Late-Season Rootworm Control Peanut Notes No. 114 2018

— Written By

Late Season Southern Corn Rootworms in Peanuts

Rick Brandenburg

Department of Entomology and Plant Pathology

The last few weeks have seen storm after storm and many areas have received high levels of rainfall after a relatively dry June and early July. As this rain has continued, the concern over southern corn rootworms has increased and the ability to get in the field has decreased. I am getting a lot of questions now about treating this late with Lorsban. First, Lorsban is slow to get into the soil and begin to work. So even with continued rains, it is going to be a week or two before it starts to work. A lot of damage has most likely occurred in rootworm prone fields but there may be more to come as more eggs hatch and more feeding occurs. An application of Lorsban at this stage is not going to protect the crop, but it COULD reduce further injury. I repeat, it COULD. Thimet (phorate) is no longer labelled for late season rootworm control and will actually be removed from our recommendations this winter. The only other product we have tested with any level of success has been granular bifenthrin and I cannot find a current label for a granular formulation from any manufacturer. Spraying bifenthrin will NOT work. Spraying Lorsban liquid will not work other than serious leaf burn.

The only product I see we can use is Lorsban granule, it will be slow to work, you will run over a lot of vines, and most likely you will still see a lot of damage.