From 0003216125@mcimail.comWed Jun 12 15:42:48 1996 Date: Wed, 5 Jun 96 11:52 EST From: Joel Grossman <0003216125@mcimail.com> To: sanet-mg Subject: Mustards as fumigants I was at the methyl bromide alternatives conference, and if my memory is correct, the problem with brassicas like mustard as a soil fumigant is that they are phytotoxic to strawberries. But for many other crops, mustards make good soil fumigants, particularly when combined with solarization. The plastic tarp used in solarization holds in the toxic gases that arise from the decomposition of the mustards [and other cole crop residues, including cabbage], providing quicker and better results than without tarping. The key with strawberries is some R&D to find out the cause of toxicity, and then find a plant variety that can be used as an alternative fumigant for the crop. But this line of research is, to the best of my knowledge, not being pursued. By the way, there is a 10-page article titled "Brassica Alternatives to Herbicides and Soil Fumigants," with a page of references on the subject, in the July 1993 IPM Practitioner [BIRC, Berkeley, CA, 510/524-2567; last I checked they were selling back issues for $5, if you're really interested in the subject]. I thought then, and still think now, that the concept of grouping fumigant green manure/cover crops is a good one. The major limitation is that when dealing with home-grown botanical products, there will be variations in levels of the toxicants in the plants and efficacy due to climate, soil, growing conditions etc. Also, these plant chemicals are not always benign -- remember the famous mustard gas of World War I was a product of these same brassicas. Joel Grossman disclaimer: I wrote the brassica article for the IPMP referred to above.