There have been a number of questions about compatibility of Apogee with other agrochemicals. Over the years we have done quite a bit of compatibility work with Apogee. I had a call from a very good farmer indicating that mixtures of Apogee with Provost caused injury. The Apogee had surfactant and nitrogen solution. He indicated that he had some burn but the new growth was fine. It is often a challenge to know severity but it was noticeable. Also, he indicated that when he applied Provost with Cadre and crop oil as well as Select and crop oil he had some foliar burn. He also indicated that a few years back be sprayed Omega 500 with Apogee and saw leaf burn. Several years ago people in the southeast saw some burn when Provost was mixed with 2,4-DB. A number of people tried to repeat that and never could.
So, it is best to encourage people to spray Provost and other materials sequentially. Also, a sound argument (against their argument to mix things) is that with Provost we are trying to get material down in the canopy and to the soil zone for stem rot control and perhaps some suppression of CBR. For Omega 500 or Endura we are also trying to get these products down to the crown of the plant for Sclerotinia blight. For these reasons we should not be applying Provost, Omega 500, Endura and other products for stem rot with Apogee because we need to add crop oil and nitrogen to Apogee. The crop oil and nitrogen hold more material on the leaves in the upper canopy and probably enhance fungicide absorption just like they enhance Apogee absorption. The Sclerotinia sprays are expensive, so we need to maximize those possibilities that negatively affect performance of soil-focused fungicides. The Apogee is expensive too so we need to avoid doing anything to reduce its efficacy. Sequential applications are the best approach.
Article first appeared as North Carolina Peanut Note (PNNC-2012-046)