Thursday, November 16, 2006 - 9:15 AM
312-5
Soybean Cyst Nematode Response to Purple Deadnettle, Annual Rygrass, and Soybean Mixtures.
Soybean cyst nematode (SCN) and winter annual weeds are an increasing problem in soybean fields in the Eastern Corn-Belt. SCN-susceptible soybean (Glycine max) and the winter annual weed purple deadnettle (Lamium purpureum) are hosts to SCN. SCN-resistant soybeans and annual ryegrass (Lolium multiflorum) are known to have adverse effects on SCN and reduce population density. The objective of this greenhouse experiment was to determine if combinations of these plant species influenced the SCN population density. This experiment contained a complete factorial treatment arrangement of four plants species, SCN-susceptible and resistant soybean, rye, and purple deadnettle. Each species was present at two levels, zero or one plant per pot. Two weeks after planting each pot was inoculated with 10,000 SCN eggs, fertilized weekly, and watered as needed. Eight weeks after the experiment was initiated, the above ground dry matter was recorded. Roots were collected to enumerate SCN cysts and eggs as well as root dry weight. The highest cyst and egg counts occurred on purple deadnettle roots growing with SCN-susceptible soybean and purple deadnettle alone. The lowest counts occurred with the combination of purple deadnettle, annual ryegrass, and SCN-resistant soybean. The root dry weights were highest in pots that had annual ryegrass and the lowest in the pot with purple deadnettle alone. Annual ryegrass was successful in reducing SCN population densities. In the pots that only had SCN-susceptible soybean or purple deadnettle the purple deadnettle had the highest SCN density per gram of root dry weight. The SCN egg density per gram of root dry weight for purple deadnettle was 169.8 eggs per gram of root and 42.4 eggs per gram of root for SCN-susceptible soybean.
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