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Soil Ecology of Grape Phylloxera and the Potential for Biological Control
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| Overview | Soils in California organic vineyards contain clues to the biocontrol of grape phylloxera, an aphid-like insect that is potentially the most serious grape pest in the world. |
| Scale | field, local region |
| Location | Davis, California, USA (38.1°N, 121.5°W) |
| Elevation | 0 to 150 meters |
| Climate | Mediterranean or Dry Summer Subtropical (Cs) |
| Agricultural Region | Mediterranean Altitudinal Zone - (H12) |
| Population Density | 17 - 35 persons / square kilometer |
| Principle Crops | Grapes (Vitis sp.) |
| Domestic Animals | none |
| Soils | Mountain Soils, ustic great groups of Alfisols, Entisols, Inceptisols, Mollisols and Ultisols |
| Natural Vegetation | Grass low (GL), Needle grass-blue grass (51) |
| Ecoregion | Mediterranean Province (H11) |
| Basic Principles addressed | Minimize Toxics, Conserve resources, Manage Ecological Relationships, Maximize Long-Term Benefits |
| Page Author and Date | Chris Bley from studies compiled by the Organic Farming and Research Foundation |
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Grape phylloxera feed on sap from grape roots, inflicting damage resulting in reduced productivity and eventual death of the vines. The current solution for phylloxera infestation involves ripping out infested vines, fumigating soils using methyl bromide, and replanting with resistant rootstock strains. This costly, toxic and labor-intensive approach depends on resistant rootstock and is becoming less effective as pure resistant lines become less common over time. |
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Relying on resistant rootstock as a main defense, traditional methods for controlling phylloxera have been successful for more than 100 years. Current vineyard practices in California, however, are optimal for the selection of virulent strains of phylloxera that can overcome rootstock resistance. Growers commonly replant resistant stocks next to infested ones, creating an optimal environment for increasingly larger and stronger phylloxera colonies. As demonstrated by recent studies, soils which are suppressive to plant pathogens such as phylloxera are seen more often in organic vineyards than in conventional vineyards. Further studies and options need to be investigated, including continued research of organic vineyards suppressiveness to phylloxera root damage.
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Minimize Toxics Reducing phylloxera damage by organic practices eliminates the use of toxins that are known to harm the environment. Conserve Resources Suppressive soils may be an alternative to replacement of rootstock and fumigation, reducing farmer expenditures. Manage Ecological Relationships Biological control of phylloxera minimizes disturbance in vineyards by reestablishing ecological relationships that occur naturally on the farm instead of reducing and simplifying them. Maximize Long-Term Benefits Creating soils that resist colonization by phylloxera incorporates long-term sustainability in agroecosystem management. |
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Phylloxera Colony
Phylloxera-resistant Rootstocks for Grapevines Don Lotter Grape Phylloxera Research
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