Author
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AJWA, HUSEIN - USDA, ARS, WMRL |
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Submitted to: HortScience
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 2/1/2003 Publication Date: 2/1/2003 Citation: N/A Interpretive Summary: Use of methyl bromide, a soil fumigant used before planting several high valued horticultural crops such as strawberry, tomato, and pepper, is being phased out. Replacement fumigants such as Telone, chloropicrin and metam sodium, may not be as effective as methyl bromide. Field trials were carried out to determine weed control effectiveness of these alternatives when injected directly into the soil and when applied with water through drip irrigation systems to strawberry beds under plastic mulch. Telone and chloropicrin controlled weeds as well as methyl bromide. These two fumigants, when applied through the drip irrigation system, controlled weeds somewhat better than with direct injection, although good control near the edge of the beds depended upon adequate water distribution through the bed. Metam sodium alone did not control weeds as well as the other fumigants, and did not improve weed control significantly when used in combination with the other fumigants. These studies indicate that adequate weed control in strawberry is possible with alternative fumigants Telone and chloropicrin. Technical Abstract: The loss of methyl bromide (MB) as a soil fumigant has created the need for new weed management systems for crops such as strawberry (Fragaria xananassa Duchesne). Potential alternative chemicals to replace methyl bromide fumigation include 1,3-D,chloropicrin (CP), and metam sodium. Application of emulsified formulations of these fumigants through the drip irrigation system is being tested as an alternative to the standard shank injection method of fumigant application in strawberry production. The goal of this research was to evaluate the weed control efficacy of alternative fumigants applied through the drip irrigation system and by shank injection. The fumigant 1,3-D in a mixture with CP was drip-applied as InLine (60% 1,3-D plus 32% CP) at 236 and 393 L ha-1 or shank injected as Telone C35 (62% 1,3-D plus 35% CP) at 374 L ha-1. Chloropicrin (CPEC, 95%) was drip-applied singly at 130 and 200 L ha-1, or shank injected (CP, 99%) at 317 kg ha-1. Vapam HL (metam sodium 42%) was drip-applied singly at 420 and 700 L ha-1. InLine was drip-applied at 236 and 393 L ha-1, and then 6 d later followed by (fb) drip-applied Vapam HL at 420 and 700 L ha-1, respectively. CPEC was drip-applied simultaneously with Vapam HL at 130 plus 420 L ha-1 and as a sequential application at 200 fb 420 L ha-1, respectively. Results were compared to the commercial standard, MB : CP mixture (67:33) shank-applied at 425 kg ha-1 and the untreated control. Chloropicrin EC at 200 L ha-1 and InLine at 236 to 393 L ha-1 each applied singly controlled weeds as well as MB : CP at 425 kg ha-1. Application of these fumigants through the drip irrigation systems provided equal or better weed control than equivalent rates applied by shank injection. InLine and CPEC efficacy on little mallow (Malva parviflora L.) or prostrate knotweed (Polygonum aviculare L.) seed buried at the center of the bed did not differ from MB : CP. However, the percentage of weed seed survival at the edge of the bed was often higher in the drip-applied treatments than in the shank-applied treatments, possibly due to the close proximity of the shank-injected fumigant to the edge of the bed.Vapam HL was generally less effective than MB : CP on the native weed population or on weed seed. The use of Vapam HL in combination with InLine or CPEC did not provide additional weed control benefit. |
