Weeds

We had another cold and mostly dry week across the state. Average temperatures this week ranged from the low teens in northern Illinois to the high 20s in southern Illinois, between 8 and 18 degrees below average. A healthy snowpack in the southern half of the state helped push nighttime low temperatures well below 0, including lows of 7 below in Taylorville and 4 below in Jerseyville. The cold end to January pushed the month as a whole to be around 2 degrees below normal statewide.…

Weed scientists at the University of Illinois and Southern Illinois University Carbondale recently announced the confirmation of glufosinate resistance in Illinois waterhemp populations. Glufosinate is a non-selective herbicide most commonly applied postemergence in Illinois corn and soybean crops engineered with resistance to the herbicide. Use of glufosinate has increased over the past decade as the efficacy of other postemergence herbicides against waterhemp has been compromised through the evolution of resistance. This confirmation marks the first time that herbicides from all site-of-action groups previously effective for postemergence control of Illinois waterhemp have instances of resistance;…

The genus Acalypha includes approximately 450 species that are mostly of tropical and temperate origin. Approximately five species are native to Illinois, although most are not considered weeds of Illinois agronomic cropping systems. One species previously known to grow in corn and soybean fields is hophornbeam copperleaf (Acalypha ostryifolia), but due to its later emergence characteristic it rarely results in crop yield loss. Other Illinois species in this genus that usually are found in non-crop areas include the common Virginia copperleaf (Acalypha virginica) and rhomboid mercury (Acalypha rhomboidea),…

The weed science program at the University of Illinois invites all weed management practitioners to our annual weed science field tour on Wednesday, June 25, at the Department of Crop Sciences field research location known as the Clem Farm, located at 1114 County Road 1200 East, Champaign. Registration begins at 8:00 a.m. and the tour will start at 9:00 a.m. Preregistration is not required, but please let us know in advance if you will be bringing a large group of participants so we can plan accordingly for meals.…

A potential scenario encountered each growing season is corn planted in fields where no soil-residual herbicide was applied. If the corn has not yet emerged, the soil-residual herbicide can be applied as originally planned. But, what if the corn has emerged and the soil-residual herbicide has not been applied? Can the application proceed as planned, or will a different product need to be selected? The answer depends on the respective herbicide.
Most, but not all, soil residual herbicides can be applied after corn has emerged.…

Utilization of soil-applied herbicides in corn and soybean production systems continues to be a common method to achieve weed control. Early preplant, preplant incorporated, and preemergence surface are the most common types of herbicide applications to soil. Regardless of when the herbicide was applied to the soil, the effectiveness of soil-applied herbicides is governed by several factors.
The primary factor which governs the efficacy of soil-applied herbicides is having the herbicide available for uptake by the germinating weed seedling.…

The weed science program at the University of Illinois invites all weed management practitioners to our annual weed science field tour on Wednesday, June 25, at the Department of Crop Sciences field research location known as the Clem Farm, located at 1114 County Road 1200 East, Champaign. Registration begins at 8:00 a.m. and the tour will start at 9:00 a.m. Preregistration is not required, but please let us know in advance if you will be bringing a large group of participants so we can plan accordingly for meals.…

This is reminder that the only two labeled formulations of 2,4-D that can be applied postemergence in 2,4-D-resistant soybean varieties are Enlist One and Enlist Duo. No other salt formulations and no ester formulations can be applied postemergence to these varieties. Ester formulations are more volatile than salt formulations and volatility can increase with the warmer air and soil temperatures that typically occur when postemergence applications are made. A bill to ban the sale and application of 2,4-D ester formulations has been introduced in the Illinois legislature multiple times;…