Identificación del agente causante de la marchitez de proteas (Leucadendron sp.)

Abstract

Plantations of proteas are new at the department of Cundinamarca, where businesses of production of Leucadendron have been carried out. In these plantations a new disease denominated wilting has been observed. To identify the causal agent of this disease conventional plant pathological tests were conducted to isolate and to verify the pathogenicity of the causal agent under laboratory conditions. Also a molecular characterization was conducted through extraction and amplification of DNA. The DNA amplified fragment was sequenced by BigDye® Terminator v3.1 Cycle Sequencing Kit according to the manufacturer specifications in a sequencer ABI3730XL (Applied Biosystems). Under laboratory conditions the pathogenicity and disease incidence caused by two isolates of fungi obtained were evaluated on the varieties Gold Strike and Petra. The fungi were inoculated both individually and in mixture, using a completely randomized design with a factorial arrangement of 2 x 4. In the inoculations was used a suspension of 105 macroconidia mL-1 of water. Also they were evaluated under field conditions at the same concentration and on the same varieties, using a complete block design with factorial arrangement of 2 x 4. The laboratory analysis indicated the presence of two species of Fusarium, which were differentiated through the color of their colonies. According to the molecular analysis, they belong to F. oxysporum (white colony) and Fusarium sp. (red colony). It was confirmed the pathogenicity of both species on the tested varieties.