|
Oklahoma State University Stillwater, OK |
|
Oklahoma Alfalfa |
|
|
|
Oklahoma State University Stillwater, OK |
|
Oklahoma Alfalfa |
|
|
EARLY HARVEST AS CONTROL OF ALFALFA WEEVIL |
|
| During most years, egg hatch and onset of feeding by weevil larvae occurs during late February and March. However, in years when winter weather is unusually cold, the onset of larval feeding may be delayed until April and populations may not reach economic threshold levels until growth of the first alfalfa crop has reached the bud stage. When this occurs, early harvest at the bud stage may be considered as an alternative to application of insecticide for weevil control. If the weather is warm with no rainfall so that the hay dries rapidly and can be baled soon after cutting, weevil larvae will die from starvation and exposure to high temperatures, and the cost of an insecticide application will be saved. However, a potential problem with early harvest exists when rainfall occurs and forage cannot be dried and baled soon after cutting. Weevil larvae may feed on hay in windrows and on the new growth beneath windrows, causing losses in both the first crop and the second crop. Also, many larvae may spin cocoons and pupate under windrows. After emerging, weevil adults may feed on new growth and cause damage in addition to that done by larvae. Thus, early harvest does involve some risk of losses in alfalfa production if weather conditions are not favorable for drying hay. |
|
| Richard Berberet,
Alfalfa Entomologist Department of Entomology and Plant Pathology Oklahoma State University |
 |
