Progress in the Fight Against Soybean Cyst Nematode

For years, much has been written and stated about how soybean cyst nematode (SCN) is becoming more invasive of varieties whose resistance mechanism was derived from the PI 88788 source. It is estimated that greater than 95% of current soybean varieties that are touted as resistant to SCN have that resistance derived from this one PI. This issue is addressed in detail in a White Paper with linked resources on this website.

Now, there is hope on the horizon that a solution to this increasing problem is forthcoming. Information contained in a recent article from the SCN Coalition provides details about a long-term effort that has resulted in a small but significant accomplishment that addresses this problem. The major points in that article follow.

•   A new soybean variety with resistance to SCN derived from PI 89772 is being released by Syngenta in small quantities for 2020.

•   This represents an SCN-resistant variety that was developed from a breeding line other than PI 88788 and Peking.

•   The trait originated in soybean germplasm from USDA that was collected in China 90 years ago.

•   After nearly 25 years of work, the variety is being released under two brand names: Golden Harvest GH2329X and NK Brand S23-G5X. Both are MG 2.3 varieties.

•   According to Syngenta, the variety has good tolerance to SDS and Phytophthora, and contains the RR2X herbicide technology trait.

•   Research has shown that this variety, when grown in the presence of an SCN population that is highly virulent on PI 88788, resulted in a significant drop in that SCN population.

•   This new resistance trait was initially bred into conventional soybean lines before transitioning to the RR2X trait.

Of course, this is a real positive for the soybean industry. However, for it to be useable by Midsouth soybean producers, it must be bred into later MG varieties that have all available herbicide tolerant traits. Hopefully, that transition will occur in the near future since there is an ongoing and effective collaborative effort among the SCN coalition’s university and industry partners.

Composed by Larry G. Heatherly, Apr. 2020, larryheatherly@bellsouth.net