Pornsilp Maneechai, Vasun Petcharat, Samerchai Chuenchit and Charassri Nualsri

pp. 25 - 37

Abstract

A total of 174 strains of bacteria antagonistic against the green mold (Trichoderma harzianum), isolated from cultivating bags and fruiting bodies of the mushrooms, were screened for effects on mushroom
mycelia and ability to control the green mold disease. Twenty-eight of them promoted the primodia formation
of the Pleurotus pulmonarius mycelia on agar plates. Twenty-two isolates were selected and further tested
in a mushroom house. Cell suspension of each isolate was prepared and sprayed onto the spawn surface of P. pulmonarius. Fifteen isolates shortened the times required from watering to 2^nd and 3^rd flushing and
increased yield of the basidiocarps by 1.1-34.3% over 30 days.
Six isolates of bacteria which showed an inhibitory effect against T. harzianum, enhanced primordia
formation and increased yield of P. pulmonarius were selected and used for control testing in a cultivation
house. The suspension of each isolate was sprayed onto the spawn surface immediately after exposure to the
air in the mushroom house, followed by spore suspension of T. harzianum two days later. The number of
infected bags was counted at 30 days after inoculation and the cumulative yield was compared after 60 days.
The results showed that bacteria isolate B012-022 was highly effective in suppressing the green mold disease.
Only 6.7% of the cultivating bags were found to be infected by T. harzianum when bacteria isolate B012-022
was applied. Cumulative yield obtained from 900 g of 94% sawdust + 5% rice bran + 1% Ca(OH)₂ was
300.0 g/bag after 60 days, 71.1% higher than the bags infected by the green mold and without bacterial
spraying. Identification of the six bacterial isolates showed all to be Bacillus spp.

Keywords

• biological control
• Trichoderma
• antagonistic bacteria
• Pleurotus