Coffee Coffea arabica (L) Lam.
is the major commercial plant in the highlands of Papua New Guinea (PNG) and is often prone to pests and diseases under humid tropical conditions. The experiment was conducted to morphologically identify the fungi and study the effects of different levels of Lecanicillium lecanii Zim. The research was carried out at Aiyura, CIC coffee research station and a smallholder coffee block at Yonki, Kainantu, E.H.P, PNG during (season) 2018. The entomopathogenic fungus (EPF) had the potential to control coffee leaf rust (CLR) Hemileia vastatrix under field conditions. Three levels of L. lecanii (1 x 106, 1 x 107 and 1 x 108 conidia ml-1) added with 2 % glycerol developed concentrations (dose) were used and disease severity was assessed at 4 periods from date of application 14, 28, 48 and 60 days after spray (DAS).
More so, based on the 60 DAS assessment, the estimated efficacy level from the different treatment of conidial suspension was selected. At the 60 DAS count, the highest L. lecanii growth mean of 2.71 on CLR leaf was obtained from coffee trees applied with 1 x 107 conidia ml-1 treatment level from Aiyura and 4.
95 from Yonki indicating significant differences between the sites. The total leaf retention of diseased leaves was observed to be from higher concentration levels after application. Therefore, the concentration 1 x 108 conidia ml-1 had the most CLR suppression and can be used within the Insect Pest Disease Management (IPDM) protocol for CLR control.
The findings of the study provide some important insights into the CLR disease management under the highlands, arid conditions of PNG.