Variables affecting linear gall growth in fusiform rust-infected loblolly and slash pines

Vertical length of fusiform rust galls in stem tissues of loblolly and slash pine is an indicator of the extent and severity of the host-parasite interaction. The objective of this study is to determine the effect of a number of observed variables on the length of galls in rust-infected seedlings and saplings both in the greenhouse and in field plantings. These variables were: pine family, growth of infected pine families, source of basidiospore inoculum in the greenhouse, and density of inoculum. Within a six-month period after inoculation, the majority of galls grew 5 to 9 mm in length in the greenhouse and 2 to 8 cm in field plantings. Frequency distribution graphs of greenhouse inoculated loblolly and slash are normal for gall lengths except for bimodal distributions for select pine families. Regression analysis indicated a significant relationship between length of galls and the variables of pine family and source of inoculum. Means for length of galls in greenhouse inoculations had low standard deviations.