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Using Weed Borders to Manage Insect Pests in California Cauliflower Fields
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| Overview | Weed borders are used in an agroecosystem to attract insects, facilitating colonization in the adjacent cauliflower crop. |
| Scale | field, patch, local region |
| Location | Santa Cruz, California, USA (36.6N, 122.0W) |
| Elevation | 0 to 150 meters |
| Climate | Mediterranean or Dry Summer Subtropical (Cs) |
| Agricultural Region | Mediterranean Agriculture - H |
| Population Density | >35 persons / square kilometer |
| Principle Crops | Cauliflower (Brassica oleracea L. var. botrytis L.) |
| Domestic Animals | none |
| Soils | Specific: Sandy loam General: Mountain Soils - Xeric great group of Alfisols, Entisols, Inceptisols, Mollisols and Ultisols (X5) |
| Natural Vegetation | Needleleaf evergreen trees (E), Douglas fir- Redwood (29) |
| Ecoregion | Mediterranean Province (H11) |
| Basic Principles addressed | Use Renewable Resources, Minimize Toxics, Manage Ecological Relationships, Diversify, Maximize Long-Term Benefits |
| Page Author and Date | Chris Bley from studies by Steve Gliessman |
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In a study undertaken in Santa Cruz, California, three types of half meter weed border strips were used to attract insects to cauliflower fields: 1) wild mustard (Brassica campestris) and radish (Raphanus sativus), 2) acorn spurry (Spergula arvensis) and 3) lamb's-quarters (chenopodium album). Insect populations that were attracted to and colonized the cauliflower field, both pests and beneficials, were then measured. Lamb's-quarters borders reduced the occurrence of two pests dramatically, the cabbage looper and flea beetle. The opposite was true of the mustard and radish border which attracted the cabbage looper and flea beetle, but which also attracted the greatest number of beneficial parasitoids, increasing parasitization of aphids on the cauliflower crop. |
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Populations of both harmful and beneficial insects are greatly affected by insecticide applications, reducing the role of insects in agroecosystems. Because monocultures attract insect pests, these pests have few predators in sprayed fields, so that pests must be killed with insecticides. Results from this study indicate that weed borders can help attract beneficial predatory insects to agroecosystems, giving organic farmers some degree of control over pest populations. In some cases these border strips can also repel pests, thereby slowing, delaying, or even preventing their arrival in the field while the plant is vulnerable. |
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Use Renewable Resources Planting weed borders attracts beneficial insects as an alternative to purchased insecticides, eliminating non-renewable off-farm inputs. Minimize Toxics Controlling insect pests with weed borders reduces or eliminates the use of materials that have the potential to harm the environment the health of farmers, farm workers, or the consumer. Manage Ecological Relationships Using weed borders to attract beneficial insects helps to manage pests instead of "controlling" them. Diversify Biodiversity is increased in agroecosystems by attracting insects with weed border plants. Maximize Long-Term Benefits The use of weed borders incorporates long-term sustainability into overall agroecosystem design and management. |
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Ruiz-Rosado, O. 1984. Effects of weed borders on the dynamics of insect communities in a cauliflower agroecosystem. M.A. Thesis, University of California, Santa Cruz.
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