Population Densities of Rotylenchulus Reniformis in Soybeans by Maturity Group and Variety Testing in Association with Dynamics of Population Development

The reniform nematode (Rotylenchulus reniformis) has long time been established as one of the South's most economically damaging pests. Current trends in the increased production of soybean acreage have brought about an increase in population numbers due to crop rotations of multiple reniform susceptible crops. Rotation among non-hosts crops such as corn, sorghum, and peanuts have been used in management of this pest. However, as crop prices fluctuate and fertilizer and chemical prices rise we look for ways to maximize profit margins. In an effort to assist producers in recommending management strategies it is essential to know at what point the population of R. reniformis thrives and eventually locate a threshold of economic and production significance. Tests were conducted in the greenhouse using six varieties from maturity groups IV through VIII with five treatments ranging from 0-10,000 vermiform stage nematodes per 500cc of soil. The test was repeated two times with each having five replications. After 60 days of growth the pots were taken up from the greenhouse and measurements and weights were recorded for each maturity group. Measurements included; shoot height, shoot fresh weigh, shoot dry weight, root fresh weight, root dry weight, and nematodes numbers extracted from 500cc of soil, and root system. These nematodes numbers were reported in nematodes per gram of root. A reproductive factor was also assigned to each plot number to analyze the population increase per pot. The reproductive factors between treatments of the lower inoculation levels of 500 and 1000 vermiform were statistically greater. Furthermore, no statistical differences were evident in shoot and root growth among any of the treatments.