Sheath blight caused by rhizoctonia solani ag1ia and narrow brown leaf spot nbls, caused by cercospora janseana are among the most important diseases affecting rice production in texas and in other regions in the southern united states. Reaction of rice genotypes to brown spot disease pathogen. Strobilurin fungicides have been used extensively to manage these two diseases, especially sheath blight. Leaf blast bl 18 panicle blast pb 19 brown spot bs 20 narrow brown leaf spot nbls 20 bacterial leaf streak bls 20 leaf scald lsc 21 bacterial blight bb 21 rice diseases caused by viruses and mycoplasmalike organism mlo 21 rice tungro disease rtd 22 rice grassy stunt 1 and 2 disease 23 rice ragged stunt disease 24. First report of brown leaf spot of rice caused by curvularia spicifera in pakistan.
The fungus can spread from plant to plant and in the field by airborne spores. Spots vary in shape and size and appear on the coleoptiles of the leaves, leaf sheath, and glumes muhammad ammar 03356337082 5. Use of uav images to assess narrow brown leaf spot. In order to control this disease, three phenolic antioxidants were tested salicylic acid, benzoic acid and hydroquinone. Among the major fungal diseases of rice, brown spot occupies not only an important position, but also historical interest. Symptoms appear as minute spots on the coleoptile, leaf blade, leaf sheath, and glume, being most prominent on the leaf blade and glumes. The disease is prevalent throughout the rice growing tracts of the world. Seed borne and transmission of bipolaris oryzae, the causal pathogen of brown spot of rice vu van ba1 and somsiri sangchote2 abstract rice brown spot bipolaris oryzae, in paddy fields was investigated to find the relationship between disease severity on flag leaf and kernel infection, at three growth stages of flowering, milky, and dough stages. Brown spot is called as sesame leaf spot or helminthosporiose or fungal blight. Varieties, brown spot, aupdc, economic yield, test weight.
Brown spots can occur at all crop stages, but the infection is most critical from maximum tillering to ripening stages. The basic color of lesions is brown, sometimes reddish brown spl26, dark brown spl16, orange spl1 and white spl20 wu et al, 2008. Epidemiology and disease management of brown spot of rice. Spots on the leaf sheath and hulls are similar to those on the leaves. Narrow brown leaf spot nbls caused by the fungus cercospora janseana racib o. This disease is more severe in areas of poor managementmajor cause of bengal famine in. Spore colony characters, pathogenicity studies, brown leaf spot of rice introduction rice oryza sativa l. The disease causes blight on seedlings, which are grown from heavily infected. In this lecture knowledge of science introduces another disease of rice. Brown spot has been historically largely ignored as one of the most common and most damaging rice diseases. Cochliobolus miyabeanus symptoms the fungus attacks the crop from seedling to milky stage in main field.
On glumes black or brown spots appear and in severe cases the greater portion of the glume may be covered by these spots causing black discoloration. Field efficacy of fungicides for management of sheath. The spots may vary in size and shape from minute dark spots to large oval to circular spots figure 2. On leaves spots appear as circular to oval reddish brown lesions often surrounded by a yellow or gold halo. Ten 10 irrigated and upland rice varieties were used in this study. But it occurs most severely in southeast asia, japan, the philippines, and the southern parts of the united states. It usually begins with leaf spot on young leaves and, if not treated properly, it can decrease yield substantially. Brown spot of rice caused by bipolaris oryzae telemorph cochliobolus miyabeanus is of worldwide occurrence and is known to cause substantial quantitative. Pdf pathogenic variability of bipolaris oryzae causing. Field experiment to evaluate the efficacy of different. Endophytic fungi are one of the biological control agents that can be used to control narrow leaf spot disease in rice. To obtain the potential range in disease development, a progressive increase in spore concentration of the imperfect state of cochliobolus miyabeanus was used on twelve rice varieties differing in their resistance to brown leaf spot. The main phenotype of rice spl mutants is that the leaf blade or the sheath turns up lesions with different colors, sizes and shapes.
In india, the disease is widespread and known to cause4. Evaluation of antifungal properties of certain plants. In this history tlls about bengal famine and who discovered it first time ie sundararaman from madras in india. Sphaerulina oryzina symptoms the fungus produces short, linear brown spots mostly on leaves and also on sheaths, pedicels and glumes. The results showed that after the application of six fungicides to control the brown. Narrow brown leaf spot nbls is a foliar disease of rice caused by cercospora janseana. Rice brown spot bipolaris oryzae tropical plant research. A field experiment was conducted to evaluate the efficacy of different doses of chemical fungicides against brown leaf spot in sabhamansuli variety of rice in the research field. Uav remote sensing, multispectral sensor, narrow brown leaf spot, disease severity, rice doi. The spots appear in large numbers during later stages of crop growth. Brown spot of rice caused by bipolaris oryzae telemorphcochliobolus miyabeanus is of worldwide occurrence and is known to cause substantial quantitative and qualitative losses in grain yield. Control of brown spot pathogen of rice bipolaris oryzae. Comparative efficacy of different chemical treatments for paddy blast pb disease in rice oryza sativa l. It is commonly thought that rapid senescence of leaves can be detrimental to yield if the rice grains have not completely filled.
Antagonism of endophytic fungi of artemisia against. Because the color of spots was defined by naked eye, thus discrepancy to. The disease is worse in dryland compared to wetland cultivation, especially under continuous cropping and other situations where fertility is low. A field experiment was conducted on fourteen rice varieties to determine the level of resistance against brown leaf spot bipolaris oryzaedisease at karma research and development center. Infected seeds, volunteer rice, infected rice debris, and several weeds are the major sources of inoculums in the field. Collar infections can kill the entire leaf and may extend a few millimeters into and around the sheath. The antifungal activity of the tested substances were investigated against b. The spots are brown, with greyish centres when fully developed. Cercospora leaf spot disease or often called narrow brown patches can result in a decrease in yields of up to 10% 2 and also cause rice plant haste 3. If youre growing a crop of rice, youll do well to keep an eye on the leaf spots. Though business farmers might have some success with making use of fungicide, it is usually not an affordable choice for house garden enthusiasts. Rice crop is widely affected by a number of diseases caused by fungi, bacteria, viruses and mycoplasma which results in considerable yield losses ou, 1985. In addition, rice ranges which declare resistance to slim brownish fallen leave area are not constantly trustworthy choices, as brandnew stress of the fungi.
On young leaves, the spots are smaller than those on older leaves. Bipolaris oryzae is the causal agent of rice brown spot disease and is responsible for significant economic losses. Leaf scald microdochium oryzae rhynchosporium oryzae. Older spots may have a bright yellow halo surrounding the lesion. In rice the pathogen infects the coleoptiles causes blighting, leaves with oval, dark brown to purplish brown spots and rigorous damages the photosynthetic activities and ultimately kills the leaf. Typical symptoms on leaves are evenly distributed ovalshaped lesions, up to 1 cm in length. Efficacy of certain botanical extracts in the management. Cochliobolus miyabeanus formerly known as helminthosporium oryzae is a fungus that causes brown spot disease in rice.
Narrow brown leaf spot is a fungal disease which impacts rice plants. Keeping this in view, a roving survey was conducted to record the disease severity of brown leaf spot of rice during kharif201516 in paddy growing cauvery command areas. Brown spot is caused by the fungus cochliobolus miyabeanus. Significant control of brown spot has been achieved using silicon fertilizers.
An analysis of the relative contributory effect of increase in lesion size and numbers on the percentage leaf area diseased was used as a basis to develop a. Chhetry department of life sciences, manipur university, canchipur 795003, india abstract antifungal activity of aqueous extracts of locally. Among the various fungal diseases of rice, brown spot or sesame leaf spot incited by helminthosporium. The most common and diagnostic symptom, diamond shaped lesions of rice blast occur on the leaves. Narrow brown leaf spot cercospora janseana sexual stage. The present study was conducted to evaluate the effects of frequency and timing of propiconazole propimax applications on rice nbls severity and grain yield in the main and ratoon second crops. Brown leaf spot rice is one of the most serious diseases that can affect a growing rice crop. An assessment of rice crop resistance to bipolaris oryzae, a causal agent of rice brown leaf spot or helminthosporium disease was carried out.
Efficacy of certain botanical extracts in the management of brown leaf spot of rice cause by helminthosporium oryzae. The disease is worse in dryland compared to wetland cultivation, especially under. Optimum timing of propiconazole to manage narrow brown. Result showed that nanocgh, nanocge and nanocgm from chaetomium globosum strain kmitl 0802 significantly inhibited curvularia lunata causing leaf spots of rice, which the ed50 values were 1. Evaluation of antifungal properties of certain plants against drechslera oryzae causing brown leaf spot of rice in manipur valley o. Bipolaris oryzae, is one of the important rice diseases resulting in high yield reduction and poor grain quality. Small spots are dark brown to reddish brown while large spots have a light, reddish brown or gray center surrounded by a dark to reddish brown margin plate 1. It spreads throughout the rice tissue by microscopic threads called hyphae and can grow at least an inch a day 24hours under favorable conditions. These results demonstrated the feasibility of using uav images as a potential tool to assess the severity of nbls, an important fungal foliar disease in rice worldwide. Brown spot is a fungal disease that infects the coleoptile, leaves, leaf sheath, panicle branches, glumes, and spikelets its most observable damage is the numerous big spots on the leaves which can kill the whole leaf. Brown leaf spot of rice causes considerable qualitative and quantitative losses in rice growing countries of asia, america and africa ou, 1985. The disease attacks the crop from the seedling stage in the nursery to the milk stage in the field. Brown spot reduces the number of grains per panicle and the kernel weight.
Brown spot is one of the most important diseases of rice worldwide. This disease was the causal agent of the bengal famine of 1943 it was considered for use by the usa as a biological weapon against japan during world war ii. Narrow brown leaf spot cercospora janseana cercospora oryzae sphaerulina oryzina teleomorph pecky rice kernel spotting damage by many fungi including cochliobolus miyabeanus curvularia spp. Caused by the fungus, cercospora janseana, leaf spot may be an annual frustration for many. Introduction brown leaf spot occurs in all rice growing areas and was responsible for the bengal famine in 1942. Response of rice varieties to brown spot disease of rice at. Figure 2 brown spot lesions on the grains and leaf of the rice plant.
In vitro evaluation of fungicides, plant extracts and. Brown leaf spot bls in this study, different fungicides were evaluated to control the rice brown leaf spot and their effect on paddy yield. The lesions of brown spot can be mistaken for blast lesions. Most commonly, rice with narrow brown leaf spot symptoms manifest in the form of narrow darkened spots on rice plants ranging in size.
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