Both herbicides are effective on most annual grasses, but Select is more effective on quackgrass and other perennial grasses. Unfortunately, while Sencor and Velpar have activity on dandelion and curly dock, none of the herbicides that can be used on actively growing alfalfa control these weeds. Where these weeds are a problem, winter application of Sencor or Velpar when alfalfa is dormant is by far the best option. It is too late in most fields to apply these herbicides, but plan on their use next winter. Canada thistle is another weed that cannot be controlled with alfalfa herbicides.
Control is limited to spot application of glyphosate, or just timely cuttings.
At one time, rootworm injury to corn was primarily regarded as a continuous corn problem since egg laying of either the northern corn rootworm or the western was usually limited to corn fields from which the eggs hatched the following season and the larvae fed on root systems of the continuous corn. In the 80s, the extended diapause behavior causing injury to 1st year corn by northern corn rootworm populations became recognized. In the 90s, the development of a new biotype of western corn rootworm resulted in egg laying in soybeans and injury to 1st year corn. During the past decade, the presence of first year corn injury in Ohio by both northern corn rootworm and western corn rootworm has been established. To facilitate risk prediction of first year corn rootworm problems, a cooperative effort to monitor adult rootworm activity in Ohio soybeans has been implemented by OSU Extension, independent consultants and agri-business personnel during the past three years.