Contro of Tylenchorhynchus clarus on soybean with systemic nematicides

Abstract

In Egypt, soybean Glycine max L. crops often are infested with Tylenchorhynchus clarus Allen and therefore trials were undertaken on chemical control, evaluating the efficacy of four granular systemic nematic ides applied at two rates. A clay loamy field, heavily infested with T. clarus, was selected in the NRC Agricultural Experimental Station, near Cairo. The experimental area was arranged as a randomized block, with 9 treatments replicated 4 times in plots measuring 18 me. The nematicides were applied at the rates shown in Table 1. The granules were incorporated in the soil covering the seed drills at sowing; foliar sprays of oxamyl in water emulsion (500 I water/ha) were applied one month after emergence of the seedlings. All plots were irrigated immediately after the soybeans were sown. Soil samples were taken for nematode counts every two weeks throughout the period of the experiment. At the end of the experiment, the yield of beans per treatment was weighed and recorded and the percentage of proteins, lipids, and ash in a composite sample from the beans in each plot were estimated according to the methods of A.O.A.C. (1975). The data were statistically analysed by Duncan's multiple range test. The highest yield of soybeans was obtained in the plots receiving the higher rate of aldicarb but all other treatments, with the exception of the lower rate of fensulfothion, gave greater yields than the untreated control (Tab. I). The percentage total protein was greatest in the aldicarb treatment which gave the highest yield of soybeans (Tab. I). Conversely, the least productive treatments had the greatest percentage lipids. There was no significant effect of the nematicidal treatments on the ash content. All treatments decreased the populations of T. clarus which remained at relatively low levels for up to six weeks in plots treated with aldicarb or ox amyl granules (Tab. II).