Soybean resistance to field populations of Heterodera glycines in selected geographic areas.

Data were collected 2006 through 2008 from 527 soil samples to determine the current effectiveness of PI 88788 and other sources of Heterodera glycines resistance in three geographically separated areas of soybean production: Tennessee and Indiana/Illinois, USA, and Ontario, Canada. In Tennessee where PI 88788 source of resistance has been used since 1978, 93% of field populations reproduced on PI 88788 (≥10% of susceptible cultivar), and no HG Type 0 populations were found. In Indiana and Illinois, where resistance was used since the mid-1980s, from 56 to 88% of the populations reproduced on PI 88788 (≥10%). PI 548402 (Peking), PI 90763, and PI 437654 had low reproduction (≤10%) unlike Tennessee where 78% of the populations reproduced on PI 548402 (≥10%) and 93% reproduced on PI 90763 (≥10%). In Ontario, where cultivars with PI 88788 resistance were used after 1989, PI 88788 in 73% of the field populations had ≤10% reproduction. But 15% of Ontario populations reproduced on PI 548402 (≥10%) and 6% reproduced on PI 90763 (≥10%), two sources of resistance not generally present in commercial cultivars grown in Ontario.