How late can you apply post emergent soybean herbicides without causing significant injury and yield reductions? Most herbicide labels specify a maximum crop stage (Table 1). A three year study by Dr. Peter Sikkema reveals that of all the herbicides tested, Pursuit (imazethapyr) and Pinnacle SG (thifensulfuron) should not be applied at advanced crop stages […]
In any given year, as much as 32,000 acres of Ontario corn is re-planted due to uneconomical plant stands. A two year study conducted at the University of Guelph demonstrated that either Assure II + Sure Mix, Excel Super or Select + Amigo could be applied the day before replanting corn to effectively control a […]
The majority of growers, crop consultants and researchers will tell you that it is always better to manage dandelions in the fall then in the spring. Fall management simply is more effective. The photo below clearly illustrates this point. The outside rounds of this field were managed last fall and there is an obvious difference […]
Co-Authors: Dr. Peter Sikkema (University of Guelph) Growers looking to optimize efficiency of field operations often inquire about applying a herbicide with 28% urea ammonium nitrate (UAN) as a carrier. In theory it makes sense. An application of 28% UAN at 400 L/ha (42 US gal/ac) as a carrier with a herbicide would save a […]
We in the weed science business are pretty good at telling producer’s to manage perennial weeds in the fall because they are controlled much better. Although its nice to believe without question, quantitative proof is always better. I recently came across a University of Guelph research report from 1977 (I was still in diapers) that […]
Co-Authors: Dr. Peter Sikkema, Dr. Clarence Swanton & Dr. François Tardif (University of Guelph) Field studies at Elora and Woodstock have evaluated soybean herbicide treatments based on their weed control efficacy and the yield protection they provided. Important differences were found among those treatments (Table 1). Table 1. Average visual control of broadleaf and grassy […]
Not surprisingly, smaller weeds are easier to control. The assumption when using a glyphosate based herbicide is that when weeds get bigger, no worries, just add more glyphosate. A recent research trial conducted by Dr. Peter Sikkema (Ridgetown Campus, University of Guelph) would suggest otherwise. Take a look at the photo below. Glyphosate tolerant corn […]
The classic explanation of “too hot, too cold, too wet, too dry, too bad” surprisingly doesn’t cover all of the possible factors for why a herbicide doesn’t deliver 100% satisfaction. A recent field walk illustrated why physical obstruction and weed density are two factors that are every bit as influential as environmental conditions when it […]
In wheat stubble fields to be planted with corn, there was an unacceptable level of volunteer wheat plants that had emerged after the late September glyphosate application. Volunteer wheat is worth controlling since a modest density of 20,000 plants/ac, when left uncontrolled has resulted in corn yield losses of 5% in Ontario*. It’s best to […]
Here is a summary of herbicide injury scenarios in soybeans (glyphosate tolerant), white beans, kidney beans and adzuki beans showcased at the South West Crop Diagnostic Days in Ridgetown on July 6th and 7th, 2011. Scenario 1: Sandea (halosulfuron) is currently not registered in Ontario. Above is a post-emergent application of the 70 g ai/ha […]
Above average precipitation in the spring of 2011 has illustrated for many, areas within their fields that are slower to drain and even prone to have standing water (see below). Certain herbicides are at greater risk of causing crop injury in areas where there is standing water. The reasons are two fold. First, the plants […]