Cultivar susceptibility and temperature-dependent recovery of Xylella fastidiosa-infected grapevines

Authors: Burbank, Lindsey

Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 10/23/2019
Publication Date: 12/19/2019
Citation: Burbank, L.P. 2019. Cultivar susceptibility and temperature-dependent recovery of Xylella fastidiosa-infected grapevines. CDFA Pierce's Disease Control Program Research Symposium. pg. 130.

Interpretive Summary:

Technical Abstract: Previous research in California demonstrated that Xylella fastidiosa (Xf) can be eliminated from infected grapevines and almond trees by exposure to cold winter temperatures. Duration and temperature of winter conditions, degree of host plant susceptibility, and time between inoculation and cold exposure are believed to play a role pathogen in rate of pathogen persistence and disease reoccurrence. Initial studies of over-winter survival of Xf a in grapevine primarily focused on climate conditions experienced in northern California regions, and included a limited range of cultivars. To better understand the dynamics of vine recovery from Xf infection following cold stress, grapevines of 3 different cultivars were subjected to cold treatment at 4°C after either 8- or 16-weeks post inoculation. Plants that underwent cold treatment at 8 weeks post inoculation were separated into two groups, one inoculated in June, and one inoculated in late August to evaluate the effect of accelerated symptom development due to hot mid-summer temperatures. All vines were tested with qPCR prior to cold treatment to determine infection status. Following 8 weeks of cold treatment, all vines were grown back from dormancy for 20 weeks and evaluated for reoccurrence of disease by symptom observation and qPCR testing. In this study, cultivar susceptibility and higher temperatures during initial infection stages had a greater impact on disease reoccurrence then duration of infection prior to cold treatment. This suggests that use of tolerant or resistant plant material should be a priority for areas at risk of Xf infection, and that summer temperatures need to be considered in addition to winter temperature and time of inoculation, when gauging likelihood of vine recovery. Further information regarding the effect of climate factors such as temperature on pathogen persistence is important to inform region-specific management strategies, and to evaluate risk of Xf spread in new areas.