Diagnostic protocols for regulated pests
Protocoles de diagnostic pour les organismes réglementés

Bulletin OEPP /OEPP 34(2):187-192. Marco Scortichini

Introduction

Symptoms caused by the bacterium currently named Xylella fastidiosa were first observed in 1892 in the grape growing region of southern California and the syndrome was called “Pierce’s disease”. Subsequently, the pathogen was reported on many fruit tree and ornamental species such as peach (phony peach), plum (plum leaf scald), almond (almond leaf scorch), citrus (citrus variegated chlorosis), pear (pear leaf scorch), alfalfa (alfalfa dwarf), periwinkle (periwinkle wilt), elm (elm leaf scorch), mulberry (mulberry leaf scorch), sycamore (sycamore leaf scorch), maple (maple leaf scald), oak (oak leaf scorch), oleander (oleander leaf
scorch), coffee (coffee leaf scorch) especially in northern and southern America. In Europe it has been found once on grapevine in the Kosovo region (ex-Yugoslavia). On the most of the host plants the pathogen induces leaf wilting, twig dieback and the decline of the plant. However, in the “phony peach” disease it is evident a reduction of the plant growth that shows shorter internodes. X. fastidiosa proliferates in the xylem vessels and natural transmission occurs via insects having a suctorial xylem sap-feeding. Transmission efficiency varies widely among vectors species. The bacterium overwinters in the xylem of the host plant as well as in weeds. From the latter it is transmitted to the host plant during spring.
This protocol currently gives methods only for strains from grapevine and citrus.