|A. Reduction of the
||a) Treatment of planting material|
|A. Reduction of the
||b) Inspection, certification,
Role of California Department of Food and Agriculture Division of Plant Industry
Designated Pest Status Ratings for Nematodes in California:
Nematode Act and associated quarantines provide an excellent example
of regulatory activities to control the spread of a
|A. Reduction of the
C. Increase in carrying capacity.
|c) Grower, advisor
|A. Reduction of the initial population.||d) Restriction of
Rate of Spread of Plant-Feeding Nematodes
The rate of movement of nematodes in soil from a point source would be quite slow if dependent only on their own activity. Active movement might be around 3 to 5 feet per year, and probably would only occur if there was food available within that radius. However, significant movement of nematodes is generated by natural and anthropogenic forces.
Nematodes with stages that are resistant to desiccation may be spread widely and for long distances in blowing dust. Wind spread of cysts of Heterodera avenae across desert regions between cereal production areas has been measured in Australia (Meagher et al).
Nematodes are readily and rapidly spread throughout a field, and among fields, by irrigation water, run-off, engineered drainage systems, and flood water.
Many nematodes, particularly endoparasites are consumed in plant material by birds and other animals (Martin). They successfully survive passage through the digestive tract and become point-source infestations along migration patterns or within territorial boundaries. Their introduction into the New Polder region of the Netherlands after reclamation of land from the sea has been associated with migratory birds.
Movement from field to field also occurs with contaminated soil adhering to vehicles and custom tillage and harvesting equipment. Consider the potential for nematodes being spread from field to field on the tires of tomato trailers and tomato harvesters that are currently swarming over Solano and Yolo counties.
Movement of the soybean cyst nematode (Heterodera glycines) in the Midwest has been associated with the purchase of used equipment from established soybean areas for use in new areas of production.
Such spread results in single or multiple point-source infestations in a new field and, left undisturbed, might take several years to become evident. However, tillage and water movement are the norm. In the irrigated agriculture of California there may be 9 to 11 separate tillage operations conducted in a field after harvest of a crop in late summer to prepare it for the new crop in the spring.
Consider the spread of water across fields in winter rainfall areas where compacted layers and decline of soil structure, resulting from intensive tillage, diminish porosity and water infiltration.
Further, consider the frequency of furrow irrigation during the summer crop. There is enormous movement of soil and its resident organisms within a field in a single year. Spread throughout a field from a point-source infestation will probably occur in one or two years under conventional production practices in annual crops in California.
The most important determinant of rate of spread in agriculture is the movement of infested plants. That underlies the rationale for the existence of the CDFA Nematode Exclusion Division.
Especially important is the import of plant material that will be used
to propagate nursery stock, and the subsequent distribution of that
nursery stock. Sale and movement of infested nursery stock, seed or
The pattern of distribution among fields is probably most intense closer to the nursery but, depending on the area serviced, may be statewide or even across state boundaries.
So, in summary, the most significant determinants of the rate of
spread of nematodes are not the innate activity of the organisms but
somewhat unpredictable effects of physical conditions, cultural
operations, and topography, and market patterns.
Spread Potential of Some Example Nematodes
Regulatory Actions to Minimize Spread of the Golden Nematode, Globodera rostochiensis, in the United States
Soon after the golden nematode was discovered in the United States, the New York State Department of Agriculture and Markets took action to prevent its spread under the broad coverage of the state's "Agriculture and Markets Law". In 1944, New York State enacted a specific quarantine against the golden nematode. The quarantine was drafted in consultation with USDA regulatory officials. The quarantine has been modified and amended with changing conditions, new information, and development of management tactics.
The Golden Nematode Act
In 1948, the Federal Government, through the Congress of the United States, announced the Government's policy for the protection of the potato and the tomato industries from the golden nematode. The Government's policy was set forth in the Golden Nematode Act, Title 7, U.S. Code, (See. 150-150g). The act stated, "It is the policy of the Government of the United States independently or in cooperation with State or local governmental agencies and other public and private organizations, associations and individuals to eradicate, suppress, control, and to prevent the spread of the pest." The Secretary of Agriculture is empowered, either independently or in cooperation with States and other agencies, to make inspections, apply suppressive measures, enforce quarantine, enforce restrictions on planting tomatoes and potatoes, destroy tomatoes and potatoes growing in soil found infested with or, exposed to, infestation of the golden nematode, and to compensate growers in areas infested with or exposed to infestation of the golden nematode for not planting tomatoes and potatoes or for losses resulting from destruction of crops. The mandatory restrictions on planting or destruction of crops must be supported by similar State authorizing legislation.
The following are the basic provisions of the New York State Golden Nematode Quarantine:
Spears, J.F. (1968) The Golden Nematode Handbook: Survey, Laboratory, Control, and Quarantine Procedures. Agriculture Handbook No. 353, Washington, D.C.
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