Bio-efficacy of Leeaniculliun lecanii local isdate against coffee rust (Hemileia vastatrix)
2019
Tad-awan, B.S. | Balanban, O.D. | Basalong, A.A.
Leaf rust due by Hemileia vastatrix is the most severe coffee disease resulting in premature flower and fruit fail. Efforts to manage the pathogen, an obligate parasite, usually involves use of systemic fungicides but putting premium on coffee as organic gourmet crop, the use of biological control agents would be more appropriate. A local isolate of Lecanicillium lecanii, previously observed parasitizing uredospores of Hemileia vastatrix, was tested for efficacy. Various spore concentrations of L. lecanii were inoculated one day before, simultaneously and one day after inoculating Hemileia vastatrix on detached coffee leaves. The number of lesions and percent infected leaf area were assessed after 21 days of incubation at 23 +- 3 deg C. The spore size of the isolate of L. lecanii ranged from 1.88 to 3.75 mum and was thus classified as group one strain. Application of conidia of L. lecanii reduced the number of rust lesions and infected leaf area. Increasing application starting from 1,400,000 conidia/ml totally controlled rust. Application of L. lecanii suspensions 24 hr before introducing Hemileia vastatrix uredospore suspension markedly reduced rust lesions and infected leaf area. L. lecanii totally prevented rust lesions when introduced starting at 1,400,000 conidia ml/1 24 hr before uredospores of Hemileia vastatrix was introduced. Field tests need to be conducted to verify efficacy and effectiveness of the fungus against coffee rust. DNA barcoding of the local isolate of L. lecanii need to be performed to establish its identify as an indigenous biological control agent against coffee rust in the Philippines.
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