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Weed control, management, ecology, and minutia
Comments:
by Brad Hanson
on May 11, 2011 at 10:01 PM
A followup comment to this story. The lab analysis indicated that the leaf tissue had 0.33 PPM (parts per million) glyphosate. That would not be an especially high concentration if there were older (less affected) leaves but given that these trees have no other leaves, 0.33 ppm glyphosaste is quite damaging.  
Brad
by Donna Anguiano
on May 20, 2011 at 10:50 AM
Thanks, I relocated a few carpet roses in a Wedding Garden - the roses were cut/pruned back very hard/ no visable leaves. I was very careful not to spray the stock. When the garden began to show signs of spring growth, I had three roses with this same leaf configeration. I was certain that it was glyphosate damage. Thanks for this shared info and the photos to show others so we can avoid this problem. Wine and Roses Hotel Restaurant and Spa
by Brad Hanson
on May 20, 2011 at 2:50 PM
Donna,  
I have caused the same type of injury on my own roses. Just like on the almond trees in the post, roses with glyphosate injury will usually express the symptoms as yellow chlorotic leaves, stunted leaves, and shortened internodes giving a "witches broom" appearance. Glyphosate and other amino acid inhibiting herbicides have the fastest and greatest activity in the areas of the most new growth like the shoot tips or new buds.  
 
Roses and similar plants can be very sensitive to herbicides like glyphosate because of their thin bark. Exposure via drift or even a few droplets on leaves, canes, or other above-ground tissues can result in pretty obvious symptoms. If the damage is not too severe, your roses will probably recover just fine although they may look pretty tough for a month or so. Good luck.
by Brad Hanson
on June 13, 2011 at 8:32 AM
A follow up to my earlier follow up. The injury observed in this orchard was traced back to a completely unexpected (by me anyway) exposure to glyphosate. Before planting, the planting crew sorted and prepared the dormant, bare-root trees on a cement floor on which glyphosate had been spilled (sprayer storage area). Some of the trees apparently picked up enough glyphosate up from the wet floor to cause the injury we observed in the field a few months later. An interesting twist for sure.
by JESUS AVILA
on July 10, 2014 at 11:05 AM
Very interesting the observations.I have detected some pecan trees with overgrowth at 20-30 cms.upper ground level and bark Split.No pathogens were found .However 3 mounth ago the orchard was applied with Glyphosate for weed control.The tres are 1.5 year old.Is posible this syntoms are caused for Glyphosate?.The orchard is in the Caborca,Sonora Mexico.
Reply by Brad Hanson
on July 11, 2014 at 8:05 AM
Jesus,  
I've never seen the symptoms you've described that could be attributed to glyphosate. That's not generally the symptomology that would be expected from that mode of action. Although I'm certainly not an expert in pomology, this overgrowth sounds more like something related to rootstock-scion compatibility.  
Good luck,  
Brad
by Alan Miner
on April 17, 2015 at 9:18 AM
Hello Brad,  
We had a Tomato field that was treated with glyhosate 5 days before planting. Only the the furrows where treated and the beds where cover with plastic mulch. Tansplant tomatos where plant and the plant showed signs of yellowing and burning. Samples were send ( entire plants plant roots and all, cleaned) We got back GLP 0.038 ppm and AMPA 0.015. I havn't been able to find out if this is a high level . I don't know if the cost of replaning is needed.  
Thank You, Alan
by Alan Miner
on April 17, 2015 at 9:19 AM
Hello Brad,  
We had a Tomato field that was treated with glyhosate 5 days before planting. Only the the furrows where treated and the beds where cover with plastic mulch. Tansplant tomatos where plant and the plant showed signs of yellowing and burning. Samples were send ( entire plants plant roots and all, cleaned) We got back GLP 0.038 ppm and AMPA 0.015. I havn't been able to find out if this is a high level . I don't know if the cost of replaning is needed.  
Thank You, Alan
Reply by Lynn M. Sosnoskie
on April 17, 2015 at 11:41 AM
Hi Alan,  
 
It can be hard, sometimes, to make a decision based solely on sample test results as these numbers can vary a lot (for example, due to plant size). Colleagues of mine in the SE USA have had some problems equating AMPA values to yield loss. If you got glyphosate on the plastic, and didn't rinse it off prior to transplanting, injury could occur. What rate of glyphosate did you apply, and were any other products applied either under the tarp or in the furrows? How many days out are you from your initial injury symptoms? How does the new plant growth look? Glyphosate is translocated to new tissues so you will want to observe the appearance and growth of young leaves at least 10-14 days after initial symptom development. If you want, you can e-mail me pictures of your original injury and pictures of the newer tissues at lynn.weed.science@gmail.com.
Reply by Brad Hanson
on April 17, 2015 at 4:13 PM
Hi Alan,  
Lynn offered some good thoughts on your symptoms and I agree. The yellowing "could" be from glyphosate but the burning is not typical from that class of herbicide. Especially if only the furrows were sprayed, I'd probably investigate other causes (fertilizer?, water quality?). I don't have a lot of experience in tomato, but the level of glyphosate and AMPA that you shared is pretty low (not far above the limit of detection in many labs) and my initial thought is that it's probably incidental if glyphosate is used in the field or adjacent areas. For your frame of reference, the almond tree in the photo in this post had about 10 times higher tissue levels of glyphosate and I've seen only very slight symptoms on almond with 5 times higher levels than your sample.  
Good luck.  
Brad
 
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