Interveinal chlorosis (yellowing between leaf veins) and leaf necrosis (tissue death) of soybean foliage, exacerbated by the presence of Soybean Cyst Nematode in the same field, has been reported to cause significant yield losses in soybeans globally. Similar infections, in conjunction with SCN, were identified on a soybean variety at Langdon Research Extension Center (LREC). Most of the samples were confirmed to be Brown Stem Rot (BSR) infections through molecular analysis. The symptoms of interveinal chlorosis and tissue death led to a decline in crop growth, and a significant reduction in yield was recorded at LREC over the past two seasons. Soil samples collected from the infected field tested positive for the presence of Soybean Cyst Nematode (SCN), and BSR (Phialophora gregata) was identified as one of the major pathogens causing interveinal chlorosis and tissue death in soybean. Among the seed treatments tested this summer, the seed treatment Trunemco™ (Bacillus amyloliquefaciens + CIS-Jasmone) showed the lowest normalized disease index (NDI) and the highest yield compared to six other seed treatments and a non-treated check. The continuation of this research for two more years holds the promise of adding a management option to combat the interveinal chlorosis caused by the combination of BSR and SCN.

The current objectives were to evaluate various seed treatments to manage the interveinal chlorosis associated with Soybean Cyst Nematode and identify the pathogens responsible for the disease-causing interveinal chlorosis and tissue death besides BSR.

Correct identification of the disease and its causing pathogen will help in designing preventative measures to manage the disease. Evaluation of seed treatments will help in identifying the best management option before the situation gets out of hand for the grower. The results can be delivered to the growers and other stakeholders by initiating outreach activities throughout the state of North Dakota.

This research underscores the urgency for soybean farmers to identify and manage the disease-causing interveinal chlorosis in soybeans and the soybean cyst nematode. The seed treatments, which have shown compelling results this year, can be a proactive measure to manage these diseases with similar efficacy in the future. This sense of urgency can motivate farmers to manage the diseases before the pathogens can cause severe losses of soybeans.