Penetration of 1,2-dibromo-3-chloropropane in a Florida soil.
Gas-liquid chromatography was used to detect movement of the nematicide, 1,2-dibromo-3-chloropropane (DBCP), in soil columns containing top- and subsoil of Astatula fine sand. Topsoil contained 1.4-1.6% organic matter and subsoil 0.20-0.25%. DBCP was applied at various rates as aqueous drenches. Depth of penetration was controlled by organic matter in topsoil and varied with the amount of water applied. Maximum DBCP penetration after 14 days was 28 cm; maximum water infiltration, 115 cm. Maximum depth of penetration was obtained with a water emulsion of 30 mug/ml of DBCP applied in 15 cm of water. DBCP applied in 5 cm of water to soils containing 2.0% and 0.125% organic matter penetrated 6 cm and 60 cm, respectively.
Postplant Fumigation with DBCP for Citrus Nematode Control in Florida.
Eleven citrus groves of diverse varieties and ages infected with Tylenchulus semipenetrans growing in differing soils in Florida were treated with three rates of 1,2-dibromo-3-chloropropane (DBCP) applied by various means. Yield, fruit size, and T. semipenetrans populations in the roots were compared between DBCP-treated and untreated trees over a period of I-3 yr. Maximum fruit size and yield were obtained by applying DBCP at 38-58 kg/hectare (ha) (34-52 lb/acre); whereas best nematode control was with a rate of 77 kg/ha (69 lb/acre). Application of chemical emulsion with a special, drilled, low-profile sprinkler irrigation ground pipe was the most suitable method. Effect of DBCP treatment generally lasted for 3 yr. A mean annual I. 1% increase in fruit diameter, 15.2% increase in fruit yield and a 55.7% decrease incitrus nematode populations was found for D BC P-treated trees in contrast to untreated trees.
The relation of food quantity to rumination behavior.
Preliminary work suggested that the quantity of food ingested by retarded individuals who usually ruminated following meals was related to the frequency and duration of ruminating responses. This possible relation was experimentally examined by systematically varying food quantity from regular portions to satiation levels for three retarded individuals who exhibited high levels of ruminating. A clear functional relation of food quantity to ruminating emerged, with satiation procedures producing rapid and large decreases in the relatively high frequencies and durations of ruminating characteristic of baseline food quantity conditions.