INHIBITION OF FUSARIUM OXYSPORUM F. SP. VASINFECTUM SPORES BY PRE-EMERGENCE HERBICIDES

Germination of micro- and macroconidia of Fusarium oxysporum f.sp. vasinfectum on water agar was differently affected by different pre-emergence herbicides (trifluralin, dinitramine, fluometuron, diuron, prometryn and dalapon). Chlamydospores germination was not affected by the herbicides used.
All tested herbicides significantly reduced the length of germ tubes of all kinds of Fusarium spores.

All tested herbicides significantly inhibited chlamydospores germination in natural soils when the pH was 6.4, 7.4 and 8.0. No effect was detected in similarly treated steamed soil.

Chlamydospore germination was also inhibited in the rhizosphere of cotton plants treated with the herbicides, especially at the highest concentration.

The inhibition was clearer in case of cotton grown in unsterilized soil.
The effect on associated fungi was then studied and only diuron was found to reduce the number of fungi present in the rhizoplane and rhizosphere of herbicide-treated cotton seedlings.
The high dose of dalapon also decreased these numbers in the rhizosphere.

Aspergillus terreus, an antagonist of F. oxysporum f.sp. vasinfectum, numbers were greater in rhizoplane of cotton seedlings treated with prometryn and diuron, especially with doses equal to double the recommended ones.
Meanwhile, numbers of Trichoderma sp., a hyperparasite, were not affected by any of the herbicidal treatments.

III International Symposium on Soil Desinfestation

A.R. Osman, M.M. El-Khadem

https://doi.org/10.17660/ActaHortic.1989.255.8