| Abstract: | The effect of the herbicides di-allate, diquat, diuron, paraquat, tri-allate and trifluralin, at a range of application rates from 0.5 to 32 times that recommended by the manufacturers, on vesicular-arbuscular (V-A) endophyte spore abundance in the soil and on infection of wheat roots was investigated in field and glasshouse experiments. Paraquat and diquat had no measurable effect on V-A endophyte spore abundance. There was a slight trend to lower V-A endophyte spore numbers at high rates of application of di-allate and tri-allate but no trend for the other chemicals. Infection intensity (% root length infected) declined at high rates of di-allate and led to lower mycorrhizal root weights. The phosphorus content of the shoots was also reduced by di-allate. High doses of di-allate, diuron, tri-allate and trifluralin reduced most parameters of plant growth more than mycorrhizal parameters. It is therefore concluded that at normal application rates these chemicals are unlikely to affect adversely endomycorrhiza formation or function. |
