These types of herbicides are also called contact herbicides. PPO inhibitor means they slow down the production of the protoporphyrinogen oxidase (PPO) enzyme, which is used in chlorophill production. This inhibition also results in the formation of highly reactive molecules that attack and destroy lipids and protein membranes which ultimately affect cell membranes. This result in leaky cells and disintegration of the tissue.
Goal (Oxyfluorfen) is one of the earliest registered of these products (1980) but has only been used widely over the about the last 16 years. This is the only one of these that has problems with “lift off” or codistillation with water. (1)
According to University of CA IPM “In dry bulb onions, GoalTender may be tank-mixed with other pesticides such as bromoxynil, but tank mixes must only be used on older onions with well-developed cuticles to avoid unacceptable crop injury. Unacceptable injury may occur if applied to small onions without adequate cuticle development, and in conditions such as after cloudy or rainy weather. Follow the label closely to avoid crop injury when tank mixing.
Oxyfluorfen has some residual soil activity after application. It controls small broadleaf weeds, some grasses, and nightshade, and controls little mallow (cheeseweed) well ”. (1)
Other PPO herbicides are: Aim or Shark, Chateau, Sharpen or Treevix, ET, and Spartan. They work as contact herbicides and do not move through the plant.
Most of these products don’t have preemergence activity but when used at higher rates Goal and Chateau do.(2) As the plant emerges from the soil and contacts the herbicide it dies, so it is recommended to avoid disturbing soil after the application of these products.
This week in Yuma oxyfluorfen uses:
- Directed application in broccoli for goosefoot, lambsquarter, and cheeseweed control.
- Broadcast application in onions for goosefoot, grasses and lambsqurter
References
