Promising Resistance to Fusiform Rust from Southeastern Slash Pines
Two hundred twenty-four disease-free slash pines with good growth and form were tested for rust resistance. Trees in Alabama, Florida, Louisiana, and Mississippi were selected. After artificial inoculations, a low percentage of open-pollinated progeny of 32 selected trees had galls. In progeny from six of those, the number of gall-resistant trees increased from 50 to 75 percent after one round of crossing. Analysis of seedling height, gall length, formation of adventitious shoots, and pith necrosis suggests that the six families may differ in their response to infection, even though they form similar percentages of galls. This resistance appears to be stable in a variety of fungus field isolates.