CROWN ROT has been one of the worst disease issues we’ve seen in corn the last couple of years. TAR SPOT is the absolute worst disease you can get in corn, with yield losses of 100 bushels or more reported in the last few seasons.
WE’RE GOING TO COVER THE BEST STRATEGIES FOR THESE DISEASES, ALONG WITH SOME INFORMATION ABOUT XYWAY AND ITS ACTIVITY ON BOTH PATHOGENS.
CROWN ROT CAN BE CAUSED BY A NUMBER OF DIFFERENT FUNGAL SPECIES. The crown of the plant is basically where all the nodal roots meet up with the main stem. Therefore, the crown is important for the transport of anything up or down in the plant, to or from the root system. That’s exactly why crown rot can impact yields so dramatically.
HERE ARE MY TOP 5 TIPS TO REDUCE CROWN ROT IN YOUR CROP:
1. FIX INTERNAL FIELD DRAINAGE.
I’M NOT TALKING SURFACE WATER HERE. I’M SAYING YOU NEED TO KEEP YOUR WATER TABLE BELOW THE ROOT ZONE AT ALL TIMES. If you already have tile in your field and you are still having drainage issues, you may need to add more lines or upsize your mains.
2. HAVE THE RIGHT AMOUNT AND BALANCE OF SOIL FERTILITY.
IF ALL YOUR SOIL’S NUTRIENTS ARE IN THE HIGH CATEGORY, YOUR PLANT IS FAR LESS LIKELY TO GET ANY DISEASE. It’s exactly like human health. The better your diet, the less you get sick. The key thing most people miss is the word balance. For example, we like magnesium-to-potassium ratios to be around 1:1 or 2:1 in terms of parts per million. We like phosphorus-to-zinc to be in the general ballpark of 10:1 and phosphorus-to copper to be somewhere around 30:1. Potassium must be at least 4% on a base saturation test; and while you want lots of nitrogen to raise a great corn crop, if your nitrogen-to-potassium ratio gets out of whack, you often have problems.
3. USE A GREAT SEED TREATMENT.
HAVING A COMBINATION OF SEVERAL EFFECTIVE FUNGICIDE MODES OF ACTION PLUS SOME NATURAL/BIOLOGICAL PRODUCTS OFTEN MEANS MORE NUTRIENT UPTAKE AND HEALTHIER PLANTS. I realize your seed company is the one that treats your corn seed, but not all companies use the best available options.
4. USE XYWAY IN THE 3RIVE 3D SYSTEM.
BY CREATING A FOAM IN THE FURROW, FMC SAYS THEY ARE GETTING 50 TIMES BETTER COVERAGE THAN WITH TRADITIONAL LIQUID. Farmers we’ve been working with who are using the 3Rive 3D system, including on our own farm, have seen better results than those using a traditional in-furrow application system. In areas last year where drainage was poor and fertility wasn’t perfect, we saw lots of crown rot, but where Xyway was used it was a noticeable improvement.
5. CONTROL BELOWGROUND PESTS.
IF ROOTWORMS, WHITE GRUBS, WIREWORMS, OR ANY OTHER INSECT DAMAGES YOUR PLANT, IT IS MORE LIKELY TO GET CROWN ROT OR ANY OTHER DISEASE. PERIOD. Very often we focus on insect control as just that, but insect control quite often also means disease control. While Bt traits can stop certain bugs like corn rootworms and seed treatments can at least suppress wireworms and a few other pests, using an in-furrow insecticide like Capture LFR, Aztec, or Force always leads to even more insect control, which is why we always use an insecticide at planting-time on our farm.
MOVING ON TO TAR SPOT, while I could have written an entire article on this disease, we’ve been talking about it a lot over the last year, so I just wanted to give you a quick update on what we’ve learned recently.
FIRST OF ALL, TAR SPOT SEEMS TO DO MORE YIELD DAMAGE THAN ANY OTHER DISEASE IN CORN, AND IT CONTINUES TO SPREAD ACROSS THE U.S. Most seed companies don’t yet have a great handle on which of their hybrids are best on this disease, but that will hopefully get better in the next few years. Hybrid selection does make a difference.
FINALLY, MULTIPLE FUNGICIDE APPLICATIONS ARE USUALLYNEEDED IF TAR SPOT SHOWS UP EARLY OR EVEN MID SEASON. One of those applications could be Xyway, as that is now labeled for suppression.
Xyway did at least have some control on tar spot, and Xyway is now officially labeled for suppression. Just keep in mind – this is only for suppression. To think that an April or May at-plant treatment is going to hold all season long is a pipe dream. You will definitely need at least one foliar fungicide application if you are in a tar spot area.
If you don’t use Xyway down and tar spot is a big threat in your region, I’d plan on spraying pre-tassel and then again after tassel. Most of the good fungicides are labeled for control. OUR ADVICE IS TO USE MULTIPLE MODES OF ACTION, PREFERABLY 3, TO PREVENT RESISTANCE FROM BUILDING AND TO MAXIMIZE CONTROL AND RESIDUAL.