Fall Management of Italian Ryegrass in Wheat

— Written By Kris Dearmin

Fall Management of Italian Ryegrass in Wheat

Tim Hambrick, Agr. Ext. Agent

September, 2014

          A single ryegrass plant in a square yard of wheat can reduce yield in that square yard by up to .4 percent. That may not sound like much of a yield penalty but consider how many times you may have more than one ryegrass plant in a square yard. In fact, a heavy ryegrass infestation can reduce wheat yield by up to 75%. That’s a much more impressive yield penalty! Ryegrass can be a tremendous yield robber and the contamination from ryegrass seed can create additional income loss due to dockage at the point of sale.

Many years ago, ryegrass was effectively controlled with Hoelon. At this time, most piedmont ryegrass has developed resistance to Hoelon. Not too many years ago, Osprey and PowerFlex (Group 2’s) were developed for ryegrass control. Today, there is resistance to these two products as well. In fact, ryegrass has demonstrated resistance to the Group 1’s (Poast, Select,etc), the Group 9’s (glyphosate), Group 10’s (Liberty), and Group 15’s (Dual, etc). That is 5 chemical classes that ryegrass can be resistant to. If we want to stay in the wheat business, we definitely need to plan well with respect to herbicide use in order to both control ryegrass and help prevent product losses due to resistance.

For effective ryegrass control, always start clean. No-tillers in particular need to scout very closely before deciding not to use a burndown. If a burndown is warranted, use a material like Gramoxone to be on the safe side and to better guarantee a good ryegrass kill. Use high quality seed, plant on time, and make sure to apply some fall nitrogen to help create a healthy, competitive wheat crop. Create a seed bed that allows all seed to be planted at a correct depth, thereby allowing all seed the opportunity to germinate quickly and uniformly.

You may also need to consider a fall applied herbicide to aid in ryegrass control.

1. Axiom @ 8-10 oz is a Group 5/15 material that give good ryegrass                   control if applied to wheat at the spike to 2 leaf stage. Axiom must be applied prior to ryegrass emergence and must receive rain to  activate and provide satisfactory control.

2. Valor @ 2 oz is a Group 14 material that gives good suppression of ryegrass and can be applied up to 7 days pre-plant. In most cases, Valor will require a follow up POST application to give  satisfactory control.

3. Zidua @ 1-1.5 oz is a Group 15 material that gives very good control if applied just after planting if there is moisture to activate it. In tests, Zidua has given nearly 100% control of ryegrass in wheat.

All three of the above materials are pre-emerge materials, therefore all three will require moisture to active them. All three must be applied prior to ryegrass emergence to be effective. All three of the above materials also help with the resistance issue as there currently is no resistance to the Group 5, 14, or 15 materials.