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Poster: Biology & Disease Mgmt: Biological Control


In-vitro control of Calonectria pseudonaviculata by bacteria recovered from irrigation water
X. YANG (1), C. Hong (2) (1) Hampton Roads Agricultural Research and Extension Center, Virginia Tech, U.S.A.; (2) Hampton Roads Agricultural Research and Extension Center, Virginia Tech, U.S.A.

Calonectria pseudonaviculata (Cps) is the causal agent of boxwood blight. This disease first observed in USA in 2011 has significantly impacted the nursery and landscape industries. The objective of this study was to develop biologically-based, long-term solutions to managing this emerging disease at production facilities and in the landscapes. Over 1000 bacterial strains recovered from irrigation water in Virginia, USA were screened for their potential as biological control agents against microsclerotia of Cps. Microsclerotia were harvested from potato dextrose agar cultures and plated on nutrient agar in 48-well plates. Two days later, fresh bacterial cultures grown in nutrient broth were added to the culture of Cps. Three replicate wells per bacterial strain were used. Sterile nutrient broth was added to three wells per plate as controls. Microsclerotia germination and resultant mycelial growth was measured based on a 0-to-5 rating scale at five and ten days after adding bacterial cultures. It was found that approximately 30% of screened bacterial strains greatly suppressed microsclerotial germination and mycelial growth with average ratings of one or less. These bacteria are promising biological control agents (BCAs) for boxwood blight and warrant further evaluation using detached leaf assay, greenhouse and field in-vivo tests.