Wild parsnip is a common weed in eastern Ontario, and is spreading in many other parts of the province. It is a biennial, or short-lived perennial (Figure 1). While wild parsnip does not have the notoriety of giant hogweed, its sap does contain some of the same chemicals (furanocoumarins). When these compounds come in contact with the skin, they cause…
The following 10 herbicide injury related scenarios where showcased at the 2013 South West Diagnostic Days held at the University of Guelph, Ridgetown Campus. These scenarios are either duplications of common mishaps that have occured in Ontario or a “look and see” based on farmer or agronomist query. It is important to point out that some of the scenarios shown…
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 you are nervous person like…
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 targeting the weeds when at…
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 most recent public data. 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 ragweed populations is also listed….
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 will either significantly damage the…
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, particularly for the control of…
A beautiful stand of red clover can provide as much as 75 kg of nitrogen per hectare (when at 40 cm tall) for next years corn crop. However, if the clover crop is not “killed off” in the fall, then preparing a suitable seedbed to plant next years crop in is often significantly delayed resulting in reduced yields. A review…
co-written by Horst Bohner When poor herbicide performance or late seed germination results in unacceptable amounts of weeds in a soybean crop, a pre-harvest herbicide treatment will aid in a quicker, more efficient harvest. Drier plant matter will pass more easily through the combine and will result in lower seed losses and reduced seed staining. Appropriate product selection for the…
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 understandable as Guardian (glyphosate +…
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 application and it was applied…
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 (between the 5th trifoliate stage…
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 poor stand of glyphosate (Roundup…
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 in the level of dandelions…
