Further Experiments on the Control of Pineapple Guminosis in Puerto Rico

Abstract

Gummosis, gumming, or gum disease of pineapples is provoked by the feeding of the larva of an undescribed species of the genus Batrachedra and continues to be a problem of importance in pineapple production with the leading variety of Puerto Rico, the Red Spanish. It is of greatest importance in the fresh-fruit market where, it may cause 50-percent losses. An unestimated loss is also sustained by the canning industry. Previous work on the biology of the causal insect had demonstrated an interrelation between egg deposition by the female Batrachedra and blossoming of the young pineapple fruit. Two chemical-control experiments conducted during the 1956 and 1957 seasons are presented in detail in this paper. Results demonstrated that gummosis can be effectively reduced by spraying only at blossoming time. Previous experiments reported by the author had shown control, but most of the sprays were applied after blossoming spaced at 2- to 3-week intervals. In general two spray applications were necessary to effect control, although some of the individual insecticide comparisons between one and two applications showed no significant differences. A higher gum index was found on fruits harvested from the sunny side than from the shaded side of the bank. Under these high-gum conditions two spray applications were superior to one. Residue data from whole-fruit analysis, or from peel and pulp analyzed separately, are given. One or two spray applications of Toxaphene or Heptachlor and one of Chlordane left residues which are below the established tolerances. Endrin showed residues above zero. Data from Rhothane were not available when this manuscript was written No analysis could be made of Parathion- or Malathion-treated fruits.