Piricularia oryzae

Table I. Inhibitory Effect of Kasugamycin on Growth of Piricularia oryzae at pH 5.0 and pH 7.0 in Rice Plant Juice Medium...

Bfx 128-130 Preventive agents against Piricularia oryzae patent of invention to use in agrochemistry (rice) [227]... 

Fertilizer balance is also reported to influence the severity of blast (Piricularia oryzae Catt.) and brown spot (H. oryzae) (21-23, 26). Nitrogenous fertilizer increases the severity of blast, whereas potash salts appear to increase resistance. Potash salts are also reported to increase resistance to brown spot. 

The blast disease of rice caused by Piricularia oryzae has been shown to be controlled by a 7.5 g/hectare spray of aureofungin, four times at 12 days interval(30).Powdery mildew of apples caused by Podosphaera leucotricEa can be effectively handled with aureofungin. Seed-borne infection... 

Blasticidins are produced by Streptomyces grieseochro -mogens and inhibit several species of bacteria and fungi (31). Pseudomonas is particularly vulnerable to blasticidin S. Piricularia oryzae causing the blast disease of rice is widely controlled with blasticidin S in Japan. It is applied to the rice plants after infection by the fungus has already ocurred(32), since the antibiotic affects the myce -lial phase more than the spore phase. It would be desirable to search for spore killing antibiotics to control soil-inhabiting microbes and to destroy the inoculum before it infects the crop. 

Rat liver homogenate Guinea pig liver homogenate Dog liver homogenate Cat liver homogenate Polystictus versicolor Piricularia oryzae... 

Transformations of aporphines by microorganisms involving O- and N-demethylation (89, 92) and CH—CH dehydrogenation (92) have been reported. In a preliminary screening study, Wolters reported the metabolism of boldine and a related alkaloid of undisclosed structure to unidentified products by Piricularia oryzae (42). More detailed studies with a series of microorganisms have been carried out by Rosazza and co-workers (89, 92). 

Nocardia restrictus is capable of oxidizing the conessine derivative 5a-conanin-3/i-ol (220) to both the A4-3-ketone 222 and the A1,4-3-ketone 221, the latter being the major product of the incubation (189). Preliminary screening experiments have demonstrated that Trichothecium rosevan transforms conessine (223), solanocapsine (224), jervine (225), and pseudojervine (226) (42). Transformation of the latter is claimed to produce 20-30% jervine by glycoside hydrolysis, along with an unidentified product that may be further biotransformation product of jervine. Jervine is also metabolized by Polystictus versicolor and Piricularia oryzae, but no products have been identified (42). 

The compound for which the best biochemical evidence has been reported for sensitization of host plant response to pathogens, rather than direct or indirect fungitoxicity or nonspecific phytoalexin induction, is 2,2-d ich 1 oro-3,3-d ime thy lcyc 1 opropane carboxylic acid (108-110). Neither the compound nor any of its metabolites generated after treatment of rice plants are directly inhibitory to the rice blast fungus, Piricularia oryzae. Constitutive phytoalexin production was not induced in rice by the cyclopropane derivative. However, infection of plants treated with the compound results in rapid localized cell death, me lanization, and production of the phytoalexins, momilactones A and B. 

Other food additives have also shown an antifungal effect, for example oxalic acid, saccharin and its sodium salt, erythorbic acid and its salts, acrylamidated and hydroxyethylated starch. Saccharin (46) in an aqueous solution of 2000 mg/kg protects rice from infestation by Piricularia oryzae fungi (Misato et al., 1973). 

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