Peter Hagar is an agricultural educator with Cornell Cooperative Extension in Clinton County, 6064 Rt. 22, Plattsburgh, N.Y., 12901. Phone 561-7450.

Nature abhors a weed vacuum

By: Peter Hagar, agriculture educator, Cornell Cooperative Extension

I recently held a field meeting during which I and a small group of farmers and graziers walked through lush pastures of grasses, clovers and of course … weeds. I’d like to think that my pastures are in the reduced weed variety but I don’t know if there is such a thing as weed free. Adaptable, fast growing, tough to eradicate and extremely competitive, weeds are some of nature’s toughest customers.

Anyone who has ever planted a vegetable garden knows what I’m talking about. If only our vegetable crops and forages would grow this persistently. What we need to understand from the start is that weeds are a natural part of the environment and that we will never get rid of all of them. What the dedicated grazier aims for is management of weeds to reduce their impact on the productivity of the more favorable forages. There are several ways to manage weeds to enhance the growth of pasture grasses and other forages.

This is defined as Integrated Weed Management, an economically and environmentally sound approach to weed management. An integrated approach involves scouting, prevention and control in a coordinated plan.

The first step to reducing weeds in your pastures is prevention. By regular scouting of your pastures, you will be able to estimate the quantity of forage available and identify the number of weeds, the species present and the severity of your weed problem. Management should focus on controlling the dominant weeds and preventing the spread of less common weeds. Knowing what types of weeds are dominant and applying the required management is key to improving pasture conditions for desired forages.

Most weeds are spread by seed, so anything you do to keep weed seeds from getting onto your soils will reduce potential weed pressure. Weed seeds can be transported in purchased hay, grass seed, mowing equipment or dispersed by the wind or wildlife. Many weed seeds will pass unharmed through the digestive tracts of birds, wildlife and livestock, thus being spread far from the seed source. Keeping hedgerows and roadways mowed and clean of noxious weed seed sources will help to reduce local seed production.

Once an established weed problem is identified, an appropriate control method needs to be determined. Cultural practices such as application of lime and fertilizer will increase the ability of desired pasture plants to compete. Generally speaking, a thick and healthy crop of grass will crowd out undesirable plants, prevent establishment of new weed seeds and utilize a majority of the water, sun and nutrients available for growth. Many weed species are indicators of poor soil fertility and are good sign that soil pH and soil nutrient testing is warranted.

Mechanical control such as mowing or clipping pastures is also an effective method of controlling weed populations. Mowing improves the pasture’s appearance, temporarily increases forage production and properly timed will prevent weeds from producing seeds. Mowing is more effective on annual weeds than perennial weeds and broadleaf weeds more than grass weeds.

Biological control involves using other living things to control weeds such as plants, herbivores, insects and nematodes. These methods are unlikely to provide complete control, but will often suppress the weed population to a manageable level.

Chemical weed control involves the use of herbicides. Herbicides should be selected based on forage species being grown, weed species to be controlled, cost and ease of application. Environmental impact should also be considered. Choosing the proper herbicide and application rate is extremely important. Herbicides must be applied at the correct rate and time to be cost effective.

Maintaining a healthy, productive pasture will reduce the population of weedy plants. Good pasture management such as pH testing, fertilization and controlled grazing will result in healthy pastures. Adding new grass and legumes by frost seeding or using a no-till drill will improve forage quality. While we can’t hope to eradicate all weeds, an integrated weed-management strategy involving scouting, prevention and control is the most economical and environmentally friendly approach to pasture weed management.

For questions regarding pasture management, grazing livestock or small-farm questions, contact Peter Hagar at Cornell Cooperative Extension’s Clinton County office at 561-7450 or email me at

Peter Hagar, agriculture educator, Cornell Cooperative Extension Clinton County, 6064 Route 22, Suite 5, Plattsburgh, 12901. Phone 561-7450 or email