No abstract

Platanus species are widely planted as amenity trees in temperate regions worldwide for their ability to survive in harsh urban streets and soil environments (Sanusi & Lvesley, 2020;Wood & Esaian, 2020).Belonging to the family Platanaceae, they are broad-leaved and deciduous trees. Platanus occidentalis L., commonly known as the American sycamore or American planetree, is a popular street tree in Korea (Woo, 2006). Several diseases and pests of this species are known, including anthracnose caused by Apiognomonia veneta, powdery mildew caused by Erysiphe platani, Hyphantria cunea, fall webworm and Corythucha ciliata, sycamore lace bug (La et al., 2009(La et al., , 2013.Mycosphaerella leaf spot, caused by Mycosphaerella platanifolia, appears in Platanus species including P. occidentalis (Filer et al., 1977;La et al., 2009). Taxonomic reassessments have been performed on the genus Mycosphaerella (Braun & Crous, 2006;Crous & Corlett, 1998). A fungus causing black leaf spot on P. orientalis in Australia was thus identified as Pseudocercospora platanigena (= Stigmina platani) (Carnegie et al., 2021). The fungal pathogen attacking P. occidentalis in Korea is currently known as

The performance of laboratory X‐ray computed tomography (XCT) for the non‐destructive imaging of root wood was evaluated. Lateral roots of oriental cherry (Prunus serrulata var. spontanea) and Japanese zelkova (Zelkova serrata) were severed in spring and maintained in soil for 6 months. Without sectioning, XCT revealed the phloem, xylem and vascular cambium structures in the root wood. A virtual transverse section showed a ring of woundwood covering the severed, lateral root of the two trees. Different levels of X‐ray absorption were evident around the cut surfaces of P. serrulata; however, they were rarely detected in Z. serrata. More adventitious roots were observed on Z. serrata than on P. serrulata. Distinct white spots in the rays were only detected in Z. serrata. These results suggest that XCT has potential applications in forest pathology, providing virtual sections of wound closure, wood density distribution, organ redifferentiation, and mineral deposition in root wood.

Kudzu (Pueraria montana var. lobata) is becoming one of the most prevalent climbing vines in urban forests. Here, surface characteristics of kudzu leaves and stems were investigated using field emission scanning electron microscopy and X-ray microanalysis. The leaf and stem surfaces were characterized by different types of trichomes. No adhesive pads, modified hooks, or tendrils were found on kudzu vines. Trichomes on the leaves and stems of kudzu could be categorized into: (i) complex bulbous glandular trichomes and (ii) needle-shaped nonglandular trichomes. Two morphotypes of the nonglandular trichomes were present on the stems: (i) long hairy nonglandular trichomes and (ii) short needle-shaped nonglandular trichomes. The leaf trichomes were appressed and oriented in an uphill direction, whereas the stem trichomes were appressed and oriented in a downhill direction. This opposite trichome orientation appears to facilitate climbing and prohibits slipping of kudzu vines through differential friction between the plants and the kudzu vines. X-ray microanalysis revealed a distinct accumulation of silicon in the leaf and stem trichomes. These results suggest that appressed, directed, and silicified trichomes may contribute to the twining behavior of kudzu vines.