FACTORS AFFECTING THE INCIDENCE OF BLACK SEED ROT IN SLASH PINE

Black seed rot of slash pine (Pinus elliottii Engelm. var. elliottii) caused by Lasiodiplodia theobromae (Pat.) Griff. & Maubl. was found to be a postharvest disease favored by premature cone harvests in conjun ction with certain cone collection practices. The incidence of fungus- damaged seeds was greatest in cones collected on the earliest collecti on date and left in contact with the ground before storage. The incide nce of disease decreased with later collection dates. Fungus-damaged s eeds were not present in cones dried immediately after collection, reg ard less of the collection date. Fungi were rarely established in seed s at the time that cones were removed from trees; they apparently colo nized seeds and caused disease during cone harvest and storage. Based on cone specific gravity and results of seed germination tests, cones and seeds were not mature on the earliest collection date. Lasiodiplod ia theobromae was associated with a majority of seeds that were fungus -damaged. Sphaeropsis sapinea (Fr.) Dyke and Sutton and a Fusicoccum s p. also were recovered from seeds; however, their relative importance in slash pine seed disease was minor.