Drought Resistance of Blue Grama as Affected by Atrazine and N. Fertilizer

Two consecutive summer droughts in north central Colorado caused considerable thinning of blue grama (Bouteloua gracilis) stands, and N fertilizer accentuated the drought effects. However, atrazine, with or without N fertilizer, prevented serious thinning of stands. Consequently, investigations were initiated to test the hypotheses that atrazine created greater resistance to, or tolerance of, drying in crown tissues. Both hypotheses were rejected. It remains to be determined whether the combined effects of weed control, slower transpiration, and changes in root distribution by atrazine treatment may reduce water consumption and, thus, protect blue grama from drought.