Managing Smooth Bedstraw (Galium mollugo L.) in Forage Crops

Managing Smooth Bedstraw (Galium mollugo L.) in Forage Crops

Summary

Smooth Bedstraw has become a problem weed in many forage crops, especially pastures and haycrops. It can significantly reduce yields of forage grasses and legumes. Smooth Bedstraw is a perennial that spreads by seed as well as vegetatively with underground rhizomes. It has numerous, relatively upright stems and produces white to greenish flowers in June and July. Individual plants can grow 1 to 3 feet tall and spread to 3 feet or more in diameter.

Bedstraw grows throughout the Northeast. The weed is prevalent in infrequently mowed hay fields of low fertility and low pH, and tolerates low soil Nitrogen and low pH better than the desired forage species. Bedstraw also thrives in well-managed fields because of its adaptation to a wide variety of environmental conditions. Smooth Bedstraw prefers moist, cool conditions, but can tolerate drought.

Many hayfields in Maine that have not been intensively managed or in rotation with row crops have experienced a proliferation of Smooth Bedstraw. Cattle, sheep and horses will not eat Bedstraw, and its spreading nature in hayfields significantly reduces grass and legume yield.

Control of Bedstraw is difficult for many livestock producers. Some herbicide options exist, but have limited effectiveness and have grazing or harvest restrictions associated with their use. Numerous calls come to Extension offices throughout the state when Bedstraw begins to flower and growers visually see how dominant the plant has become in their fields.
Four possible options will be investigated and evaluated to control Smooth Bedstraw in established pastures and hayfields. Two herbicide treatments, (Roundup or glyphosate, and Crossbow), a fertility treatment (Nitrogen applications), and a tillage treatment will be compared to a control (two mowings per year).

Fertility management is probably the easiest and most likely option for many growers. By fertilizing the existing grasses, it is anticipated that they will out-compete the bedstraw and reduce its vigor. Tillage, cover crop and bare fallow will probably be the most effective in eradicating the weed, but also may have the highest price tag and have minimal use with small and part time farmers who lack the equipment to perform these operations. Many livestock producers are also unwilling to use herbicides, so alternatives must be investigated.

Objectives/Performance Targets

The Cooperating farmer, Welles Thurber, owns a hayfield with a remarkably uniform stand of bedstraw.

Our research design involves a randomized complete block design with four treatments and a control (mowing 2X per year). Each block will be 50X50 feet with the plots being 10X50 within each block. We will be using an area approximately 300X50 with buffer strips between each block. Treatments are as follows:

1) Control (mowing 2X during the summer to replicate a hayfield or pasture situation)

2) Nitrogen Management (200 lbs. per acre of N applied in a split application with one in spring, and the second after mowing in July)

3) One mowing with Crossbow herbicide applied in September (traditional broadleaf herbicide recommendation)

4) Glyphosate herbicide applied just prior to flowering in June. Re-seed using a no-till drill.

5) Repeated tillage beginning in June, with a buckwheat cover crop and a short fallow period. Re-seed in August.

Evaluation of plots will be conducted before treatments are applied (spring 2004) and after (spring 2005) using three methods as suggested by Eric Gallandt, Weed Ecologist at the University of Maine.

1) Plant cover with a line intersect

2) Stem density in 3, 50 cm by 50 cm subplots

3) Average height of Bedstraw above ground at the three subplots

Accomplishments/Milestones

Research plots were marked and randomized in May. Fertilization of the nitrogen subplots was done immediately, along with soil samples and documentation of existing plant species. The participating farmer suggested an additional treatment (burning) for a possible option in the spring of 2005. The glyphosate treatment was done in June, prior to flowering and the tillage plots with cover crops (buckwheat) was also done in June. Glyphoste treatment provided a good kill of the existing forage and bedstraw population. Three weeks after glyphosate treatment, a no-till drill was used to seed a pasture mix of grasses and legumes (Hobby Horse mix). The tillage treatment received two crops of buckwheat with tillage between both treatments and a final seeding of forage in late August (Hobby Horse Mix). The Crossbow herbicide treatment was also applied to the plots in late August.

Impacts and Contributions/Outcomes

Outreach efforts have included a fall field day at the site with three farmers participating (Rain and cold day). There have been 12 email requests for information related to the project. I was invited to a pasture workshop in Dresden to discuss the project progress (60 people) and also discussed the project at a forage pesticide recertification meeting at Maine Farm Days in Clinton (85 people). Additional outreach was conducted at the Maine Grass FArmers Network Conference in October (110) farmers and NRCS employees. I have been invited to speak on Bedstraw at the New England In-Service training for Agricultual Professionals (Certified Crop Advisors). Articles about the project have been published in Country Folks, Maine Farmer, Agriculture Today and several local papers, including an electronic paper http://belfast.villagesoup.com/Community/Story.cfm?StoryID=26135

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