Hydraulic Conductance in Susceptible versus Tolerant Peach Seedlings Infected with Leucostoma persoonii

Abstract

<jats:p>Eight open-pollinated peach families <jats:italic>[Prunus persica</jats:italic> (L.) Batsch] were selected from a germplasm collection that was screened for tolerance to <jats:italic>Leucostoma persoonii</jats:italic> (Nits.) Höhn. [imperfect state, <jats:italic>.Leucocytospora leucostoma</jats:italic> (Pers.) Höhn] following field inoculation. The eight peach families were either susceptible or tolerant to L. <jats:italic>persoonii</jats:italic> infection based on canker length measurements. Three open-pollinated seedlings per family were chosen for evaluation. Following artificial inoculation, measurements of hydraulic conductance per pressure gradient (K<jats:sub>h</jats:sub>) were made on 2-year-old branch segments from the 24 seedlings, and safranin dye was used to mark the conductive xylem pathways. For the peach families tolerant to L. <jats:italic>persoonii,</jats:italic> the specific K<jats:sub>h</jats:sub> of the canker branch segments was greater than that for the most susceptible peach families. The inoculated branch segments from the tolerant peach families maintained ≈15% to 30% of the water transport of control segments. Safranin dye movement indicated that the sapwood in inoculated branch segments of seedlings from the susceptible peach families was almost completely blocked. Isolation experiments indicated deeper penetration of the fungus into the xylem of seedlings of susceptible than tolerant families. Xylem dysfunction appears to be correlated with a reduction in K<jats:sub>h</jats:sub>, and the seedlings in the tolerant peach families are better able to maintain water transport through the stem segment invaded by the fungus.</jats:p>

Characterization of Cytospora isolates from wood cankers of declining grapevine in North America, with the descriptions of two new Cytospora species

“…Infections are generally initiated through cracks and wounds to the bark created by wind, pruning wounds and freeze damage, and breakage of shade‐weakened twigs and branches (Tekauz & Patrick, ; Biggs, ). The disease mainly impacts branches, but can cause more destructive infections in the larger scaffolds, thus limiting the longevity and productivity of orchards (Chang et al ., ). Tree mortality in affected orchards may reach up to 5% per year, with compounding effects due to the perennial nature of the wood infections (Grove & Biggs, ).…”

Molecular phylogeny of Cytospora species associated with canker diseases of fruit and nut crops in California, with the descriptions of ten new species and one new combination

“…(Biggs & Grove 2005, Wang et al 2011, Fan et al 2015a). Cytospora species mainly impact branches, but they can cause more destructive infections in the trunks and larger scaffolds, severely limiting the longevity and productivity of orchards (Biggs 1989, Chang et al 1991).…”

Fungal species associated with apple Valsa canker in East Asia

“…It is a common species associated with Rosaceae plants, particularly with Prunus (Adams et al 2002). Cytospora canker, caused by C. leuscostoma and L. cincta, is one of the most serious diseases of peach worldwide (Chang et al 1991). C. leuscostoma has been reported from Malus hosts in China, Japan, South Africa and USA (USDA 1960;Adams et al 2002Adams et al , 2006Zang et al 2012).…”