From rossk@ext.missouri.eduWed Jun 12 15:26:24 1996 Date: Tue, 11 Jun 96 15:42:46 cdt From: rossk@ext.missouri.edu To: x1dlewis@exnet.iastate.edu, a.harris@mirinz.org.nz, flowers@rt66.com, gina-fernandez@ncsu.edu, sanet-mg@amani.ces.ncsu.edu Subject: alternative fumigants I have attached all the articles I received both over sanet and the small fruit mail group along with my original message so that all who are interested may learn as much about this subject as I did. My sincere thanks to everyone. Karen Ross Dallas Co., MO Extension Assistant/Water Quality rossk@ext.missouri.edu Dear Friends, I recently attended one of the research stations field days on Strawberries. There seemed to be a great dependence on chemical fumigants to control weeds, and kill every other living creature. It was mentioned that there is a variety of mustard being used as a fumigant. I am interested in finding out what variety it is. It was also suggested that there is a fairly good cropping rotation in use in the New York area to control diseases and pests. I would also be interested in this information. Thanks in advance. Karen Ross Extension Assistant/Water Quality rossk@ext.missouri.edu P.O. Box 1070 Buffalo, MO 65622 Karen, All of the brassicas and crucifers and radishes have some fumitoxic effect when used as a green manure because they contain isothiocyanates/glucosinolates which contain sulfur. However, some of the crops that are used more specifically include: rapeseed 'Humus' is the variety bred for high-glucosinolates for use as a fumitoxic green manure. Bred at Idaho State University. oilseed radish (Raphanus sp.) is big in Canada/Europe mustards used as cover crops When solarization with clear plastic is used in combination with a fumitoxic brassica, the effect is pronounced; this is limited to a high-value crop (such as strawberries) as a matter of practicality though. All of this stuff is much better in the context of a whole-farm approach that emphasizes biological processes such as crop rotation, composting, green manuring, microbial inoculants, etc. rather than a single practice (crucifer solution) within a largely chemically-dependent farming system. Take care, steve diver steved@ncatfyv.uark.edu Several researchers presented results of using cole crops, particularly broccoli, as a soil fumigant at teh 1995 Annual International REserach Conference on Methyl Bromide Alternatives And Emissions Reductions in San Dieo, Calif. For California strawberry production, see: F. V. Sances (Pacific Ag Research, Arroyo Grande, CA), and E.L. Ingham (Oregon State University, Corvallis, Oregon). For verticillium wilt control: Chang-Lin Xiao, Judith Hubbard, et al, Dept. Plant Pathology,U California- Davis. If you cannot find their addresses elsewhere, you may want to contact the conference coordinator: Margie Killacky, 3425 N. First #101; Fresno, CA 93726; tel 209-244-4710. Suzanne Cady, Extension Agent Hillsborough County Cooperative Extension Service University of Florida SWCA@gnv.ifas.ufl.edu We in New Hampshire are looking at the annual hill production system for strawberries and have relied on Chandler as our primary cultivar to date. In addition, about 100 strawberry growers in the state rely on standard short-day cultivars such as Allstar, etc. Methyl bromide use is unusual simply because there are no commercial applicators to do the job (2 growers do have their own equipment). Most growers have a 5 or 6 year rotation scheme that includes a year of Sudan grass as part of the rotation to reduce nematode pressure. For our annual hill system, we do fumigate under the plastic mulch but not in the aisles. Bill ------------------------------------------------------------------------ William Lord (wgl@christa.unh.edu) Extension Specialist, Fruits and NH State Liaison, IR-4 and NAPIAP Department of Plant Biology 137 Spaulding Hall, 38 College Road Fax: (603) 862-4757 Univ of New Hampshire, Durham, NH 03824 Phone: (603) 862-3203 ------------------------------------------------------------------------ I believe the mustard you are talking about is a rape (canola). It is used to reduce the nematode population. Other pathogens that fumigation kills may not be affected by only using the canola. I know that Dr. John Halbrendt at Penn State University Fruit Research and Extension Center, PO Box 309, Biglerville, Pa 17307 has done a lot of work with canola as a cover crop and green manure crop. However, I'm pretty sure Dr. Halbrendt has not done any work with strawberry. Especially as to annual production. agaus@coop.ext.colostate.edu or agaus@lamar.colostate.edu Al Gaus Colorado State Univ. Rogers Mesa Research Center 3060 HWY 92 Hotchkiss, CO 81419 Phone: (970) 872-3387 fax: (970) 872-3397 ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! 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. 0003216125@mcimail.com Hi Karen, I recently attended the USDA_ARS weed control field tour in Prosser, Washington. The rapeseed variety Jupiter and the brown mustard variety Green Wave both appeared fairly effective in controling weeds after incorporation. Hope this helps. Joe Bennett joeb@cfarm.com This is in response to Karen's question about brassicas as a soil fumigant. Last year I set up an experiment in a commercial pea field here in SW Washington to investigate the pest control potential of several crops planted as overwintering covercrops. I will say right off that my experiment was washed down the river in 3 successive floods this spring. Oh well - the trials and tribulations of on-farm research. But what I did learn was some of the literature on the subject. Excuse the ad nausium message. Just thought others might be interested in the topic. I am always collecting information for future reference and would appreciate hearing from others who are researching or following this topic. This is an experiment which I hope to repeat in the near future. Soil fumigants are expensive and in some cases being phased out. I think we need to seriously investigate alternatives. Managment of the cover crop is critical to the success of pest control. Winter cover crops are fall planted and plowed down in the spring. Fall planting should be timed so that the cover crop puts on enough growth before winter, but not so much growth that flowering occurs before plow down. Not only is excess vegetative growth difficult to plow down, but also, the seed can become a weed. Winter hardy plants are likely to be the most effective for pest control because it is the decomposition of green plant material which gives these plants their pesticidal properties. Correct me if I am wrong, anybody, but I do not think that a dead plant when plowed down will produce the same chemicals as decaying green tissue. I have not seen any tests of this, just my opinion. Planting of the successive crop should not occur within 2 weeks of plow down - otherwise the crop will likely suffer the same fate as the pests. The mode of action of these cover crops does not appear to be very discriminatory. They likely affect beneficial organisms as well as pathological ones. I do not know if any research has measured this, but it is my understanding. To enhance the action of the pesticidal crop, tarping is suggested - this will prevent the active chemicals from being volatilized. Weed control - small seeded weeds are the most likely to be controled due to some penetration factor. I am sure this is related to seed coat and uptake, but I do not have any results to quote. Current research includes: 2 references from SARE/ACE report: 1. 1992. Rapeseed planted as a green manure in potatoes for control of root-knot nematode. Control was up to 80%, yields were boosted 10-50%, and weed biomass was reduced up to 50% - compared to standard pesticide plots, I believe (not clearly stated in abstract). Project coordinator is Jeffrey Stark, U. of Idaho, 208-397-4181. 2. 1992. European fodder radish as alternative to aldicarb (soil fumigant) in sugarbeets for cyst nematode control. Infestation reduced 57%, yields boosted by 5 tons/A (30% greater than aldicarb-treated plots). Radish acts as a trap crop. Project Coordinator is David Koch, U of Wyoming, 307-766-3242. 1994. Weed control with green manures and cover crops - white mustard, rapeseed, annual rye, and sudangrass - in green pea, potato and mint. Kassim Al-Khatib, WSU Mt Vernon Research Station, 360-424-6121. I do not know if any results have been published yet. Some papers: Suppression of root-knot nematode populations with selected rapeseed cultivars as green manure. H. Mojtahedi, et al. 1991. J of Nematology 23(2):170-174. Managing M. chitwoodi (Columbia root-know nematode) on potato with rapeseed as green manure. H. Mojtahedi, et al. 1993. The American Phytopathological Soc. 77(1):42-46. Cover crops for root lesion nematode (P. penetrans) suppression. 1994(?), Oregon Hort Society, Diane Kaufman & Russ Ingham, OSU. Carol A. Miles, Ph.D. Washington State University Extension Agricultural Systems 360 NW North Street Chehalis, WA 98532 PHONE 360-740-1295 FAX 360-740-2792 milesc@wsu.edu at Cornell regarding the crop rotation for strawaberries. He used it w/ matted row system, northern adapted varietes. If you get any useful information on alternatives to methyl bromide could you please pass this information on to me? Thanks ********************************* Gina Fernandez North Carolina State University 207 Research Station Rd. Plymouth, NC 27962 Email:Gina_Fernandez@ncsu.edu Tel: 919-793-4428 Fax: 919-793-5142 ******************************** Karen Ross while this may be true we have had some problems with mustards such as rapinni which seems to be a collector of insects of all types which is great as long as that is not your crop i would be interested in seeing other results for the mustards especially for fumigation .how wouldyou use the mustards for this ? Martin Connaughton Wilderness Flowers Flowers@rt66.com Rt 19 Box 111-D Santa Fe, NM 87505 505 988 3096 This letter was printed the other day in the Watsonville Register-Pajaronian. It was written in response to several venomous letters from the strawberry industry assailing a local teacher for teaching about pesticides (methyl bromide) and getting her kids to write letters to the paper. Feel free to use it in your endeavors. Kert *************************** June 1, 1996 Register- Pajaronian The Editor P.O. Box 50055 Watsonville, CA 95077 To the editor, I am writing to deliver some factual evidence to the debate on Watsonville school children being educated about the hazards of pesticides. Not only do the children of Watsonville have the right to learn the truth about the health impacts of pesticide use in their communities, it is only through such education that they can begin to protect themselves from harm should they take jobs in the agricultural sector or live near farmland. The truth is, the Watsonville area, according to data submitted to the California Department of Pesticide Regulation by farmers themselves, has some of the most intensive use of pesticides in the entire state and indeed the nation. A new study published jointly by the University of California and the state found that strawberries, a major Watsonville area crop, are by far the most intense users of pesticides in California at 234 pounds of pesticides per acre of berries. That equals almost 150,000 pounds per square mile, to put it in more tangible terms. While the vast majority of this total pesticide use is made up of the soil fumigants methyl bromide and chloropicrin, over thirty different synthetic pesticides were used by the strawberry farmers of Santa Cruz County last year. This same study found that the use of pesticides has increased in recent years and that state wide, pesticide use amounts to six pounds per capita. In Santa Cruz County pesticide use totaled 1.5 million pounds in 1993, the last year for which complete data are available. Pesticide use in Monterey County totaled 8.2 million pounds that same year. County records show that in 1995 growers used almost 633,000 pounds of methyl bromide on 1,865 acres of Santa Cruz county farmland. Strawberry fields accounted for at least 80 percent of this use (506,000 pounds). In 1992, the strawberry crop was the target of 61percent of all the pesticides applied county wide ( including 98 percent of the Captan used (a Prop 65 listed carcinogen) and 79 percent of the Benomyl used (a Prop 65 listed reproductive toxin). It is not an exaggeration to say that your area is one of very heavy pesticide use, even for California. However, even more important than the heavy use of pesticides is the high potential for human illness from offsite drift of these pesticides. Breathing methyl bromide for example is serious health threat. Methyl bromide is a highly toxic gas and it never stays where it is put. According to the latest studies, anywhere from 30-60 percent gets into the air depending on the application method and weather, despite the plastic tarping placed on top. Methyl bromide goes right through plastic. It doesn't take a plastic glue failure, a strong wind or kids ripping off the plastic for there to be methyl bromide in the air around strawberry fields. Applications of methyl bromide to California strawberry fields average around 200 pounds per acre. That means 60 to 120 pounds vaporizes into the surrounding breathing space from each acre of strawberries. The Department of Pesticide Regulation and the farmers know this. But instead of monitoring how much methyl bromide is in the air, they use computer models to guess where the methyl bromide will go after it leaves the field and use this information to establish a "buffer zone" around fields where methyl bromide is used. It is dangerous to enter this buffer zone after a methyl bromide application. The DPR's methods of computer modeling have been questioned by experts in the field of risk assessment. As reported last February in the Los Angeles Times, the DPR is using an old version of the computer model and using weak meteorological data averaged statewide, instead of local weather data that gives a better picture of where the methyl bromide will drift. The scientist who developed these computer models while working for the state (now a private consultant on air pollution) compared the DPR buffer zones to more realistic buffer zones using an updated computer model and local, up-to-date weather data. He found that in Salinas for example, DPR buffer zones should be 4 to 10 times larger than currently mandated for various field sizes and pesticide application rates. A DPR buffer zone of 40 feet should be 510 feet, A DPR buffer zone of 140 yards should be more than a quarter mile. This raises serious questions about the safety of people living, working and going to school close to methyl bromide treated fields. In testimony before the California Assembly in February, Dr. William Pease, a toxicologist at UC Berkeley and the Environmental Defense Fund, illuminated the health effects of methyl bromide as a nerve toxin, a reproductive and developmental toxin, and went on to show that the state has not established methyl bromide air pollution standards to protect humans from chronic exposure to methyl bromide. Nobody is monitoring how much is in the air and the methyl bromide levels that are legally allowed in the air are derived from studies on rats and rabbits, even though primates, including humans, have been shown to be more sensitive. The one study that attempted to measure the chronic effects of low level exposure ended with six dead beagles after just a few days. It was determined by the researchers that "the cumulative effect for methyl bromide induced neurotoxicity made it difficult to estimate an exposure level which the dogs could tolerate for a 28-day or 1 year exposure study." Methyl bromide is being used near people. Subdivisions and schools are increasingly close to agricultural areas in California. An Environmental Working Group (EWG) report completed in February found that Santa Cruz county had three elementary schools and day care centers within 1.5 miles of over 25,000 pounds of methyl bromide use. Neighboring Monterey County had 24 schools within the same range and 4 schools within 2 miles of more than 80,000 pounds of annual methyl bromide use. One of these, the Ohlone elementary school, is literally surrounded by strawberry farms, a pastoral but potentially dangerous setting. In addition to methyl bromide, strawberry fields get their share of toxic fungicide and insecticide treatments as well. A recent record of pesticide applications during from March and April to a strawberry field in Castroville reads like a hit list of noxious pesticides. This one field was treated with multiple fungicides, insecticides and herbicides during the two month period: three times with Captan, twice with benomyl (Benlate), twice with iprodione (Rovral), once with metalaxyl (Ridomil), five times with Malathion, once with glyphosate (Roundup), twice with abamectin (agri-mek) and six times with sulfur along with several other compounds. Benomyl, captan and iprodione are all classified by the EPA as carcinogens. Malathion is a potent nervous system toxin. It is hardly surprising that some of the pesticides that go onto strawberries in the fields remain on the fruit when it gets to the supermarket. An Environmental Working Group report, "The Shopper's Guide to Pesticides in Produce", in which we analyzed FDA pesticide residue data, , found that when compared to 41 other fresh fruits and vegetables, strawberries ranked worst for pesticide contamination. This report is available on the World Wide Web at www.ewg.org. The facts speak for themselves and should not be obscured by those condemning the Watsonville teacher for using the classroom to convey "political" beliefs. There is nothing political about the right-to know. And one more thing, it is worth noting that Teresa Thorne, who penned a recent sharply worded letter to the Pajaronian assailing the teacher and public schools generally as havens for misinformation, failed to mention that she is an employee of the California Strawberry Commission. It is not surprising that the strawberry industry was the first to condemn the discussion of pesticides in Watsonville schools. Knowledge is a powerful thing. Sincerely, Kert Davies Environmental Working Group Washington, DC *<>*<>*<>*<>*<>*<>*<>*<>*<>**<>*<>*<>*<>*<>*<>*<>*< >*<>*<>*<>*<>*<>* Kert Davies ENVIRONMENTAL WORKING GROUP 1718 Connecticut Ave. NW, Suite 600 Washington, D.C. 20009 e-mail: kert@ewg.org EWG web page: http://www.ewg.org 202-667-6982 fax 202-232-2592 Any opinions expressed are mine and not my employer's. *<>*<>*<>*<>*<>*<>*<>*<>*<>**<>*<>*<>*<>*<>*<>*<>*< >*<>*<>*<>*<>*<>*  From woody@cfarm.comWed Jun 12 15:30:21 1996 Date: Tue, 11 Jun 1996 14:12:18 -0700 From: "DERYCKX, WOODY" To: 'sanet-mg' , 'Joel Grossman' <0003216125@mcimail.com> Subject: RE: Mustards as fumigants I personally agree with you about the value of brassicas as alternatives to soil fumigants but would like to remind us all that green manures in general have the value of generally feeding the bottom of the soil - detrital food chain which must promote an increase in soil respiration, competition, antibiosis, and at some point, biodiversity. Most any green manure crop when turned under green and young is, therefore, apt to have a beneficial effect on the disease problem potential situation on following crops. When we select soil fumigant act alike green manures such as the brassicas and sudan grass, we get the double effect of direct initial mortality to most anything in the soil including the disease causitive organisms we are concerned about plus apparently some species of small seeded weeds followed by a great energy rich food source for recolonizing saprophytes and food wed they support. Otherwise they would be of limited ecological value - just home grown cheep fumigants. I still believe that we are missing the boat by talking about "alternatives to Methyl Bromide". The fact is that Methyl Bromide IS the alternative; the alternative to good husbandry and soil health. And thanks for your excellent article in IPM Practitioner, it informed and inspired a lot of people. >---------- >From: Joel Grossman[SMTP:0003216125@mcimail.com] >Sent: Wednesday, June 05, 1996 9:52 AM >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. > > From 0003216125@mcimail.comWed Jun 12 15:38:02 1996 Date: Thu, 6 Jun 96 19:04 EST From: Joel Grossman <0003216125@mcimail.com> To: sanet-mg Subject: Mustards & Cabbage Dry Residues as Fumigants To: sanet-mg@amani.ces.ncsu.edu, rossk@ext.missouri.edu Subject: Re: mustard as a fumigant This is in response to Karen's question about brassicas as a soil fumigant. Last year I set up an experiment in a commercial pea field here in SW Washington to investigate the pest control potential of several crops planted as overwintering covercrops. I will say right off that my experiment was washed down the river in 3 successive floods this spring. Oh well - the trials and tribulations of on-farm research. But what I did learn was some of the literature on the subject. Excuse the ad nausium message. Just thought others might be interested in the topic. I am always collecting information for future reference and would appreciate hearing from others who are researching or following this topic. This is an experiment which I hope to repeat in the near future. Soil fumigants are expensive and in some cases being phased out. I think we need to seriously investigate alternatives. Managment of the cover crop is critical to the success of pest control. Winter cover crops are fall planted and plowed down in the spring. Fall planting should be timed so that the cover crop puts on enough growth before winter, but not so much growth that flowering occurs before plow down. Not only is excess vegetative growth difficult to plow down, but also, the seed can become a weed. Winter hardy plants are likely to be the most effective for pest control because it is the decomposition of green plant material which gives these plants their pesticidal properties. Correct me if I am wrong, anybody, but I do not think that a dead plant when plowed down will produce the same chemicals as decaying green tissue. I have not seen any tests of this, just my opinion. Planting of the successive crop should not occur within 2 weeks of plow down - otherwise the crop will likely suffer the same fate as the pests. The mode of action of these cover crops does not appear to be very discriminatory. They likely affect beneficial organisms as well as pathological ones. I do not know if any research has measured this, but it is my understanding. To enhance the action of the pesticidal crop, tarping is suggested - this will prevent the active chemicals from being volatilized. Weed control - small seeded weeds are the most likely to be controled due to some penetration factor. I am sure this is related to seed coat and uptake, but I do not have any results to quote. Current research includes: 2 references from SARE/ACE report: 1. 1992. Rapeseed planted as a green manure in potatoes for control of root-knot nematode. Control was up to 80%, yields were boosted 10-50%, and weed biomass was reduced up to 50% - compared to standard pesticide plots, I believe (not clearly stated in abstract). Project coordinator is Jeffrey Stark, U. of Idaho, 208-397-4181. 2. 1992. European fodder radish as alternative to aldicarb (soil fumigant) in sugarbeets for cyst nematode control. Infestation reduced 57%, yields boosted by 5 tons/A (30% greater than aldicarb-treated plots). Radish acts as a trap crop. Project Coordinator is David Koch, U of Wyoming, 307-766-3242. 1994. Weed control with green manures and cover crops - white mustard, rapeseed, annual rye, and sudangrass - in green pea, potato and mint. Kassim Al-Khatib, WSU Mt Vernon Research Station, 360-424-6121. I do not know if any results have been published yet. Some papers: Suppression of root-knot nematode populations with selected rapeseed cultivars as green manure. H. Mojtahedi, et al. 1991. J of Nematology 23(2):170-174. Managing M. chitwoodi (Columbia root-know nematode) on potato with rapeseed as green manure. H. Mojtahedi, et al. 1993. The American Phytopathological Soc. 77(1):42-46. Cover crops for root lesion nematode (P. penetrans) suppression. 1994(?), Oregon Hort Society, Diane Kaufman & Russ Ingham, OSU. > Dear Friends, > > I recently attended one of the research stations field days > on Strawberries. There seemed to be a great dependence on > chemical fumigants to control weeds, and kill every other > living creature. It was mentioned that there is a variety > of mustard being used as a fumigant. I am interested in > finding out what variety it is. > > It was also suggested that there is a fairly good cropping > rotation in use in the New York area to control diseases and > pests. I would also be interested in this information. > > Thanks in advance. > > Karen Ross > Extension Assistant/Water Quality > rossk@ext.missouri.edu > P.O. Box 1070 > Buffalo, MO 65622 Carol A. Miles, Ph.D. Washington State University Extension Agricultural Systems 360 NW North Street Chehalis, WA 98532 PHONE 360-740-1295 FAX 360-740-2792 milesc@wsu.edu From 0003216125@mcimail.comWed Jun 12 15:43:52 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. From SWCA@gnv.ifas.ufl.eduWed Jun 12 15:46:03 1996 Date: Tue, 04 Jun 1996 10:25:30 -0500 (EST) From: SWCA@gnv.ifas.ufl.edu To: rossk@ext.missouri.edu Cc: sanet-mg@amani.ces.ncsu.edu Subject: Re: mustard as a fumigant Several researchers presented results of using cole crops, particularly broccoli, as a soil fumigant at teh 1995 Annual International REserach Conference on Methyl Bromide Alternatives And Emissions Reductions in San Dieo, Calif. For California strawberry production, see: F. V. Sances (Pacific Ag Research, Arroyo Grande, CA), and E.L. Ingham (Oregon State University, Corvallis, Oregon). For verticillium wilt control: Chang-Lin Xiao, Judith Hubbard, et al, Dept. Plant Pathology,U California- Davis. If you cannot find their addresses elsewhere, you may want to contact the conference coordinator: Margie Killacky, 3425 N. First #101; Fresno, CA 93726; tel 209-244-4710. Suzanne Cady, Extension Agent Hillsborough County Cooperative Extension Service University of Florida