Evalution of crop operation and cultivar tolerance in control of bacterial wilt disease of potatoes Pseudomonas solanacearum
1999
Samavatian, Hosein | Mortazavi Bak , Ahmad
Bacterial wilt of potato caused by Rahtonia solanacearum biovar II (race 3)is widespread throughout most potato growing areas of Iran. The pathogen spreads through cultivation of infected potato tubers and following its introduction and establishment in soil,infects the crop in subsequent years. A research project entitled 'Evaluation of the effects of cultural practices and the tolerance levels of potato cultivars in controlling bacterial wilt of potato" composed of 4 trials proposed and the work carried out in Faridan (the major potato growing area of Isfahan) and in the Experiment stations of Kabootar-Abad and Dastguerd during 1993-1996. Effects of three- and four- year crop rotations, employing wheat, barley, corn, bean and sainfoin in reducing incidence of the disease were determined in a completely randomized block design in the Faridan area.Reductions in disease incidence averaging 34.2% and29.07% were obtained in the rotations consisting of potato-com-potato and potato-sainfoin-sainfoin-potato respectively. Tolerance levels of potato cultivars Muren, Famosa, Atlas , Aola, Kozima and Marfona towards the disease were compared in a separate field experiment carried out in Kabootar-Abad Experiment Station. Muren, Famosa and Aola were the more tolerant cultivars among the ones tested. In another experiment, carried out in Kabootar-Abad Experiment Station batches visually disease- free seed tubers were forced to display the signs or symptoms of infections, by storing, for three- week, period, at 35°C and 85% relative humidity. Through subsequent selection and cultivation only of the symptomless tubers, a significant reduction in wilt incidence compared to the control (no selection and selection of apparently healthy tubers without any prior treatment) was obtaired. In two year experiment conducted in Dastgaerd Station, recurrent selection of symptomless tubers with and without 3-week storage treatment at 35° C and 85% RH (Selection and cultivation of apparently healthy tubers and again selection and cultivation of the resulting crop for the second year) resultejjn, a significant reduction in disease incidence compared to the control.
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