This project was initiated preceding the incorporation and standardization of KPIs. The progress of objectives are as follows:
Achieving the objectives:
• Over 1000 soil samples were tested from soybean production fields in 11 Southern states. Reniform nematode was the most prevalent species. Other plant parasitic nematodes found were; cyst, root-knot, lesion, lance, ring, stunt, spiral, dagger and stubby root. Across all the states, 73-100% of the fields were infested with one or more nematode species. As a result of this survey, two AL counties in AL and 4 in GA were found for the first time to have R. reniformis. New Meloidogyne infestations were identified in two AL counties, one in AR, one in GA, two in MS, four in SC, and one in TN. Heterodera glycines distribution was unchanged from published distribution maps.
• Greenhouse data comparing the reaction of root-knot to soybean lines with known resistance to commercially available varieties was completed. Gall index value data on the standard Meloidogyne incognita (root-knot) resistant and susceptible soybean lines was consistent, as was the reaction on Hornbeck 5226 and 5421.
• The multi-year field study of resistant and non-resistant lines with and without nematicide revealed that the resistant lines contribute to lessoning soil nematode numbers, it is important for growers to pay attention not just to the soybean lines they are planting, but also to understand the nematode species and numbers in their fields and the impact of other host crops that may be grown in rotation.
• The result of greenhouse experiments to develop a damage threshold for R. reniformis was that shoot fresh weight decreases when R. reniformis levels are above 5000 eggs/cm3.
• Soil texture analysis suggests that soil type did not dictate which nematode was present but played a role in the population level of the nematodes. Heterodera glycines and Meloidogyne species often occurred together in the same field; however, R. reniformis often did not occur with H. glycines or Meloidogyne species.
• A draft of the extension publication on management of these three economically important nematodes in southern soybean production fields has been initiated.
Not Achieving the Objectives:
• Some microplots and field tests had to be abandoned due to environmental conditions. This is a common occurrence in field work and is why experiments are planned for multi-state and multiple years. Useful data was obtained from the experiments that were able to be completed.
• The researchers were also unable to establish a damage threshold for Meloidogyne. The results were inconsistent. The researchers now believe that the reason may be that there were different species of Meloidogyne present, each with differing ability to infect soybean.