Punyisa Charirak1, Weerasak Saksirirat1,2*,
Sanun Jogloy3 and Suwita Saepaisan1,2

1Section of Plant Pathology, Department of Plant Science and Agricultural
Resources, Faculty of Agriculture, Khon Kaen University, KhonKaen 40002, Thailand.
2Agricultural Biotechnology Research Center for Sustainable Economy,
Khon Kaen University, Khon Kaen 40002, Thailand.
3Plant Breeding Research Center for Sustainable Agriculture,
Khon Kaen University, Khon Kaen 40002, Thailand.

Abstract

Soil solarization was reported that effective method to control stem rot disease caused by Sclerotium rolfsii thereby the aim of this study was to improve soil solarization method by combining of biocontrol and chemical. The experimental was done in the laboratory, pots, greenhouse and micro plot. The effect of high temperatures (45°C, 50°C and 60°C) on the survival of S. rolfsii sclerotia were conducted in the laboratory. At 45 °C, sclerotia treated for 6 hours showed germination of 36%. However, treated at 50°C and 60°C for 1 hours, the sclerotia could not germinate. The effect of soil solarization on sclerotial survival of S. rolfsii was carried under green-house and small plot conditions. The sclerotia were placed deeply under 2 soil levels of 5 and 10 cm and evaluated weekly on germination rate. After 1 week of soil solarization, sclerotia germinated 7.2% at 5 cm depth and 0% after 2 weeks. At 10 cm depth, sclerotia were could not germinate after 1 week of soil solarization. For small plot experiment of soil solarization, the germinated of sclerotia at 5 cm depth was 0% after 3 weeks of soil solarization while 35.2% germination for non solarization. Integrated control of stem rot using fungicide, biocontrol agents and soil solarization was conducted under green-house condition. The result was clearly that soil solarization alone or in combination with others were effective methods against the disease with disease index 0. Without soil solarization, T. harzianium T9 with carboxin caused low disease index of 0.2. The integrated control of stem rot was also undertaken in small plot (1.5×1.5m) experimentwith comparison on disease incident and tuber yield of H. tuberrosus. Using soil solarization with T. harzianium T9 and Glomus clarum was the best method that reduced disease with index of 0.33 and provided high yield of 1.69 kg/m2.

Keyword: Helianthus tuberrosus, Sclerotium rolfsii, Trichoderma harzianium, Bacillus      firmus, carboxin.