14 



Fall application of glyphosate generally resulted in similar or 

 higher seedling densities than those from spring treatments (Table 8) . 

 With fall-applied herbicides, establishment and first-harvest yields 

 were usually better with an earlier, compared with a later, spring 

 seeding date (Tables 8-10). This was due, in part, to the effects of 

 competition from the surviving species on alfalfa seedlings. Seed- 

 lings would obviously be smaller and more vulnerable to competition 

 if seeded later in the spring since the surviving weeds will begin 

 spring growth without regard to the date the alfalfa was seeded. Fall- 

 applied glyphosate with a followup application in late May, 1980, 

 produced a stand better than that from any other treatment at Lee 

 (79% ground cover rating, vs. 67% gound cover for the next best treat- 

 ment). Baird, et al. (1) reported superior control of quackgrass when a 

 given amount of glyphosate was split-applied between the fall and spring, 

 rather than in one application. 



The advantage of delaying seeding following spring treatment must 

 be weighed against the likelihood that later seedings will encounter 

 summer dry periods, having had less time for seedlings to develop 

 root systems. An advantage of sod seeding, however, is that once 

 the sod is killed and left in place, moisture is effectively conserved, 

 in contrast to conventionally prepared seedbeds. This may allow for later 

 spring planting with sod seeding, compared with conventional seeding. Also, 

 by delaying spring seeding, surviving fall treatment and early germinating 

 annual weeds can be more effectively controlled. Early seeding in the 

 spring, made possible by fall application of herbicides would likely be 

 most beneficial on sandy, droughty soils. 



Comparative results of an August and a late spring no-till seeding 

 in 1977 are shovm in Table 11. The August seeding in 1977 received less 

 than 0.4 inches of rainfall during the first two weeks after seeding, 

 in contrast to 1.7 inches for the June 4 seeding. Under conditions as 

 dry as those encountered by the August seeding, the value of glyphosate 

 in preventing moisture depletion by the sod is clearly evident. However, 



