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Oklahoma State University Stillwater, OK |
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Oklahoma Alfalfa |
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Oklahoma State University Stillwater, OK |
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Oklahoma Alfalfa |
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Weed Control During Winter January and February are a good time to evaluate old alfalfa stands and determine management practices for the upcoming year. To evaluate your stands, take a soil sample and determine stand density (alfalfa stems/ft2) in each field. If weeds are present and less than 30 alfalfa stems/ft2, or if first cutting last year had 5% weeds, then it will pay to control cool-season weeds. Fertilize according to soil test recommendations if you want to maintain good alfalfa production. There are a number of herbicide options for control of cool-season weeds and they are listed in the Extension Agents' Handbook. SINBAR and VELPAR continue to be the most popular with producers. Both give good control of cool-season grasses and broadleaf weeds. SINBAR is less water soluble, so it is usually best choice for the eastern part of the state while VELPAR is best suited for the western part. With El Nino and the recent rainfall, I am suggest the following. On sandy soils, wait until late February or early March to apply VELPAR in the western counties and SINBAR on central and eastern areas. On heavier soil that will take time to dry out, apply SINBAR on frozen soil in January or February on a day that air temperature gets above freezing. DO NOT spray herbicide on snow or ice covered fields. Update on ZORIAL, a herbicide recently labeled for alfalfa. It is one of the most dependable herbicide labeled for season-long control of warm-season annual grasses such as crabgrass and foxtail, if applied at 2.5 lb/acre during the winter dormant season. My main concern is that 2.5 lb/acre rate may not be profitable. We have had excellent season-long control of summer grass with a 1.25 lb/acre rate of
ZORIAL applied after 1st harvest when summer grasses were just emerging and
rain was received within a couple of days. If it does not rain within a couple of day,
grasses are not controlled and a translocated herbicide like POAST PLUS should be applied
for established grasses. My advice to those of you who hate sum summer grass is to try some
Zorial to see how it works for you. |
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| Jim Stritzke Former Alfalfa Weed Control Specialist Department of Plant and Soil Sciences Oklahoma State University |
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