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1.
Abstract Incidence and geographical distribution of downy mildew (Peronosclerospora sorghi) on maize (Zea mays) were determined in a systematic survey of 181 maize fields in the major maize‐growing regions and ecological zones of Nigeria. Downy mildew was observed in the forest and Guinea savanna ecologies, but no disease was detected in other ecologies. Highest levels of disease incidence (63%) were observed in the forest zone, and progressively less disease incidence was found at the southern and northern Guinea savanna zones. Spatial pattern analysis indicated an aggregation and randomness of infected plants in the northern Guinea savanna and the forest zone, respectively. Disease incidence was positively correlated with the presence of downy mildew infected sorghum plants and relative amount of sporulation on infected sorghum (Sorghum bicolor) but negatively correlated with plant age and cropping pattern. Relative sporulation on maize plants was negatively correlated with age of maize plants. Higher levels of disease incidence were observed when the previous crop was either maize or sorghum than when previous crops were cassava, okra, tomatoes, or rice. 相似文献
2.
The possibility of reducing Striga hermonthica (Del.) Benth. parasitism in severely infested fields, by means of deep planting - thereby reducing the root length in the upper layers of the soil where Striga seeds are predominantly found - was tested in field trials with maize and sorghum in western Kenya. Sorghum seeds were planted in Striga-infested fields approximately 2.5 cm deep in the soil or at the bottom of conically-shaped plant holes (15-20 cm deep). Depth of plant holes for maize varied from 0 to 30 cm, in un-tilled soil. Deep planting in un-tilled soil gave higher (up to double) grain yields, compared with standard planting in tilled soil. Parasite emergence was related negatively to planting depth of maize (p< 0.05). Deep planting in tilled soil gave 74% more sorghumgrain yield relative to standard planting. In this treatment Striga seed production was not reduced but in un-tilled fields with deeply planted sorghum Striga seed production was completely suppressed. Therefore, a combination of zero-tillage and deep planting seems to be the most effective treatment. The probable mechanism causing these results is avoidance of Striga seed by the host root system, resulting in a delay in the onset of Striga attachment and the formation of smaller numbers of attachments. 相似文献
3.
J. A. J. Veenenbos T. W. Brandsma 《European journal of plant pathology / European Foundation for Plant Pathology》1957,63(6):375-379
Summary Seeds of oats contaminated with loose smut were used for testing the fungicidal value of cereal seed disinfectants. As it was impossible to obtain contaminated seed from the field in recent years several methods for artificial contamination were tried.The best result (14% of smutted panicles), was obtained with the wet vacuum method ofHaarring. With the aid of a dessiccator and a water jet pump the air between the glumes and kernels was replaced, by a spore suspension. The degree of infection was the same when the nutrient solution was replaced by tap water.The method used byPonchet gave 10% of diseased panicles. Here the seed is merely submerged in a spore suspension or is presoaked in tap water and mixed afterwards with dry spores. To obtain contaminated seeds of oats for the testing of seed disinfectants this method is preferable, because of its easy application and the satisfactory degree of infection obtained.Some other methods of mixing seed and spores without the addition of water gave only 1% of smutted panicles. The highest degree of diseased plants was obtained when the seed was dried directly after the artificial contamination. 相似文献
4.
“早衰”是高粱生产和育种上存在的普遍现象。长期以来被认为是一种生理性病害。经4年研究证明它是草酸青霉(Penicilliem axalicum)和纤细交链孢霉(Allernaria allernala)于初花期浸染而引起的一种高粱穗部病害。主要症状是颖壳及与其连接的枝梗组织坏死,阻止了养分、水分向上输导,造成籽粒秕瘦变小。一般减产10％以上。这是国内首次报道的高粱新病害,定名为高粱青霉颖枯病,此病在初花期用多菌灵防治有较好效果。 相似文献
5.
Effects of N, P and K on Striga asiatica (L.) Kuntze seed germination and infestation of sorghum 总被引：2，自引：0，他引：2
Sorghum (Sorghum bicolor (L.) Moench) plants were grown in pots with 12.5 and 50 mg applied N kg?1 soil. With an increase of soil N, the Striga asiatica (L.) Kuntze infestation, as well as the sorghum shoot dry matter losses due to infestation, decreased. The relative differences in stimulant capacity to induce Striga seed germination among the four sorghum genotypes were not consistent over the 0 to 150 mg N 1?1 range. The sorghum root exudate was considerably more active at 0 mg N 1?1, than at 30 mg N 1?1, and the stimulant produced at 150 mg N 1?1 failed to induce Striga seed germination. Presence of N in the growth medium considerably reduced the effectiveness of the stimulating substance produced by sorghum roots, whereas K promoted stimulant activity only in the absence of N. The presence or absence of P in the growth medium did not affect Striga seed germinability, probably due to the inability of this element to interfere with the production or activity of the stimulating substance from the host plants. It can be concluded, therefore, that sorghum plants seem to produce active root exudate only in conditions of N deficiency. 相似文献
6.
Abstract Studies were conducted to determine the influence of plant growth stage, inoculum density, temperature, and relative humidity (RH) on development of rust (Puccinia pupurea) in sorghum (Sorghum bicolor). Rust development was maximum (>80% severity), when plants of a susceptible sorghum genotype (IS 18420) were inoculated at the four‐ to five‐leaf stage with an inoculum concentration of 4 × 106 urediniospores per ml and incubated at 20–25°C under high RH (>90%) for 24 h. Disease severity (percentage leaf area covered with rust pustules) scores were taken 2 weeks after inoculation. Using this technique, 29 sorghum genotypes were screened for rust resistance in a greenhouse. This technique proved effective In discerning resistant and susceptible genotypes, and IS 3979, ICSH 110, ICSH 86647 and ICSH 871035 were identified resistant (<20% rust severity) compared with a susceptible control IS 18420 (90% rust severity). This technique is simple and rapid, and can be used effectively and economically to screen, on a large scale, germplasm lines and breeding populations in the greenhouse. 相似文献
7.
HANWEN WU STEVEN R. WALKER VIKKI A. OSTEN GEOFF ROBINSON 《Weed Biology and Management》2010,10(3):185-193
Field studies were conducted at two locations in southern Queensland, Australia during the 2003–2004 and 2004–2005 growing seasons to determine the differential competitiveness of sorghum (Sorghum bicolor L. Moench) cultivars and crop densities against weeds and the sorghum yield loss due to weeds. Weed competition was investigated by growing sorghum in the presence or absence of a model grass weed, Japanese millet (Echinochloa esculenta). The correlation analyses showed that the early growth traits (height, shoot biomass, and daily growth rate of the shoot biomass) of sorghum adversely affected the height, biomass, and seed production of millet, as measured at maturity. “MR Goldrush” and “Bonus MR” were the most competitive cultivars, resulting in reduced weed biomass, weed density, and weed seed production. The density of sorghum also had a significant effect on the crop's ability to compete with millet. When compared to the density of 4.5 plants per m2, sorghum that was planted at 7.5 plants per m2 suppressed the density, biomass, and seed production of millet by 22%, 27% and 38%, respectively. Millet caused a significant yield loss in comparison with the weed‐free plots. The combined weed‐suppressive effects of the competitive cultivars, such as MR Goldrush, and high crop densities minimized the yield losses from the weeds. These results indicate that sorghum competition against grass weeds can be improved by choosing competitive cultivars and by using a high crop density of >7.5 plants per m2. These non‐chemical options should be included in an integrated weed management program for better weed management, particularly where the control options are limited by the evolution of herbicide resistance. 相似文献
8.
Abstract Seeds of Sorghum vulgare stored under different conditions were collected to isolate the fungi associated with them. Species of Helminthosporium, Gloeocercospora, Curvularia, Aspergillus and Rhizopus were isolated. It was observed that incidence of fungi was greater in the case of the seeds stored in gunny bags* than with those stored in panicles. Species of the first three fungi were found to cause seed rot as well as seeding blight and the latter two were found to have a detrimental effect on germination of seeds. Seed treatment with Agrosan G.N.** and Ceresan dry at the rate of 2.5 g/kg of seed were found to be most effective in controlling these fungi. An attendant problem of Jowar (Sorghum vulgare) growing is a number of diseases, many of them due to fungi associated with seeds. Investigations were undertaken to discover the fungi associated with seed during storage causing rot of seedlings and methods of their control. Pathogenicity tests and seed treatments with different fungicides were also conducted. 相似文献
9.
早衰是高粱生产和育种上存在的普遍现象。长期以来被认为是一种生理性病害。经4年研究证明它是草酸青霉(Penicilliem axalicum)和纤细交链孢霉(Allernaria allernala)于初花期浸染而引起的一种高粱穗部病害。主要症状是颖壳及与其连接的枝梗组织坏死,阻止了养分、水分向上输导,造成籽粒秕瘦变小。一般减产10%以上。这是国内首次报道的高粱新病害,定名为高粱青霉颖枯病,此病在初花期用多菌灵防治有较好效果。 相似文献
10.
Field response of near‐isogenic brown midrib sorghum lines to fusarium stalk rot,and response of wildtype lines to controlled water deficit 
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下载免费PDF全文 To increase digestibility for ruminant livestock and for lignocellulosic ethanol conversion efficiency in sorghum (Sorghum bicolor), brown midrib (bmr) lines carrying bmr6 or bmr12 and the double mutant (bmr6 bmr12) in two backgrounds (RTx430 and Wheatland) were developed, resulting in lines with significantly reduced lignin, as compared with the near‐isogenic wildtype. Under greenhouse conditions, these lines had previously demonstrated no increased susceptibility, and some lines were more resistant to the highly virulent stalk rot pathogen, Fusarium thapsinum, compared to the wildtype. Fusarium stalk rot of sorghum is a destructive disease that under high temperatures or drought conditions may lead to lodging. To determine if greenhouse observations could be extended to field environments, bmr and near‐isogenic wildtype lines were inoculated with F. thapsinum at field locations, Mead (irrigated) and Havelock (dryland) in Nebraska, USA. Analysis of mean lesion lengths showed those of most bmr lines were statistically similar to the wildtype. Across both genetic backgrounds, bmr6 and bmr6 bmr12 double mutant plants grown at Mead had significantly smaller mean lesion lengths than the corresponding wildtype (P ≤ 0.05). To assess responses of the two genetic backgrounds to controlled (greenhouse) water stress, wildtype RTx430 and Wheatland plants were inoculated with F. thapsinum under well‐watered and water stress conditions. Mean lesion lengths resulting on water deficit plants were significantly larger than those on well‐watered plants (P = 0.01). These results indicate that this bioassay can be used to screen sorghum lines in the greenhouse for increased resistance or tolerance to both drought and fusarium stalk rot. 相似文献
11.
Abstract Field research was conducted near Hyderabad, India, during 1981 and 1982 to investigate zero‐tillage and reduced‐tillage systems for production of sorghum (Sorghum bicolor (L.) Moench.) under semi‐arid tropical conditions. Part of the investigation compared post‐seeding hand weeding and herbicide treatments for weed control efficacy. The results showed that shallow pre‐seeding tillage was just as effective as deep cultivations in producing high sorghum fodder and grain yields provided weeds were controlled after crop emergence. Both tillage regimes were more effective than a no tillage regime which received only a mixture of glyphosate and 2,4‐D prior to seeding. Post‐seeding weed control practices were essential to maintain high fodder and grain yields of sorghum. Hand weeding and inter‐row blade harrowing were more effective than atrazine applied pre‐emergence or 2,4‐D applied post‐emergence. 相似文献
12.
In this study, the effects of Striga hermonthica (Del.) Benth. on a sensitive and a tolerant sorghum genotype were investigated, and the underlying tolerance mechanisms were distinguished. The sensitive sorghum cv. CK60-B and the tolerant sorghum landrace Tiemarifing were grown in pots with and without seed infestation. Both sorghum genotypes responded to infection by the parasite, but it was evident that CK60-B was more strongly affected than Tiemarifing. Sorghum plant height, final leaf number, green leaf area, kernel yield, number of kernels and 1000-kernel weight were significantly reduced by infection, which also had a marked effect on the phenological development of CK60-B; the majority of the plants remained vegetative and, in the remaining plants, flowering was delayed by about 2 weeks. No effect on the phenological development of Tiemarifing was observed. The tolerant landrace showed significantly lower and delayed emergence of S. hermonthica than the sensitive cultivar, and this could be explained by a delay in the onset of attachment. Significantly higher numbers of reproductive parasitic plants were found in the pots with the sensitive sorghum plants. It is concluded that differences in root architecture and the resulting early infection and higher S. hermonthica numbers are partly responsible for the stronger effects of the parasite on the sensitive cultivar. 相似文献
13.
Plants derived from bulked seed samples of Smyrnium olusatrum collected from small patches of plants in Anglesey, Gwynedd, Shropshire and Suffolk were all susceptible, but expressed quantitative differences in disease severity, when inoculated with either aeciospores or teliospores of Puccinia smyrnii from the same or similar locations under controlled environmental conditions. Latent periods (mean 16 and 11 days for appearance of telia and spermagonia, respectively) were longer in 1996 compared with repeat inoculation in 1997 when the rust was more severe. Summation of mean numbers for each year of both aecia and telia, for rust isolate × host accession combinations, showed significantly different numbers of aecia in both years but not of telia. Incidence and severity of P. smyrnii varied on plants derived from seed from Anglesey, Shropshire and Suffolk when transplanted into a naturally rust-affected population of S. olusatrum at Gwynedd, but all plants were susceptible. Experimental transfer of spermatia between spermagonia confirmed that P. smyrnii is heterothallic. 相似文献
14.
F. J. Simmonds 《国际虫害防治杂志》2013,59(1):41-43
A survey was conducted to gain insight into the perceptions of Lesotho's farmers with regard to insect pests of maize and sorghum, to identify management practices that could impact on stalk-borer numbers and to shed light on other farming practices such as variety selection and crop residue management. Field studies were conducted to determine the incidence and distribution of Busseola fusca (Lepidoptera: Noctuidae) and Chilo partellus (Lepidoptera: Pyralidae) larvae in sorghum and maize residues and to determine the effect of certain crop residue management practices on stalk-borer survival. Results indicated that farmers regard stalk-borers as important pests that sometimes need to be controlled. However, most farmers never apply control measures, mainly due to lack of resources. Residues of maize and sorghum plants are largely used as animal fodder with maize being cut and fed to animals after harvest. Sorghum crop residues are largely left on fields after harvest to be used by free-grazing animals. While stacks of maize stalks were not important in the winter survival of B. fusca larvae, stacking of sorghum ensures winter survival of C. partellus larvae. Detasselling of maize plants is commonly done at plant senescence and the upper halves of plants are fed to animals. Detasselling of maize plants had no effect on the number of borer larvae in plants at harvest. 相似文献
15.
N. Monaghan 《国际虫害防治杂志》2013,59(2):172-176
Abstract Sorghum halepense (L.) Pers. (Johnson grass) is an important weed in many countries. In Australia it invades crop lands, provides a harbour for diseases and insect pests of sorghum and maize, contaminates sorghum grown for seed and constitutes a safety hazard along roadsides. 相似文献
16.
RENATA D. WULFF 《Weed Research》1987,27(2):79-85
Plants of soybean (Glycine max) and sorghum (Sorghum bicolor) were grown either alone or in combination with 1, 2, 4, 8 and 16 Amaranthus dubius plants per pot in controlled environment chambers at 31/24 and 25/18°C day/night temperatures. Above-ground dry weights, leaf areas and heights were measured at 17 and 35 days after planting. Growth of both species increased with temperature. At the second harvest, at both temperatures, even one A. dubius plant per pot had a significant effect on growth of the crop species, and the effects of the two highest densities were equivalent. Shoot dry weights of A. dubius plants were significantly lower when grown with soybean than with sorghum at the same conditions. Linear regressions showed that the dry weights of the crop species were more highly correlated with biomass than with numbers of the interfering weeds, and suggest that soybean may be more affected by an increase in abundance of A. dubius than is sorghum. 相似文献
17.
A commercially developed cytokinin and seaweed extract formulation “Dravya” was used at 0.3% concentration for soaking of sorghum seeds for 12 h to test its effect on germination, vigour index, chlorophyll content and defense enzyme activity against seed mycoflora of sorghum. Among the treatments, Dravya (0.3%) with Dithane M-45 (0.1%) and GLSTIN (0.1%) or separately or in combination resulted is maximum percentage of seed germination, seedling vigour and reduced the incidence of seed mycoflora besides defense enzymes enhancement was noticed. In this study, Dravya was used for seed soaking, foliar spray, separately as well as in combination with GLSTIN and Mancozeb M-45 to test its efficacy in the enhancement of seedling vigour, chlorophyll content and defence enzyme activities. Hence, it is inferred that Dravya is a good growth promoter and improves natural resistance to disease in sorghum. 相似文献
18.
Ergot is an important disease of sorghum (Sorghum bicolor) in parts of Africa and Asia. Studies were conducted to determine the relationship between flowering biology and ergot infection, and to develop an artificial field-screening technique to identify ergot resistance in sorghum. Spikelets resisted infection after anthesis, but each day's delay in anthesis after inoculation supported 8-3% more ergot. The screening technique consisted of three components: trimming of panicles to remove pollinated spikelets before inoculation, a single inoculation of trimmed panicles, and panicle bagging for 7-10 days. Inoculated panicles were evaluated by a qualitative visual rating method (on a 1-5 scale) and a quantitative spikelet counting method. Selected accessions from the world collection of sorghum germplasm were screened at Karama Research Station, Rwanda, for two seasons and 12 ergot-resistant lines were identified. These were also resistant at ICRISAT Centre, India. 相似文献
19.
Can wild relatives of sorghum provide new sources of resistance or tolerance against Striga species?
Summary The genus Striga contains some of the most noxious parasitic plants, which have a devastating impact on cereal production in Africa; of most importance are Striga hermonthica and Striga asiatica . Complete resistance to infection by Striga species does not exist in cultivated cereals. Of great interest is the possibility that wild relatives of cereals may provide a genetic basis for resistance or tolerance to infection and may be of enormous value for the development of resistant crops. A wild relative of cultivated sorghum, Sorghum arundinaceum , demonstrated tolerance to infection by S. asiatica , with little impact of S. asiatica on host growth or grain production compared with the detrimental impact of the parasite on cultivated sorghum. Infection by S.hermonthica , however, had a significant influence on host performance for both wild and cultivated sorghum. Differences in host:parasite responses may be explained by the timing of parasite attachment and differences in host specificity for these two Striga species. 相似文献
20.
Batches of glasshouse-grown flowering sorghum plants were placed in circular plots for 24 h at two field sites in southeast Queensland, Australia on 38 occasions in 2003 and 2004, to trap aerial inoculum of Claviceps africana. Plants were located 20–200 m from the centre of the plots. Batches of sorghum plants with secondary conidia of C. africana on inoculated spikelets were placed at the centre of each plot on some dates as a local point source of inoculum. Plants exposed to field inoculum were returned to a glasshouse, incubated at near-100% relative humidity for 48 h and then at ambient relative humidity for another week before counting infected spikelets to estimate pathogen dispersal. Three times as many spikelets became infected when inoculum was present within 200 m of trap plants, but infected spikelets did not decline with increasing distance from local source within the 200 m. Spikelets also became infected on all 10 dates when plants were exposed without a local source of infected plants, indicating that infection can occur from conidia surviving in the atmosphere. In 2005, when trap plants were placed at 14 locations along a 280 km route, infected spikelets diminished with increasing distance from sorghum paddocks and infection was sporadic for distances over 1 km. Multiple regression analysis showed significant influence of moisture related weather variables on inoculum dispersal. Results suggest that sanitation measures can help reduce ergot severity at the local level, but sustainable management will require better understanding of long-distance dispersal of C. africana inoculum. 相似文献