Dry weather this year has stressed the crops enough in many areas. This additional stress has made many underlying issues visible that were normally masked with good growing conditions. Elevated populations of soybeans cyst nematode (SCN) are being found in areas of stunted and yellow soybeans. Especially in light textured soils with a history of frequent soybean crops. Other species of nematodes are impacting corn.
The best time to sample for SCN is in the fall just prior to harvest to determine max population levels in whole field sampling. Diagnostic sampling for SCN focuses samples to be collected in a smaller area where the soybeans are affected during the growing season. This earlier testing may not indicate maximum seasonal population but can identify the location and relative severity of SCN infestations. Collect a minimum of eight 0-8” deep cores near the affected soybean rows to make a composite sample. It is best to collect another sample just outside the impacted area, near the soybean rows, to determine if the injury is due to an isolated population in the field.
When collecting and shipping nematode samples to the laboratory, do so quickly and avoid exposing the samples to extreme temperatures. Overnight shipping is not required. Nematode samples sent to ALGL should request the NCYST test package that will return SCN adult and cyst numbers, along with interpretations of potential percent of yield reduction. For other crops, request the N3 package which is an adult only count of a wide variety of nematodes that impact other crops. This test will also yield an interpretation of crops that maybe impacted by the species of nematodes present.
Not All Nematodes Are the Same - Corn Nematodes