Deep Turning Reduces Annual Ryegrass Populations
Posted by romeethredge on August 26, 2014
Georgia wheat production is in jeopardy due to herbicide resistant ryegrass which is a weed problem in wheat. Ryegrass resistant to all currently labeled postemergence controlling herbicides has been documented and is becoming very common. Heavy ryegrass infestations, if uncontrolled by poor management or herbicide resistance, can eliminate production. Drs. Culpepper and Webster, UGA Scientists, have done some research concerning this weed and have some good news.
Ryegrass has proven that it is capable of rapidly developing resistance to any and all herbicides used for management; even more so than Palmer amaranth. A systems approach to management is the only sustainable option and may include rotating herbicide chemistries, rotating crops, and maybe even implementing deep tillage in the more severely infested fields.
Current research is being conducted to determine the potential benefits for deep turning to reduce annual ryegrass emergence. In our first experiment, we planted ryegrass at 0.5 inch deep and followed with no tillage (our control) or deep tillage.
Our objectives were to determine the following:
1) Could deep turning effectively invert seed on the soil surface?
2) Could inverted seed placed 10-12 inches deep in the soil profile germinate?
Results showed a reduction in ryegrass emergence by over 99% with deep turning (figure/picture below). Although this experiment does not address ryegrass seed spread throughout the soil profile as is the case in grower fields, it does suggest ryegrass emergence is greatly reduced when it is placed deep in the soil profile. The next step is to better understand how long the seed will live when buried in our soils under our environmental conditions.
Rarely will any cultural or mechanical practice effectively control ryegrass by itself. Thus, an herbicide program will usually be needed. See the wheat production guide or pest control handbook for herbicidal options.