Time to kill barley cover crop in onions and carrots

Barley is growing rapidly and can cause crop stunting and stand loss.

According to Michigan State University Extension field staff, all the onions and many carrots have been planted in Michigan, and most are planted with barley as a “companion” or “nurse” crop. Barley emerges rapidly after seeding and protects the young onions and carrots from wind and water erosion and injury. Barley is planted at a rate of 0.75 to 1.5 bushels per acre. Barley planted at the higher rate provides more protection quicker, but also becomes a serious competitor to the crops sooner. Barley should be killed with a graminicide (Fusilade DX, Poast, SelectMax or generics) when it is 4-5 inches high. Barley dies slowly and provides protection for another one to two weeks.

Barley has been growing rapidly with the wet conditions and moderate temperatures. Onions and carrots have emerged, but do not have the ability to grow as rapidly as barley. Most onions are in the flag to one leaf stage, and cannot compete with the barley. Growers should spray barley as soon as possible, either by ground equipment or air. Some fields are too wet for ground sprayers and should be sprayed by airplane or helicopter.

To obtain complete barley kill, use the highest recommended rate for each herbicide for use in that crop. Addition of nonionic surfactant or crop oil concentrate will increase graminicide activity, but also may result in some crop burn. Even with minor crop attrition from the application, the potential for crop loss is greater with uncontrolled barley. The damage to the crop can occur very rapidly, especially under dry conditions. Most fields currently do not have a water shortage, so desiccation should not be an issue. However, the continuing competition from the barley can reduce yields, and should be resolved soon.

Dr. Zandstra’s work is funded in part by MSU’s AgBioResearch.

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