Progress 10/01/02 to 09/30/06
Outputs
Research has shifted from applying bioherbicides to working with cropping systems that have greater weed seed mortality, possibly due to increased weed seed pathogen activity. Many California vegetable crops are now routinely established with transplants. If soil pathogens attack weed seeds but do not affect transplants, we have a system for weed control with reduced herbicide and other inputs. We are nearing the end of our multiyear tillage experiment. We found significantly higher mortality of weed seeds when soil organic matter increased. It is hypothesized that the organic matter supports higher populations of weed seed pathogens. Current research centers on how increasing organic matter affects the diverse cropping systems of the desert region.
Impacts
Research shows that organic amendments have benefits beyond soil fertility. They may also reduce reliance on pesticides. On farm use of organic amendments may also be a way of recycling urban yardwaste. We appear to have shown reduced weed populations as yet another reason to encourage organic amendment of low organic matter soils.
Publications
- No publications reported this period
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Progress 01/01/05 to 12/31/05
Outputs
Research has shifted from applying bioherbicides to working with cropping systems that have greater weed seed mortality, possibly due to increased weed seed pathogen activity. Many California vegetable crops are now routinely established with transplants. If soil pathogens attack weed seeds but do not affect transplants, we have a system for weed control with reduced herbicide and other inputs. We are nearing the end of our multiyear tillage experiment. We found significantly higher mortality of weed seeds when soil organic matter increased. It is hypothesized that the organic matter supports higher populations of weed seed pathogens. Current research centers on how increasing organic matter affects the diverse cropping systems of the desert region.
Impacts
Research shows that organic amendments have benefits beyond soil fertility. They may also reduce reliance on pesticides. On farm use of organic amendments may also be a way of recycling urban yardwaste. We appear to have shown reduced weed populations as yet another reason to encourage organic amendment of low organic matter soils.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/31/04
Outputs
Research has shifted from applying bioherbicides to working with cropping systems that have greater weed seed mortality, possibly due to increased weed seed pathogen activity. Many California vegetable crops are now routinely established with transplants. If soil pathogens attack weed seeds but do not affect transplants, we have a system for weed control with reduced herbicide and other inputs. We are nearing the end of our multiyear tillage experiment. We found significantly higher mortality of weed seeds when soil organic matter increased. It is hypothesized that the organic matter supports higher populations of weed seed pathogens. Work for the coming year will emphasize information dissemination.
Impacts
Research shows that organic amendments have benefits beyond soil fertility. They may also reduce reliance on pesticides. On farm use of organic amendments may also be a way of recycling urban yardwaste. We appear to have shown reduced weed populations as yet another reason to encourage organic amendment of low organic matter soils.
Publications
- Ngouajio, M. and M.E. McGiffen, Jr. 2004. Sustainable vegetable production: effects of cropping systems on weed and insect population dynamics. Acta Hort. 638:77-83.
- Ogbuchiekwe, E.J., M.E. McGiffen, Jr., and M. Ngouajio. 2004. Economic return in production of cantaloupe and lettuce is affected by cropping system and management practice. HortScience 39:1321-1325.
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Progress 01/01/03 to 12/31/03
Outputs
In 2000, we observed decreased emergence of common lambsquarter and other annual weed species when desert soils were amended with composted yardwaste. Since then, the population dynamics of the weeds was directly correlated with the amount of organic matter added to the soil, and did not appear to be affected by tillage (reduced or conventional) or whether the plots were farmed organically or conventionally. In the summer of 2003, experiments were conducted to determine if the suppression of weed emergence was directly related to weed seed pathogens. Known quantities of common weed (common lambsquarter, pigweed, common purslane) seed were established in a factorial design that included various levels of tillage and organic soil amendment. There were no observed differences in weed seed emergence, and no seed pathogens were recovered. A search for an improved experimental design has begun to allow for better recovery of weed seed.
Impacts
Research shows that organic amendments have benefits beyond soil fertility. They may also reduce reliance on pesticides.
Publications
- Ngouajio, M., M.E. McGiffen, Jr., and C.M. Hutchinson. 2003. Effect of cover crop and management system on weed populations in lettuce. Crop Protection 22(1):57-64
- Ngouajio, M., and M.E. McGiffen, Jr. 2002. Going organic changes weed population dynamics. HortTechnology 12:95-99.
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