Anco Comments SC June 18 Peanut Notes No. 91 2020
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Some breaks in the rain this week have allowed for more field work to move ahead in some parts. Other areas continued to get more rain on top of wet soils. This can impact our timing of fungicide, herbicide and land plaster application. Depending on how long we are kept out of a field, this may just push some timings back a bit.
Boron application can go out with the first fungicide spray, and sometimes it is applied earlier with herbicide applications where needed. Season application totals should stay below 0.5 lb boron to avoid toxicity. In general, different products often perform similarly, so long as the actual boron amount is comparable.
If rain and wet fields are delaying access to apply land plaster for calcium at first bloom, we will in most cases be alright to apply it when we are able to (before 60 DAP if we can). There are many different products out there. Anything that is applied and is claimed to provide needed calcium by being absorbed through the leaves will not help for pod fill. That needs to happen at the soil-shell interface.
The general guideline I use when considering delayed ground application versus calling in airplane application is going with the airplane if ground application would not be able to be conducted for another 5 or more days after when we could get a plane. Alternatively, or when the plane simply isn’t available, coming in with the ground sprayer with a stronger systemic treatment like prothioconazole plus micronized sulfur would help too. Applying fungicide preventatively generally provides more effective management when possible, but so it goes with what’s possible and what’s practical.
Depending on the fungicide program, if Miravis is used around 60 DAP to extend intervals, this could also impact our timings on when we plan to go through the field in terms of when we would put out manganese if needed. Mn deficiency shows up as interveinal yellowing near the top/new growth of the canopy. Generally for Mn we target a split application near 60 and 75 DAP so that new growth coming out near the time of application and then later can be supplemented. If we are extending fungicide intervals and not going into the field at 75 days, adding Mn to the tank the next time we go out would be helpful, assuming we don’t intend on making a nutrient-only trip across the field. Putting a double dose of Mn early on would not be the same as sequential applications spaced out, since new growth would still be deficient even if a higher rate was applied up front.
In addition to Miravis being used to extend fungicide intervals, the label for Revytek lists a spray interval of up to 21 days. Our university data on its performance over extended intervals is limited so far. Barring surprises, we should have a better idea at the end of this year from trials we have running.
There are a lot of good fungicides available. If Miravis is used, it needs to be paired with a white mold fungicide (tebuconazole/Elatus/Convoy). Extending intervals has its benefits certainly, but where white mold control is a primary concern such as with susceptible runners in fields with a history, it increases the importance of timely wash in either by irrigation if available, or from available rainfall for dryland fields. A lack of fungicide wash-in where needed would be another reason to consider coming back into the field sooner.