Many of you remember that WeeBee Farms has some herbicide contamination of our Spring seedlings due to contaminated worm castings 2 years ago. We lost 1200 potted tomato and pepper seedlings.
Recently a few of my gardening customers have told me they have had confirmed herbicide contamination, and many more are telling me stories that lead me to believe they probably have had herbicide damage. (Garlic not coming up and tomatoes with gnarly, twisted leaves etc.) Usually they say they purchased straw from a local farm for mulch.
I have started advising my customers NOT to mulch your garlic unless you know for sure that it is not contaminated. Many farmers now use the long-lasting herbicides, and herbicides are commonly used on barley crops which are sold for straw. Newer herbicides can last 2-7 years and can remain that long in the manure of the animals that eat the crop that was treated. These herbicides are becoming common in lawn and garden products as well.
It's not too hard to test soil for contamination, but it takes about 3 weeks to find out. I now test my worm castings every Spring using tomato and pepper seeds as they are the most vulnerable to the herbicides used.
Here's an article link on how to test:
http://www.organicgardening.com/learn-and-grow/how-to-test-compost-for-herbicide-contamination
Testing the actual straw would be trickier and would take more time. You could chop it up and mix it with moist soil and let it compost a bit before testing the soil. If you have some straw now, you can compost a small amount over the winter then test it before using it in the spring.
