Weeds

The weed science program at the University of Illinois invites all weed management practitioners to our annual weed science field tour on Wednesday, July 10.  Please note the tour will begin at our off-campus field location (“The Lost Forty”) which is located on Cottonwood Road (County road 1700 east) approximately one-quarter mile north of County road 1850 North (see map).  Registration will begin at 8:00 a.m. and refreshments (coffee, juice, and doughnuts) will be available.  Preregistration is not required,…

Persistent wet field conditions have increased the likelihood that many farmers will opt to take the prevented planting option through their crop insurance policy.  Even though no crop will be planted, weed control practices still should be implemented to reduce seed production from summer annual weed species.  Any weed seed produced in 2019 will add to future weed control costs.  The old weed science adage “One year’s seedling equals seven years weeding” reinforces the need to adequately manage weeds on prevented planting acres.…

Much of the vegetation visible from the road is comprised of winter annual species, including the now obvious yellow-flowered species cressleaf groundsel (a.k.a. butterweed) and yellow rocket.  Some summer annual weed species, including common lambsquarters, smartweeds giant ragweed and waterhemp, also have begun to emerge.  When field conditions become conducive for planting, several possible scenarios exist for the management of existing weed vegetation.  One possible scenario is that planting will occur before any type of weed management program (tillage or herbicide application) is implemented to control existing vegetation. …

On March 1, 2019 the Illinois Department of Agriculture (IDOA) announced it will require Special Local Needs labels (referred to as 24(c) labels) during the 2019 growing season for the four commercial dicamba-containing products labeled for use in dicamba-resistant soybean varieties.  The Special Local Needs labels include five elements, one of which is a June 30 application deadline.  IDOA recognizes the importance of this technology to Illinois soybean growers and is taking this proactive step to reduce the instances of damage to dicot plant species (including sensitive soybean,…

The continual evolution of weed species and populations resistant to herbicides from one or more site-of-action groups represents one of the most daunting challenges facing weed management practitioners.  Waterhemp has evolved resistance to herbicides from more site-of-action groups than any other Illinois weed species, including resistance to inhibitors of acetolactate synthase (ALS), photosystem II (PSII), protoporphyrinogen oxidase (PPO), enolpyruvyl shikimate-3-phosphate synthase (EPSPS), hydroxyphenyl pyruvate dioxygenase (HPPD), and synthetic auxins.  The University of Illinois weed science program recently announced confirmation of waterhemp populations resistant to Group 15 herbicides (Table 1),…

Goal to reduce off-target movement of dicamba products
SPRINGFIELD, IL – The Illinois Department of Agriculture (IDOA) announced today it will require Special Local Needs labels, including new restrictions, for the use of the herbicide dicamba on soybeans in Illinois for the 2019 growing season. Dicamba is primarily used on soybeans to control post-emergence broadleaf weeds.
On February 15, IDOA notified the manufacturers of the three dicamba-containing products approved for over-the-top application to dicamba-tolerant (DT) soybeans that additional application restrictions will be required for the 2019 growing season.…

The United States Environmental Protection Agency (EPA) renewed the labels of three dicamba-containing products used in dicamba-resistant soybean varieties on October 31, 2018.  These renewed labels also contain new restrictions and requirements that did not appear on the original labels.  Each application must completely satisfy all label requirements and restrictions, but the following three new requirements might necessitate additional forethought and planning.
Additional in-field buffers
Fields that exist in counties that might harbor endangered terrestrial dicot plant species must have an in-field,…

The extension weed science programs at The Ohio State University, Purdue University, and the University of Illinois recently collaborated to revise suggestions and precautions for use of dicamba in dicamba-resistant soybean.  The United States Environmental Protection Agency renewed labels of Xtendimax, Engenia, and FeXapan last October, and this updated extension weed science publication offers additional suggestions to help further reduce off-target dicamba movement.
Dicamba Precautions_2018 Update…

The weed science programs at Southern Illinois University and the University of Illinois are participating in a research project sponsored by the United Soybean Board to survey and monitor the potential for the evolution of weeds with resistance to glufosinate and dicamba.  Early detection of evolved resistance to these herbicides could alert soybean farmers of the imposing threat in time for changes in management strategies that avoid herbicide failures.  Researchers in Illinois will collect seed from at least two of our most challenging weed species,…