Depending on the specific geography, soybean emergence has either already taken place or soon will as soybean planting has begun to progress over the last week across much of the Hoegemeyer footprint. With some of the significant and frequent rain events along with the potential for some slightly cooler temperatures, it is possible that we may see some minor to moderate visual injury symptoms to fields that have certain pre-emerge herbicides such as the PPO inhibitors and photosynthetic inhibitors applied. Active ingredients for these herbicide groups include sulfrentrazone, saflufenacil, and metribuzin. Pre-emerge herbicides with these active ingredients have become quite popular due to the fact that they are generally quite effective at controlling troublesome small seeded broadleaf weeds that have become resistant to glyphosate (such as waterhemp and several others). Soybeans emerging under cool and wet conditions or when emergence directly coincides with a heavy rain event could be more vulnerable to injury. However, in the vast majority of cases, the visual symptoms which could include seedling stunting and cotyledon necrosis are short lived. The seedlings will typically resume normal growth once environmental conditions improve and the plant is better able to metabolize the herbicide.
ILeVO® fungicide soybean seed treatment (fluopyram) from Bayer Crop Science which was recently approved for commercialization in 2015 is very effective at protecting soybeans from both Sudden Death Syndrome (SDS) as well as Soybean Cyst Nematode (SCN). It is highly systemic into the root and crown of the seedling. Nearly 100% of all seedlings will exhibit minor to moderate visual injury symptoms on the cotyledons at emergence regardless of environmental conditions. Bayer calls this the “halo effect”. The most significant symptoms may take place in fields where ILeVO treated seed was used in conjunction with one of the pre-emerge herbicides listed above, especially under cool and wet conditions. However, once again the bark is often worse than the bite as research is showing that there is most often no impact on final stand or yield! Ironically, it is those cool and wet conditions that are also most favorable for SDS infection soon after planting.
So be aware, but not alarmed if you see what looks like some visual injury symptoms in a field of soybeans at emergence. There are multiple factors that could be playing a part. If you have any questions, be sure to contact your Hoegemeyer DSM or Agronomist.
Note: The vast majority of all Hoegemeyer soybean test plot seed was treated with Right Stand® + ILeVO® this year in order to give our products the best chance at fulfilling genetic potential.
Below are some links to resources including photos that may be useful in preparing for this potential situation.
ILeVO is a registered trademark of Bayer CropScience. Right Stand is a registered trademark of Hoegemeyer Hybrids.