In response to farmer inquiries on the effectiveness of using unincorporated preemergent herbicides, a demonstration was held at the Wilkie Direct Seeding Field Day.
Four herbicides, Avadex, Fortress, Edge and Treflan were
applied to standing stubble in October 1995. The plots had grown
approximately 25 Bu of wheat per acre and had the straw and chaff
spread uniformly. The original height of the crop was 12 - 18
inches with approx. 3 inches of stubble remaining. No harrowing
was done in the plots. The plots were seeded May 10 to canola.
Three different types of openers were used, a sidebanding knife
opener, a disc opener and a sweep. Because this was a
demonstration field sized equipment ( 40 feet ) was used. Due to
adverse weather conditions and low soil temperatures crop
emergence occurred May 24 and wild oats emerged several days
later. Wild oat counts were done June 10. The following table
summarizes what was found.
|
Spoon/Knife |
Disc |
Sweep |
|
| Avadex |
5 |
5 |
4 |
| Fortress |
5 |
5 |
2 |
| Edge |
8 |
3 |
2 |
| Treflan |
12 |
10 |
13 |
| Check |
37 |
36 |
25 |
This demonstration was not research so only a general trend can be concluded. The fall application of these chemicals gave from 65 % to 85 % control. The type of opener did not seem to affect control or wildoat numbers. Overall one can conclude that fall application of preemergent herbicides without incorporation shows definite promise in zero till systems.