By Gared Shaffer, SDSU Weeds Field Specialist
Many emotions set in on farmers that hear the word “non-GMO”, but it could help them in times like today when prices are low for many farm products in South Dakota. As some may already know, non-GMO soybeans are being contracted in South Dakota at Miller by the South Dakota Soybean Processors. What could this mean for producers? It may mean a niche market for soybean producers to make a little more per acre when higher crop prices are needed. Some markets suggest that non-GMO soybeans can fetch a dollar or more a bushel than GMO soybeans. The big question that comes to mind with non-GMO soybeans is weed control. Is it possible to continue to farm No-Till and plant non-GMO crops with resistant weeds growing in your fields? The answer is yes with a little more homework, producers can control weeds and keep their soil healthy!
Non-GMO Weed Management
These management strategies are not uncommon even in GMO soybeans. The basics are the same. First we always need a weed-free start at planting. This means, do not plant unless the weeds prior to planting are controlled. To give you some time for a post application and to give your soybeans a head start, make sure to apply a PRE-herbicide before planting. Then apply if needed a POST application when weeds are less than four to six inches tall, which may be anytime between two to six weeks after soybean emergence. Refer to herbicide label before application for proper application methods and any restrictions.
Burndown Herbicide Options
This cannot be stressed enough with any crop, but you need to start with a clean field before planting. To do this use a burndown herbicide that controls a broad spectrum of weeds such as glyphosate, paraquat, or glufosinate before or at planting. Other herbicides that may add in weed control could include 2,4-D ester and a metribuzin product.
The biggest decision here is to choose herbicides that will give a window to control early weeds and give soybeans a head start. Examples of herbicide active ingredients to look into could include: Imazethapyr, sulfentrazone (non ALS Kochia), metribuzin, flumioxazin, pyroxasulfone, S-metolachlor, etc.
It is best that weeds be controlled from two to four inches tall but never allow them to reach over six inches. Also use a spray volume of at least 15 gpa for ground application and nozzles that produce medium-sized droplets.
- Fomesafen (East of 281) or lactofen or acifluorfen (areas west of 281), fluazifop+fenoxaprop, etc. + COC or MSO + AMS
- If applied with 28%, this may improve weed control but also increase crop injury.
- If necessary for late emerging weeds apply Lactofen (crop damage may occur) three weeks later if troublesome broadleaf weeds exist, add a grass herbicide if late emerging grasses are a problem.
Fall herbicide applications are not as long lasting or effective compared to those applied in the spring. Never substitute a fall treatment for a spring treatment. There are options for fall application but usually they end up costing more and then a spring application is almost always necessary. One combination that may be an option in the fall may be glyphosate + 2,4-D. Fall application is needed if a producer has biennial or winter annual weeds.
There are management options that increase cash crop yields and decrease weeds as well those include: crop rotation, cover crops, row spacing and livestock integration if proper soil structure has been obtained.
Disclaimer: The preceding is presented for informational purposes only. SDSU does not endorse the services, methods or products described herein, and makes no representations or warranties of any kind regarding them.