Crop Scouting September 29th 2015

Crop scouting #1. If you have acreage you could not plant, or was washed out, there is likely an abundance of weeds. MO weed specialists say, "Most of this acreage was left fallow without any sort of weed management program and these fields grew up into a weedy mess. These weeds have matured and produced viable seed that, in most cases, have already been deposited back into the soil seed bank." The weed varieties are the types that are abundant seed producers. "In short, the number of weed seed sitting in the soil seedbank waiting to germinate and wreak havoc next year may be unlike anything we've ever experienced before." (Could that also describe ponds in your fields?)

Weeds Overtake Field

Weeds Overtake Field

Crop scouting #2. If sugarcane aphids began decimating your corn, sorghum, or other crops, you likely used Transform or Closer insecticides. Although the EPA approved the active ingredient sulfloxaflor in 2010, the court says that should not have happened and the Dow product should not be used because of its threat to bees. Dow and EPA officials say the label protected bees, but they are working jointly to keep the product on the market at least for the balance of this season.

Sulfloxaflor Should Not Be Used

Sulfloxaflor Should Not Be Used

Crop scouting #3. More tar spots are showing up on late season corn. The outbreak was in north central IN a couple weeks ago, and now they have been found in several north central IL counties. Typically the fungi causing the black rough spots has only been in cool, humid areas of Latin America, says USDA. The fungi currently being found usually does not result in yield loss, as will a related fungi that does decimate yields. It has not been found in the US. How did it get here? Experts think it arrived with Tropical Storm Bill in June, just like Asian soybean rust arrived on a 2004 hurricane. Tar spot has to live on live vegetation, so the winter should bring its demise.

Tar Spots on Corn Crops

Tar Spots on Corn Crops

Crop scouting #4. How much diplodia do you have in your corn, and do you know why you are so lucky? Diplodia is caused by a fungal infection that occurred just after silking, if you had a significant rain. Such rains splash fungus from the soil-based residues onto the corn plant and it penetrates near the ear shank. Yield is lost because of smaller kernels and light test weight, and quality is deteriorated because of moldy kernels and fines. However, diplodia does not produce a mycotoxin that results in toxin contamination. (Be thankful for that!)

Diplodia in Corn

Diplodia in Corn

Crop scouting #5. Focus on reducing the source of diplodia and minimizing stress to reduce ear rot potential. Fungal pathogens that cause ear rots are mostly derived from corn residue, and some hybrids are more prone to issues than others. Crop rotation will help reduce the amount of corn residue and tillage also will help reduce the amount of available inoculum in a given growing season. Bt hybrids will reduce insect damage and places for fungi to enter. There are fungicides that have ear rot suppression on their labels. However, you can imagine that adequate coverage of the silks and husk is going to be an issue. Remember that the fungicides will move up plant tissues with water gradients. Therefore, the fungicide is not likely to have any direct effect on the kernels themselves, but rather the silks and husk.

Help Reduce Ear Rot Potential

Help Reduce Ear Rot Potential

Crop scouting #6. So, what is your plan to prevent corn rootworm issues in 2016? There were few issues this year for most farm operators, but entomologists say that is no reason to ignore them for next year. And they add, it’s not too soon to begin evaluating the value of corn rootworm inputs for 2015 and their potential value for the 2016 growing season. They have prepared a 20 min web presentation for you to watch to help with your 2016 decision.

Corn Rootworm

Corn Rootworm

Crop scouting #7. Fall treatment for marestail can be beneficial, particularly if you have populations with heribicide resistance in a field destined for soybeans in 2016. Canopy/Cloak plus 2,4-D is a good option. If you also have chickweed and want to knock out the winter annual, go with Canopy EX or Cloak EX or Fallout with 2,4-D instead. Other options that work for fall applications if you're going to either corn or soybeans next spring include glyphosate and 2,4-D or dicamba and 2,4-D, which are good choices if dandelions are a problem as well as marestail. One recommendation ahead of corn is Simazine plus 2,4-D. The other is Basis/Harrow and 2,4-D. These recommendations are in the fall application section of the IL, IN, OH Weed Control guide.

Don’t expect it to solve your resistance problems, but the House Agriculture Committee has scheduled a December 4th hearing to discuss the growing resistance of weeds to herbicides, particularly glyphosate. Expect the new formulations of glyphosate with 2,4-D and dicamba to also be on the agenda, since both Dow and Monsanto are urging farmers to use multiple weed strategies along with their new herbicide formulations. Don’t be surprised if the burden is placed on farmers for relying too heavily on glyphosate and not using integrated pest management methods.

Fall Treatment for Marestail

Fall Treatment for Marestail

Get 17 pages of tips like these and more when you subscribe to the weekly Cornbelt Update!
Subscribe to the Cornbelt Update and get 52 weekly issues for only $75.
Contact Stu at StuAgNews@aol.com

Posted in AskThePlant Blog.