RESULTS AND DISCUSSION 



Control of grasses 



As shown in Table 1, all stands except the one at Pembroke, were 

 dominated by grasses. Quackgrass, bromegrass, and orchardgrass were the 

 most aggressive species present. At all locations at least one of these 

 species was present in significant amounts when the experiments were initiated. 



The response to fall-applied glyphosate at various rates is shown 

 in Table 2. Good control of grasses was obtained when glyphosate was 

 applied at 1.0 to 3.0 lbs/acre to green growth at least five inches high. 



At Northwood, dry weather in late summer-early fall of 1978, in 

 combination with the low soil fertility, caused the grasses to be 

 yellow and brown in color in September and October. Grasses in this 

 condition were unaffected by glyphosate, even at the highest rate used. 

 At Epsom, the field had been closely grazed in September of 1978. 

 Glyphosate at 2.5 lbs/acre was needed for 50% control of grasses on 

 October 23, whereas on November 13, when the grass had reached 4-5 

 inches, only 1.1 lbs/acre of glyphosate was needed for comparable grass 

 control. This is evidence that previous management and soil conditions 

 can affect response to glyphosate. 



The rate of fall-applied glyphosate necessary to provide good 

 control of grasses varied with site and year, probably due to differ- 

 ences in translocation of the herbicide from the leaves into the root 

 system, which would be influenced by amount of leaf area present and 

 the photosynthetic activity of leaves. Control of healthy cool-season 

 grasses has been reported to improve slightly when glyphosate was applied 

 immediately following a light frost (4) . 



The effectiveness of pronaraide was influenced more by rate of 

 application than by condition of grasses at time of treatment (Table 3). 

 This is expected since pronamide enters plants through the roots only (16). 

 Pronamide at 3.0 lbs/acre was needed to adequately control vigorous 



