Combinations of Fungicide and Cultural Practices Influence the Incidence and Impact of Fusiform Rust in Slash Pine Plantations

Abstract

Abstract Slash pine was grown in central Louisiana under four levels of culture with or without repeated sprayings of the systemic fungicide triadimefon for protection against fusiform rust. The eight treatment combinations were: (1) no fungicide, weed control or fertilizer; (2) weeded; (3) weeded, applied inorganic fertilizer, and bedded before planting; (4) weeded, bedded, and applied inorganic fertilizer in the sixth growing season (delayed fertilization); (5) applied fungicide but no weed control or fertilizer; (6) applied fungicide and weeded; (7) applied fungicide plus treatment 3; and (8) applied fungicide plus treatment 4. Fungicide applications greatly reduced fusiform rust impact in 10-yr-old slash pine stands. Fungicide treatments resulted in higher survival fewer trees with stem galls, fewer trees with galls encircling 76%-100% of the stem circumference, greater total volume/ac, and less volume/ac among infected trees. The fungicide-treated trees had fewer stem galls below 5 ft of tree height compared with untreated trees, indicating that the fungicide treatment protected planted seedlings through several growing seasons. Weed control increased fusiform rust incidence. The fungicide-treated plots receiving delayed fertilization yielded the most volume (3,018 ft3/ac) after 10 growing seasons because of high stocking and accelerated growth following fertilization. South. J. Appl. For. (2):53-59.