Canker and fine‐root loss of Malus sieversii (Ldb.) Roem. caused by Phytophthora plurivora in Xinjiang Province in China

Abstract

In recent years, the distribution and population of the Xinjiang wild apple, Malus sieversii, a protected vulnerable plant among endangered rare germplasm resources of China, have been decreasing. A field survey conducted during 2015–2017 detected decline and dieback of Xinjiang wild apple in the Yili region in Xinjiang Province. Two Phytophthora spp. were isolated from cankers and soil samples around symptomatic M. sieversii trees: One isolate was shown to cause infection, based on Koch's postulates. The isolate was identified as Phytophthora plurivora based on morphological features, physiological characteristics, ITS1–5.8S–ITS2 rDNA and cox1 sequence analyses. This is the first report of P. plurivora pathogenicity on Xinjiang wild apple in Xinjiang Province in China, constituting a new host for this pathogen. The potential of P. plurivora to cause damage in pure stands of Xinjiang wild apple in Xinjiang Province should be determined.

Phytophthora Species from Xinjiang Wild Apple Forests in China

“…This species can cause dieback and root loss and is most frequently associated with cankers in Europe, North America, and Asia [31][32][33][50][51][52][53][54][55]. Via the examination of plant tissues and soil samples, it has been reported to cause cankers in wild apple forests in Xinjiang [17], corroborating its discovery in stream water and soil samples in the present study.…”

“…Some of these Phytophthora species, including P. cactorum, P. cinnamomi, and P. plurivora, have shown strong involvement in the decline and dieback of forests, while the exact role in forest ecosystems of many other species, such as P. cryptogea, P. chlamydospora, and P. gonapodyides, is unclear [16]. In a recent study, P. plurivora was found to cause damage to the fine roots and stems of M. sieversii in the declining wild fruit forests of Xinjiang Province, China [17]. However, the findings described in that report were based on a limited number of samples.…”