Preventative measures: Currently, the best way to manage Xylella fastidiosa is to prevent the spread of its vectors and to detect and remove infected plants as early as possible. Special attention must be given to the landscape around agricultural areas because many ornamentals can be hosts for X. fastidiosa and show no symptoms of infection. Although no chemicals are currently registered in the US for treatment of Pierce’s Disease, landscapes and agricultural crops in high-risk areas should be treated with insecticides to prevent transmission by insects (Purcell 2001). UCANR (2003) reports that a broad-spectrum of antibiotic tetracycline is being tested for the treatment of Pierce’s Disease.
Another University of California - Davis project is researching whether the infection of grapevines by X. fastidiosa can be prevented by raising the levels of essential plant bacterial micronutrients, such as zinc, iron, copper and molybdenum. Laboratory studies have established what concentrations are toxic to the bacterium and field trials are under way at UC Davis and in Temecula. These scientists are also looking at different methods of introducing the nutrients into vines, including foliar applications to leaves, tiny plastic screws inserted into vines, hand-held injection devices, and irrigation drip lines. Their strategy is to protect the plants against infection, rather than treat them after the fact. University of California scientists from Davis and Berkeley, in collaboration with colleagues from the University of Florida, are examining the effects of xylem chemistry on the spread of X. fastidiosa . The objective is to restrain the growth and colonization of the bacterium by changing the host plant’s chemistry.
Physical: Pruning is the major control method for Citrus Variegated Chlorosis in Brazil and has been effective in controlling Almond Leaf Scorch disease. However, early identification of infected branches is critical. Once the bacterium is widespread in a plant, pruning is not successful in controlling X. fastidiosa. Scientists have shown that early pruning also controls Pierce’s Disease in grapes, but the plants are not as productive following regeneration. Research is underway to determine how effective and costly this technique would be to the grape industry.
Biological: According to UCANR (2003), scientists from the Berkeley, Davis, and Riverside campuses and Cooperative Extension county offices are evaluating new methods, including the use of other bacterial species and bacteriophages (viruses that attack bacteria), for control of X. fastidiosa in host plants.