Jacqueline Edwards

Comparison of the Molecular Tests - Single PCR, Nested PCR and Quantitative PCR (SYBR Green and TaqMan) - For Detection of Phaemoniella Chlamidospora During Grapevine Nursery Propagation

Summary. Water, callus media and plant material were sampled from commercial nurseries during two propagating seasons: 2003 and 2005. Various methods were tested for their ability to detect Phaeomoniella chlamydospora in the samples. Nested PCR and quantitative PCR were the most sensitive, although further research is required to optimise their use. When molecular techniques were used, all water samples tested positive for P. chlamydospora, indicating that the grapevine propagation process is a potential source of infection.

Impairment of grapevine xylem function by Phaeomoniella chlamydospora infection is due to more than physical blockage of vessels with 'goo'

Phaeomoniella chlamydospora is a vascular pathogen that colonises the woody xylem tissues of the grapevine. It is associated with the grapevine trunk diseases, esca and Petri disease. Infection is usually accompanied by a dark tarry substance, commonly refered to as ‘black goo’, in some of the xylem vessels. Examination of field grown Verdelho demonstrated that infection reduced xylem function by 16% for each 1% increase in ‘goo’-blocked vessels, indicating that vessel blockage is not solely responsible for loss of xylem function.

The impact of Phaeomoniella chlamydospora infection on the grapevine's physiological response to water stress Part 2: Cabernet Sauvignon and Chardonnay.

Phaeomoniella chlamydospora is a vascular pathogen that colonises the xylem tissues of the grapevine. It is associated with the diseases, esca and Petri disease, often considered to be ‘stress-related’ diseases. In glasshouse experiments using Cabernet Sauvignon and Chardonnay, stomatal conductance was higher in infected plants, implying that infection interferes with stomatal control. In Cabernet Sauvignon, leaf water potentials were lower in infected plants subjected to water stress, indicating that infection made it more difficult for the vine to get water to the leaf. This was less apparent in Chardonnay. Clearly, infection alters the grapevine response to water stress and some cultivars are affected more than others.

The impact of Phaeomoniella chlamydospora infection on the grapevine's physiological response to water stress. Part 1: Zinfandel

Summary. Phaeomoniella chlamydospora is a vascular pathogen that colonises the xylem tissues of the grapevine. It is associated with Petri disease, which is often considered to be ‘stress-related’. In glasshouse experiments using Zinfandel, stomatal conductance was higher in infected plants, implying that infection interferes with stomatal control. Leaf water potentials were lower in infected plants subjected to water stress, indicating that infection made it more difficult for the vine to get water to the leaf. Clearly, infection alters the grapevine’s physiological response to water stress.