Effects of plant protection chemicals on vesicular‐arbuscular mycorrhizas

Abstract

The effects of eight plant protection chemicals on the development of vesiculararbuscular mycorrhizas were influenced by the identity of the host plant and fungal endophyte, the soil type, and the composition and concentration of the biocide. These effects ranged from stimulatory (as with the fungicide chloroneb, applied to inocula of Glomus microcarpus used with pot-grown lettuce), through negligible (aldicarb on G. mosseae in pot-grown onions and field grown barley with indigenous mycorrhizal fungi) to short-term inhibition (drazoxolon on G. mosseae in onion) and longer term inhibition (the fungicides benomyl and triadimefon on G. mosseae in onion).

Effect of Agrochemicals on Mycorrhizae

“…Several studies have indicated that benomyl AMF and carbendazim inhibit the formation of AMP belonging to Endogone and Glomus in various crops such as barley, clover, maize, onion, soybean, and wheat (Bailey and Safir, 1978;Bertoldi et al, 1977;Boatman et al, 1978;Jalali and Somsch, 1975;Spokes et al, 1981;Sutton and Sheppard, 1976). However, other zygomycetes fungi appear to be relatively insensitive to benomyl (Bollen and Fuchs, 1970;Edgington et al, 1971) and some species ofMortierella, a genus taxonomically related to theEndogonaceae.…”

“…growth (Vyas, 1988;. Benomyl has been found to have deleterious effects on VAM; delaying, diminishing or preventing the formation ofsymbiosis between fungi and roots (Menge, 1982;Spokes et al, 1981); and disrupting their ability to translocate phosphate (Botman et al, 1978). Tommerup and Briggs (1981) found that a sandy soil containing upto 100 ng-1 carbendazim was notinhibitory to germination or disruptive to hyphal growth ofthe VA mycorrhizal fungi.…”

“…It was further observed that infection by G. microsporum was reudced to 1/2 ofthe control when treated with triadimefon and was decreased 3-fold bychloroneb. Terrazole was found to be ineffective to it (Spokes et al, 1981).…”

“…PCNB and benodanil decreased basidiocarp production. The mycelium ofboth fungi was affected by the fungicides in agar medium more than in soil (Spokes et al, 1981).…”

“…According to Spokes et al (1981) different endophyte species vary in infectivity in soils treated with different fungicides. It was reported that the application ofchloroneb to inocula ofG.…”