I asked about Toxic Potting Soil in an earlier question. The rhododendron cutting I planted in a pot of Vigoro potting soil started to develop what lo...
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Toxic Potting Soil 2.0 #720450
Asked September 03, 2020, 10:14 AM EDT
I asked about Toxic Potting Soil in an earlier question. The rhododendron cutting I planted in a pot of Vigoro potting soil started to develop what looked like chlorosis. Other plants around my garden exposed to this soil as an amendment also developed yellowing of leaves and stunted top growth. Now I find out about an herbicide called AMINOPYRALID which is used on pastures and translocates into the manure of horses and cattle feeding there. The manure carries the herbicide compounds into potting soil and compost procured from commercial products--including bagged mixes, yard and garden bulk centers and...POTTING SOIL!!!
I am willing to bet that is my problem. I am very surprised that I was advised to simply put fish emulsion on my sickly baby rhododendron, after I had described using iron to fix chlorosis symptoms and additional Miracle-Gro to boost it. It did not have much effect. If it is indeed toxic potting soil, the symptoms would not be overcome. I have since moved the plant into a new pot and am monitoring it. I also plan to conduct a test by trying to germinate peas in the affected potting soil--which I saved. According to Charles Dowding in England, peas and beans are good indicator plants for toxicity to Aminopyralid.
Please let me know if OSU is doing any studies on this herbicide. I would like a link to those studies. Would you like to reconsider the advice you gave me?
Clackamas CountyOregon
Expert Response
Hi again,
Your original question described yellowing new growth and green veins, which is consistent with iron and manganese deficiency. The recommendation fish emulsion would help with both of these and provide nitrogen and other macro nutrients to spur growth.
You now describe stunted top growth, which is new information. Plant problems unfold over time.
Herbicide contaminated compost in your potting soil could be the cause.
You might contact the vendor if you determine that contaminated compost or soil mix is the cause. They may offer a refund for the material. Letting them know about the situation helps others avoid the problem.
To report suspected contamination or file a complaint about an unresponsive vendor, the Oregon Department of Agriculture (ODA) investigates pesticide complaints in Oregon.
Yes, the rhododendron had the chlorosis symptoms and two doses of chelated iron, 3 weeks apart, had no effect. MiracleGro didn't help either. It just sat there looking at me. I lifted it from the pot filled with Vigoro and rinsed the roots, put it in a different pot with old soil that had been growing chard successfully and gave it some more MiracleGro. I am still waiting for improvement.
I had also used the Vigoro soil to fill up some tomato plants in pots. The cherry tomato transplanted into one pot looked great for about a week and then just turned yellow and stunted. The other tomato plants
grew for about a week and then the tops started to curl and the foliage curled up, too. I was afraid I had curly top disease, but I raised these plants from seed and I did not bring in plants from commercial growers. It didn't look like curly top to me. I got little production and tore the vines out in frustration. I will attempt the "bio-assay" treatment with peas and beans in those pots as well. Here's one guy at OSU who has written about this: https://smallfarms.oregonstate.edu/aminopyralid-residues-compost
If you think it might help, I can keep you posted. Scientific methodology might work to figure out the problem. I have peas and beans to plant today. In another AAE thread on this site, someone had asked about pollution standards for bagged soil mixes. That had a little information, too. Anyway,thanks for your answers.
Report
of Alleged Loss Due to Pesticides Form - According to the Liability Claims
Procedure in Oregon Revised Statutes (ORS 634.172), filing a “report of loss”
protects your right to pursue civil action against the commercial pesticide
operator.
