PARENT SESSION
Oral Session #45: Herbivory: Effects on Plants. Presiding: T. Craig.
Wednesday, August 8, 2001. 8:00 AM to 12:00 PM. Hall of Ideas H.
Induced response of fertilized and irrigated pines to wounding and inoculation.
Klepzig, Kier1, Fowler, Glenn2, Robison, Dan2, Allen, Lee2, Hain, Fred2, 1 2
ABSTRACT- Southern pine beetle can kill healthy pines and carries a fungus, Ophiostoma minus, which may hasten tree death. We investigated the responses of loblolly pine, grown under four management intensities, against mass wounding and inoculation. We addressed the simultaneous effects of fertilization and irrigation on constitutive and induced resin flow, and on secondary defenses against fungi. We worked at SETRES, a randomized complete block design site with four blocks (control, irrigation, irrigation + fertilization, fertilization). We selected two loblolly pines per plot and subjected each to wounding (400 wounds/m2); wounding+inoculation (wound-inoculated with O. minus at 400/m2); or control (unwounded and uninoculated). We measured 24 hour oleoresin flow 1-day before, and 1, 15 and 105 days after wounding and inoculation. We also removed the outer bark in the area of wounding/inoculation at 105 days post treatment to measure phloem necrosis. Pre-treatment resin flows did not differ significantly among silvicultural treatments. One day after treatment, resin flow was reduced in wounded and wounded + inoculated trees. Resin flows did not significantly differ at 15-days post treatment. At 105-days post treatment, wounded + inoculated trees produced significantly higher resin flows than control or wounded-only trees. This may indicate an induced response to fungal inoculation. Irrigated and irrigated + fertilized trees produced the highest observed resin flows. Future studies will define the nature of the induced response and its biological significance.
KEY WORDS: defense, induced resistance, herbivores, pathogens