Abstract
The association of Heterobasidion annosum with reduced radial growth was observed in loblolly pine (Pinus taeda) infested with southern pine beetle (SPB) (Dendroctonus frontalis). Plots with SPB and controls were established in thinned plantations and natural stands of loblolly pine. Only sites infested with SPB for less than 8 wk were selected for experimental evaluation. A control plot was established 20 m from each SPB plot. Trees infested with SPB produced an average of 6% less radial growth over the last 1-5 yr in the loblolly pine plantations as compared to the noninfested control plots (P = 0.05). Mean H. annosum colonization of excavated root systems in SPB and control plots in plantations were 23.1 and 10.9% (P = 0.05), respectively. Within the plots infested with SPB located in plantations, the SPB-infested trees produced 28% less radial growth for the last 1-5 yr, respectively, as compared to the noninfested trees (P = 0.01). Mean H. annosum colonization of excavated root systems in SPB-infested and noninfested trees in ht eSPB plots were 54 and 11% (P = 0.0001), respectively. It was concluded that loblolly pines preferred by SPB were being stressed by H. annosum prior to SPB attack and that this stress was being expressed through reduced radial growth.
Keywords
annosum root rot, Fomes annosus, radial growth, bark beetle, predisposition