2014 Progress Report

Transcription

1 2014 Progress Report Control of Johnson grass with Pastora when mixed with common Phonxy Herbicides Site Location: Cooperators: Authors: Erath and Somervell Counties David Halford Bob Miller James Jackson, Extension Program Specialist, Stephenville Lonnie Jenschke, County Extension Agent, Erath County County Extension Agent, Somervell County Summary Two sites were established in 2014 to research the efficacy of DuPont Crop Protection herbicide Pastora on Johnson grass when tank mixed with common phonxy weed herbicides and at various rates. Evaluations of plots were conducted frequently after application was made. The Johnson grass was estimated for percent brownout and the coastal was estimated for percent damage. Objective Johnson grass (sorgam halepense) is of excellent grazing value when in pastures, however; when in coastal fields it is seen as a weed due to its invasive nature and its ability to compete with the Coastal Bermuda. This causes lower quality hay as well management problems due to the Johnson grass rate of growth as well as its ability to create a monoculture by out competing with the Coastal Bermuda. The objective of this trial was to evaluate if there was any antagonistic effects when Pastora is tank mixed with at two different rates and Pastora is tank mixed with at two different rates. Materials and Methods Sites were established in the spring of 2014 to research the effects of the common phonxy herbicides and when mixed with Pastora. The Erath County site was placed

2 on the David Halford property outside of Stephenville with the Somervell County site being placed on the Bob Miller property outside of Glen Rose. Each site received all 6 treatments with the control being the area outside the plots. All plots were sprayed with a handheld CO2 sprayer with VS nozzles on 18 inch spacing. The Erath County plots were 20 ft. X 60 ft. with the Somervell County plot size being 20 ft. X 120 ft. The plots were sprayed at above the top of the Johnson grass that was 6-24 tall at the time of application at both sites. The evaluations were made at frequent intervals after application was made. During the evaluations the Johnson grass was analyzed for percent brownout with the Coastal Bermuda being analyzed as percent damage to coastal. Table 1 gives the conditions at the site at the time of application and Table 2 gives the specific details of each treatment applied at both sites. Table 1. Environmental conditions on the day of application for Johnson grass trials established in Site Date Spray Time Wind Speed/ Direction Soil Temp. Air Temp. Soil Type/ Moisture RH Erath Co. 5/21/14 6:45-7: mph/s Rocky/Low 74% Somervell Co. 6/11/14 9:00-11:00 9 mph/s % Table 2. Treatment details from both sites that were put out at Somervell and Erath Counties. Treatment Herbicide Material/Plot Material/Acre TSV/Plot Somervell Co. Crop Oil Concentrate 1.31 g 0.35 g 15.6 ml ml ml 0.84 oz 0.22 oz 1.00% v/v

3 Treatment Herbicide Material/Plot Material/Acre TSV/Plot Erath Co. Crop Oil Concentrate 0.65 g 0.17 g 15 ml ml ml 0.84 oz 0.22 oz 1.00% v/v Results and Discussion The results were collected by visual observation by estimating the percent brownout of the Johnson grass and the percent damage on the Coastal. The values listed in Table 3 are the average of the reps of the same treatment. The Somervell county site was cut for hay production at 28 days after treatment and the Erath County site was cut at 22 days and 60 days after treatment for hay production. As noted in the results the amount of coastal damage was present at the evaluation that took place 1 month after treatment, however; the damage to the coastal was not present at later evaluations. Figure 1 represents the average results of both sites at 4 weeks after treatment. As noted in Figure 1 it appears that there may have been some antagonistic reactions between the Pastora and at the Erath County site, however, this was not seen at the Somervell County location. More research is needed to come to any conclusions on the antagonistic reactions that may occur between Pastora and common weed herbicides.

4 Table 3. Rates of application and results for Johnson grass plots that were established in 2014 in Erath and Somervell Counties. Treatment Herbicide Rate/Acre 14 DAT 21 DAT 48 DAT 104 DAT Erath 30% JC 30% JC 60% JC COC 1.00 v/v 66.6% JC 6.6% CD 66.6% JC 6.6% CD 70% JC 75% JC 75% JC 80% JC 80% JC 0.25 % v/v 66.3% JC 21.6% JC 15% JC 63.3% JC % JC 5% CD 15% JC 10% JC 0% JC 90% JC 20% JC 25% JC Somervell 28 DAT 84 DAT 56.5% JC 14% CD 43.3% JC COC 1.00 v/v 45% JC 11.6% CD 61.6% JC 60% JC 8.3% CD 85% JC 0.25 % v/v 61.6% JC 35% CD 35% JC 5% CD 31.6% JC 1.6% CD 78.3% JC 65% JC 91% JC

5 % Apparent Brownout 80 Pastora Effect on Johnson Grass when tank mixed with weed Herbicides Johnson grass control Coastal Damage 0 Figure 1. Results of Johnson grass plots were treated with Pastora that was tank mixed with common weed herbicides. Graph depicts average results of both locations at 4 weeks after treatment. Acknowledgements This project was supported by DuPont Crop Protection, Erath and Somervell Counties and the cooperating landowners. Trade names of commercial products used in this report is included only for better understanding and clarity. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by Texas AgriLife Extension Service and the Texas A&M University System is implied. Readers should realize that results from one experiment do not represent conclusive evidence that the same response would occur where conditions vary.