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Grape regulations
Introduction
Grapes (Vitis spp.) are one of the most valued cultural and economic crops in the world. Unfortunately, grape plants are plagued by many natural enemies. Regulations governing the trade of grape plants are some of the most strict and complicated in the business. This grape regulation page will cover the common pests and pathogens and the various quarantines that apply.
 
Historically, one of the most important pest outbreaks on grapes began in 1860 in Europe. A tiny aphid-like organism called grape phylloxera, Daktulosphaira vitifoliae, was accidentally introduced from North America and spread throughout Europe. Grape phylloxera feed on leaves and roots of grape plants. The resulting damage causes root girdles that lead to severe decline or death of plants. North American grapes (Vitis labrusca) are fairly resistant to phylloxera but European wine grapes (Vitis vinifera) are highly susceptible. France in particular lost nearly 90% of all of its vines by the late 1800s. As a solution, grape plants throughout Europe were replaced with vines grown on North American rootstock.
 
More recently, Xylella fastidiosa, the bacterium that causes Pierce's disease, gained a lot of attention in California. The disease was documented in California in the late 1800's, but became a major problem with the introduction of the leafhopper insect, Homalodisca vitripennis, in the 1990's. H. vitripennis, commonly known as the glassy-winged sharpshooter, was accidentally introduced into California from the southeastern United States. Pierce's disease was able to spread rapidly with the aid of this vector insect. The disease destroys the water-conducting xylem of grape plants, leading to plant death in 1 to 5 years. California mounted an extensive control effort against the sharpshooter that appears to be paying off. There are currently hotspots of Pierce's disease in Napa and Sonoma counties, and in other countries such as Mexico and Venezuela.
 
Another major concern for grape plant sanitation is viruses. Some resources claim that there are over 50 viruses known to infect grapes throughout the world. Viruses are especially worrisome because they can be difficult to detect, easy to spread, and difficult to control. Some grape viruses such as grapevine fanleaf virus (GFLV) and tobacco ringspot virus are vectored by nematodes (nepoviruses). Others such as grapevine leafroll-associated viruses (GLRaV) and corky bark disease are vectored by insects like leafhoppers and mealybugs. GLRaV is of special concern to Oregon at this time. The virus stunts plants and can reduce crop yield by as much as 40%. While GLRaV has already spread to all grape-growing regions of the world, it has a limited distribution in the Pacific Northwest.
 
The vine mealybug (Planococcus ficus) was recently introduced into California from Europe or Mexico in the mid-1990's. P. ficus, like aphid, suck sap from host plants and result in reduced plant vigor. The mealybug is also more effective in spreading GLRaV than other vectors, and also excretes much more honeydew than other mealybug species. The honeydew alone can ruin a grape harvest. Vine mealybug has rapidly spread through California since it was first detected in 1994, but it has never been found in Oregon. The ODA recently adopted an emergency quarantine order for vine mealybug on grapes being transported into Oregon for crushing or as table stock.

 


Regulations
The United States controls grape vine health through the maintenance of foundation blocks that are regularly indexed for grape viruses. Foundation blocks serve the wine and grape industry by providing high quality certified stock to growers. There are only two certified foundation blocks in the United States (University of California in Davis, and the NRSP5 facility associated with Washington State University in Prosser), although two other regional blocks (one at Cornell University in NY, and one in SW Missouri) may be added in the future. The only way that grape plants can be imported into the United States is through the Northwest Grape Foundation Service located in Prosser, WA, or through the USDA Plant Germplasm Quarantine Program in Beltsville, MD.
 

There are no federal regulations in the United States for trade of grape nursery stock among states, so individual states are free to adopt their own regulations. Five states with large grape industries have their own regulations for importing grape plants:

 

  • Oregon: Certification for freedom from glassy-winged sharpshooter and Xylella fastidiosa is required from regions where the insect is known to exist.  Field grown grape plants are prohibited. Potting media must be treated for root pests such as vine mealybug. Plants must be certified free from dangerous pests and diseases. The ODA must be notified at least one day prior to shipment of grape plants into Oregon.
  • California: There is no general exterior quarantine on grape plants. Regulation is at the county level. Plants must be certified free from grape phylloxera, grape leaf skeletonizer, and glassy-winged sharpshooter into various counties. The Pierce’s disease control program is in effect.
  • Washington: Grape plants must meet regulations for freedom from phylloxera and vine mealy bug. Plants must be tested for viruses (including GFLV, GLRaV, stem pitting and corky bark) through an official certification program. The Washington State Department of Agriculture must be notified prior to shipment of grape plants.
  • Idaho: Vitis vinifera (European wine grapes) need certification for freedom from virus diseases. All grape species need fumigation or heat treatment for pests harmful to grapes.
  • New York: Certification is required for freedom from GFLV, GLRaV, corky bark disease and the phytoplasma Flavesence dorée.

 

International trade in grape stock is highly restricted. Individual regulations vary by country but an import permit is nearly always required. Our principal nursery trade partner, Canada, will only permit grape stock from virus-indexed plants from the states of California, Oregon, and Washington. Oregon currently has 15 nurseries that are virus-certified every year and therefore have registered grape blocks that meet Canada’s requirements. British Columbia also requires that plants be treated for nematodes and grape phylloxera. As for the European Union, importing grape plants is simply prohibited.