EVALUATION OF SOME PESTICIDES ON MYCELIAL GROWTH AND SPORULATION OF FUSARIUM OXYSPORUM F. SP. STRIGAE, A BIOCONTROL AGENT FOR MANAGING STRIGA HERMONTHICA

Abstract

Studies were carried out to determine the ability of growthenhancement by five (0.0x, 0.5x, 1.0x, 1.5x and 2.0x) rates of benomyl,carbendazim, mancozeb, hexaconazole, carbendazim + mancozeb,imidacloprid + metalaxyl-M + tebuconazole (IMT) and metsulfuronmethyl on Fusarium oxysporum f. sp. strigae, a biocontrol agent ofStriga hermonthica. The chemicals were incorporated into moltenpotato dextrose agar to determine growth and sporulation of PSM 197and Foxy 2, which were isolates of F. oxysporum f. sp. strigae usedagainst S. hermonthica. Two hundred and eighty Petri dishescontaining amended and un-amended media were inoculated with 14-day-old cultures of PSM 197 and Foxy 2 using flame-sterile 5 mm corkborer. Petri dishes were arranged on laboratory bench in aCompletely Randomized Design (CRD) and observations taken at 24hours interval. Mycelial growth and development of conidia werecompletely inhibited in media amended with benomyl, carbendazim,and carbendazim + mancozeb. Increasing mancozeb rate from 18 to24 g/L resulted in complete inhibition of mycelia and conidia for PSM197 and Foxy 2. Fourteen days after incubation, mycelial diameter ofboth isolates was low on media amended with highest rates ofhexaconazole (1 ml/L), metsulfuron methyl (4.6 g/L) and (IMT) (8g/L). With respect to all parameters considered, (IMT) had the highestpercent variations than hexaconazole, mancozeb and metsulfuronmethyl. The study therefore shows that metsulfuron methyl at 2.3 g/Lpromoted growth and sporulation of PSM 197 and Foxy 2 and shouldbe used in the management of S. hermonthica.