Kernel Smut Research Articles

Increase in rice yield through the use of quality seeds in Bangladesh

A farmer participatory research was conducted to determine the yield advantage of cleaned seeds over farmer-saved seeds in seven sites in Bangladesh in five cropping (three Boro and two transplant Aman) seasons. In each site, 30 participating farmers transplanted seedlings from cleaned seeds and their saved seeds of the same variety in adjacent plots in their fields. The results show a significantly higher grain yield in the cleaned seed than the farmer-saved seeds of 10.1% in Boro season and 11.3% in transplant (T) Aman season. The highest advantage in yield of cleaned seeds over farmer-saved seeds of 12.2% was observed in Barisal in Boro season, and 15.5% in Habiganj in T. Aman season. In the Boro season, significantly lower mean incidences of weeds below canopy, rice hispa, whiteheads, brown planthopper and bakanae were observed for cleaned seeds than for farmer-saved seeds. In the T. Aman season, significantly lower mean incidences of deadheart, whiteheads, gall midge, green leafhopper, other defoliators, sheath blight, sheath rot, and kernel smut were observed for cleaned seeds than for farmer-saved seeds. This indicates that using cleaned rice seeds increased grain yield, enhanced crop growth and also reduced damage from weeds, insect pests and diseases. Key words: Rice, seed health, quality, yield, farmer participatory research.

Cultural characteristics of Sporisorium sorghi and detection of the pathogen in plant tissue by microscopy and polymerase chain reaction

Despite the economic importance of covered kernel smut of sorghum (Sporisorium sorghi) in many African states and other parts of the world, only limited information is available on laboratory cultivation methods for this fungus and techniques for its diagnosis in plant tissue. The current paper describes laboratory and greenhouse experiments performed with field material of S. sorghi. When intact sori were kept at 5°C, 80% of the spores germinated even after 24 months of storage. Spore germination on agar medium and production of mycelial dry weight in still culture were highest between 20° and 35°C, with a peak at 30°C. Both showed a steady increase from pH 4.5 to pH 7.5, followed by a decline at pH 8.5 and 9.5. In shake culture in different broth media the addition of 0.3% peptone from soybean caused an increase in fungal growth compared with the media alone. Of the media tested, mycelial production was highest in malt dextrose broth supplemented with peptone. When cultivated on different agar media, the morphology of single spore isolates differed both among isolates and depending on the agar medium. In greenhouse experiments, five short, early maturing sorghum breeding accessions proved to be partially or fully resistant to covered kernel smut. Among the plant materials tested, cv. ‘Dorado’ appeared to be the one best suited for greenhouse experiments with covered kernel smut. By microscopy of hand-cut sections stained with trypan-blue, hyphae of S. sorghi were seen in apical buds and in nodes of young sorghum plants. Diagnostic PCR amplified a 903 bp element comprising the internal region of the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) encoding gene and enabled the detection of S. sorghi in both nodes and apical buds of infected sorghum seedlings. Both techniques, i.e., microscopy and diagnostic PCR, have the potential to be used in studies for the identification of effective sorghum seed treatments already at the seedling stage.

Evaluation of improved and local/landrace/sorghum varieties for covered kernel smut

Twelve varieties of improved and local (landrace) sorghum were tested under artificial inoculation conditions. Out of 12 sorghum varieties evaluated with covered kernel smut, notably local cultivar ‘Tetron’ was found to be highly resistant. Disease incidence and severity on the rest of the cultivars varied from 21 to 47% and 40 to 53% respectively. Differences among cultivars in yield loss were also observed. The highest yield loss (40%) was recorded on 97 MW 6129 (NVT-11 4) and for Tetron yield loss was nil. The effect of disease on germination was noticed but cannot be considered as conclusive due to moisture stress at the time of germination.

Influences from Long-Term Crop Rotation, Soil Tillage, and Fertility on the Severity of Rice Grain Smuts.

False smut (Ustilaginoidea virens) and kernel smut (Neovossia horrida) are diseases of rice (Oryza sativa) that reduce both grain yield and quality. Susceptible rice cultivars are in widespread use on production acreage in the United States, and the effects from crop management practices on smut control are poorly understood. We studied the long-term effects of crop rotation, soil tillage, and fertility level on rice smut severity. The highest levels of false smut observed in this study were on cultivars grown in rotation with soybean, on traditionally tilled soils, with high fertilizer treatments. The highest levels of kernel smut were observed in a rice-soybean rotation with winter wheat grown between summer crops. These rotations are commonly used in rice-growing regions of the southern United States. Using combinations of crop rotation, soil tillage, and fertility rate, several alternative crop-management practices were identified that provided effective control of smuts in susceptible rice cultivars. The most effective method for controlling both false smut and kernel smut was in 3-year rotations of rice, soybean, and corn. Regardless of rotation order or tillage and fertility treatments within the rotations, rotating out of rice for 2 years was the most effective approach for smut control.

Effect of Furrow Irrigation on the Severity of False Smut in Susceptible Rice Varieties.

False smut (Ustilaginoidea virens) is an important emerging disease of rice (Oryza sativa) in the southern United States, where all major rice cultivars and hybrids are susceptible to the disease. False smut susceptibility was evaluated in traditional paddy-rice fields and under furrow-irrigated conditions to determine the effects of alternative agricultural practices on the severity of this disease. Highly effective false smut suppression was observed in furrow-irrigated rice, where the disease was nearly eliminated in susceptible rice entries. False smut suppression was observed for two hybrids and one conventional rice cultivar, demonstrating that suppression was not limited to specific germplasm sources. Kernel smut severity was also monitored, but no effect on this disease was observed from the irrigation treatments. Therefore, suppression of disease severity in nonflooded rice appears to be a phenomenon unique to the rice-false smut pathosystem, which can be exploited to achieve effective field resistance to this disease.

The underlying cause of the 2009 sorghum failure in Kongwa district and its implications for Tanzania’s vulnerability to climate change

Low rainfall has been blamed for the recent crop failure in Kongwa district, within Tanzania’s Central Zone, when 310 out of a total of 331.2 mm of rainfall were concentrated into the first 4 months (November to February) of the 2008-09 cropping season. In May 2009, farmers in this district, expected yields from early maturing (short/intermediate) varieties of sorghum, such as Macia and Pato that were late planted in January and February, to be less than 250 kg/ha. They complained that late delivery of seed of these varieties had led to the poor yields. Records kept by thirty seven subsistence farmers throughout the cropping season indicated that an average of 62 kg of sorghum grain of both early and late maturing varieties was harvested per household by June 2009. This is sufficient for just 14 day’s food supply for an average household comprising three adults, two adolescents (aged 10–18 years) and two children (aged less than 10 years). In addition, each household had accrued financial losses, averaging Tsh64, 527.65 (€33.79) from expenditure on wasted inputs. Furthermore, the high incidence of Covered Kernel Smut in sorghum fields suggested that farmers had been supplied with contaminated seed, while the limited availability of seed of the Striga-resistant sorghum varieties, Hakika and Wahi, had allowed this parasitic weed to flourish in their fields. It was estimated that these two pests could have caused sorghum losses in excess of 50%. Each household that was impoverished by this crop failure will have to raise an average of Tsh436, 070 (€228.36) to cover its grain deficit until June 2010.

Effect of Cultural Management Practices on the Severity of False Smut and Kernel Smut of Rice.

False smut (Ustilaginoidea virens) and kernel smut (Neovossia horrida) are diseases of rice (Oryza sativa) that reduce both grain yield and quality. False smut is an emerging disease worldwide that is rapidly gaining in importance, whereas kernel smut has historically been a chronic minor disease with sporadic outbreaks that cause considerable losses. Highly effective disease control was obtained for susceptible cultivars by employing conservation tillage (69% reduction in false smut), continuous rice cropping (88% reduction in false smut), and moderate nitrogen fertility rates (34 and 60% reductions in false smut and kernel smut, respectively). Combining these treatments nearly eliminated smuts from cultivars that were fully susceptible under conventional cultivation practices. Furthermore, using a nursery designed to promote smut diseases, two rice hybrids were identified that possessed kernel smut resistance under the most favorable disease conditions. The genetic basis of the resistance is unknown. However, the utility for disease control is great because hybrids occupy significant portions of production rice acreage.

Tilletia barclayana: biologia e manejo em arroz irrigado

A cárie-do-arroz (Tilletia barclayana), doença considerada secundária na cultura do arroz irrigado, vem ganhando importância nos últimos anos devido aos níveis elevados de infestação e à redução do rendimento. A doença é favorecida por temperatura e umidade do ar elevadas, doses altas de nitrogênio e semeadura tardia. Para o manejo, recomenda-se uso de resistência varietal, semeadura na época recomendada e adubação equilibrada.

Effect of biofumigation with volatiles from Muscodor albus on the viability of Tilletia spp. teliospores

Volatile organic compounds produced by the fungus Muscodor albus inhibit or kill numerous fungi. The effect of these volatiles was tested on dormant and physiologically active teliospores of the smut fungi Tilletia horrida, Tilletia indica, and Tilletia tritici, which cause kernel smut of rice, Karnal bunt of wheat, and common bunt of wheat, respectively. Reactivated rye grain culture of M. albus was used to fumigate dormant teliospores in dry Petri dishes and physiologically active teliospores on water agar for up to 5 days at 22 degrees C. Teliospores of all 3 species were incapable of germination when fumigated on agar for 5 days. When T. tritici on agar was fumigated only during the initial 48 h of incubation, viability was reduced by 73%-99%. Fumigation of dry loose teliospores of T. tritici caused a 69%-97% loss in viability, whereas teliospores within intact sori were not affected. Dormant teliospores of T. horrida and T. indica were not affected by M. albus volatiles. It appears that M. albus has potential as a seed or soil treatment for controlling seedling-infecting smuts where infection is initiated by germinating teliospores prior to seedling emergence. The volatiles were not effective for postharvest control of teliospores under conditions used in these experiments.

Effect of Low-Input Management on Pest Damage to Rice (<i>Oryza Sativa</i> L) Under Natural Infestation in Southeastern Nigeria

Seven rice lines, selected for their good performance under Low-input management condition, were studied under low and high-input management conditions in Umudike in Abia State and Uyo in Akwa-Ibom State , to establish the effect of low-input management on diseases and pests of rice under natural infection and infestation in the humid zone of Southeastern Nigeria. The experiment was laid out in a randomized complete block design (RCBD) with three replications. Data were collected on leaf blast, glume discoloration, brown leaf spot, kernel smut, and stem borer infestations under both low and high-input management conditions. Glume discoloration was most severe under zero fertilizer rate. However, there were no clear trends in the attack by diseases and insect pests based on management levels. Damage level by insects were not significantly different under low-input and high-input management conditions and infection levels by diseases were also not significantly different under low-input and high-input conditions. Therefore low-input cannot be said to aggravate pest infestation or disease infection in rice. Keywords: Low-input, High-input, management, diseases, insect pests and rodents.Journal of Agriculture and Food Sciences Vol. 5 (1) 2007: pp. 1-10

Antifungal properties of Agapanthus africanus L. extracts against plant pathogens

Crude extracts of various Agapanthus africanus plant parts were screened in vitro against eight economically important plant pathogenic fungi. Radial mycelial growth was inhibited significantly ( P<0.05) in five test organisms, while Pythium ultimum, and to a lesser extent Fusarium oxysporum and Alternaria alternata, showed a degree of tolerance. Subsequently, these crude extracts were tested in vivo in the greenhouse against Mycosphaerella pinodes, the cause of black spot or Ascochyta blight in peas. Fourth internode leaves were removed from 4-week-old pea plants, placed on moist filter paper in Petri dishes and inoculated with a M. pinodes spore suspension 30 min before and after treatment with the extracts. The control of Ascochyta blight by different concentrations of the crude extracts was measured in terms of lesion size over a 6-d period at 20 °C in a growth cabinet. All crude extracts significantly reduced lesion development caused by M. pinodes when leaves were inoculated with spores both before and after treatment with the extracts. Neither of the extracts showed any phytotoxic reaction on the leaves, even at the highest concentration applied. A combined aerial part crude extract of A. africanus was additionally evaluated against sorghum covered ( Sporisorium sorghi) and loose ( Sporisorium cruentum) kernel smuts under field conditions over two seasons. The extract and a standard fungicide, Thiram that served as a positive control, were applied as seed treatments 1 h after artificially inoculating separate sets of sorghum seed with smut spores. Inoculated, but untreated seeds served as a negative control. The extract reduced the incidence of both loose and covered kernel smuts significantly ( P<0.05) and compared favourably with the prescribed fungicide, Thiram. Both treatments resulted in significant yield increases compared to the untreated control. From these results it was concluded that the aerial part crude extract of A. africanus possesses sufficient in vivo antifungal activity to warrant a further investigation.

In vitro and in vivo antifungal activity of crude extracts and powdered dry material from Ethiopian wild plants against economically important plant pathogens

In Ethiopia extracts from specific plants are used traditionally as natural fungicides in small scale farming systems where synthetic chemicals are out of reach of the average subsistence farmer while no scientific base exists for this practice. Subsequently, methanolic crude extracts from Dolichos kilimandscharicus and Maerua subcordata roots as well as Phytolacca dodecandra berries were screened in vitro for antifungal activity against Botrytis cinerea Pers.:Fr., Fusarium oxysporum Schlechtend.:Fr., Sclerotium rolfsii Sacc., Rhizoctonia solani Kuhn,, Botryosphaeria dothidea (Moug.:Fr.) Ces & De Not. and Pythium ultimum Trow, using an agar diffusion method. Compared to the other plants as well as specific standard fungicides for each pathogen, the root extract of D. kilimandscharicus showed the highest broad-spectrum in vitro antifungal activity by inhibiting the mycelial growth of three of the six test organisms. Additionally, in vivo antifungal activity of dry powdered material from these plants against sorghum covered (Sporisorium sorghi) and loose kernel (Sporisorium cruentum) smuts was screened under field conditions by artificially inoculating separate sets of sorghum seed with smut spores before treating with plant material or two traditionally used fungicides, Thiram® and Apron Plus® that served as positive controls. Although the incidence of both loose and covered kernel smuts were significantly reduced by material from all plant species, the dry powdered berries of P. dodecandra were most effective. Compared to the untreated control, treatment with the plant material as well as standard fungicides resulted in significant yield increases. It was concluded that a rationale has been established for further investigation into the structured utilization of natural vegetation indigenous to Ethiopia in the agricultural industry.

Cultivar and Seeding Date Effects on Kernel Smut of Rice

Rice (Oryza sativa L.) cultivars vary in susceptibility to kernel smut (Tilletia barclayana). The incidence and severity of kernel smut is believed to increase as rice seeding is delayed. The research objective was to evaluate the influence of seeding date on kernel smut incidence and severity of rice. Kernel smut incidence and severity and grain yield were evaluated on selected cultivars seeded on three or four dates at 7 site‐years in Arkansas. Grain yield was generally greatest when rice was seeded in April and declined as seeding was delayed until June. Kernel smut incidence (r = 0.38) and severity (r = 0.38) were significantly, albeit weakly, correlated with seeding date. Depending on site‐year, kernel smut incidence and severity were affected by cultivar, seeding date, or their interaction. Within each site‐year, incidence and severity were generally lowest numerically for the first (earliest) seeded rice. With subsequent seedings, kernel smut incidence and severity increased at 1 site‐year, remained constant at 2 site‐years, or showed no trend (i.e., fluctuated) among seeding dates at 4 site‐years, but 3 of the 4 site‐years had greater incidence than the first seeding. Cultivars rated highly susceptible to kernel smut generally had greater incidence and severity values than susceptible or moderately susceptible cultivars. Kernel smut incidence and severity averages were not significantly correlated with air temperatures or precipitation for 20 d after anthesis or 7 d before and after anthesis. Data suggest that seeding the least‐susceptible cultivars during the earliest recommended period may reduce damage from this disease in most years.

Enhancing disease resistances of Super Hybrid Rice with four antifungal genes

A plant expression vector harboring four antifungal genes was delivered into the embryogenic calli of '9311', an indica restorer line of Super Hybrid Rice, via modified biolistic particle bombardment. Southern blot analysis indicated that in the regenerated hygromycin-resistant plants, all the four antifungal genes, including RCH10, RAC22, beta-Glu and B-RIP, were integrated into the genome of '9311', co-transmitted altogether with the marker gene hpt in a Mendelian pattern. Some transgenic R1 and R2 progenies, with all transgenes displaying a normal expression level in the Northern blot analysis, showed high resistance to Magnaporthe grisea when tested in the typical blast nurseries located in Yanxi and Sanya respectively. Furthermore, transgenic F1 plants, resulting from a cross of R2 homozygous lines with high resistance to rice blast with the non-transgenic male sterile line Peiai 64S, showed not only high resistance to M. grisea but also enhanced resistance to rice false smut (a disease caused by Ustilaginoidea virens) and rice kernel smut (another disease caused by Tilletia barclayana).

Optimal application timing of simeconazole granules for control of rice kernel smut and false smut

We investigated the optimal timing of simeconazole (RS-2-(4-fluorophenyl)-1-(1H-1,2,4-triazol-1-yl)-3-trimethylsilylpropan-2-ol) application for controlling rice kernel smut in field trials in Miyagi Prefecture, Japan, using formulations of simeconazole (1.5% granules). The field tests revealed that a submerged application of simeconazole granules (450–600 g ai/ha) at 1–5 weeks before heading was highly effective against kernel smut, with treatments 1–2 weeks before heading being the most effective. Submerged application of the fungicide at 2–5 weeks before heading was also highly effective against false smut, with treatment 3 weeks before heading being the most effective. These periods overlap the timing for optimal application of simeconazole to control rice sheath blight and ear blight. Consequently, we concluded that treatment with simeconazole 2–3 weeks before heading can be a useful tool for controlling all four diseases.

Nonsystemic Bunt Fungi—Tilletia indica and T. horrida: A Review of History, Systematics, and Biology

The genus Tilletia is a group of smut fungi that infects grasses either systemically or locally. Basic differences exist between the systemically infecting species, such as the common and dwarf bunt fungi, and locally infecting species. Tilletia indica, which causes Karnal bunt of wheat, and Tilletia horrida, which causes rice kernel smut, are two examples of locally infecting species on economically important crops. However, even species on noncultivated hosts can become important when occurring as contaminants in export grain and seed shipments. In this review, we focus on T. indica and the morphologically similar but distantly related T. horrida, considering history, systematics, and biology. In addition, the controversial generic placement and evolutionary relationships of these two species are discussed in light of recent molecular studies.

Grain Yield and Kernel Smut of Rice as Affected by Preflood and Midseason Nitrogen Fertilization in Arkansas

Kernel smut, Neovossia horrida (Tilletia barclayana), of rice (Oryza sativa L.) has been a persistent disease in Arkansas for more than 50 yr. Recently, epidemic levels of kernel smut have occurred on highly susceptible cultivars, which have increased awareness within the rice industry of this disease. Nitrogen fertilization treatments consisting of four preflood (50–152 kg N ha−1) and three midseason (0–100 kg N ha−1) N rates were arranged in a factorial design and used to delineate the effects of N rate and application timing on rice yield and disease incidence and severity in five site‐year–cultivar studies (environments). Significant environment × preflood N rate interactions occurred for yield, incidence, and severity. The minimum preflood N rates, averaged across midseason N rates, that produced maximum yields varied among the environments and ranged from 84 to 152 kg N ha−1. Depending on the environment, disease incidence ranged from 2 to 93% and severity ranged from &lt;0.1 to 4.8% among preflood N rates. Preflood N rate had no significant effect on smut incidence and severity for three environments receiving optimum‐to‐excessive N and a fourth environment receiving inadequate‐to‐optimum N. For the remaining environment that received optimum‐to‐excessive N, incidence increased linearly (43–93%), and severity increased nonlinearly (0.5–4.8%) as preflood N rate increased. Midseason N rate did not affect severity but caused a positive, linear increase for incidence. Data suggest that excessive preflood N has the greater potential to increase kernel smut but only when environmental conditions are favorable for kernel smut.

Grain Yield and Kernel Smut of Rice as Affected by Preflood and Midseason Nitrogen Fertilization in Arkansas

Grain Yield and Kernel Smut of Rice as Affected by Preflood and Midseason Nitrogen Fertilization in Arkansas

Sporisorium sorghi . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Sporisorium sorghi . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASE: Covered smut or covered kernel smut of sorghum. Development of functional ovaries and anthers is prevented in infected parts of the plants. HOSTS: Panicum miliaceum , Sorghum bicolor, S. dochna, S. halepense, S. plumosum, S. sudanense and S. vulgare ( Poaceae ). This species has also been recorded from Ischaemum ciliare (VISWANATHAN et al. , 2000). GEOGRAPHICAL DISTRIBUTION: Worldwide, see CMI Distribution Maps of Plant Diseases No. 220, edn 4 (1987). In addition it has been recorded from AFRICA: Mauritania (FRISON &amp; SADIO, 1987). CENTRAL AMERICA: Nevis. TRANSMISSION: In addition to dissemination on infected seed, there is evidence that this species can also be spread by air-borne chlamydospores (SHENOI &amp; RAMALINGAM, 1976).

Prevalence, Incidence, and Severity of Sorghum Diseases in Western Kenya.

To assess the prevalence and severity of sorghum diseases in western Kenya, a 2-year survey was conducted (July 1995 and 1996), in 91 and 109 farmers' fields, respectively. Fields were generally <0.5 ha and production environment ranged from warm-humid to warm-semi-arid. Fourteen foliar and six panicle diseases were observed, with limited variation in disease prevalence and severity between the 2 years. The most common foliar diseases observed were (in decreasing order of prevalence) oval leaf spot (Ramulispora sorghicola), rust (Puccinia purpurea), ladder leaf spot (Cercospora fusimaculans), zonate leaf spot (Gloeocercospora sorghi), gray leaf spot (Cercospora sorghi), leaf blight (Exserohilum turcicum), and anthracnose (Colletotrichum sublineolum); with prevalence ranging from 95 to 97% of fields for oval leaf spot, and 44 to 65% of fields for anthracnose. Head smut (Sporisorium reilianum), was observed in 73 to 75% of fields, covered kernel smut (S. sorghi) 42 to 43% of fields, and loose smut (S. cruenta) 14 to 24% of fields. Head smut incidence was >25% in 3% of fields surveyed. Grain yield reduction from smut diseases alone was estimated to be 5%. Out of eight probability distribution functions compared, the double Gaussian model best described the frequency of disease severity levels for most diseases. Based on the best-fitting model, the proportion of fields with disease severity level thought to cause yield loss (severity rating >5 on a 1 to 9 scale, where 1 = no disease) was calculated as 26.6% for oval leaf spot, 15.3% for rust, 14.8% for anthracnose, 4.8% for ladder leaf spot, and 1.5% for leaf blight. The production environment influenced the prevalence of disease severity. Severe anthracnose, leaf blight, and ladder leaf spot were confined to fields in the humid LM1 and LM2 agro-ecological zones, rust was ubiquitous, and severe gray leaf spot was more prevalent in the dryer LM4 zone.