Influence of Winter Annual Cover Crops on Soybean Cyst Nematode Populations.

Cash cover crops are those that provide additional economic returns to prevailing cropping systems, such as the Midwestern corn-soybean rotation. Economic return is vital for adoption of these cover crops. Systems including the winter oilseeds pennycress (Thlaspi arvense) and camelina (Camelina sativa) are already under development. Seed oils can be processed for profit in food, bioproduct, and fuel markets. Previous studies showed that pennycress is a host of soybean cyst nematode (SCN, Heterodera glycines), a major pest of soybean, while no reproduction of SCN on camelina has been reported. The impact of the two new crops as winter cover crops on the SCN population in the field is unknown.  A greenhouse experiment initiated in 2016 at the University of Minnesota was conducted to assess the host susceptibility of pennycress and camelina to SCN. The experiment was established in a factorial arrangement with a randomized complete block design including seven crop treatments and seven SCN HG Type and inoculation density combinations. The crop treatments were three lines of pennycress and three lines of camelina from the UMN breeding program, and a SCN-susceptible soybean cultivar. The HG Types of three SCN populations selected were HG Type 2.5.7 (race 1), HG Type 0 (race 3), and HG Type 1.3.6 (race 14), which represent the most important HG Types in Minnesota soybean production. Three SCN inoculation levels were: 0, 2000, and 20000 eggs/100 cm³ of soil that represent none, moderate, and high SCN population densities.  Preliminary results from this experiment indicate that pennycress is a host of SCN, while camelina is a weak,or non-host. The HG Types of SCN in this experiment exhibited reproduction on the three lines of pennycress, while no reproduction was exhibited on the three lines of camelina.