California Pepper Commission - Complete Final Report, 2013
Title: Preemergence Weed Control Trials in Peppers
Principle Investigators:
Richard Smith
Farm Advisor, Monterey County 1432 Abbott Street
Salinas, CA 93901
(831) 759-7350; (831) 758-3018 FAX
rifsmith@ucdavis.edu
Timeline: March 1, 2013 to February 28, 2014
Objective
Examine pre-transplant (herbicides for weed control.
Summary: This trial provided an excellent opportunity to evaluate the efficacy and safety of a number of materials for use on bell peppers. Zeus was used under a research authorization. Zeus had the lowest number of malva plants per plot. This is a key weed in pepper production fields in the coastal production district. There was some indication that 4.5 oz/A of Zeus caused delay in the maturity of bell peppers as there were fewer red fruit at harvest, but no overall reduction in yield. Zeus should be further evaluated in 2014 to further test safety and efficacy against problematic weeds.
Methods: The trial was conducted on a commercial bell pepper farm east of Gilroy on a site with Pleasanton loam soil. Treatments were applied to shaped beds prior to transplanting on May 15. The bell pepper variety Baron was transplanted the next morning on May 16 in two seedlines on the beds; transplants were watered with sprinkler irrigation immediately after planting. Each plot was one 40-inch bed wide by 20 feet long and replicated three times in a randomized complete block design. The two Zeus treatments were also applied under a Research Authorization two two beds by the length of the field. All materials were applied with two passes of a one-tip wand with an 8008E nozzle applying the equivalent of 69 gallons per acre. See tables for evaluations and dates.
Table 1. Phytotoxicity rating and weed counts (no./20 ft2) on June 10
| Treatment | Material/A | Phytotoxicity | Malva | Sow Thistle | Nightshade | Purslane | Pigweed | Groundsel | Other Weeds | Total Weeds |
| Untreated | ---- | 0.0 | 11.0 | 9.8 | 5.0 | 0.5 | 0.3 | 1.3 | 2.8 | 30.5 |
| Dual Magnum 7.62 | 1.67 pt | 0.0 | 4.8 | 0.3 | 0.5 | 0.5 | 0.3 | 0.3 | 0.3 | 6.8 |
| Prowl H2O | 2.00 pt | 0.0 | 7.0 | 2.8 | 3.0 | 0.0 | 0.0 | 1.3 | 1.0 | 15.0 |
| Dual Magnum 7.62 Prowl H2O | 1.67 2.00 | 0.0 | 6.6 | 0.3 | 0.3 | 0.0 | 0.0 | 0.0 | 0.3 | 6.8 |
| Outlook 6.0 | 14.0 oz | 1.5 | 5.8 | 0.5 | 1.0 | 1.5 | 0.3 | 0.0 | 0.5 | 9.5 |
| Zeus 4F | 3.0 oz | 1.5 | 0.8 | 0.8 | 4.3 | 0.0 | 0.0 | 0.0 | 0.0 | 5.8 |
| Zeus 4F | 4.5 oz | 2.5 | 0.5 | 0.0 | 3.8 | 0.3 | 0.0 | 0.0 | 0.3 | 4.8 |
| Nortron 4SC | 24 oz | 3.0 | 14.5 | 3.3 | 0.8 | 0.3 | 0.0 | 0.5 | 0.3 | 19.5 |
| Pr>F treat | <.0001 | 0.2673 | <.0001 | 0.6049 | 0.0690 | 0.6430 | 0.0366 | 0.1272 | 0.0214 | |
| LSD 0.05 | 1.1 | NS | 3.4 | NS | NS | NS | 1.0 | NS | 15.0 |
Table 2. Yield evaluations (lbs/10 plants) on October 8.
| Treatment | Material/A | Red fruit | Green fruit | Culled fruit | Total fruit | ||||
| No. | lbs | No. | lbs | No. | lbs | No. | lbs | ||
| Untreated | ---- | 43.0 | 22.7 | 3.7 | 1.4 | 2.3 | 0.9 | 49.0 | 25.0 |
| Dual Magnum 7.62 | 1.67 pt | 42.3 | 20.8 | 4.3 | 1.5 | 2.0 | 0.9 | 48.7 | 23.1 |
| Prowl H2O | 2.00 pt | 46.7 | 23.1 | 2.0 | 0.5 | 2.3 | 1.1 | 51.0 | 24.6 |
| Dual Magnum 7.62 Prowl H2O | 1.67 2.00 | 43.0 | 22.2 | 2.7 | 0.8 | 1.7 | 0.6 | 47.3 | 23.6 |
| Outlook 6.0 | 14.0 oz | 37.0 | 19.9 | 7.7 | 2.7 | 1.0 | 0.5 | 45.7 | 23.0 |
| Zeus 4F | 3.0 oz | 43.7 | 20.7 | 5.7 | 1.7 | 1.7 | 0.5 | 51.0 | 22.9 |
| Zeus 4F | 4.5 oz | 36.0 | 18.6 | 10.0 | 3.0 | 2.0 | 0.5 | 48.0 | 22.1 |
| Nortron4 SC | 24 oz | 46.3 | 22.8 | 6.3 | 2.0 | 1.7 | 0.5 | 54.3 | 25.3 |
| Pr>F treat | 0.2328 | 0.0488 | 0.2239 | 0.1746 | 0.991 | 0.9514 | 0.398 | 0.1142 | |
| LSD 0.05 | NS | 2.9 | NS | NS | NS | NS | NS | NS | |