Evaluating Metarhizium brunneum F52 microsclerotia in hydromulch formulations using different tackifiers under forest and orchard conditions

Microsclerotia of the entomopathogenic fungus (Metarhizium brunneum Petch strain F52; Hypocreales: Clavicipitaceae) were sprayed in a hydromulch formulation onto wood samples to test persistence and biological control efficacy when exposed on forest and orchard trees. The density of viable conidia and retention of hydromulch were not significantly affected by the tackifier in the formulation (psyllium, xanthan, or a mixture of both). Forest samples had a maximum conidial density and more viable conidia (7.2 × 10⁵ conidia cm^?2) than orchard samples (1.4 × 10⁵ conidia cm^?2). Increased rainfall, temperature and the time that samples were outdoors were critical factors for conidial density. Asian longhorned beetles [Anoplophora glabripennis (Motschulsky); Coleoptera: Cerambycidae] exposed to orchard samples in laboratory bioassays did not have significantly less mortality compared to forest samples, indicating that hydromulch may be feasible in open sunny conditions, if sufficient moisture is present.