Overlap of timing for weed, insect and disease control will occur over the next six weeks.  Fungicides are being applied on a two-week interval in many fields and it is convenient to co-apply products to address issues.  There is also the need to address micronutrient issues over the next month and Apogee/Kudos will need to be applied in many fields, especially with our current rainfall patterns.  Many of the possible mixtures are compatible from a weed, insect and disease management perspective.  Broadleaf/sedge herbicides are not affected by PGRs, insecticides, and fungicides based on the work we have done in North Carolina over many years (but we have not looked at all of the possible mixtures in recent years.)  Efficacy of clethodim was reduced by chlorothalonil products, Abound, Headline, and Omega 500 in research conducted years ago.  Folicur and Provost did not affect control of clethodim or Cobra in similar work.  Recently, grass control was not affected by Miravis plus Elatus or Convoy or when applied with residual herbicides like Dual Magnum, Zidua, or Anthem Flex.

BUT, it has been a decade since we looked at 4 and 5 way mixtures, and we know adjuvants applied with herbicides (they are needed) can affect fungicide efficacy.  For example, products that need to reach the base of the plant to control soil-borne pathogens might not reach the place they need to be if they are applied with a PGR or herbicide that includes nitrogen solution or crop oil concentrate. However, when it comes to disease control a slight reduction in control in one spray out of a 5-spray program likely will have not negative impact on disease control at the end of the season.

So, outside of Cobra or Ultra Blazer or Basagran applied with clethodim OR clethodim applied with chlorothalonil, Abound, or Headline (the latter two we are not using on a lot of acres), reductions in control seldom exceed 15%.  We can live with that because of the positives of mixing given logistics.  BUT, we do not know much about compatibility with products like Revytek or Priaxor, or Lucento.  And, we certainly do not have a feel for mixtures with a lot of products included, differing adjuvants, size and stress of pests, and water quality.

If you are applying a complicated mixture, especially with manganese or boron, make sure the spray solution does not settle in the tank.  That can be a disaster.  Less is better in the tank when manganese is applied.  Just use caution.