Welcome to Chinese Journal of Tropical Crops,

Chinese Journal of Tropical Crops ›› 2019, Vol. 40 ›› Issue (1): 130-138.DOI: 10.3969/j.issn.1000-2561.2019.01.019

• Crop Pests, Diseases and Their Control, Environmental Protection • Previous Articles     Next Articles

Survey, Pathogen Identification of a White Spot Disease on Cassava and Its Biological Characteristics in China

CAI Jimiao,SHI Tao,LI Chaoping,WANG Guofen,LU Cuimei,HUANG Guixiu()   

  1. Environment and Plant Protection Institute, Chinese Academy of Tropical Agricultural Sciences / Key Laboratory of Integrated Pest Management on Tropical Crops, Ministry of Agriculture and Rural Affairs / Hainan Key Laboratory for Monitoring and Control of Tropical Agricultural Pests, Haikou, Hainan 571101, China
  • Received:2018-07-16 Revised:2018-09-23 Online:2019-01-15 Published:2019-01-15
  • Contact: HUANG Guixiu

Abstract:

During cassava disease survey from 2007 to 2018, one new leaf spot disease was found in the main cassava planting areas of China. The pathogen mainly infected the cassava leaves with densely formed round or irregular, white to tawny lesions. The disease was widely happened in Yunnan, Hainan, Guangxi and some other provinces, and most of the main cassava planting varieties and part of late breeding germplasms were also infected. The results of pathogen isolation, pathogenicity test, strain morphology observation, sequences analysis of Internal Transcribed Spacer and beta-Tubulin gene showed the disease was caused by Alternaria alternata. The pathogen in vitro cultured showed V9, OA, CA or CMA medium, 28 ℃, D-maltose, D-sorbitol or D-lactose, NaNO3, alternative light and pH 8 were the optimum conditions for mycelial growth. The optimum temperature for conidia germination was 28 ℃ and the lethal temperature for conidia was 60 ℃ remained for 5 min. Sensitivity test confirmed 10% difenoconazole WG and 25% pyraclostrobin WG had the best mycelium inhibition effect from 10 fungicides, and the EC50 value was 0.12 mg/L and 0.47 mg/L, respectively.

Key words: cassava white spot disease, Alternaria alternata, biological characteristics, fungicides