Control of the Strawberry Rootworm in Commercial Rosehouses

Abstract

The results of three years' study of the seasonal and life histories of the strawberry rootworm (Paria canella Fab.) under greenhouse conditions, are briefly reviewed as a basis in formulating an effective control program. Due to the long period of egg-laying the maximum numbers of beetle are present in June and July. The second brood emerges during September and October. The practice of replacing plants and soil at intervals of several years aids materially in ridding a house of these insects. Various control measures which have been tested in different localities on a commercial scale are discussed. A series of fumigations with hydrocyanic-acid gas during the drying-off period, using 2 ounces of sodium cyanid per 1,000 cubic feet of space with an exposure lasting 2 hours, killed m per cent of the beetles. (Muslin curtains proved effective in confining the gas in separate sections of open-range houses). In one establishment as many as 60,000 beetles were collected in a week by persistent handpicking. Keeping the foliage dusted with a mixture of 10 or 15 pounds of lead arsenate and 90 or 85 pounds of superfine sulphur from February to November, protected the plants and killed many beetles. Scraping a layer of soil 2 inches deep from the beds after the plants were cut-back at the end of the drying-off period removed many beetles. The cut-back plants were then sprayed with arsenate of lead at the rate of 4 pounds to 50 gallons of water to protect the breaking eyes. Filming the surface of the water, which remains on the beds after syringing, with kerosene-nicotine oleate killed many beetles. A layer of wood ashes and tobacco dust on the beds operated to some extent against the larvae and pupae in the soil. Composting soil for several months or sterilizing before it is used in beds aids in keeping a greenhouse free from infestation.