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United States Department of Agriculture

Agricultural Research Service

Title: Soil Fumigation for Liatris Production.

Author
item Gerik, James

Submitted to: Proceedings of International Research Conference on Methyl Bromide Alternatives
Publication Type: Proceedings
Publication Acceptance Date: August 27, 2004
Publication Date: November 1, 2004
Citation: Gerik, J.S. 2004. Soil fumigation for liatris production.. Proceedings of International Research Conference on Methyl Bromide Alternatives. August 2005, pg. 883-887.

Interpretive Summary: Liatris spicata (L.) Willd. also known as gay feather is grown commercially in California in open fields as a cut flower. Many weed species can quickly overgrow the sparse canopy of the crop. It is susceptible to several soil borne pathogens, including Sclerotinia sclerotiorum, which causes stem rot. Pre-plant soil fumigation with a 67/33 formulation methyl bromide/chloropicrin is commonly employed as a means of weed and disease control. The soil is usually fumigated using shank application with a polyethylene tarp over the soil. Two experiments were established to evaluate alternative fumigants applied through drip irrigation tape for Liatris production. Experiments in the fall 2002 and fall 2003 were initiated in a field located approximately 11 km south east of Carpinteria, CA. Fumigants and irrigation water were applied through 4 irrigation tapes evenly spaced over the width of the bed, and buried approximately 2 cm deep. All plots were covered with polyethylene sheeting before chemigation. The 2002 trial included 8 treatments: (1) 448 kg/ha Midas (28.5% Iodomethane + 66.5% chloropicrin), (2) 336 kg /ha Chloropicrin, (3) 577 kg/ha InLine (60.8% 1,3-dichloropropene + 33.3% chloropicrin), (4) 560 kg/ha SEP-100 (20% Sodium azide), (5) 477 kg/ha Vapam HL, (42% Metham sodium), (6) 672 kg/ha Multiguard FFA (75%) furfural + 25% allyl isothiocyanate), (7) 672 kg/ha Multiguard Protect + Vapam (50% furfural + 50% Vapam) and (8) a non-treated control. The materials were applied in 50 mm of water. The applications were made on 18 & 19 November 2002 with half the treatments made on each day. The 2003 trial, in a different area of the same field, included 12 treatments: (1) 448 kg/ha Midas (47.5% Iodomethane + 47.5% chloropicrin), (2) 477 kg/ha Vapam HL, (3) 336 kg per Chloropicrin followed a week later with 477 kg/ha Vapam, (4) 251 kg/ha InLine, (5) 251 kg/ha InLine followed a week later with 238 kg/ha Vapam, (6) 251 kg/ha InLine followed a week later with 477 kg/ha Vapam, (7) 560 kg/ha SEP-100, (8) 672 kg/ha Multiguard Protect , (9) 672 kg/ha Multiguard Protect + Vapam( 50%-50%), (10) 448 kg/ha dimethyl disulfide (DMDS), (11) 448 kg/ha DMDS + Vapam (50%-50%), and (12) a non-treated control. The materials were applied in 38 mm of water on 7 November 2003. The sequential applications of Vapam were made on 14 November in 13 mm of water. The trial was planted with corms on 24 November 2003. The best drip applied fumigants did a good job of controlling P. ultimum both years. This organism seems particularly easy to control with these chemicals. Control of F. oxysporum seems more difficult with better results the first year compared to the second. Stem rot caused by Sclerotinia sclerotiorum appeared in the trial the first season. The metham sodium, furfural + metham sodium, sodium azide, and chloropicrin with and without iodomethane treatments had significantly less disease compared to the control plots. No stem rot caused by S. sclerotiorum appeared in the second year so control of this disease could not be evaluated. Weed control, although better the first year, was not adequate for either trial. Weed pressure was much greater in the second year and control of it was minimal. Even the sequential application a week apart did a poor job of controlling weeds. Over all, some of the alternative chemicals do a fair job at disease control, but weed control is proving more difficult.

Technical Abstract: Liatris spicata (L.) Willd. also known as gay feather is grown commercially in California in open fields as a cut flower. Many weed species can quickly overgrow the sparse canopy of the crop. It is susceptible to several soil borne pathogens, including Sclerotinia sclerotiorum, which causes stem rot. Pre-plant soil fumigation with a 67/33 formulation methyl bromide/chloropicrin is commonly employed as a means of weed and disease control. The soil is usually fumigated using shank application with a polyethylene tarp over the soil. Two experiments were established to evaluate alternative fumigants applied through drip irrigation tape for Liatris production. Experiments in the fall 2002 and fall 2003 were initiated in a field located approximately 11 km south east of Carpinteria, CA. Fumigants and irrigation water were applied through 4 irrigation tapes evenly spaced over the width of the bed, and buried approximately 2 cm deep. All plots were covered with polyethylene sheeting before chemigation. The 2002 trial included 8 treatments: (1) 448 kg/ha Midas (28.5% Iodomethane + 66.5% chloropicrin), (2) 336 kg /ha Chloropicrin, (3) 577 kg/ha InLine (60.8% 1,3-dichloropropene + 33.3% chloropicrin), (4) 560 kg/ha SEP-100 (20% Sodium azide), (5) 477 kg/ha Vapam HL, (42% Metham sodium), (6) 672 kg/ha Multiguard FFA (75%) furfural + 25% allyl isothiocyanate), (7) 672 kg/ha Multiguard Protect + Vapam (50% furfural + 50% Vapam) and (8) a non-treated control. The materials were applied in 50 mm of water. The applications were made on 18 & 19 November 2002 with half the treatments made on each day. The 2003 trial, in a different area of the same field, included 12 treatments: (1) 448 kg/ha Midas (47.5% Iodomethane + 47.5% chloropicrin), (2) 477 kg/ha Vapam HL, (3) 336 kg per Chloropicrin followed a week later with 477 kg/ha Vapam, (4) 251 kg/ha InLine, (5) 251 kg/ha InLine followed a week later with 238 kg/ha Vapam, (6) 251 kg/ha InLine followed a week later with 477 kg/ha Vapam, (7) 560 kg/ha SEP-100, (8) 672 kg/ha Multiguard Protect , (9) 672 kg/ha Multiguard Protect + Vapam( 50%-50%), (10) 448 kg/ha dimethyl disulfide (DMDS), (11) 448 kg/ha DMDS + Vapam (50%-50%), and (12) a non-treated control. The materials were applied in 38 mm of water on 7 November 2003. The sequential applications of Vapam were made on 14 November in 13 mm of water. The trial was planted with corms on 24 November 2003. The best drip applied fumigants did a good job of controlling P. ultimum both years. This organism seems particularly easy to control with these chemicals. Control of F. oxysporum seems more difficult with better results the first year compared to the second. Stem rot caused by Sclerotinia sclerotiorum appeared in the trial the first season. The metham sodium, furfural + metham sodium, sodium azide, and chloropicrin with and without iodomethane treatments had significantly less disease compared to the control plots. No stem rot caused by S. sclerotiorum appeared in the second year so control of this disease could not be evaluated. Weed control, although better the first year, was not adequate for either trial. Weed pressure was much greater in the second year and control of it was minimal. Even the sequential application a week apart did a poor job of controlling weeds. Over all, some of the alternative chemicals do a fair job at disease control, but weed control is proving more difficult.

Last Modified: 12/21/2014
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