Invasive Species Compendium

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Abstract

First report of leaf spot on rubber tree caused by Lasiodiplodia pseudotheobromae in China.

Abstract

Rubber tree (Hevea brasiliensis) is an important economic crop in the tropical regions of China, which used to produce natural latex and is mainly grown in Hainan, Guangdong, and Yunnan Provinces. In August 2017, leaf spots were observed on nearly 33% of the rubber trees (n=200, clone RRIM600) in a plantation of Sanya, Hainan Province, China, and the crown disease severity rating was 5 (scale 1, 3, 5, 7, 9). The disease occurred in hot weather, with temperatures ranging from 26-35°C. The disease mainly endangers the adult leaves of rubber trees. Symptomatic leaves initially exhibited small, dark brown, round or oval spots with an obvious yellow halo, subsequently expanding into round, semicircular, or irregularly shaped gray-white lesion with scattered black spots. There was a distinct dark brown necrotic zone at the junction of the diseased and healthy tissue, surrounded by a yellow halo. Lesion expansion was not limited by the lobular veins, but the main vein. Finally, the leaves with extensive lesions gradually dried and dropped off of the plant. The causal pathogen was isolated and identified as Lasiodiplodia pseudotheobromae based on morphological characteristics, sequence analysis of the internal transcribed spacer (ITS) region, and pathogenicity test. This is thought to be the first report of leaf spot disease on rubber tree caused by L. pseudotheobromae in China.