Fungicide - Spray or Not?
This is generally the most asked question this time of year. For those who have been pretty deeply involved in our journey at AgriBio Systems, you know we don’t want to. Mainly due to the antagonism of this and soil regeneration.
However, through this journey, our message has always been, “Pick Battles You Can Win.” Currently, with recent weather, saturation, etc. brix levels have consistently dropped in half from avgs of 6-12 to current levels of 3-6. Once in a while we might find a peak Brix level at 8.
First, if you haven’t done so already, buy a refractometer. It is the absolute best tool that can be used for making this decision. One will cost you around $100. Use this link. Don’t buy the cheap one’s for $15-20. You get what you pay for here also.
There are 3 tools that every grower, agronomist/consultant, and seed person should always carry with them in their truck – a shovel, a tile probe or penetrometer, and a refractometer (and some modified vice grips to squeeze the plant sap). These 3 tools can explain a tremendous amount of many of the issues we face – weeds, insects, diseases, poor yields, etc. In total, this trio might cost you $500.
You have 3 options:
- Do nothing and hope that disease doesn’t ravage your crop –
- This battle is not easily won right now.
- This option is my least favorite currently and not recommended (unless brix levels are 12+)
- Apply more foliars to provide the necessary nutrients plants need.
- This late in the season I am somewhat skeptical with the myriad of stresses and nutrient deficiencies that we can bring plants back to constant 12+ brix readings.
- One approach that is worth trying is a Ca + Si mix. We can get you the necessary RX to do this if you’d like to try it. This combo in the past in others research has shown some very promising results vs. fungicides, though we do not have any data of our own. We will for this year.
- Apply a fungicide.
If you’re going to use the “scout and decide” method, you must make at least 3 scouting trips for 3 consecutive weeks and you also must use a refractometer to measure your brix levels to see your rate of photosynthesis. If you are 12+ (for at least 3 consecutive days), you’ve got a pretty darn good chance of having the natural plant immunity that all growers should be striving for. This brix reading should be done between noon and 5 pm. Just because you “see” no disease doesn’t mean your safe. I know of several instances in 2020, that fields were nearly disease free up to the milk stage and then Tar Spot came in a killed plants prematurely, devastating corn yields. Crown Rot showed up also, and created some similar issues. Generally also, the longer you wait the less ROI and once severe disease symptoms appear it’s definitely too late. Kind of like nutrient deficiencies. Once they are visible – too late.
There also isn’t really any major differences in corn on corn vs. corn on beans. In other words, just because a field is planted after beans doesn’t mean it is “safe” and should be ignored. Some of the largest ROI/yield preservation we’ve experienced in past years were on rotated ground. Why? Higher yield potential and also likely hybrids planted after beans with poorer natural disease resistance.
What if a hybrid has a tremendous track record of not showing a ROI? Use your refractometer. If your refractometer reading is below 6 in these type of hybrids, still spray it. The highest yield potential will also have the most consistent ROI.
Many fields today are in great danger of running out of nitrogen (also a major Boron and sugar issue due to poor nutrient balance/photosynthesis), and this needs addressed before a fungicide gets applied in these situations.
How about the disease triangle? You know that triangle that says for the development of disease you have to have 3 things? A host, pathogen, and environment.
Well it’s missing one very critical important piece – you can have the correct environment, pathogens present, and a host but, if your plants are healthy enough they cannot get infected. Every plant, every human, and every living organism on this planet has this ability. This is one that our government and health care folks have missed immensely since COVID started (and also pre-COVID). Behind every disease, is one or more nutrient deficiencies. This is exactly why we have preached for years about the importance of nutrient balance and the use of SAP tests and challenging status quo.