ISHS Acta Horticulturae 823: XI International Symposium on the Processing Tomato
EFFECT OF TIMING AND RATE ON TOMATO TOLERANCE TO POSTEMERGENCE APPLICATIONS OF S-METOLACHLOR |
| Authors: | D.E. Robinson, A.S. Hamill |
| Keywords: | crop tolerance, Solanum lycopersicum, tomato injury, yield |
| Abstract:
The strategy of applying metribuzin in successive, low rate treatments is currently used by growers, but s-metolachlor is currently only applied in one treatment prior to transplanting. The objective of this study was to determine whether an alternative strategy to a single pre-plant incorporated (PPI) treatment of s-metolachlor plus metribuzin, could be developed that would maintain crop safety and extend the length of control of common broadleaf weeds. Field studies were conducted at Ridgetown and Harrow, Ontario, from 2003 to 2005 to determine weed control and tolerance of tomato to various rates and timings of s-metolachlor. Tomato showed excellent tolerance to post-transplant (POST) applications of s-metolachlor (400, 600 and 800 g a.i. ha-1) applied 28 days after transplanting (DAT), after an initial PPI application of s-metolachlor+metribuzin (800+375 g a.i. ha-1). Visual injury ratings were similar to the currently accepted industry standard. Control of common ragweed, common lamb’s-quarters, and eastern black nightshade was greater than 80% at all POST applications of s-metolachlor (400, 600 and 800 g a.i. ha-1) applied 28 DAT, after an initial PPI application of s-metolachlor+metribuzin (800+375 g a.i. ha-1). Efficacy was similar to the currently accepted industry standard for all weeds in the study. POST applications of s-metolachlor at 800 g a.i. ha-1 caused significant and commercially unacceptable visual injury to tomato when timed at 7 and 14 DAT. This injury did not correspond to a yield reduction. Despite this lack of a significant yield reduction, growers would likely be reluctant to accept the level of visual injury that was associated with the earlier treatments, since it did not improve weed control. | |
Download Adobe Acrobat Reader (free software to read PDF files) | |
