THE EFFECT OF GLYPHOSATE, PARAQUAT AND PACLOBUTRAZOL ON LOLITREM-B LEVELS IN ENDOPHYTE-INFECTED PERENNIAL RYEGRASS

Two herbicides (glyphosate and paraquat) and a plant growth regulator (paclobutrazol) were applied to endophyte-infected (Acremonium lolii) perennial ryegrass swards. Subsamples of these swards were then chemic ally analysed at intervals up to 28 days later for lolitrem B, the com pound responsible for perennial ryegrass staggers in domestic livestoc k. Glyphosate and paclobutrazol had no effect on lolitrem B concentrat ions. Paraquat applications decreased lolitrem B concentrations in the herbage. Because none of the chemicals tested increased the concentra tion of lolitrem B in the herbage, they are unlikely to be directly im plicated in perennial ryegrass staggers in grazing animals.