Six-year comparison between organic, IPM and conventional cotton production systems in the Northern San Joaquin Valley, California.

摘要

Three cotton production strategies (certified organic, conventionally grown, and reduced insecticide input/integrated pest management or IPM) were evaluated in the Northern San Joaquin Valley (NSJV), California, USA, from 1996 to 2001. Arthropod abundance, plant development, plant density, pesticide use, cost of production, lint quality, and yields were evaluated. The overall pest abundance was low, and the population of a key cotton fruit pest, Lygus hesperus (western tarnished plant bug), did not exceed action thresholds in any treatment. Organic fields had higher densities of generalist insect predators than conventional fields during at least one seasonal interval in all but one year. While there were no significant differences in plant development, plant densities at harvest were lower in organic fields than in conventional and IPM fields. Some measures of lint quality (colour grade and bale leaf rating) were also lower in the organic treatment than in either the IPM or the conventional treatment. Synthetic insecticides, not allowed for use in organic production, were also used in significantly lower quantities in the IPM fields than in the conventional fields. Over the 6-year period of the study, IPM fields averaged 0.63 kg of active ingredient (AI) insecticide per hectare, compared to 1.02 kg AI ha-1 for conventional fields (a reduction of 38%). Costs of production per bale were on average 37% higher for organic than for conventional cotton. This cost differential was primarily due to greater hand weeding costs and significantly lower yields in organic cotton compared with either IPM or conventional cotton. The average 6-year yields were 4.4, 5.4 and 6.7 bales ha-1 for organic, IPM and conventional treatments, respectively. Low world cotton prices and the lack of premium prices for organic cotton are the primary obstacles for continued production in the NSJV. [1 bale=217.72 kg].