Cooler conditions and rain have brought a reprieve from the heat of recent previous weeks. Warm days moving forward will be helpful to fill out pods and keep maturity development on track for a timely harvest. The tropical system in the Atlantic that was possibly heading to the states now looks like it will veer north and away. More than a couple times in recent years we have needed to adapt management plans based on field access that was affected by tropical storm systems. Timely fungicide coverage throughout the season helps not only to protect health of the peanut crop, but it also gives us much needed latitude downstream if we become delayed in an application or as we plan harvest operations.
Rhizoctonia
Where Rhizoctonia is developing including on leaves in a field, we have several fungicides with activity against it, but depending on spray programs earlier in the season some situations may be at the maximum label rate for tebuconazole. This comes out to 4 applications of a teb fungicide at 7.2 fl oz/A, or also it is nearly met via two teb apps plus 2 Provost Silver apps. Rhizoctonia usually is not as large of an economic concern as late leaf spot, but we still have enough growing season ahead of us where we are not done yet. By harvest, we can tolerate 20 to 30% of leaflets affected before seeing impact on yield. Additional fungicides outside tebuconazole that have efficacy against Rhizoc include azoxystrobin/Quadris, Elatus, Provost, and Convoy/Umbra (but watch PHI as those last two have 40 day PHI and Elatus has a 30 day PHI).
Insect Intruder
Also attached is the recent Newsletter from Dr. Jeremy Greene detailing the two-spot cotton leafhopper that has recently been identified in the state. Information on potential impact on peanut is still yet to be determined, but it is good to be aware of as fields are examined and efficacy of insecticide applications (where present) for leafhopper is assessed. We normally are reserved when considering a treatment for our standard potato leafhopper in peanut due to the potential to increase risk of spider mites. From initial screening, there is a possibility the two leafhoppers may vary in susceptibility to available insecticides (pyrethroids). We have seen varied insecticide efficacy in different systems, for example acephate insensitivity in thrips in regions further to the northeast of SC, that has not presently been the same situation as we see in SC. Still, different pests and situations can bring different challenges, and increased awareness helps to increase an informed response.
