Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2007
Publication Date: 7/28/2007
Citation: Chen, J., Ledbetter, C.A., Groves, R. 2007. Susceptibility of Prunus rootstock seedlings to Xylella fastidiosa strains isolated from almond in California. American Phytopathological Society, Annual Meeting, San Diego, CA, July 2007, (abstracts of meeting not published).
Technical Abstract: Almond leaf scorch disease (ALSD) has a historical presence in California. ALSD is caused by the infection of Xylella fastidiosa, a nutritionally fastidious bacterium. In the past few years, the disease has re-emerged in the Central Valley of California. Like Pierce’s disease (PD) in grapes, there are no effective control measures for ALSD. In California, commercial almond trees are all grafted on rootstocks to maximize nut production. A majority of the rootstocks used in almond production are Prunus spp. In 2005, we performed an experiment to test the X. fastidiosa susceptibility of diverse Prunus rootstock seedlings. In this greenhouse experiment, seven seed-propagated rootstock accessions (Flordaguard, Nemaguard, Okinawa, P. davidiana, Q27839, Tsubuka No. 4, and Y113-20-99) were challenged with two strains of X. fastidiosa isolated from almond in California , both singly and in combination. We observed the characteristic leaf scorching symptom three months after inoculation in Y113-20-99. Interestingly, we also observed stunting symptoms (shortening of internodes) from strain M23 and the mix inoculation of M12 and M23. PCR and bacterial isolation also confirmed the presence of X. fastidiosa. However, no obvious leaf scorching symptoms were observed in the other Prunus rootstock seedlings during the six month test period.