ILeVO Halo Effect
The Halo effect is associated with ILeVO-treated soybean seed. Regardless of the halo severity on early leaves, stand is not affected, the plants will recover, and the crop will be protected against early SCN and SDS.
Show in Image 1, the ILeVO Halo Effect is a discoloration of the outside edges of the cotyledons. We have seen this every year since ILeVO was launched, so most growers are familiar with it. However, this year the first planted ILeVO treated soybeans to emerge had little to no halo effect. Then as the planting season progressed, the halo effect became more prevalent.
So why would this happen? The cosmetic injury associated with the halo (yellowing/browning on the cotyledons) is a light-sensitive reaction, meaning that its severity is determined by solar radiation. Because of this, differences in the appearance of the halo are related to differences in solar radiation at emergence.
Does this mean that the halo is worse on sunny days? Not necessarily – the relationship between solar radiation on sunny versus cloudy days is complex. The appearance of the halo is further complicated by the fact that emergence occurs over a period (early spring) where the plants are exposed to varying levels of solar radiation and temperatures.
Bean Leaf Beetles
I am seeing more and more bean leaf beetle feeding in soybeans. Image 2 shows what an adult bean leaf beetle looks like and Image 3 highlights the kind of feeding damage they can do.
If you purchased an insecticide seed treatment like Gaucho or Poncho VOTiVO, I wouldn’t worry about a little bean leaf beetle feeding. The plant above had an insecticide seed treatment and even though there is a small amount of feeding, the bean leaf beetles must feed on some leaf tissue to ingest the systemic insecticide. Populations of bean leaf beetles must be very high before the seed applied insecticide won’t give adequate control of this pest early in the growing season. However, if you chose not to have your soybean seed treated with a seed applied insecticide like Gaucho or Poncho VOTiVO, I would be scouting and looking at percentage defoliation.
The economic threshold for this pest pre-bloom is 40 percent defoliation, but I would consider treating at 20 percent defoliation if you are in an area that is experiencing dry weather right now. (Stress on stress – insect feeding on top of drought stress). I would recommend treating with 2.8 oz. of Leverage 360. Leverage 360 will give you knockdown and residual for a wide variety of insect pests and provide stress shield as well.
PPO Crop Response
I am getting a lot of phone calls about PPO (protoporphyrinogen oxidase inhibitor herbicides) crop response on soybeans, although I have seen no fields that concern me at all. Image 5 shows typical PPO injury on soybean. It is typical to see this “burning” on the hypocotyl from PPO herbicides. Soybeans can withstand a lot of this and can fully recover. Again, I have not seen a field of PPO crop response that concerns me at all this season but be on the lookout.