Dynamics and control of tungro virus disease in pure stands and mixtures of rice cultivars with different types of resistance
2001
Pedroso, J.P. | Raymundo, A.D. (Western Mindanao State Univ., Zamboanga City (Philippines))
Tungro disease progression in time and space was studied in pure stands and mixtures of rice cultivars with resistance to either virus or vector or both during the wet and dry seasons of 1999 in the western coasts of Zamboanga City [Philippines] where the disease has been devastating. Disease increase and spread were slower in resistant cultivars and cultivars mixture than in the susceptible cultivar. Mixtures where component cultivars were planted in rows, mixtures of three cultivars, mixtures of four cultivars, and mixtures of two cultivars in 20 x 20 cm plant spacing had lower tungro incidence than mixture in 25 x 25 spacing, mixtures in 15 x 20 cm spacing, mixtures of cultivars planted alternately in rows, and mixtures of two cultivars. It appears that the inhibition of tungro disease progression in mixtures is a function of the number of component cultivars and the effectiveness of the resistance genes possessed these components. The increased density of the resistance plants in mixtures with more components seemed to enhance the effect as barriers by delaying or impending infection of the susceptible components of the mixture
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