Effect of Different Herbicides on Various Legume Crops in Interior Alaska

Abstract

One of the major problems in the production of successful forage/green manure legume crops in Alaska is weed control. Many species of legumes are slow to establish from seeds as their seedlings are relatively noncompetitive with weeds such as chickweed, common lambsquarters, and mustards. These weeds, if not controlled, can cause total failure of new legume crop stands. Many of the herbicides that are very effective in controlling the common Alaskan weeds in barley cannot be used in legume crops since they will also kill or severely damage legumes. Only a few herbicides are available for controlling broadleaf weeds in legumes. Of these, several are labeled for “established” plants only. Very little work has been done in Alaska on the effect of herbicides on legumes. The spectrum of weeds to be controlled is different from those in most temperate agricultural areas where these herbicides were developed and tested. Also, root systems of established plants in cold subarctic soils are closer to the surface than is normally true in temperate regions, thus they may be more susceptible to herbicide injury. Therefore, we decided to do a preliminary study to determine the effects of several different herbicides on selected legumes, some non-legume crops, and weeds at two sites in interior Alaska.