Weeds

Accurate identification of weedy Amaranthus species during early vegetative stages sometimes can be difficult.  Differentiating between smooth pigweed and waterhemp is relatively easy since one species (smooth pigweed) has pubescence on the stem and leaves while the other does not.   However, differentiating between waterhemp and Palmer amaranth during early vegetative stages can be much more difficult.  To assist weed management practitioners in accurately identifying Palmer amaranth, we will accept tissue samples from suspected Palmer amaranth plants and use tools of molecular biology to identify whether the plant is Palmer amaranth or another species of Amaranthus. …

Integrated weed management programs offer the greatest potential for long-term, sustainable solutions to weed populations demonstrating resistance to herbicides from multiple families.  Soil-residual herbicides are important components of integrated weed management programs and provide several benefits, including reducing the intensity of selection for resistance to foliar-applied herbicides.  Recent survey data indicate the percentage of Illinois soybean acres treated with soil-residual herbicides has increased during the past few years.
In the vast majority of instances, soil-applied herbicides control target weed species with little to no adverse effect on the crop. …

Planting progress may have been slowed by the recent precipitation, but weed emergence continues despite wet field conditions.  Be aware that Palmer amaranth has begun to emerge. We scouted our Palmer amaranth field location west of Kankakee on May 8 and observed emerged Palmer amaranth plants (Figure 1).
 
We returned to the field on May 15 to find a very robust Palmer amaranth population (Figure 2).  The largest Palmer amaranth plants found on May 15 were approximately 2 inches tall with 6 to 8 true leaves.…

We invite you to attend the 2014 University of Illinois Weed Science Field Day on Wednesday, June 25th at the University of Illinois Crop Sciences Research and Education Center, located immediately south of the main campus.  Coffee and refreshments will be available under the shade trees near the Seed House beginning at 8:00 a.m.
Similar to past years, we will car pool to the fields where participants can join in a guided (but informal) tour format. …

A few weeks ago we published recommendations for the management of Palmer amaranth in Illinois agronomic crops.  Those recommendations are now available in a file format that can be downloaded and printed.  Please don’t hesitate contact me if you have any questions or problems with the file.
Palmer Amaranth 2014 HI…

Recently, the weed science program at the University of Illinois published recommendations for the management of Palmer amaranth in Illinois agronomic crops.  One particular recommendation emphasizes the need for timely application of foliar-applied herbicides; in particular, foliar-applied herbicides must be applied before Palmer amaranth plants are taller than four inches.  Most weed management practitioners are very familiar with the growth rates of waterhemp and many other weed species, but perhaps are less familiar with the growth rate of Palmer amaranth.…

The number of acres in Illinois seeded with various cover crops has increased during the past few seasons.  Those cover crops that do not winter kill are usually controlled the following spring with herbicides.  Dr. Bob Hartzler, extension weed scientist at Iowa State University, recently published an excellent article in which he describes several factors that can impact the performance of spring-applied herbicides used to terminate cover crops.  We sincerely appreciate Dr. Hartzler’s willingness to allow us to reproduce his article which follows.…

Palmer amaranth is a weed species that must be thoughtfully and carefully managed; simply attempting to control Palmer amaranth often leads to ineffective herbicide applications, substantial crop yield loss, and increasing weed infestations.  Ignored or otherwise not effectively managed, Palmer amaranth can reduce corn and soybean yield to near zero.  The threat of Palmer amaranth during the 2014 growing season is very real across a large portion of Illinois.
In January 2014, the weed science program at the University of Illinois developed recommendations for management of Palmer amaranth in agronomic crops. …