With its prolific root system and economical price tag, annual ryegrass is one of the most popular cover crops no-tillers have at their disposal. It’s also gotten a bad rap for being tough to manage, says Dan Towery.
But if no-tillers stick with a few rules of thumb when it comes to seeding and termination, they’ll have far more success with annual ryegrass, says the consultant for Ag Conservation Solutions. Towery shared several keys to success during the recent National No-Tillage Conference.
1. Read the Tag
No-tillers should avoid bags of annual ryegrass that say “VNS” as that stands for “Variety Not Stated,” Towery says. This means multiple species or varieties of annual ryegrass may have been blended together and may break dormancy as much as 2 weeks apart.
Le Roy, N.Y., no-tiller Donn Branton says this happened on his farm. After applying 2,4-D and glyphosate to annual ryegrass as a burndown in the spring and planting corn, the ryegrass greened up again 2 weeks later.
He found that some of the product was Italian ryegrass and the plants probably weren’t all at the same growth stage during termination. Branton says it took 3 years to get the ryegrass problem cleaned up in some of his fields.
“Your cover-crop dealer needs to know the particulars of the variety they’re selling and when it starts to grow,” Towery says. “And do not seed a blend.”
2. Plant on Time
Towery says he hears too many growers say they’ll plant annual ryegrass when harvest is done. That probably won’t work in the central or northern Corn Belt, since annual ryegrass needs about 60 days of growth before winter arrives.
“When your corn and soybeans are going to be harvested is irrelevant. If you’re going to use annual ryegrass as a cover crop, then the ideal planting window is when it needs to be planted,” he says.
Until no-tillers gain a few years’ experience using annual ryegrass, they should mark on a calendar what the ideal planting window is in their region. For example, in Lafayette, Ind., where Towery is located, the window is Aug. 20 to Sept. 15.
| “If you plant it late and it doesn’t get very tall and the roots are shallow, annual ryegrass is much more susceptible to winterkill…” |
3. Seeding Methods Key
The ideal seeding rate for annual ryegrass is 10-25 pounds an acre, or up to 30 pounds if it’s being used for forage. But if no-tillers plant it earlier and/or drill it, they can reduce the seeding rate, Towery says.
Because annual ryegrass seed is small, the seeding method is important. Drills probably offer the best seed-to-soil contact, and a high-clearance seeding or aerial application can be used in regions where the seeding window in fall is very short. Aerial seeding annual ryegrass typically costs $12-$15 an acre and the typical seeding rate is about 25 pounds an acre.
“You need to have a good pilot because annual ryegrass only weighs about 26 pounds a bushel,” Towery says. “Aerial seeding in a wind greater than 7 mph may result in seed landing where you don’t want it. The pilot also needs to calibrate for speed and altitude for the lighter seed weight.”
4. Ryegrass Can Winterkill
If wind chills fall to -20 or -30 F and there’s no snow cover, winterkill can occur. Towery notes that some annual ryegrass varieties are more winter hardy than others.
“If you plant it late and it doesn’t get very tall, and the roots are shallow, the plant is much more susceptible to winterkill,” Towery says.
But don’t give up on it too early in the spring, he adds. He’s seen stands that looked grim bounce back when the weather warmed up. He says it mostly depends if the growing point in the plant was killed or not.
5. Don’t Jump the Gun
The No. 1 thing to remember when terminating annual ryegrass in the spring is to spray it when it’s actively growing, Towery says. That requires at least a 3- to 5-day stretch of warm weather to ensure all plants are growing and the herbicide will be translocated.
Results will be better if conditions are sunny and morning dew has dried up, with the application targeted between 10 a.m. and 2 p.m.
Towery says 2-3 pints of glyphosate per acre, mixed with 8-12 gallons of water, should be sufficient to kill annual ryegrass, but don’t include atrazine or Callisto in the mix because it will antagonize the glyphosate.
6. Pretreat Water
Towery says no-tillers should pretreat sprayer water with ammonium sulfate before loading glyphosate into the spray tank to make sure water hardness doesn’t nullify glyphosate’s effects.
“If you don’t have that water pretreated for hardness, you may have significantly reduced its effectiveness,” he says.
7. Adjust Burndown pH
Adding an acidifier (if needed), such as food grade citric acid may help with glyphosate burndown. A pH around 5 seems to be optimal.
8. Think About Resistance
The days of relying on glyphosate to terminate annual ryegrass are likely over, Towery says. If the first glyphosate application doesn’t kill ryegrass, applying a second shot of the same herbicide isn’t the best answer.
He adds that there are good corn residuals like Princep, Basis, Balance Pro, Prowl H20 and Resolve Q that can be mixed with glyphosate or applied about 10 days after the initial burndown.
“Nothing will work quite as well as glyphosate. Some growers tell me they want to use annual ryegrass and not glyphosate, and I tell them to use another cover crop.”
