Resistance Fighter: Ask the Expert

Wet and Weedy in Central Illinois

Chuck Foresman — Thu, 25 Jun 2009 15:52:00 GMT

Recent travel east of St. Louis, in south central Illinois, underscored the fact that this season has been very wet and frustrating indeed. The wet spring and summer means growers are facing delayed planting, thinning populations, postponed herbicide applications and very weedy conditions. As evidenced in the photo below, some fields, like this one, are overly saturated with standing water.

This photo not only shows standing water in the field, but also documents waterhemp, which growers will see more of in the next month as populations begin to emerge and become more evident.. Other weeds that were prominent in fields were giant ragweed, common ragweed, volunteer corn, lambsquarters and marestail (horseweed).

You can see in this photo what a problem glyphosate-resistant horseweed has become. Even though this field was treated with glyphosate recently, you can see the tops of the horseweed plants starting to green up again, and grow out of the herbicide application.

Because the wet weather has made any kind of trip across the field difficult, weeds have had more opportunity to compete with the crop. This picture below shows early emerging soybeans and the weed competition that stands in the way of healthy growth.

What has the wet weather meant for your crop and weed populations? How are you managing weeds in your field? Have you been able to see the benefits of a pre-emergence application, like Lexar® or Prefix®?

Is waterhemp a problem in your fields? What weeds do you expect to be the biggest obstacle for you this year?

Palmer pigweed reigns in Arkansas

Chuck Foresman — Tue, 16 Jun 2009 19:10:00 GMT

A recent trip to Arkansas once again confirmed that Palmer pigweed is the top weed concern for growers in area. This season, those growers and consultants who used residual herbicides are seeing the benefits.

For instance, the photo above shows an effective program; treated with dicamba and Gramoxone Inteon® at burndown, followed by Sequence® at the cotyledon stage. Where as the photos below show Johnsongrass and Palmer pigweed breaking through treatments.

As one grower commented, "You are better off spending money up from on residuals and getting it right so you don't have to spray all summer."

One thing for growers to consider is the importance of developing and practicing a weed resistance management program before resistant weeds permeate their fields. The mindset that "resistance is not a problem until I see it on my field" is one that can put growers on a path of continually catching up and letting glyphosate-resistant weeds become established.. While the prospect of changing to a more complex management system may seem daunting or too expensive to some, the amount saved by protecting fields before there a resistance problem develops can be easily seen in the short term and long term, with a healthy field and productive crop.

What’s happening in northern Illinois

Chuck Foresman — Wed, 10 Jun 2009 21:37:00 GMT

Driving around the Midwest, one can see a wide variety of scenarios - from planters still in the fields, to sprayers applying herbicides, to corn emerging (like the picture taken here from a northern Illinois field), to soybean fields that have just been drilled, and much more. As Mother Nature continues to make things difficult and adjust plans for many out there, this photo illustrates why getting a pre-emergence herbicide applied is so important.

Here, the grass was controlled with a half-rate application of a pre-emergence herbicide. The grass was burned, but, because of spray timing and weather conditions, not completely controlled. At the point the photo was taken, competition had already caused 1 bu/A yield loss. If not controlled before corn reaches the V3 stage, it will cause a yield loss of nearly 5.5 bu/A according to WEEDsoft^®.

In this example we showed why pre-emergence herbicide important for corn, but soybeans can benefit from it as well. As glyphosate-resistant weeds become more prevalent, applying a residual pre-emergence herbicide can help control early weeds that compete with the crop, and it involves using an additional mode of action on glyphosate-tolerant soybean acres.

How has herbicide application timing been affected by weather on your fields? Do you think you've seen a yield loss due to delayed applications? If so, how much?

WEEDsoft^® is a registered trademark of the University of Nebraska-Lincoln.

Don’t Count This Year’s Crop Out

Chuck Foresman — Wed, 03 Jun 2009 19:49:00 GMT

As an update to last week's post, corn and soybean planting as well as emergence remain behind schedule according to yesterday's USDA-NASS Crop Progress report. Though things are a bit behind, progress has been made.

Usually for this time of the year, 97 percent of the corn crop is in the ground.

As of Sunday, 93 percent was planted.
Of that crop, 73 percent has emerged, compared to 86 percent a year ago.

Soybeans are seeing similar lags. Almost 80 percent of soybeans are usually planted by the first week of June.

66 percent of the crop has been planted.
36 percent emerged.

Iowa Farmer Today hosts the Corn Cam, where visitors can view the current state of an Iowa corn field via the Web. Corn planting may be nearly wrapped up in Iowa, but that simply changes focus to delays in post herbicide applications. ISU Extension Agent Clarke McGrath notes, "Often as we watch the corn grow while we cannot get a field sprayed, the conversation turns to what growth stage of the corn will trigger any necessary herbicide changes." As weather delays potentially force plans to change, proper management of your crop and weed populations will help to keep fields healthy and weed-free, thereby increasing your profit potential and yield.

How has planting and emergence this year compared with years past? Are you feeling optimistic about your crop? How have management decisions been affected by any delays you may have experienced?

Spring Field Reports: Midwest

Chuck Foresman — Fri, 29 May 2009 21:09:00 GMT

April showers bring May showers, or so it seems. Just as in the South, Midwest growers have experienced planting delays due to heavy rainfall. According to the Illinois Department of Agriculture's Crop Report in Prairie Farmer, on May 18, corn was 20 percent planted and by May 25, 62 percent of the corn crop was planted.

Fields in this southern Ohio field are typical of the wet conditions that growers are experiencing around the Corn Belt. Wet weather has delayed field work so that weeds are not receiving an herbicide application at ideal timing. Lambsquarters, giant ragweed and glyphosate-resistant marestail (horseweed) can be seen in this glyphosate-tolerant soybean field. This field has been sprayed with 3.5 pt. Gramoxone Inteon®, 2 pt. 2,4-D, 2 oz. metribuzin, and 2 gal of COC in order to help control glyphosate-resistant horseweed. This example shows burndown applications before the crop has been planted, but also demonstrates the typical challenges growers are facing as they hit the fields this spring.

Wet conditions are impacting herbicide applications. While growers may not be able to spray weeds at the ideal weed height due to bad weather, ideally weeds should be sprayed as close to the ideal time as possible, for maximum weed control. Purdue University researchers recently confirmed Syngenta recommendations, saying that in order to give crops the best head start on weeds, it is important to start with a clean field. Delayed herbicide applications increase competition, allow weeds to gain height and environmental conditions are affected.

Gramoxone Inteon® is a Restricted Use Pesticide. Important: Always read and follow label directions before buying and using these products. Gramoxone Inteon® is a registered trademark of a Syngenta Group Company.