Ag Radio programs for August 23 - 29, 2007
Nitrates in forages
This is Ag Outlook 2007 on 1420 KJCK, I'm Chuck Otte, Geary County, K-State Research and Extension Ag & Natural Resources Agent. Anytime we get into August and September and we start having hot and dry weather, we start getting concerned about nitrates in forages, especially the sorghums, but nitrates can be a problem in other forage crops too. Let's review the two major toxicity concerns that we can have with sorghum forages. These are prussic acid and nitrates. Prussic acid is a cyanide based compound that can cause very quick illness and death in livestock. And by very quick I mean cattle dying with forage in their mouth. Fortunately, once a plant is harvest or frozen, the prussic acid ceases to become an issue in less than a week. So for baled sorghum or ensiled sorghum, prussic acid is very unlikely to be an issue. Nitrates are a different story. Nitrates can kill an animal, but not quite that fast. Cattle can even build up tolerance to high levels of nitrate over time through careful feeding of higher and higher nitrate feeds. But unlike prussic acid, harvest or a frost does not reduce nitrate levels. Ensiling will usually reduce nitrates by about half. We do have a quick test to see if there are potentially high nitrates, but this is no substitute for a quantitative lab analysis. I did pull some forage sorghum out of a field a few days ago and tested it with my quick acid test. These plants were less than 100 feet apart in a field. One area was very drought stressed and the other area had had more moisture and the plants were growing great and heading out. Guess what? The drought stressed forage showed lower nitrate levels than the healthy growing stuff. So don't depend on anything, get it tested! This has been Ag Outlook 2007 on the Talk of JC, 1420 KJCK, I'm Chuck Otte.
This is Ag Outlook 2007 on 1420 KJCK, I'm Chuck Otte, Geary County, K-State Research and Extension Ag & Natural Resources Agent. Even though we've had hot and dry weather, we also have a lot of volunteer wheat in these stubble fields. And any rain showers that we might get in coming weeks will just add to the problem. Sure, we've talked about wheat curl mite and wheat streak mosaic, but one that we also need to be talking about is hessian fly. Hessian fly is taking more and more yield every year, but nobody seems to be getting too cranked up about because of so many other things happening to the wheat crop. But I have seen individual fields in Geary County in recent years, that easily have lost 1/3 to ½ of a crop because of hessian fly. Hessian fly has been waiting out the summer as a pupae or flax seed in the wheat stubble. Those adult flies will start emerging from now through mid October or even beyond, depending on the weather. Once those flies emerge, and they are tiny like a gnat, they mate and the females head to the greenest wheat she can find to lay her eggs. If that happens to be a field of your volunteer wheat you may not be concerned if you are going to tear it up before planting. But if you are leaving it until next spring, because you will plant something else, well those hessian flies will just feed away, pupate and come out next spring as an adult, to fly over and infest your planted fields. Spring hessian fly infestation is not as devastating as fall infestation, but it can still hammer yields more than you want to know. So start evaluating all your stubble fields and let's get that volunteer destroyed and dead by the end of September, or at least two weeks ahead of wheat planting. That'll take care of the wheat curl mites AND those pesky hessian flies! This has been Ag Outlook 2007 on the Talk of JC, 1420 KJCK, I'm Chuck Otte.
Soybean and Sorghum issues
This is Ag Outlook 2007 on 1420 KJCK, I'm Chuck Otte, Geary County, K-State Research and Extension Ag & Natural Resources Agent. Probably the number one issue with soybeans and sorghum this month has been the lack of rain. But let's talk about some of the other things we've been seeing as well! Glyphosate flash, or Roundup flash, is a condition in soybeans where the leaves, especially the newer top most leaves turn various shades of yellow following an application of glyphosate. The exact cause is not totally known, though we do know that the nutrient manganese is involved some way in all of this and it has to do with photosynthesis as well. We also know that not all varieties react the same and that we are more likely to see flash where there were spray overlaps and turn rows. Normally, earlier in the season the beans grow out of this within a few days. This year, the flash is sticking around a lot longer and it appears to be connected to the high temperatures, more mature beans and slower growing conditions. Not much that can be done about it and the general feeling is that the impact to yield will be minimal. As for the yield potential on late planted beans.... it all depends on rainfall from now through the middle of September. The only up side to all this heat is that it sure keeps the soybean rust potential down. Grain sorghum seems to be hanging on a bit better than beans, but that's because grain sorghum is darn near related to cacti. We do need to keep an eye out for sorghum headworms. Sorghum headworm can be corn earworm, fall armyworm or true armyworm. Regardless, they are starting to show up and all it takes is one per head to justify spraying. Keep walking those fields and looking at those developing milo heads for problems. This has been Ag Outlook 2007 on the Talk of JC, 1420 KJCK, I'm Chuck Otte.
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