How to Choose a Safe and Effective Orchid Insecticide

Derris is a perennial vine of the Fabaceae family, growing in South China and the Fujian and Taiwan regions of China; cultivated varieties include hairy derris (a trailing type) and Malayan derris (an upright type). The active ingredient is rotenone, a pure white crystalline substance that is odorless and tasteless, insoluble in water, and readily soluble in solvents such as benzene, acetone, and ether. The liquid formulation is brown or brownish. It readily decomposes and loses effectiveness under the influence of sunlight, air, high temperatures, and alkaline substances. Derris has contact and stomach-poison action, as well as a certain repellent effect; it also has a regulating and growth-stimulating effect on plants. It has a broad insecticidal range, leaves no residue, is safe for plants, and has low toxicity to humans and livestock; however, it is highly toxic to fish. Formulations: 2.5% and 5% derris extract emulsion, 4% derris powder. Targets and methods of use: dilute the 2.5% emulsion with water at 5OO to 8OO times and spray to control leafhoppers, aphids, red spider mites, and others. Precautions: 1. Do not mix with alkaline substances. 2. Diluted liquid should be used as soon as it is prepared and must not be stored. 3. Store the pesticide in a cool, dark place to prevent decomposition and loss of effectiveness. (Liu Zhongjian)