North Central and Northeast Iowa
Tom Larson says farmers in his area have endured a variety of drastic weather events, which has drawn out the planting season. The corn needs some heat and moisture to push it along, especially in some stressed areas where some yellowing is occurring.

With the possibility of uneven emergence in soybeans, Tom says it’s time to scout for bean leaf beetles. Last year fields in north central Iowa that had spotty emergence saw infestations of eight to 10 times more than the economic threshold.  These beetles move pretty quickly, so spend some time walking fields and looking for the classic “shotgun” effect in the first trifoliate of leaves, a lesion on the stem, or a complete cutting of the upper half of the plant.

Central Iowa
In central Iowa, Bart Peterson reports the corn is up to the V6 growth stage and is close to forming a canopy.  The area has also received timely rains, and the soybeans are coming along nicely.

East Central Iowa
Wayde McNeil says that two cases of cutworm in western Marshall County have caused 4% damage. He has also noticed a couple of small cases in central Poweshiek County. In the past week, parts of his territory have received up to two inches of rainfall. He says the corn is coming along good with some in the V6 growth stage. Soybeans are anywhere from VE to V2 growth stage. Farmers are working hard making hay, as well.

Eastern Iowa
Brad Beatty reports corn planting has finished, and the soybean planting is 98% done. Farmers’ focus is turning to spraying both corn and soybeans, and Brand is reminding growers to also scout for cutworms in corn. Producers who have alfalfa are all hoping for a window of opportunity to finish making their first cutting. He advises producers to check with their suppliers on NH3 prices as he has heard prices that are half of what they were last year.

South Dakota
Soybean planting is pretty much complete and 80% has emerged, according to Bill Eichacker. Right now a lot of corn is being sprayed, and he is advising farmers to read and follow label directions. Corn is up to the V5 growth stage. Farmers also have been working hard on cutting alfalfa, and at least 60% of first crop is complete.

Eastern Nebraska
Brian Banks reports that once again rains have been spotty, and where it does rain, it is not enough. Cooler than normal temperatures help compensate for lack of moisture. Overall, the corn is growing well despite the lack of moisture.  Corn growth stage ranges from 4- to 7-leaf.  Dry land corn fields are 2 to 4 inches shorter than they should be at this time.

Cutworm has not yet been much of a problem.  He has only found a couple fields with damage to more than 1% of plants; both black and dingy cutworms are responsible.  Post-emergence herbicide applications are in full swing this week. Pre-emergent residual herbicides are holding on in irrigated fields, but dry land fields are getting very weedy since there wasn’t enough moisture to get a good recharge on the herbicide.

Even in these challenging growing conditions, the performance of Latham Hi-Tech Hybrids LH 6598 VT3 is standing out.  On more than one occasion, LH 6598 VT3 emerged before other (competitive) hybrids that were planted 5-7 days earlier!

Current soybean seeding development ranges anywhere from emergence to 2nd trifoliate.  There are a few guys who are just finishing up planting soybeans in the northern part of the territory.  Emergence has been pretty good, but there are some uneven stands because of inconsistent planting depth.  Normally we get enough rain to get those beans near the surface to sprout, but this year most places were not so lucky.  Populations are still at or above 85% of what was put in the ground, so we haven’t ran in to any replant situations yet.  It looks like the L 2635 R and L 3184 R2 have had the best emergence this year.  Some post herbicide applications have started on soybeans but mostly in cases where there was not a burn down prior to or at planting time.

Make no mistake, the Roundup Read system in both corn and soybeans is poosibly the greatest boon to farming over the past 20 years. Still, it was only a matter of time until nature would greet us with some form of resistance, as is happening now. Soybean farmers need to be vigilant when it comes to weed resistance to glyphosate herbicides like Roundup® and Glyphos™.

Ryegrass and marestail have been documented as exhibiting resistance to glyphosate and there is some strong evidence that waterhemp, common lambsquarter and giant ragweed are showing signs as well.

Let’s look at a few simple techniques that growers can start using right away in their soybean program to help minimize weed problems in this Roundup Ready era:

1. Start clean- Stay clean.
   By starting the growing season weed-free in your soybean field, you can help eliminate your reliance on glyphosate alone. If a farmer is no-tilling, the use of a proper burndown, consisting of more than just a glyphosate product, is essential. There is a wide range of burndown products that can be used with glyphosate or by themselves. If you plan to use tillage, then get rid of that temptation to just use glyphosate and add some other modes of action into the mix.  The old “yellow” herbicides (Treflan, Prowl, etc.) are fairly reliable for grass control and will also help with many small-seeded broadleaves. Keep your fields clean by using the right rate of glyphosate at the right time. Also, don’t forget the cultivator. It might be time to drag out that old beast put it back to work. Better a little bit now than a lot later!
2. Right rate- Right time.
   The Roundup Ready system for both corn and soybeans might just work too well! For instance, the labeled rate for most annual weeds on the Roundup WeatherMAX label is 22 ounces/acre when the weeds are between 3″ and 6″ high. However, most farmers will tell you they have had great success using that rate for weeds up to twice that height and there lies the problem! We start to rely on a low rate of glyphosate to control weeds that are taller than the labeled height. Therefore, we are artificially selecting those weeds that have a tendency toward resistance just so we can tell our friends and neighbors that we only sprayed our soybean fields once and did it at the lowest rate possible. Don’t fall into that trap!
   
3. Rotate herbicide programs.
   Growers should use glyphosate crops in farming rotation where they have the greatest economic and management value. Rotating between glyphosate-tolerant crops and conventional crops or crops with other types of herbicide resistance (LibertyLink® for example) can help prevent weed resistance.

Make it a priority in 2009 and beyond to address weed resistance to glyphosate herbicides. It will definately benefit you in the long run. For more information on weed resistance issues, contact our Latham Seed2Soil® specialists, or leave us a question in the comment box below!

Some farmers have asked us whether Roundup®-resistant weeds could develop in their fields. While there is a potential for weed resistance to develop, it can be greatly minimized through best management practices.

A pre-emptive strategy to minimize the problem in corn can be accomplished by integrating tillage, crop rotation, rotation with herbicides with different modes of action (preferably soil applied herbicides) and tank mixes of different herbicides.

Roundup Ready technology can be used effectively, year after year, while minimizing the risks of developing weed resistance. One of the biggest pluses for corn growers in meeting the resistance challenge is the fact that they can learn from the experience gained from other Roundup Ready crops introduced over the past two decades.

In Summary:

• Know your weed pressure in each field and understand weed emergence patterns to ensure timely post-emergence applications.
• Use a residual herbicide to manage early-season weed flushes.
• Be sure fields are weed-free when planting starts. Corn is especially sensitive to weed competition early in the season.
• Remove weeds before they get 4 or 5 inches tall or there can be a dramatic decline in yield.
• Apply a full rate of Roundup herbicide when weeds are the right size.

For hard-to-control weeds, consider using a diversified weed control strategy, such as cultivation and herbicide with a different mode of action.