natural soil fumigants from plants

Keith Kridler Mt. Pleasant, Texas One of Texas A&M graduates that is now a plant pathologist for the state is saying that their research is looking good for using some plants tilled under to replace methyl bromide as a soil fumigant.
To fumigate garden soil to kill root knot nematodes and various common plant pathogens you use various varieties of Mustard, in this case he saw we were planting “Florida Broadleaf Mustard” in our Master Gardener garden. He said to grow it during the fall/winter as a complete cover crop and till it under as it matures and blooms. The chemicals in the plant that create the “hot” taste of mature mustard are lethal to a variety of soil pests. BUT it is also lethal to tomatoes and a few other common garden plants the following spring before they completely break down. It works better as a two year rotational crop and it works better when covered with plastic after tilling.
Sudan grass can be grown during the summer and tilled in while green. When it breaks down in the soil he claims it releases cyanide gas in sufficient quantities to kill off various soil pests and diseases. Both are supposed to work better if the plot is covered in plastic after they are worked into the soil. Not sure if there are specific varieties that work better than others.
In Israel they use fresh barn yard fertilizer tilling this into the soil and cover this area with plastic. The ammonia released from the loss of nitrogen in the manure can again kill off various soil pathogens.
You might check with local research centers to see what your country is experimenting with as chemicals are getting more expensive to use and harder to get in the first place. Keith Kridler