|Blue cucumber seeds|
Hmm. Am I growing blue cucumbers this year? What’s going on here?
I took a closer look at the packet, which I had bought from Johnny’s Selected Seeds. This warning appears at the bottom of the packet front: CAUTION: SEED TREATED WITH THIRAM. DO NOT USE FOR FOOD, FEED OR OIL.
Later I checked Johnny’s catalog and noted that the Diva cucumber seeds were available “Treated” or “Untreated.” The “Glossary of Terms” in the catalog explains: “Treated—Seeds that have a coating of fungicides and/or insecticides intended to protect the seeds from rotting or insect damage in the soil before germination.”
A quick check on Wikipedia informed me that thiram is an organic, sulfur-based fungicide with many agricultural uses, including use as an animal repellant. The Wikipedia entry on the fungicide said thiram “is nearly immobile in clay [typical central Maryland soil] or in soils of rich organic matter [your garden]. It is not expected to contaminate groundwater because of its in-soil half life of 15 days and tendency to stick to soil particles.”
Why the packet warning? Wikipedia said thiram is “moderately toxic” if you eat it and “highly toxic” if you inhale it.
Why does a “white to yellow crystalline powder” end up as a blue coating on a cucumber seed? Perhaps it’s another warning that something is different and should be checked out. Would a more appropriate color be red?
If I reorder Diva cucumber seeds next year, I’ll have to consider whether I want to buy treated or untreated seeds. I suppose the amount of thiram on the seeds is so small that I should have no major concern, but, still, do I want to introduce another toxin—however beneficial—into my garden?
Note: I queried Johnny’s about thiram on July 3 and have not yet received a response.