![]() GWSS has successfully invaded French Polynesia (1999), Hawaii (2004), Easter Island (2005), and the Cook Islands (2007). The GWSS can now be found in highpopulations in areas of San Diego, Orange, Riverside, San Bernardino, Los Angeles, Ventura, Kern and Santa Barbara counties. Another huge economic problem lies in the transport of ornamentals by wholesale nurseries as this industry is subjected to rigorous inspections and mandatory insecticide applications to minimize the accidental shipment of GWSS into uninfested areas of California.ĭistribution: Since its initial introduction, the numbers of GWSS and associated problems have increased as the insect spreads throughout southern California. In the city of Tustin (Orange County), approximately $200,000 was requisitioned to pay for removal of oleanders maintained on city greenbelts and for replanting other ornamental species. It is estimated that Caltrans alone stands to suffer at least a $52 million loss if oleander on highway plantings is lost. The California Department of Transportation (Caltrans) maintains oleander in over 2,100 miles of freeway median. Oleander is found in 20% of all home gardens in California, and is a mainstay of landscapes in shopping centers, parks and golf courses. In ornamental horticulture, an important part of the landscape in the southwest will be lost if oleander leaf scorch continues to spread and resistant oleander varieties are not found. ![]() ![]() Other crops at risk include almonds (almond leaf scorch), and alfalfa (alfalfa dwarf), which are infected by the same strain of X.f.thatinduces Pierce's disease, and potentially other ornamental and fruit trees.Įconomic Impact: Currently, GWSS is responsible for outbreaks of Pierce's disease in several wine-grape growing areas of California, including Temecula, Bakersfield, Ontario, and Coachella. fastidiosa that induces a lethal disease of oleander named oleander leaf scorch. In southern California, GWSS spreads the Pierce's disease bacterium and a new strain of X. The best known of these maladies is Pierce's disease of grapevines. Different strains of this bacterium induce severe diseases in many agricultural and ornamental plants. Even more important is the capacity for the GWSS to acquire and spread a plant pathogenic bacterium, Xylella fastidiosa. In infested citrus orchards, tree canopies take on a white-washed appearance by mid-summer due to the buildup of residues after the evaporation of this watery excreta. Thus, this pest produces copious amounts of watery excreta and are a social nuisance as the liquid rains down from large populations feeding on ornamental trees. Because nutrients are diluted in xylem fluid, GWSS must process large volumes to meet nutritional needs. Damage: GWSS feeds on plants through straw-like mouthparts inserted into the xylem tissue which conducts water throughout the plant.
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