These areas should be sprayed with Roundup Ultra or Touchdown to control the weeds. Since many of these areas have lots of large grasses in them, Gramoxone Extra is not a good choice. For best results, apply Roundup Ultra or Touchdown alone rather than as a tank-mixture, but this may require an additional application. Due to the size of some of the weeds an in-crop treatment maybe necessary, particularly if the combine header cut off a large portion of the weed. The way the soybeans look right after application is often not a good indicator of yield loss.
Many factors go into determining the yield, with moisture at flowering being the most critical.
Leaf speckling is often superficial and within 10 days it is difficult to see the effect. However, herbicides that cause soybeans to drop their leaves right after application can affect yields. Select the herbicide based on its weed control performance. Avoid additives that can increase crop injury. For instance, additional nitrogen can increase injury and crop oils cause more injury than non-ionic surfactants.