With three consecutive days of morning frost in many parts of the province, the two most common questions are 1) Will the corn be alright? and 2) When can I start to apply herbicides? Question 1 is answered nicely by Greg Stewart in this story (the abbreviated version is that things will be fine but if […]
co-authors: Dr. Clarence Swanton and Dr. Francois Tardif You may be faced with a scenario where there is an abundance of weeds at or near the maximum leaf-stage for effective control, yet the soybean crop is not at the growth stage specified on the product label. As a producer or consultant, do you focus on […]
With an increase in the number of confirmed populations of glyphosate resistant Canada fleabane in Ontario, many are looking for ways to control these populations and to eliminate any seed production. Management options in soybeans have been discussed in an earlier post, but with weed control in cereal crops imminent it is worth reviewing the […]
Below is a summary of all weed samples sent into the University of Guelph by producers and agronomists that suspected resistance to a particular herbicide during the 2012 season. Also included are herbicide options with different modes of action that are effective on each species. The latest summary of glyphosate resistant Canada fleabane and Giant […]
How do you control chickweed in alfalfa? It is a question asked annually. If you don’t know what chickweed is search it on google images. Of course there is always www.weedinfo.ca. There are three main points on chickweed infesting an alfalfa crop that I have learned over the years. Any herbicide that is effective at controlling chickweed […]
It seems to be an annual question. Do I add ammonium sulfate (AMS) to glyphosate? Will it improve weed control especially if my water source is hard? The short answer is no. Skeptical? I understand. There are many areas within the United States that insist the addition of ammonium sulfate (AMS) to glyphosate is critical, […]
Below are examples of corn and soybean injury demonstrated at the FarmSmart field expo, July 12, Elora Research Station (University of Guelph) Scenario 1: Just this past spring, I had contact with a producer who had accidentally applied Guardian Plus (glyphosate + chlorimuron + flumioxazin) post emergent to his glyphosate tolerant soybeans. This mistake is […]
Below is an overview of herbicide injury scenarios presented at the SouthWest Crop Diagnostic Days . Scenario 1: A field of corn has been replanted due to a poor stand. After planting the producer has decided to remove the existing stand as it is effectively a weed to the new crop. Unfortunately weather delayed the graminicide […]
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 […]
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 […]