At a recent ag univ tomato seminar, there was a warning on the use of manure, hay and straw. There are some new and very 'perisitent' pesticides that remain on the hay and straw. The pesticides pass thru the animls and remain effective in the manure. One was mentioned with a two year effectiveness. Several market growers have lost acres of annual crops due to this. One prof said you have to be sure the hay or straw used for mulch or tea is not sprayed with anything. Tests are ongoing as to the long term effects on shrubs and trees.

That sounds scary BB.
I read that propionic acid is used mainly for anti rotting(preservative) and/or a means of sterilizing the tools.
What must organic gardeners do, grow their own hay/straw? I have used some hay/straw in the past and is a good mulching product. Nowadays its all in the big name stores and industrial crap.

Being in San Diego there is a moderate equestrian population, and all the feed stores(on outskirt of the county) carrier the big name crap with all the chemicals and /or nutrient additives. Alfalfa pellets, chicken grit - forgetabaddit.

I use alfalfa pellets (horse feed). You can grow alfalfa in San Diego, but I see you aren't into that. Buy alfalfa by the bale in Lakeside. Only way I know of to find out about growing practices is go or call hay suppliers in El Centro. Surprised to hear about a product made from timothy in San Diego, but that's Walmart for you. You can buy alfalfa meal for organic gardening for 5x as much from Peaceful Valley in Grass Valley, but the horse pellets do a good job.

Hope this helps. I was part of the equestrian population, by the way.

Here is info on what blueberrier1 referred to.

tj

Here is a link that might be useful: Herbicide Carryover

SoTX-thanks for the tips asking the habits of growers in El Centro. I had forgotten about El Centor's crop influence.

tsugajunkie-thanks for the link.

Pretty sad , sounds like big corp monoculture, herbicides are still with us. Wonder what their slogan could possibly be in this " green age".

People may want to read the article on page 56 of the current, Oct/Nov 2011, issue of Organic Gardening magazine about the pridine family of heprbicides appearing on the market. These are being used not only on hay fields and grain fields but on turf grasses so grass clippings should not be composted or used as mulch.

As long as you are not using the chemicals--whatever they be--on your own place, grass clippings are fine both to compost and as mulch.

Those "chemicals" in the pridine family of herbicides are Restricted Use Herbicides and can, legally, only be used by licensed pesticide applicators. If you never purchase material from a source off your own property you do not have any concerns, but if like many of us you do pick up grass clippings, bagged leaves, etc. from others there may well be some concern.