Study on Soil Properties and Species Conformity of Phytophthora Species in a Pineapple Field

Abstract

Phytophthora heart rot is the most important disease associated with Phytophthora pathogen losses pineapples in the most pineapple farm in Indonesia. This work was carried out to study soil properties around pineapples, confirm Phytophthora species, and examine the soil-applied sulfur in ‘Smooth Cayenne’ MD2 pineapple. The species conformity was done molecularly by sequencing cytochrome c oxidase 1 (COX 1) region at Oomycete Research Laboratory, Gifu University, Japan. The physical and chemical soil properties around the healthy pineapples (healthy soil) and infected pineapples (infested soil) were observed at Great Giant Pineapple (GGP) Laboratory. To find the effects of sulfur in lowering soil pH, about 15 kg of soil was treated with sulfur at doses of 0, 7.5, 15 and 22.5, 30 g. The species of genus Phytophthora which attacked pineapples at GGP was identified as P. nicotianae Breda de Haan (syn. P. parasitica Dastur) Tucker. The basic local alignment search tool (BLAST) search result, showing 98% similarities to the COX 1 gene of P. nicotianae. The infested soil contained significantly more clay and fewer sand particles, considerably higher soil compactness and average soil pH than healthy soil. The soil-applied sulfur, equaling a dose of 500 kg ha-1, was enough to lower soil pH from 6.3 to 5.1‒5.4 when it needed. The result showed that a strategy to control heart rot disease would be more effective when it could modify soil environment to be unfavorable for pathogens to grow and infect the plants. Further work is needed to improve integrated disease management