缺水地區鳳梨粉介殼蟲防除改進試驗

Abstract

數種粒狀殺蟲劑（Granular insecticides)，如有機磷類之Disyston 5% G, Solvirex 5% G, Thimet 10% G,，及氨基甲酸鹽類之Sevin 5% G , Ortho-Bux 10% G,，撒施於鳳梨基部之葉基，防除鳳梨粉介殼蟲有優異之成效。惟有機磷之數種粒狀殺蟲劑較氨基甲酸鹽類者，有較快速之殺蟲效果。其施用量Disystion 5% G,，和Solvirex 5% G每公頃40公斤，Thimet 10% G 每公頃20公斤，於鳳梨種植食約1~2個月施用，每隔2~3個月施用一次，連續三次，即可達成完全防除粉介殼蟲之目。 Parathion 47% EC has been used for the control of pineapple mealybugs very satisfactorily by dipping the plant materials and following by three times filling with the same material in field with an intervals of three months. However, this successful measure was untenable for overall extension, because, during the dry seasons in Winter and Spring in central and suth Taiwan, water inaccessible on those upland plantations where pineapples are grown mostly. Meanwhile, mealybugs multiply rapidly in the dry and temperate seasons and so it is the proper time to control the pest. Although 3% parathion dust was used for controlling pineapple mealybugs in 1957, but the chemical was found very toxic to human beings, and up to now, there is no adequate instrument availabe for safe handling of the application. The purpose of this paper is to report the results of tests with some granular insecticides, such as (1) Disyston; (2) Sovirex; G; 5% 0-0 diethyl-S-2ethylthioethy1-phosphorodithioate. (3) Thimet, G, 10% 0,0-diethyl S-(ethylthio) methy1 phosphorodithioate. (4) Ortho-Bux G; 10% m-(1-methy1 butyl) phenyl methyl carbamate and m-(1-ethyl propyl) phenyl methyl carbamate. (5) Sevin, G;5% 1-naphthyl N-methylcarbamate., for control of mealybugs on pineapples, so as to improve the current application methods. The granular insecticides as mentioned above were evaluated in the laboratory for studying both effectiveness and mehods of application before they were put to the field experiment. Pineapples were planted in pots, and mealybugs were then inoculated to the pot pineapples. Granular insecticides were applied as soon as the mealybugs had established. As showing in Table 1 and 2, the results of the organo-phoshporous granular insecticides are better than that of the carbamate compounds in both contact and systemic actions. The function of the granular insecticides is that the contact treatments, as in general, are better than the systemic treatments since the soil was so dry that influenced the uptake of the active ingredient by the pineapple roots. The effectiveness is excellent in both contact and systemic treatments if 200 cc of water per plant was poured noto the position where the insecticides applied. After laboratory evaluation, the field experiment was then carried out in Fengshan, Ta-lin and Ting-hsin-tso where are somewhat the district representative of the pineapple plantation. Insecticides were principally applied to the base of leaves where mealybugs mostly infested. Three applications were made in November 1968, January and March 1969 respectively, dosage was at the rate of 0.5 g for 10% G while 1.0 g for 5% G of the chemicals per plant. Disyston, Solvirex and Thimet showed better effectiveness than that of Sevin and Ortho-Bux as examined the infestation of mealybug two months after the first application, but there was almost not different effectives in controlling the mealybugs among the insecticides two months after the third application. Different degree of Phytotoxicity was observed in the central leaves as the granulates occasionally dropped on, but there was no evidence of bad result of pineapple growing in the serious phytotoxicities as observed latterly. Some of the granulars, such as Disyston, still remained a certain amount in the base of the leaves as observed two months after application. For economic sake, the intervals of application could be extended to as long as three months. From the results of trial, granular insecticides are promisingly to be used in controlling the mealybugs on the upland areas instead of parathion emulsion A suitable applicator must also be designed for the purpose of safe and precise of applying the granular insecticides.