Agronomic tip of the week
Are Iowa’s SDS problems in 2009 a reflection of a growing SCN problem?
By Greg Tylka, ISU nematologist
The widespread reports of soybean sudden death syndrome (SDS) occurring throughout most of Iowa in 2009 are alarming. But did you know that soybean cyst nematode (SCN) can cause SDS symptoms to occur earlier in the season and become more severe, leading to greater yield loss?
One has to wonder whether all of the SDS occurring in the state this year isn’t also an ominous reflection of Iowa’s SCN situation. The fact that SCN can make SDS much worse is yet another reason it is critically important for Iowa soybean growers to check fields for SCN.
Fall is an ideal time for soil samples to be collected from Iowa fields and tested for SCN. Fields in which corn or soybeans had been grown in 2009 can be sampled for SCN. Results of testing will indicate if fields are infested with SCN. And for known infested fields where SCN-resistant varieties have been grown in the past, soil sample results can reveal if SCN population densities (numbers) are being kept in check or if the SCN numbers are building up despite use of resistant soybean varieties.
SCN soil samples should consist of 15 to 20 soil cores, 8 inches deep, collected in a zigzag pattern, ideally from an area no greater than 20 acres. Large fields may require several separate samples be collected. The Iowa State University (ISU) Plant and Insect Diagnostic Clinic processes soil samples for SCN, as do several private soil testing laboratories in the state. Samples for the ISU clinic should be sent to ISU Plant and Insect Diagnostic Clinic, 327 Bessey Hall, Iowa State University, Ames, IA 50011. The cost is $15 per sample.
Get a head start on higher soybean yields for 2010 and beyond by having fields sampled for SCN this fall.
