Variation in virulence among four root-inhabiting Ophiostomatoid fungi on Pinus taeda L., P. palustris Mill, and P. elliottii Engelm. seedlings

Abstract

Ophiostomatoid fungi have been implicated in root disease of pines in the southeastern United States. To understand more about their virulence, inoculation studies were conducted on loblolly (Pinus taeda), longleaf (Pinus palustris), and slash pine (Pinus elliotii). One-year-old bareroot seedlings, after being planted and established for 11 weeks, were wound-inoculated with one of four prominent North American ophiostomatoid fungal species. After three months, a darkened lesion, extending from the point of inoculation was observed for all species. Grosmannia huntii (L. huntii) caused the greatest lesion and occlusion length in loblolly pine and slash pine. Leptographium procerum and L. terebrantis caused similar lesion and occlusion lengths and were the least virulent among the fungi tested. These studies indicate clear virulence differences among the four North American fungi. Grosmannia huntii, previously not known to be pathogenic, was observed causing significant damage compared with other well-known Leptographium species. Finally, lesion and tissue occlusion lengths were significantly smaller in longleaf pine for all fungal species when compared to loblolly and slash pine.