Responses of conifer species of the Great Lakes region of North America to inoculation with the pitch canker pathogen Fusarium circinatum

Abstract

SummaryFive conifer species grown in the Great Lakes region of North America were examined for their susceptibility to Fusarium circinatum, (syns. Fusarium subglutinans f. sp. pini and F. moniliforme var. subglutinans), the causal agent of pitch canker. Three‐year‐old (3‐0) seedlings of red (Pinus resinosa), jack (P. banksiana) eastern white (P. strobus), Scots (P. sylvestris) and Austrian (P. nigra) pine were planted in 4 l pots in a greenhouse at Auburn University in November 1998. In April and June 1999, seedlings were inoculated by removing a needle fascicle approximately 5 cm from the terminal bud and placing a drop containing F. circinatum conidia on the wound. Resin production, canker length and seedling mortality were recorded 12 weeks later. Jack, Scots and eastern white pine were the most susceptible with Austrian and red pine more resistant to the fungus. F. circinatum was re‐isolated from 37% to 96% of inoculated seedlings. The susceptibility of jack, Scots and eastern white pine indicates a potential risk to these important species of the region if F. circinatum were to be introduced into the area.