PROJECT RESULTS

Forage and Forage Seed Crop Herbicide/Weed Control Evaluation Program

Applicant: 

Michelle Watts

Manitoba Forage Seed Association

Arborg, Manitoba  R0C 0A0  Canada

Table of Contents:

• Background and Objectives
• Seedling Trials
• Established Trials
• Conclusions

ARDI Project:

#00-416

Total Approved:

$30,000

Date Approved:

April 9, 2001

Project Status:

Completed March, 2003

Background and Objectives:

There were over 110,000 acres of forage seed produced in Manitoba in 2000.  Registered options available to both forage and forage seed growers remain limited causing a high rate of unregistered pesticide use in both industries.  To obtain a User Requested Minor Use Label Expansion (URMULE), the Pest Management Regulatory Agency requires at least 2-3 years of research that includes crop tolerance and impacts on seed yield.  Weed control issues have been identified as the number one limitation to increasing seed yield and quality in forage and grass seed crops across Manitoba.  Development of effective and economical weed control programs is necessary for the industry to continue growing and maintain stability.

The Manitoba Forage Seed Association conducted a broad-spectrum herbicide tolerance screening trial in 2000.  Results from this trial were used to determine products to pursue for registration.  Trials in 2001 and 2002 were coordinated with government specialists from British Columbia, Alberta, and Saskatchewan.  Both seed trade and producers from western Canada were consulted and provided valuable input.  Trials in 2001 focused on seedling crops while trials in 2002 targeted established crops.  Herbicides tested have a determined weed spectrum and a major registration.  Treatments included products to address both grassy and broad leaf weed problems such as cleavers, wild oats, green foxtail barnyard grass, Canada thistle, perennial sow-thistle, dandelion, as well as others in forage seed crops.

Seedling Trials:

Procedure and Project Activities

In 2001, large blocks of forage seed crops were solid seeded in Arborg and St. Norbert, Manitoba to conduct herbicide trials.  Species seeded included alfalfa (Medicago sativa), perennial ryegrass (Lolium perenne), timothy (Phleum pratense), tall fescue (Festuca arundinacea) and annual ryegrass (Lolium multiflorum).  All species were successfully established at Arborg while only perennial and annual ryegrasses were successfully established at St. Norbert.  Seedling grasses were sprayed at the 2-4 leaf stage and seedling alfalfa was sprayed at the 3-4 trifoliate stage.  Crop tolerance ratings, using the scale in Figure 1, were taken approximately 3, 14 and 28 days after treatment.  Plots were 2m x 6m and were sprayed with a bicycle sprayer.  A 10g/acre (45L/acre) water volume was used to spray all treatments.  An area of 3m² from each plot was clipped, bagged, dried and threshed to obtain seed yields.  The annual ryegrass plot in Arborg was not harvested for seed yield due to a flooding period, which affected fertility and seed production.  As well, the timothy plot in Arborg was not taken to seed yield to due poor establishment.

Figure 1.  0-100% Crop Tolerance Ratings

< 70% crop tolerance to herbicide is not commercially acceptable

Results and Discussion

Most of the chemicals tested were tolerated by the crops and did not significantly reduce seed yields in comparison to the untreated weed free check.  Everest on seedling tall fescue, timothy, annual and perennial ryegrass caused significant and unacceptable visual damage (Tables 1-4).  Tall fescue seed yield was lightly reduced, and both annual and perennial ryegrass seed yield was significantly reduced in comparison to the untreated weed free check.  However, seed yield for plots sprayed with Everest at the 2x rate had an average seed yield of 429 kg/ha.  This result is not expected and probably does not reflect the injury and damage that can be caused by spraying at this rate with this chemical.  Actual plot population was approximately 30-50% less than the rest of the plots.  However, the other plots had a significant amount of residue, which may have suppressed seed yield, whereas the plots sprayed with Everest at the 2x rate did not.

Table 1.  Tolerance of seedling tall fescue to herbicide application at Arborg, Manitoba.  Plots were sprayed July 5, 2001.  Ratings were taken 3, 14 and 28 days after treatment (DAT).  Plots were harvested for seed July 31, 2002.

* Significantly different from untreated weed free check (P=0.05).

Table 2.  Tolerance of seedling perennial ryegrass to herbicide application at Arborg and St. Norbert, Manitoba.  Plots were sprayed July 7 and 10, 2001 respectively.  Ratings were taken 3, 14 and 28 days after treatment (DAT).  Plots were harvested for seed August 7, 2002.

* Significantly different from untreated weed free check (P=0.05).

Table 3.  Tolerance of annual ryegrass to herbicide application at Arborg and St. Norbert (Brett Young), Manitoba.  Plots at Arborg were sprayed July 5, 2001 and plots at St. Norbert were sprayed July 9, 2001.  Ratings were taken 3, 14 and 28 days after treatment (DAT).  Plots were harvested for seed September 5, 2001. 

* Significantly different from untreated weed free check (P=0.05).

Table 4. Tolerance of seedling timothy to herbicide application at Arborg, Manitoba.  Plots were sprayed July 7, 2001 and measurements were taken 3, 14 and 28 days after treatment (DAT). 

Avenge caused severe initial damage to seedling timothy (Table 4), however, injuries tended to outgrow by 28 days after treatment.  Timothy plots were not harvested for seed because plant stand densities were neither high nor consistent enough to produce reliable results.

Puma Super 2x reduced seed yield significantly from the untreated weed free check on annual ryegrass at St. Norbert and had unacceptable tolerance ratings at both sites (Table 3).

Most Refine treatments, as well as Tropotox and Tropotox Plus 2x treatments were hard on seedling alfalfa initially (Table 5).  However, these injuries were outgrown by 28 days after treatment and didn’t significantly affect seed yield in comparison to the untreated check.

Table 5.  Tolerance of seedling alfalfa to herbicide application at Arborg, Manitoba.  Plots were sprayed July 6, 2001.  Ratings were taken 3, 14 and 28 days after treatment (DAT).  Plots were harvested for seed September 23, 2002. 

* Significantly different from untreated weed free check (P=0.05).

Established Trials:

Procedure and Project Activities

In 2002, herbicide trials were conducted on both producers’ fields and on blocks that were seeded the previous year.  Testing was conducted on established perennial ryegrass, tall fescue, timothy and alfalfa.  Seed yields obtained from the timothy trials were much lower than what was obtained from cooperating producers therefore they will not be discussed in this report.  Lower yields than expected may be attributed to harvesting and threshing methods.  Established grasses were sprayed before stem elongation and established alfalfa was sprayed approximately 20 cm in height.  Plots were 2m x 6m and sprayed using a bicycle sprayer.  A 10gal/acre (45 L/acre) water volume was used to spray all treatments.  Visual tolerance ratings, using the scale in Figure 1, were taken approximately 3, 14, and 28-30 days after treatment.  An area of 3m² from each plot was clipped, bagged, dried and then threshed to obtain seed yield.

Results and Discussion

All herbicides tested on tall fescue (Table 6) produced very little visual injury and did not decrease seed yields significantly from the untreated weed free check.

Table 6.  Seed yield (kg/ha) following spring application of herbicide applied at 1x and 2x the recommended rate on tall fescue and perennial ryegrass in Arborg, Manitoba .

* Significantly different from untreated weed free check (P=0.05).

Assert lx was fairly hard on perennial ryegrass but only decreasing yields slightly, while Assert 2x caused both crop injury and a significant decrease in seed yield. Accord seemed to have caused some injury at 28 days of treatment, however seed yield was not affected significantly.

Results for established alfalfa (Table 7) were interesting.  Some of the treatments produced severe injuries to the crop indicated by low ratings for the first two rating dates. Injuries, severe as they were, tended to outgrow and none of the treatments produced significantly lower seed yield than the untreated check.

Table 7.  Tolerance of established alfalfa at Fisher Branch and Arborg, Manitoba.  Plots were sprayed June 4 and June 5, 2002, respectively.  Ratings were taken at varying days after treatment.  Plots were harvested for seed October 9 (Fisher Branch) and October 16 (Arborg), 2002. 

* Significantly different from untreated weed free check (P=0.05).

Conclusions:

The harmful effect of Everest on forage seed grasses is an important result obtained from testing.  It was hoped that it would become a product that could be used for controlling wild oats and green foxtail in several grass seed crops.  Data from these trials has been used to help support minor use registrations.  Recent minor use registrations include:

1. Attain on seedling and established tall fescue - obtained in February, 2002.

2. Prestige on established tall fescue - obtained in July, 2002.

3. Tropotox Plus on seedling alfalfa - obtained February, 2003.

Applications have been made to include established Timothy (seed and forage) on Prestige, Spectrum and Curtail M labels.

The federal government is currently in the process of developing a new minor use program to facilitate registration.  They are in the process of developing a national priority list of products and crop kinds that will receive complete funding to pay for the research and personnel required to obtain registration.  Results obtained from this and previous years’ research has been vital in determining products and crops to propose for this list.  Results obtained will be used to obtain registrations for products not on the national priority list.  The Manitoba Forage Seed Association plans to continue working with Alberta, British Columbia, and Saskatchewan on obtaining minor uses for forage seed crops and screening new herbicides that come on the market.

Acknowledgement:

We wish to thank the following producers and seed companies for their participation in the forage seed herbicide program: Lorne Johnson, Bill Mamchuk, Len and Linda Loewen, Brian and Eric Fridfinnson, Johnson Seeds and Brett-Young Seeds.  We are grateful for the technical assistance provided by Anthony Mintenko (Manitoba Agriculture, Food and Rural Initiatives), Sydney Ramnath, Jennifer Blandford, and Kendell Malenchak.

Funding for this research was provided by the Agri-Food Research and Development Initiative (ARDI).

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