Study on the effect of Rhizoctonia root and crown rot on the quality and quantity of sugar beet
2003
Mahmoudo, Seyyed Bagher | Soltani, Jamshid | Rahnamaeyan, Mehrdad | Babae, Babak | Tavangar Ranjbar, Bahman | Banisadr, Fereydon | Arjmand, Mohammad Naser
Three type of sugar beet root rot symptoms including brown root and crown rot, dry rot canker and violet root rot was observed in the vicinity of Lorestan and Chenaran sugar factories. About 25% of samples showed root and crown rot symptoms and 30% of them had dry rot cankers. Violet root rot was endemic and 3.3% of the samples showed the symptom. Rhizoctonia solaniAG-2 and Rhizoctonia solani AG-4 were isolated from brown root and crown rot symptoms and Rhizoctonia crocorum also isolated from violet root rot symptoms. Using seedling traps bioassay of infected soils could not trapped any Rhizoctonia isolate. Infected fields vicinity Lorestan sugar factory was estimated 32%, while for Chenaran factory 45% was estimated. Sugar content of diseased roots with disease severity of 3-4 (0-7 scale) was measured half of their healthy plants. The amount of Na and K and aminonitrogen was measured in diseased roots (with moderate and sever disease severity) 2-3 times of their healthy plants. Considering these findings and due to develop the disease in storage periods, using roots with disease severity above 3 is not recommended.
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