OPTIMALISASI KONSENTRASI MIKROKONIDIUM DALAM FORMULASI AGENS HAYATI FUSARIUM OXYSPORUM F. SP. CEPAE AVIRULEN DAN DOSIS PENGGUNAANNYA UNTUK PENGENDALIAN PENYAKIT MOLER PADA BAWANG MERAH

Abstract

An effective biological control agent, avirulent Fusarium oxysporum f. sp. cepae (Foc33), was developed to control moler disease on shallot and was well formulated in zeolite powder. However, its effectiveness was affected by several factors including dose of application and concentration of microcodia in the formula. This study was carried out to find the appropriate dose of application and microconidia concentration of the agent in controlling moler diseases and giving the best yield of shallot. The research was single factor with three replications arranged in completely randomized design. The treatment was the application of biological control agent of Foc33 formulated in zeolite powder with five levels, i.e. A = Control, B = the dose of 35 kg/ha (0,22 g/polybag) with the concentration of 104 spore/ml, C = the dose of 40 kg/ha (0,25 g/polibag) with the concentration of 104 spore/ml, D = the dose of 35 kg/ha (0,22 g/polibag) with the concentration of 104 spore/ml, E = the dose of 40 kg/ha (0,25 g/polibag) with the concentration of 106 spore/ml. Shallot bulb (Kuning variety) was planted in the polybag 25 cm in diameter containing planting medium of soil and cow manure mixture with the ratio of 2:1 v/v. Before planting, Foc33 was applied by placing the zeolite formula in the planting hole as much as the dose used in the treatment. Pathogen inoculation was done before Foc33 application by pouring 20 ml microconidium suspension of virulent Fusarium oxysporum f. sp. cepae with the concentration of 106 spore/ml. Moler disease intensity, growth variable (plant height, leaf number, and plant fresh weight), and yield variable (bulb number, bulb diameter, bulb weight after harvest, and bulb sun-dried weight) were observed. Data was analyzed using ANOVA. The results showed that effectiveness of Foc33 in controlling moler disease was affected by its dose and concentration. The higher the dose and concentration, the lower the disease intensity. The best treatment is E (the dose of 40 kg/ha (0,25 g/polibag) and the concentration of 106 spore/ml) with lowest disease intensity of 47 per cent. The use of Foc33 could increase the plant height and leaf number but did not improve bulb number and bulb diameter. However, the use of this biological control agent with the appropriate dose and concentration (treatment E) was able to save about 40 per cent of yield loss based on the bulb sun-dried weight. Key words: moler disease, Foc33, application dose, microconidium concentration