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Wilt of Loblolly Pine Inoculated with Blue-Stain Fungi of the Genus Ceratocystis. H. G. Basham, Graduate Student, Department of Plant Pathology, North Carolina State University, Raleigh, Present address: Department of Plant Pathology, Cornell University, Ithaca, New York 14850. Phytopathology 60:750-754. Accepted for publication 6 October 1969. DOI: 10.1094/Phyto-60-750.

Isolates of Ceratocystis ips, C. minor, C. montia, and C. pilifera caused a deeply penetrating blue stain of the sapwood of loblolly pine (Pinus taeda) and killed the trees. C. olivacea, C. multiannulata, and C. coerulescens caused little blue stain and no mortality. This is the first evidence that blue-stain fungi are pathogenic to loblolly pine and that C. pilifera is pathogenic to any host. Seedlings were more susceptible than saplings in terms of per cent of trees killed and average time to death. Vigorous saplings (rated by crown class and stem diam) were more resistant than weaker saplings. Blue-stain fungi cause wilt by a blockage of the ascent of sap. Dye conduction in the stem of the host occurred only in tissues not colonized by the fungi. Moisture content of the sapwood of infected trees was reduced in and above the infected portion of the stem. A high percentage of the pits was aspirated in and above the region colonized by the fungi. Symptoms of seedlings killed by withholding water were indistinguishable from those of inoculated seedlings. Color reactions indicative of phenolic compounds were observed in the infected region of the stems of living inoculated or wounded trees, but not in trees killed by the fungi.