PRELIMINARY LABORATORY AND FIELD TRIALS OF CURB, A POSSIBLE AVIAN REPELLENT

Grape growers in California lose between three and four million dollars annually from damage caused principally by two bird species: Linnets (carpodacus mexicanus) and Starlings (sturnus vulgaris) (DeHaven, 1974; Crase, et al., 1975),. Few effective tools exist for the growers to use in reducing crop losses from bird damage; and current bio-political trends may preclude the use of toxicants to control local depredating bird populations, especially Linnets. The use of chemical repellents is a possible alternative. Testing of the chemical repellent methiocarb [3,5-dimethyl-4-(methylthio) phenol methylcarbamate] to protect California wine grapes has been conducted by Denver Wildlife Research Center personnel (Guarino, 1972; DeHaven, 1974; Crase, et al., 1975; and Crase & DeHaven, 1976). Results with methiocarb on grapes appear successful on a small scale. Other researchers (Stone & Toms, 1970) investigated a compound called CURB, aluminum am- monium sulfate, and obtained limited success when used on vegetable, cereal, and fruit crops including grapes. Leinati (1968) used CURB as a seed dressing to reduce seedling pulling by pheasants. Dar (1974) completed a series of trials at eight different Israeli agricultural stations, using CURB on seedling sugar beets, cucumbers, radishes, lettuce, celery, beans, kohlrabi, and strawberries. Data indicate that CURB provides good protection for plants with large leaf surface area, but results of trials to reduce seedling pulling by birds varied too much for valid conclusions. Trials on legumes raised for seed and sorghum were encouraging. Tests with CURB-treated wine grapes in Australia and South Africa have yielded inconclusive results about its effectiveness as an avian repellent. In Israel, specialists indicate that the metallic salts of CURB affect wine flavor (Stone, 1976). Although test results with CURB appear variable and inconclusive, General Vineyard Services in Salinas Valley, California, offered grape acreage for test plots to evaluate the potential of CURB as an avian repellent. This paper reports on preliminary cage and field trials