檬果螟蛾(Chlumetia transversa Walket)爲害情形之觀察及其藥劑防除試驗

Abstract

1. The larvae of mango twig-borer (Chlumetia transversa Walker) bore into the twigs both of young shoots and inflorescences of mango trees and cause them wilting or unfruitfulness. The damage percentage of this pest reaches 19.93-23.52% per year and equals to a loss of NT$ 2,925,522.3-5, 321,599.7 in this island. 2. An observation on the conditions of damage caused by the mango twig-borer was carried out in July, 1965 to June, 1966 at the mango orchard of Fengshan Tropical Horticultural Experiment Station. According to the results of this observation, there are two outbreaks of this insect pest in a year round. One is in March when the mango tree shoots its inflorescences, and the other is in November when the mango tree shoots its new branches. And the damage caused by the pests of first outbreak is more serious than that of the second one. There is no significant difference of injury among the five varieties, as Keitt, Irwin, Haden, Kent and Zill of mango. 3. The control work consisted of spraying at branching period and blooming period, and studied at the mango orchard of Fengshan Tropical Horticultural Experiment Station and at Zen-mei village, Niau-song country, Kaohsiung district, respectively. In total of eight kinds of chemicals; Lebaycid e.c. 0.05%, Sumithion e. c. 0.05%, Sevin w. p. 0.1% & 0.05%, EPN e. c. 0.05%, Diazinen e. c. 0.05%, Dimecron s. 0.05% and Elsan e. c. 0.01% were tested. From the result we cleared that treatment at blooming period was more efficient than that of the same at branching period. The better three among eight chemicals were Sumithion e. c. 0.05%, Lebaycid e. c. 0.05% and Sevin w.p. 0.1%, which occupied the 1st to 3rd degrees respectively. 4. The first outbreak of mango twig borer appeared in March and the second one in November. The former coincide with the blooming period and the latter which was less seriously infected than the former, just agreed with the branching period of mango tree. It is suggested that a better time for control should begin in early January for the first outbreak, and in early October for the second outbreak. Though the competent time for spraying is depend upon the conditions of branching and blooming, it would be better to spray more than four times in order to secure an effective control.