Weeds

Nearly all herbicide labels (soil-applied or postemergence) have rotational crop intervals that specify the amount of time that must elapse between herbicide application and planting a rotational crop.  This becomes particularly important with late-season herbicide applications.  These intervals are established to reduce the likelihood that herbicide residues will persist in sufficient quantities to adversely affect the rotational crop.  Some herbicide rotational restrictions are based solely on time, while other factors, such as soil pH and the amount of precipitation received after herbicide application,…

As a reminder, dicamba-resistant soybean fields that exist in counties that might harbor endangered terrestrial dicot plant species and that will be treated with dicamba must have an in-field, 57-foot omnidirectional buffer. The new 57-foot buffer will occur on three sides of the field and be in addition to the required 110-foot downwind buffer.  Non-sensitive areas, as defined in the renewed labels, can be included in the omnidirectional buffer calculation.  This new buffer requirement includes fields in at least 27 Illinois counties (Figure 1).…

Applying soil-residual herbicides with non-residual, foliar-applied herbicides can help reduce additional weed emergence following application and, therefore, reduce the need for another application later.  The “lateness” of this year’s soybean crop undoubtedly will decrease the number of acres where layered residuals are applied, but nonetheless keep in mind that labels for most soil-residual herbicides used in foliar applications include soybean growth stages or time intervals beyond which applications cannot be made.  Additionally, these labels include time intervals for rotational crops,…

SPRINGFIELD, IL – The Illinois Department of Agriculture (IDOA) announced today it will extend the application date the herbicide dicamba can be applied on soybeans in Illinois for the 2019 growing season until July 15. In February, the Department approved state-specific labels allowing for dicamba use on soybeans only until June 30.  Dicamba is primarily used on soybeans to control post-emergence broadleaf weeds.
“Due to the extraordinary wet weather seen in this state during the spring planting season and with still over 50% of the soybean crop to be planted,…

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.…