Response of tomato (Lycopersiconesculentum Mill) infected by Phytophthora infestans (Mont.) de Bary with the treatment of copper and potassium phosphate on plant development

Abstract

Phytophthora infestans is an important disease in the highland of Karo Regency, North Sumatera, Indonesia. The disease caused a failure of tomato production. P. infestans mainly damages the leaves causing disruption to plant growth and development. This study was to evaluate the development of tomato plants infected by P. infestans treated with potassium phosphite and copper. The experimental was set in a completely random design, consisted of two factors. The first factor was copper with 2 doses namely 0 %, 0.07 % and the second was potassium phosphate with 4 level doses each 0%, 0.4%, 0.8% and 1.2%. The result showed that potassium phosphate could significantly reduce disease severity of P. infesting by 31.62 % to 36.40%, 40.26 to 63.65 % at dose of 0.4 % and 0.8 % respectively. Tomato infected by P. infestans showed a positive response to copper and potassium phosphate treatments which characterized by an increase in the plant dry weight, the plant height and the plant stem diameter. The best dry weight of plant was obtained from Cu at dose of 0.07 % and potassium phosphate at dose of 1.2 % while the plant height was obtained from Cu at dose of 0.07 % and potassium phosphate at dose of 0.4 %.