HAIRY VETCH

Abstracts:

• The Influence of a Hairy Vetch (Vicia villosa) Cover Crop on Weed Control in Corn. W. S. Curran and L. D. Hoffman, 1993. Proc. NEWSS 47:73.
  
  
• The Influence of a Hairy Vetch (Vicia villosa) Cover Crop on Weed Control in Corn. W. S. Curran and L. D. Hoffman, 1993. WSSA Abstracts 33:20; 1994, Weed Technol. 8:777-784.

The Influence of a Hairy Vetch (Vicia villosa) Cover Crop on Weed Control in Corn. W. S. Curran and L. D. Hoffman, 1993. Proc. NEWSS 47:73.

Cover crops are promoted for reducing soil erosion, providing or scavenging nitrogen, and possibly suppressing weed growth and competition. Hairy vetch is a cover crop that appears to do well in Pennsylvania conditions. However, methods for killing or suppressing hairy vetch and the residual weed control requirement for the cover crop-grain crop system have not been well defined. The objectives of the following study were to determine the best method of killing hairy vetch prior to corn establishment and to identify the need for residual weed control.

The study was established in 1991 and 1992 in central Pennsylvania in a site that was previously in small grains. Hairy vetch was seeded in mid-August at 30 lb/A and killed the following May using either tillage, mowing, or a preplant application of the butoxyethyl ester of 2,4-D. Treatments containing no vetch were included for comparison. Residual herbicide treatments included 0.5, 0.75, or 1X the recommended rates of metolachlor plus atrazine, the recommended rate of a postemergence application of nicosulfuron plus thifensulfuron, or cultivation.

Vetch was adequately controlled with all preplant treatments in 1991, however mowing was less effective in 1992. The vetch recovered from the majority of the mowing treatments in 1992 probably due to the premature stage of development at the time of mowing. In 1991, the vetch was turning reproductive by mid-May, while in 1992, vetch development was delayed. Corn population was unaffected by cover crop method of kill or residual weed control treatment in 1991, but was significantly reduced in all vetch containing treatments in 1992, due to insect pests during corn emergence and inadequate vetch control in the mow treatments. Method of hairy vetch kill produced variable weed control results. In general, the treatments that left the greatest amount of vetch residue on the soil surface had fewer early season weeds compared to the tilled or no vetch plots. However, residual herbicide performance was better where less surface vetch residue remained. Annual weeds including smooth pigweed (Amaranthus hybridus L.) and giant and yellow foxtail (Setaria faberii Herrm. and Setaria lutescens (Weigel) Hubb.) were reduced in number with all three residual herbicide treatments as well as the postemergence application. Cultivation effectively reduced the weed population in 1991 preventing a reduction in grain yield, but did not sufficiently reduce the weed infestation in 1992. By late season, weed biomass was less in residual and postemergence herbicide treatments, but similar regardless of how the cover crop was killed.

In summary, mowing was not a dependable method for suppressing hairy vetch in corn. A preplant application of 2,4-D was effective at killing the hairy vetch and also providing a good surface mulch that sometimes inhibited early season weed emergence. Soil applied residual herbicide performance was reduced in the presence of hairy vetch residues, regardless of whether the cover was left on the surface or incorporated. Postemergence herbicide applications were equally effective in vetch and no-vetch containing plots and cultivation provided adequate weed suppression as long as the weed infestation was relatively light.

The Influence of a Hairy Vetch (Vicia villosa) Cover Crop on Weed Control in Corn. W. S. Curran and L. D. Hoffman, 1993. WSSA Abstracts 33:20; 1994, Weed Technol. 8:777-784.

Hairy vetch control or kill and residual weed control were examined in corn. The experiment was established in central Pennsylvania in a previous small grain field. Hairy vetch was seeded in mid-August at 13.6 kg/ha and killed the following May using either tillage, mowing, or a preplant application of the butoxyethyl ester of 2,4-D. No vetch containing treatments were included for comparison. Residual herbicide treatments included 0.5, 0.75, or 1X the recommended rates of metolachlor plus atrazine, the recommended rate of a postemergence application of nicosulfuron plus thifensulfuron, or cultivation. Vetch was adequately controlled with all preplant treatments in 1991, however mowing was less effective in 1992. Corn population was unaffected by cover crop method of kill or residual weed control treatment in 1991, but was significantly reduced in all vetch containing treatments in 1992, due to insect pests and inadequate vetch control in the mow treatments. Method of hairy vetch kill produced variable weed control results. In general, the treatments that left the greatest amount of vetch residue on the soil surface had fewer early season weeds compared to the tilled or no vetch plots. However, residual herbicide performance was better where less surface vetch residue remained. Annual weeds including smooth pigweed (Amaranthus hybridus L.) and giant and yellow foxtail (Setaria faberii Herrm. and Setaria lutescens (Weigel) Hubb.) were reduced in number with all three residual herbicide treatments as well as the postemergence application. Cultivation effectively reduced the weed population in 1991 preventing a reduction in grain yield, but did not sufficiently reduce the weed infestation in 1992. By late season, weed biomass was less in residual and postemergence herbicide treatments, but similar regardless of how the cover crop was killed.