- Author: Trina Kleist
- Posted by: Gale Perez
'Herbicide Injury" tutorial builds on popular website
A cartoon character that looks suspiciously like a Department of Plant Sciences professor leads an animated, online tutorial that recently won a 2022 Gold Award from the Association for Communication Excellence. UC Davis weed experts Kassim Al-Khatib and Brad Hanson worked with the University of California Statewide Integrated Pest Management Program to create “Diagnosing Herbicide Injury,” which debuted in October 2021 on Extension Foundation Campus.
The free, self-guided course explains how herbicides may – or may not – be the culprits behind plant maladies. The cartoon guide walks viewers through interactive slides describing common herbicide-related problems, their diagnoses and solutions; short quizzes solidify the viewer's knowledge at the end of each module. The course fulfills continuing education credits for several institutions; those who complete the course can get a certificate for a small fee.
“This project builds on previous work in which I developed an interactive website to help people investigating herbicide injury symptoms,” said Al-Khatib, the Melvin D. Androus Endowed Professor for Weed Science. The website, built in 2015 by programmer Chinh Lam of UC's Integrated Pest Management program, offers 1,500 photographs showing herbicide injuries in more than 150 crop and ornamental plants. Such problems often are caused by incorrect application, drift and carry-over from a previous crop. Visitors can look for information by crop, herbicide, chemistry, mode of action and how symptoms appear. Each year, Al-Khatib adds hundreds of new images.
“As Extension weed scientists, we often get questions about herbicide injury,” added Hanson, a professor of UC Cooperative Extension. “If you suspect an herbicide and want to find out what the injury symptoms look like, this is a really useful website.”
Al-Khatib's site proved widely popular in the agricultural community. That lead to a handful of in-person short courses the two professors offered through the UC Weed Research and Information Center, focusing on symptoms that appear in the field.
Separately, beginning in 2016, the information technology people at UC IPM were starting to put their collection of in-person courses online. They were experimenting with different formats to make online learning more attractive, said team member Petr Kosina, who developed the award-winning video. “My vision was, we needed to make the online courses more interactive, more entertaining and more engaging,” said Kosina, a plant biologist with a degree in instructional design.
Video course has ‘thousands' of potential viewers
The gold-winning video is among more than two dozen courses the UC IPM team has put online in recent years. Other team members involved in the course's development were Kimberly Steinmann, Cheryl Reynolds and Tunyalee Martin.
Programmer Chinh Lam, left, of UC's Integrated Pest Management program, built the original website about herbicide injuries. Petr Kosina, center, and Tunyalee Martin are part of the UC IPM technology team that created the gold-winning video, based on the website's information.
The video's purpose is to help people distinguish herbicide-caused injuries from those caused by dozens of other potential factors, including insects, diseases, fertilizers, poor nutrition and environmental stressors such as drought. The course describes common patterns of herbicide injury and how to use laboratory analysis to confirm potential culprits. Its audience: growers, pest control advisers, sales representatives for chemical companies, field investigators and insurance adjusters who need guidance gathering information. Nearly 170 people finished the course in 2021, and more than 80 had enrolled by mid-2022, Kosina said. "There are several thousand potential learners in California alone," Martin wrote in the award application.
The animated, cartoon guide is a stock image that Kosina doctored to riff off of Hanson's beard and rectangular glasses; Hanson also narrates. The character brings a human element to the video and puts viewers at ease. Research shows that a cartoonish approach to a topic can improve adult viewers' response when they might see the material as intimidating or dry.
Viewers, indeed, have become fans. Here are a few comments from people who have taken the online course:
- “The avatar is a kick.”
- “I do not care for cartoons, but Brad's ‘character' was great! And his manner of speaking was great – grade A+.”
- “The use of several different types of multi-media concepts combined with the methodical and well-thought-out delivery of technical information really helps keep the online participant engaged.”
The course has been approved for continuing education units by the California Department of Pesticide Regulation, the Certified Crop Adviser program of the American Society of Agronomy, and the Arizona Department of Agriculture.
RELATED LINKS: Watch a short video by the UC IPM team that describes the course, how they approached the design and addressed accessibility and diversity.
Media Resources: Trina Kleist, tkleist@ucdavis.edu, (530) 754-6148 or (530) 601-6846.
Original source: UCD Department of Plant Sciences News. July 26, 2022
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- Author: Amber Vinchesi-Vahl
- Posted by: Gale Perez
Root-inhibiting herbicides (like pendimethalin or trifluralin) are soil-applied and pre-plant incorporated as a standard practice for conventional processing tomatoes in the Sacramento Valley.
Pendimethalin was applied pre-plant, a common practice for this particular grower, but never with this result. So the question remained, “how did this happen?” If the herbicide was only in the top two inches of soil and the transplant plug/root ball is inches below that, how did the plant take up the herbicide to cause this damage?
I was told similar injury (not from pendimethalin specifically but similar herbicides) had been seen more in 2021 on tomatoes than usual, possibly because of the low water at planting.
References
- Weed Science Society of America Herbicide Handbook, 7th Edition, 1994, pages 230-233.
- NC State Extension, Herbicide Injury Factsheets, Root Inhibitors: https://content.ces.ncsu.edu/root-inhibitors
- Author: Brad Hanson
A colleague at Ohio State University (sorry, I mean The Ohio State University) shared a recent series of extension publications they put together related to specialty crop injury from the auxininic herbicides dicamba and 2,4-D.
Dicamba and 2,4-D Fact Sheet Series
Admittedly (and thankfully!) we do not have the same challenges with these herbicides in California specialty crops as they do in the Midwest where small grains, corn, and more recently dicamba- or 2,4-D-tolerant soybeans are grown on millions of acres. However, I thought these fact sheets were well done and provide relevant information with regard to herbicide drift and investigating and documenting herbicide injury.
Link to landing page: https://ipm-drift.cfaes.ohio-state.edu/dicamba-and-24-d-fact-sheet-series
/h1>- Author: Drew A Wolter
- Author: Dani Lightle
- Posted by: Gale Perez
Introduction
In order to prevent herbicide damage in young trees, especially from postemergence herbicide, standard pomological practice is to apply white latex paint to the bottom 2 to 3 feet of trunk of newly planted trees, before applying herbicides. While this may provide some level of protection, research to support this practice is lacking. In order to assess the efficacy of white latex paint in mitigating herbicide damage, a field experiment was conducted in Arbuckle, CA to evaluate the impacts of latex paint on herbicide injury in young almond trees.
Methods
To conduct this experiment, second-leaf almond trees were grouped into three categories: old paint (9-week old), new paint (2-day old), no paint (hardened-off for 9 weeks), and cartons. On June 20th, 2019 treatment combinations of different rates (see treatment table below) of glyphosate (Roundup PowerMAX), glufosinate (Rely 280), or a tank mix of both were applied. Each treatment combination had 4 replicates.
Herbicide applications
Herbicide applications were made using a CO2 backpack sprayer at 35 psi, and a spray volume of 20 gallons/acre. A single nozzle was held 18 inches from the trunk, moving vertically (from top to bottom) for one second on both the eastern and western side of the trees.
Herbicide Treatments | |
Top Label Rate | 3x Label Rate |
Glufosinate- 1.5lbs/ac | Glufosinate - 4.5lbs/ac |
Glyphosate- 2.75lbs/ac | Glyphosate - 8.25lbs/ac |
Glufosinate + glyphosate- 1.5 + 2.75lbs/ac | Glufosinate + glyphosate- 4.5 + 8.25lbs/ac |
Trunk protection
In 2017, the block used to conduct this experiment was planted with greenhouse-grown trees. Each tree came with preinstalled cartons. Nine weeks before the herbicide applications for this experiment took place, the cartons for the “no paint” and “old paint” treatments were removed for the first time, exposing green bark. Valspar interior latex paint diluted 50:50 with water was then applied using a painter's mitt to the group of trees in the old paint treatment. This also allowed for the no paint treatment to harden off for nine weeks prior to the herbicide application. Two days prior to the herbicide application, the cartons for the new paint treatments were removed for the first time (again, exposing green bark) and painted. The cartoned treatments in this experiment never had their cartons removed.
Trunk Protection |
Old Paint (9-week old paint) |
No Paint (hardened-off for 9 weeks) |
New Paint (2-day old paint) |
Carton |
Evaluations
Evaluations across three categories of tree stress were taken on a weekly basis, starting three weeks after treatment (WAT) to allow symptoms to develop.
- Trunk damage: Assessments made from 3WAT-5WAT quantified the number of individual gumming sites on each trunk (see Figure 1). No further trunk gummosis was observed starting five weeks after the herbicide applications.
Rating scale--Trunk Damage | |
1 | 0 – 10 Individual sites |
2 | 11 – 20 Individual sites |
3 | 21+ Individual sites |
- Canopy stress: Evaluations were taken from 5-8WATassessingthedegreeofinterveinalchlorosis,mottledchlorosis, spotting,stackedinternodes, necrosis and stem die back.
Rating scale--Canopy Stress 1 Coming out of stress, exhibiting new growth. 2 Damage, new growth may be present but injured. 3 Leaf drop and further necrosis; no new growth present.
- Defoliation: Ratings were taken from 5-8 WAT assessing the degree of defoliation for each tree (see Figure 2).
Rating scale--Defoliation | |
1 | Less than 25% |
2 | 25-50% |
3 | Greater than 50% |
4 | Complete defoliation |
Results
Preliminary results indicate that paint as a trunk protection method may not provide significant protection from glyphosate or glufosinate. Tree stress caused by trunk-applied herbicides was lowest in most treatments with no paint at all, which suggest that hardening of the bark is key to mitigating herbicide damage in young trees. Examples of treatment combination results shown in images and graphs below.
Trunk damage:
Five weeks after herbicide treatments, data from the top-of-label-rate tank-mix application showed a 22% increase in trunk damage in trees with old paint, and a 4% increase in damage in trees with new paint, when compared to trees with no paint.
Canopy stress:
Eight weeks after treatment, the label rate tank-mix applications showed a 29% increase in canopy stress in trees with old paint, and a 14% increase in damage was observed in trees with new paint, when compared to trees with no paint.
Defoliation:
Eight weeks after treatment, the high rate (3x) tank-mix applications showed a 40% increase in defoliation in trees with new paint, and a 20% increase in defoliation was observed in trees with old paint, when compared to trees without paint that were allowed to harden-off for 9 weeks.
Figure 2. These three images demonstrate the level of defoliation observed 5 weeks after the high rate tank-mix applications were made. Arranged in order of stress response severity: new paint (2a, above) exhibiting the highest level of defoliation, old paint (2b, above), and no paint (2c, below).
Conclusion:
Preliminary results indicate that in most treatment combinations, old and new paint as trunk protection methods did not reduce tree stress caused by trunk-applied herbicides. Allowing the bark of young almond trees to harden off for at least nine weeks reduced herbicide damage. The most efficacious trunk protection option for young almonds trees is to install a carton, though remember when cartons are eventually removed green bark may be present and susceptible to herbicide injury. Therefore, as the trees mature and cartons are removed, allow the bark on trunks of trees to harden off to minimize herbicide damage.
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- Author: Lynn M. Sosnoskie
It's that time of year again. Time to get small grains seeded, especially considering that there is the potential for a weather system to move through our area next week (Wednesday, November 21, 2018).
Water in our weather? Current forecasts suggest that rain could move through the area next week.
As we move into winter, it's also time to start thinking about the potential injury that can result due to environmental conditions. Last year, farm advisors in the Central Valley received a number of calls regarding injury to small grains (wheat, oats, triticale, etc…) that were later determined to be the result of cold injury. To address this issue, Dr. Michelle Linefelder-Miles, a Farm Advisor for Delta Region, authored a really good blog post describing the situations that she experienced. Her post can be accessed at: https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=26545.
Yellowing of small grains observed in March 2018 near Turlock, CA.
Frost injury in small grains can present as tip burn, leaf chlorosis, or stem lesions; look carefully at the whorl for dead leaves or try splitting the stem to see if the growing point is water-soaked or necrotic. Remember, other types of injuries, deficiencies, diseases, and disorders can cause similar symtomology. Alternate reasons for yellowing include nitrogen deficiency, sulfur deficiency, and injury resulting from herbicide carryover from a preceding crop. To distinguish between potential scenarios, think about the following questions:
What do other small grain field in the region look like? Are the symptoms wide-spread or isolated. Are early– and late-planted field differentially affected? Was there a significant cold spell that occurred prior to the observation of injury? You can access local weather data, online, using the CIMIS network https://cimis.water.ca.gov/Stations.aspx
What parts of the plant are affected? Is the yellowing seen on older or newer tissue? For example, nitrogen deficiencies are worse on older leaves and sulfur deficiencies on younger tissue.
What is the soil texture like? Did a significant rainfall occur? Could denitrification or leaching account for the observed symptoms? Was the field fertilized properly? What were the results from your most recent soil test? Is the soil excessively wet and are the roots stunted and unhealthy looking?
Within a field, are you observing any patterns that could suggest the movement of a pest or pathogen? Are there patterns to suggest that fertilizer applications were not made uniformly? What crop preceded small grain planting and could herbicide carryover injury account for the observed symptoms? What herbicides were applied within the small grains crop? Some ALS-inhibiting herbicides registered for use in small grains can cause injury when plants are going in cool, wet soils.
So on to the important question...will this injury result in yield loss? Unfortunately, the answer is it depends. It depends on the growth stage of the plant when symptoms develop (for example, did cold injury occur when the plants were tillering (and the growing points were more protected) or when the plants were close to heading out?). It depends on whether the symptoms can be remedied (for example, is the injury the result of herbicide carryover or is it the result of a nutrient deficiency?). Please feel free to contact your local farm advisor if you see these (or other unexplained symptoms) in the coming months.
Interested in this topic? For more information about yellowing in small grains, please see the following websites:
http://blog-crop-news.extension.umn.edu/2014/05/early-seasoning-yellowing-of-wheat.html
https://cropwatch.unl.edu/soils/nutrient-deficiency-wheat
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=26545.
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