Abstract
With a view to determining the effectiveness of organic insecticides upon the injurious insects of various fruit trees, a series of experiments has been carried out with results as given in the summary that follows:
1. DDT dust is effective for the persimmon fruit moth (Kakivoria flavofasciata NAGANO) as well as lead arsenate, without causing any trace of damage to the tree. DDT with bentonite or kaolin as the carrier is more effective than with other carriers.
2. DDT wettable spraying is able to control the infestation of growing peach shoots by the oriental peach moth (Grafolitha molesta BUSCK.) and of leavs by the leaf hopper (Erythria zonata MATSU.) while their population densities are small, resulting in increase of red spider mite.
3. The damage to pear by the oriental peach moth and to peach by the fruit moth (Dichocrocis punctiferalis GUEN.) are not well controlled by the sprayings of the various organic insecticides. such as DDT, BHC and Clordane though capable of being controlled by the paper bag painted with DDT emulsion.
4. DDT emulsion spraying indicates no toxicity to the larva of Ceroplastes rubens MASKELL, though capable of better controlling the overwintering adult by spraying with a mixture of machine oil and DDT emulsion than with the former only.
5. The mixture of BHC and pyrethrum emulsion acts as an evasive factor for the attachment of citrus leaf miner (Phyllocnistis citrella STAINTON) and it is used as a substitute for nicotine sulphate.
