|Fennimore, Steve - UNIVERSITY OF CA-DAVIS|
|Haar, M. - UNIVERSITY OF CA-DAVIS|
Submitted to: Proceedings of Methyl Bromide Alternatives Conference
Publication Type: Proceedings
Publication Acceptance Date: November 6, 2000
Publication Date: N/A
Technical Abstract: The phase-out of methyl bromide requires the development of alternative fumigant systems for both nursery and fruit production systems. Alternative fumigants in evaluation include chloropicrin alone, iodomethane plus chloropicrin mixture 50:50, 1,3-D plus chloropicrin mixture 65:35, and metam sodium. Iodomethane evaluation in nursery production showed percentage viable common purslane and prostrate knotweed seed was much lower for seed treated with IM/Pic or MeBr/Pic compared to untreated seeds. Both IM/Pic and MeBr/Pic reduced the number of common lambsquarters, carpetweed and prostrate spurge. The number of little mallow was lower in the MeBr/Pic treated plots compared to controls. Less time was required to hand weed plots treated with MeBr/Pic or IM/Pic compared to untreated areas. These results suggest that the weed control efficacy of IM/Pic 50:50 at 350 lb./A was approximately equal to MeBr/Pic 57:43 at 355 to 400 lb./A. Emulsified fumigant evaluation in fruiting fields found all fumigant treatments signifcantly reduced common chickweed (Stellaria media) and shepherdspurse (Capsella bursapastoris) biomasses compared to the untreated check. Bur clover (Medicago polymorpha) and little mallow biomass was greater in the MeBr/Pic treatment than in the untreated check. Results indicate that drip-applied 1,3-D + Pic EC provided better weed control than similar rates of shank-applied 1,3-D + Pic. Similarly, drip-applied Pic EC provided better weed control than shank-applied Pic. Sequential applications of metam sodium did not improve the weed control provided by drip-applied 1,3-D + Pic EC or Pic EC.