HEAT TREATMENT OF PINEAPPLE: SUBSEQUENT GROWTH AND OCCURRENCE OF MEALYBUG WILT OF PINEAPPLE
Mealybug wilt of pineapple (MWP), a plant disorder associated with populations of mealybugs feeding on pineapple plants, presents a serious threat to commercial pineapple production wherever mealybugs occur as pests. Recently, a pineapple closterovirus (PC) was found widely distributed in commercial pineapple in the Hawaiian islands and proposed as a potential cause of MWP. Following heat treatment of pineapple crowns, PC could no longer be detected and growth was more rapid than that observed in non-heat treated plants. Planting of heat treated, putatively PC-free pineapple in a commercial plant crop with severe MWP showed that heat treated plants were not readily colonized with mealybugs, nor did they show symptoms of MWP, even after more than 2 years adjacent to commercial plants with high mealybug populations and severe MWP symptoms. Following the harvest of the second ratoon crop, these plants were dissected and found to have varying numbers of the mealybug, Dysmiococcus brevipes, on the roots and at the base of leaves. The ant, Pheidole megacephala was present throughout the area and observed on leaves with mealybugs. Other pest species found among the heat treated plants were nematodes of various types (spiral, root knot and pin) and the fungus, Phytophthora sp. Plants have not yet been tested for presence of PC. While we are unable to draw any conclusions from this work on the etiology of MWP, our findings in this and previous experiments suggest that heat treatment of pineapple warrants further investigation as a means for improving pineapple growth and possibly protecting pineapple from MWP.
Ullman, D.E., Williams, D.F., Fleisch, H., Hu, J.S., Sether, D. and Gonsalves, A. (1993). HEAT TREATMENT OF PINEAPPLE: SUBSEQUENT GROWTH AND OCCURRENCE OF MEALYBUG WILT OF PINEAPPLE. Acta Hortic. 334, 407-410