Ten days ago we sprayed the second shot of manganese (Mn) mixed with Provost and Omega for disease control. We have heard that Provost can produce leaf burning if mixed with other products (with boron for example) but those incidents appeared to be unpredictable and inconsistent. This year, mixing Mn with Provost did affect us! The fields that were sprayed later in the day (the hottest part of the day) showed more severe burning than the ones sprayed in the morning. However in none of the fields the burning exceeded 5%; note, however, that the injured leaves were those at the top of the canopy with the best light capture and photosynthetic activity.

Peanuts were sprayed with a mixture of manganese, Provost, and Omega.

How do we know it was the mixture? Because in one field only half received Mn plus Provost plus Omega (leaf burning occurred) and half only received Provost and Omega (no leaf burning was observed). It could have been only Mn, however. Either way, I would caution farmers to double check labels and percentages of Mn before mixing with fungicides, Provost in particular. Also a good practice would be to apply chemicals, micronutrients in particular, early in the morning to avoid the heat.