CHARACTERIZATION OF THE INDUCED RESPONSE OF SLASH PINE TO INOCULATIONWITH BARK BEETLE VECTORED FUNGI

Six 25- to 30-year-old slash pine, Pinus elliottii Englm. var. elliott ii, trees were inoculated with Ophiostoma minus (Hedge.) H.P. Sydow, O , ips (Rumb.) Nannf or sterile water. Two, 4 and 6 weeks after inocula tion, the lengths of developing lesions and the monoterpene concentrat ion of the necrotic tissue within each lesion were measured. Both ster ile and fungal wounding resulted in the development of lesions in the phloem-outer xylem. At both 4 and 6 weeks after inoculation, lesions i nduced by O. minus were significantly larger than lesions induced by O . ips or sterile water, whereas the lesions induced by O. ips and ster ile water were similar in size at all sampling periods. At 2, 4 and 6 weeks after inoculation, lesions induced by O. minus had significantly greater concentrations of monoterpenes than lesions induced by O. ips or sterile water. The monoterpene concentration of lesions induced by O. ips was significantly greater than that of lesions induced by ster ile water only at the 6-week sampling period. Visual examination of th e lesions indicated that O. minus but not O. ips was inhibiting the de velopment of callus tissue, suggesting that the strain of O. ips was e ither nonpathogenic or avirulent.