Growers, or the agronomist they work with, should have a plan to scout fields each month of the summer. This includes walking a field and stopping at multiple locations to look for symptoms. Of course with today’s UAV technology it is easier than ever to identify problem spots for the air and then you can walk right to that spot. However not on symptoms will be readily viewable from the air at a few hundred feet.
When walking a field look for damaged leaves, insect infestations, weeds, nutrient deficiencies and other growth issues.
- Take stand counts in the field and determine of problems were related to the planted or soil and weather conditions.
- Scout for weed outbreak and species. If you plant soybeans with the Roundup Ready trait will the glyphosate alone control all the species that are emerging? Do your homework and decide whether to tank mix in a post-herbicide that control tough weeds like waterhemp, Palmer amaranth, or ragweed. And spray early before weeds exceed 2 inches. Consider adding manganese to your glyphosate application as glyphosate can tie up manganese in the plant.
- Scout for discoloration or deformities or seedling damage.
- Consider pulling tissue samples at V3 or V4 to see if nutrient levels are sufficient or deficient. Consult with a laboratory on how to sample and submit samples. They will analyze and interpret the results report then as deficient, sufficient or excess.
- When plants get 6 to 8 inches tall and reach V2 or V3, look for the presence of nodules. Nodules will be found on in the top 8 inches of soil where air is more prevalent.
If leaves are discolored it could be due to lack of nitrogen deficiency or another nutrient deficiency, poor root growth due to compaction or water logging, or high soil pH.
If leaves are puckered or have a burned look it is probably due to herbicide damage, either pre or post. If you applied a residual PPO herbicide this spring, they may have been some slight damage since the cool weather slowed down plant growth and reduced the plants ability to metabolize the herbicide. Of course any puckering or dropping could be due to wilting as well.
If leaves are shredded leaves or planted partially eaten or gone, the damage could have been due to wind, sand blasting, hail plants, insects or wildlife. As an agronomist I have always believed that soybeans could lose 25% of its leaves and yield wouldn’t be impacted.
Fortunately little setbacks in June doesn’t put yield at risk if the plant are there since soybeans can easily compensate later for setbacks early on.
Agronomist Dr. Daniel Davidson posts blogs on agronomy-related topics. Feel free to contact him at firstname.lastname@example.org or leave a comment below.