Pierce's Disease
Research Updates


What is Pierce's Disease?

Pierce's Disease is a bacterial infection, which is spread by bugs that feed on grapevines, particularly the "glassy winged sharpshooter." Grapevines that become infected with PD can quickly become sick and die.

glassy-winged sharpshooter

Metabolic alterations detected in Natal orange trees infected by Xylella fastidiosa

  • Author(s): Guzzo, Sylvia; Harakava, R.; Martins, Elza; Palazzo, Deniza;
  • Abstract: Leaf extracts of 14 years old sweet orange Natal grafted on Cleopatra mandarin, infected (1,6 X 109 bacterial cells /g of fresh tissue) or not by Xylella fastidiosa and extracts of detached healthy leaves treated or not with resistance inducers (xanthan gum, 10 mg/ml or Bacillus thuringiensis var. kurstaki, Thuricide-HP, 50 mg /ml), were analysed concerning their lignin and phenolic contents, and the activities of beta-1,3-glucanase, chitinase and peroxidase enzymes. The total phenolic content and the activities of beta-1,3-glucanase, quitinase and peroxidase were significantly higher in infected leaves and in treated leaves with resistance inducers than in the leaves without citrus variegated chlorosis symptoms or treated with distilled water, respectively. Cellular walls of central veins of diseased leaves showed higher lignin content than in healthy leaves.
  • Publication Date: Nov 1999
  • Journal: Summa Phytopathologica