GRAZING ANIMALS AS WEED-CONTROL AGENTS

Literature on the effectiveness of grazing animals (especially cattle, goats, and sheep) in controlling weeds is reviewed. Availability of a nimals and the ability to fence them onto or off weed infestations are essential. Weeds of pastures are the most suitable subjects for contr ol, although weeds of arable crops, forestry, and waste places are som etimes amenable to control by grazing animals. Although grazing animal s themselves often cause weed problems in pasture, adjusting grazing t iming or intensity or both can sometimes redress the balance. Increasi ng sheep or cattle stocking rates prevents animals from grazing select ively and can help control some weeds. Adjusting grazing pressure can also improve the growth of desirable pasture species so that these are more competitive and able to resist invasion of annual or biennial we eds. Introducing a different class of stock, like sheep into a cattle system or goats into a sheep system can control many weeds. Goats are capable of browsing on and controlling spiny or poisonous brush weeds, including gorse and poison ivy, without suffering adverse effects. Ex amples are given of the use of grazing animals for weed control in cro ps and forestry.