in February.

In rice, “I don't think we ever took the ryegrass down,” says Smith. “We sprayed with Roundup, but by that time it was too large. Another factor may be rice producers mixing Roundup and Command. If you take that tank-mix into a rice field, it won't take out ryegrass. Instead, it'll reduce the Roundup activity enough to let ryegrass escape.”

Ryegrass is the number one weed in wheat, says Smith. If someone doesn't develop a residual product to control the weed, “we'll be facing serious questions and problems. We need to be able to spray a product in February — a product with residual. There is no such product now. If one isn't developed, ryegrass will get worse and worse.”

Next year, says Johnson, “We've got to be on a hyper-aggressive burndown program in February. If you don't get the ryegrass when it's small, forget it. When it's small, though, you can go out with a quart of glyphosate and take it out. That's not going to happen this year — I'm seeing ryegrass with seed heads all over the state.”

In corn, ryegrass pilfers much nitrogen. “It's a thief — corn will be yellow and ryegrass will be bright green. Ryegrass grows at lower temperatures than corn, and that's why it's so aggressive.”

Many farmers, says Johnson, are using Steadfast (DuPont) and atrazine to deal with ryegrass in corn. “Steadfast has pretty good activity on ryegrass — it may not kill the weed, but it'll make it wish for the grave.”

As producers go to more no-till, the ryegrass problem could get worse, warns Smith. “Don't misunderstand: minimum-till is an awesome system. But there are problems and tradeoffs. Obviously, if you spray ryegrass and then till, land-plane, float it, whatever, that helps keep ryegrass in check. But no-till may lead us to make separate applications just to control ryegrass.”

Baldwin agrees. Ryegrass is one that “as we go to more no-till, may turn into more of a headache. It isn't tolerant of glyphosate, but it is more difficult to control with glyphosate than other weeds are. If we ever fool around and get glyphosate-resistant ryegrass, that will be a hell of a problem. There is confirmed glyphosate-resistant ryegrass in Australia, so it can happen. That's a major concern.”

Ryegrass is a tough plant. “It loves good fertility but will also thrive on poor, red clay hillsides,” says Baldwin. “Many times it's an edge problem. One or two passes of a herbicide around the edge of a field often controls 90 percent of the ryegrass in the whole field.

“We need to learn more from Australia. We need to look at what they're doing regarding an integrated management scheme to control ryegrass. We must do a better job of controlling the weed on fencerows, turnrows and fallow land. The idea that we can spray one herbicide in our wheat and one in no-till fields and have control of ryegrass is overly optimistic.”

A few seasons ago, Baldwin was involved in a study on Hoelon-resistant ryegrass. What was found is that a fall fallow program will “work wonders” in controlling the weed.

“Ryegrass is a very aggressive germinator. In fields that are grown up now and aren't going into wheat, producers might consider a fallow program: take some of these bad ryegrass fields and prepare seedbeds as if you're going to plant wheat. The first two or three days of moist conditions — when you've got to wear a jacket in the morning — 90 percent of the ryegrass seeds will germinate. Then, every time it gets dry enough, a producer can go out and hit that land with a field cultivator.”

Many farmers make the mistake of thinking that if they've summer-fallowed a field, a ryegrass problem will be alleviated. This is a false belief, says Baldwin. “Ryegrass germinates in the fall and grows through the winter. During a summer fallow, all that's happening is seed being stirred.”

Regarding the ryegrass problem, there is no hope beyond chemicals, says Smith. “What's frustrating is our salvation — minimum tillage — is exacerbating the ryegrass problem. But we need minimum-till. We're damned if we do, and damned if we don't.”


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