Rice Rhizoctonia solani

Polyoxins are used in the control of several pathogens, notably sheath blight of rice (Rhizoctonia solani). Polyoxin is specific to Alternaria, Botrytis, and powdery mildew. Differences in activity between members of the polyoxin group probably reflect dissimilar uptake characteristics, which are governed by specific peptides. Different peptides may limit polyoxin activity at the level of the uptake mechanism and may also determine their resistance traits. 

Flutolanil is a benzanilide fungicide discovered and developed by Nihon Nohyaku Co., Ltd. Flutolanil exhibits excellent control against the following pathogens at rates of 300-1000gha (foliar spray), 1.5-3.0gkg (seed treatment) and 2.5-10.0 kg ha (soil incorporation) Rhizoctonia solani on rice. 

Iron toxicity is a syndrome of disorders associated with large concentrations of Fe + in the soil solution. It is only found in flooded soils. A wide range of concentrations produce the symptoms, from 1000 to only 10mgL in soils with poor nutrient status—especially of P or K—or with respiration inhibitors such as H2S. There are large differences in tolerance between rice varieties. The effects include internal damage of tissues due to excessive uptake of Fe + impaired nutrient uptake, especially of P, K, Ca and Mg and increased diseases associated with imbalanced nutrition, such as brown leaf spot (caused by Helminthospo-rium oryzae), sheath blight (caused by Rhizoctonia solani) and blast (caused by Pyricularia oryzae). 

Validamycin A is the only commercial fungicide active against this target (Figure 4.9). The compound is an aminoglycosidic pseudosaccharide and is a secondary metabolite produced in the fermentation of Streptomyces hygroscopicus var. limoneus. Validamycin A was introduced by Takeda Chemical Industries Ltd. for the control of Basidiomy-cetes and Corticiaceae, especially sheath blight, Rhizoctonia solani, in rice. 

Several trehalase inhibitors have been isolated from natural sources these include deoxynojirimycin, validamycins, validoxylamines, salbastatin, calystigin B4, and trehazolin, the last one being the most potent. Trehazolin is used to control blight sheath of rice, caused by the plant pathogenic fungus Rhizoctonia solani, and it thus has potential fungicidal activity.12 15... 

HI 26 Trehalase and inositol synthesis Glucopyranosyl antibiotics Validamycin Specific for rice sheath blight Rhizoctonia solani)... 

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