共查询到20条相似文献，搜索用时 62 毫秒
1.
Leaf scald (Xanthomonas albilineans) incidence and its effect on yield in seven sugarcane cultivars in Guadeloupe 总被引：1，自引：0，他引：1
Seven 5—month-old sugarcane cultivars difTering in resistance to leaf scald disease were inoculated by the decapitation technique with Xanthomonas albilineans. The effects of disease progress and incidence on yields were studied for the plant (first harvest) and two ratoon crops (second and third harvest). The percentage of diseased stalks and disease severity at first harvest 5 months after inoculation were 0·7 and 0·4, respectively, for the most resistant cultivar and 71·0% and 63·3, respectively, for the most susceptible cultivar. They decreased in all cultivars in both ratoon crops, but were still important in one cultivar (B69379). Significant ( P = 0·05) yield reductions of 12% and 21% occurred in two of the seven cultivars (B69566 and B69379, respectively). The number of symptomatic sugarcane stalks in the first ratoon crop (second harvest) was lower than the number of stalks colonized by the pathogen. Symptoms and yield losses of cultivars R570 and B69566 varied with the crop. Yield losses occurred in cultivar R570 only in the plant crop when this cultivar displayed numerous symptoms. Cultivar B69566 appeared to recover from the disease to a certain extent from the plant to the second ratoon crop (third harvest), as did the resistant cultivars in the first ratoon crop. In contrast, severe leaf scald symptoms were observed in the case of cultivar B69379 regardless of the crop, and significant yield losses occurred in the two ratoon crops. These results support the recommendation that cultivar B69379 should not be replanted in Guadeloupe. 相似文献
2.
从100余个稻瘟病菌单孢株中选择代表近年来在浙江省水稻上出现的主要小种的10个菌株，分别来自6个籼稻和4个粳稻品种。将10个菌株分别接种到230个籼稻和183个粳稻品种上，研究从籼、粳稻上分离的稻瘟病菌（籼、粳菌）的致病性。籼菌主要侵染籼稻，侵染后中等发病和重发病的品种比例分别为25．22％和12．61％。均高于侵染粳稻后这两种发病程度的品种比例；粳菌主要侵染粳稻，侵染后重发病的品种比例为40．44％，明显高于侵染籼稻后重发病的品种比例。在籼稻中被籼菌侵染后发病比被粳菌侵染后发病重的品种占籼稻总数的69．57％，并且被籼菌侵染后轻发病、中等发病和重发病的品种比例均明显高于被粳菌侵染后这几种发病程度的品种比例；在粳稻中被粳菌侵染后发病比被籼菌侵染后发病重的品种也占有较大的比例，在被籼菌侵染的发病品种中以轻发病的品种为主，在被粳菌侵染后的发病品种中以重发病的品种为主。 相似文献
3.
Sulcotrione soil persistence in spring maize ( Zea mays L.) crops grown on a sandy loam soil was greater at pH 5·5 and 6·0 (soil half-life T 1/2 ≈58 days) than at pH 7·1 ( T 1/2 = 44 days). Sulcotrione was also applied as recommended on a summer maize crop at the five- to six-leaf growth stage, grown on a sandy loam soil. Sulcotrione soil half-life was 44 days, and the herbicide remained mainly in the 0- to 5-cm surface soil layer during the cropping period, in spite of the high water solubility and the heavy rains at the end of August; lower sulcotrione concentrations (10–18% of the total during the 2-month period after sulcotrione application) were detected in the 5- to 10-cm surface soil layer. The herbicide was applied pre-emergence to winter wheat ( Triticum aestivum L.) at four sites that differed in their soil texture and composition: loamy sand, sandy loam, loam and clay loam. Persistence was greater in the soils containing more organic matter. In soils having similar organic matter contents, persistence was lower in the soil containing more sand relative to loam and clay. During the winter crops, sulcotrione moved down to the 10- to 15-cm soil layer, in spite of the fact that the rains were lower in winter than in summer. Sulcotrione most generally was not detected in the 15–20 cm soil layer of the maize and winter wheat crops. 相似文献
4.
Natural Variation at the Pi-ta Rice Blast Resistance Locus 总被引：1，自引：0，他引：1
ABSTRACT The resistance gene Pi-ta protects rice crops against the fungal pathogen Magnaporthe grisea expressing the avirulence gene AVR-Pita in a gene-for-gene manner. Pi-ta, originally introgressed into japonica rice from indica origin, was previously isolated by positional cloning. In this study, we report the nucleotide sequence of a 5,113-base pair region containing a japonica susceptibility pi-ta allele, which has overall 99.6% nucleotide identity to the indica Pi-ta allele conferring resistance. The intron region shows the levels of sequence diversity that typically differentiate genes from indica and japonica rices, but the other gene regions show less diversity. Sequences of the Pi-ta allele from resistant cultivars Katy and Drew from the southern United States are identical to the resistance Pi-ta sequence. Sequences from susceptible cultivars El Paso 144 and Cica 9 from Latin America define a third susceptibility haplotype. This brings the total number of Pi-ta haplotypes identified to four, including the resistance allele and three susceptibility alleles. The Pi-ta locus shows low levels of DNA polymorphism compared with other analyzed R genes. Understanding the natural diversity at the Pi-ta locus is important for designing specific markers for incorporation of this R gene into rice-breeding programs. 相似文献
5.
Effect of temperature on latent period of septoria leaf blotch on winter wheat under outdoor conditions 总被引：1，自引：0，他引：1
D. J. Lovell † T. Hunter S. J. Powers S. R. Parker ‡ F. Van den Bosch 《Plant pathology》2004,53(2):170-181
Batches of two winter wheat cultivars (Riband and Apollo) were inoculated with conidia of Mycosphaerella graminicola at weekly intervals over a 2 year period. Following 72 h incubation, plants were placed in ambient temperatures ranging between −7 and 32°C with mean batch temperatures of 2·9–20·2°C. Latent period until the first visible symptoms ranged between 11 and 42 days. The relationship between development of lesions and accumulated thermal time was described using a shifted cumulative gamma distribution model. The model provided good estimates of lesion development with r 2 > 0·92 for both cultivars. Base temperatures, below which the pathogen did not develop, were estimated from the model as approximately −2·4°C for the two cultivars. Latent period was estimated as being 250 and 301 degree-days above the estimated base temperature, when defined as time from inoculation to first lesion and time to 50% of maximal lesions, respectively, for cv. Riband. The values for cv. Apollo were similar, but with estimates of thermal time periods c . 5% higher. The relationship between mean temperature and inverse latent period, expressed as days either to first lesion or to 50% of maximal lesions, was best described by a linear regression with r 2 > 0·96 for both cultivars. The opportunity for plants to outgrow disease was reduced when prolonged periods of cold temperature occurred, because the base temperature for growth of the pathogen was less than that for the crop. 相似文献
6.
Infection and colonization of melon roots by Monosporascus cannonballus in two cropping seasons in Arizona and California 总被引：1，自引：0，他引：1
M. E. Stanghellini † D. H. Kim M. M. Waugh D. M. Ferrin T. Alcantara S. L. Rasmussen 《Plant pathology》2004,53(1):54-57
Although canopy collapse of melons (one of the above-ground symptoms of vine decline caused by Monosporascus cannonballus ) occurred late in the growing season, the onset of root infection occurred much earlier. In three early winter-spring and two late winter-spring crops, the onset of root infection occurred 47–65 and 35–36 days after planting, respectively. In contrast, in four summer-autumn crops, the onset of root infection occurred within 9–17 days after planting. Vine decline occurred commonly in winter-spring crops, but did not occur in any of the summer-autumn crops. Following the onset of root infection, the percentage of plants infected increased at rates of 0·031–0·036 and 0·038–0·070 per unit per day for winter-spring and summer-autumn crops, respectively, based on the monomolecular disease progress model. Root lesions were first observed 14–42 days after the onset of infection in winter-spring crops, and 14–28 days after the onset of infection in summer-autumn crops. Pathogen reproduction occurred primarily at the end of each growing season. 相似文献
7.
水稻矮缩病的研究——Ⅱ.病害感染、发生和防治 总被引：1，自引：0，他引：1
水稻矮缩病的潜育期因气温、水稻生育期、介体黑尾叶蝉(Nephotettix cincticeps)的虫龄、性别等不同而异,一般为10～15天。水稻在分蘖初期到盛期最易感病,这些病株均不能抽穗结实;分蘖末期感染者,产量损失达80%以上。病毒在虫体内越冬,越冬代带毒成虫传毒给早稻,第2、3代带毒虫传毒给晚稻。第1、4代经卵带毒虫,还能分别引起早、晚稻再次侵染。以早栽双季晚稻和杂交晚稻发病最重,其主要感染期是在本田初期。以农业防治为基础,治虫防病抓适期的综合防治措施,能有效地控制病害流行。病区在连片种植的基础上,对早栽双季晚稻本田初期喷药治虫1～3次,能收到显著的防病效果。 相似文献
8.
1983-2007年,对南方稻区水稻区域试验品种、组合的白叶枯病抗性进行了研究。结果表明,在1 805个参试品种、组合中,78个表现抗白叶枯病,抗病品种频率为4.3%;其中,常规水稻74个,占抗病品种的94.9%。在1 219个籼型杂交水稻中,抗病的组合3个,中抗的76个,抗病和中抗组合频率分别为0.2%和6.2%。不同类型和不同生态型水稻的抗病品种频率差异显著,晚粳>早籼>中籼>晚籼;常规水稻>杂交水稻。籼型杂交水稻中抗病组合频率为:杂交晚稻>杂交早稻>杂交中稻。1990-2004年,17个抗或中抗白叶枯病的优良水稻新品种、组合通过国家审定。 相似文献
9.
Successful crop production depends on effective weed control. Weed seedbanks were determined after 12 years of dryland cropping with winter wheat and grain sorghum under different tillage methods (no- and stubble mulch) and cropping sequences. Seeds of 12 species were detected. Amaranthus retroflexus was most abundant, but seed numbers were similar under all conditions. Portulaca oleracea , Panicum capillare , Setaria viridis and Sorghum halepense seed numbers differed because of some factors, with those for P. oleracea being greatest. For others, seed numbers were low (≤0.11 kg−1 soil), except for Digitaria sanguinalis with 7.8 kg−1 soil and Bromus japonicus with 1.3 kg−1 soil. Most seeds were near the surface with both tillage methods, with enough present under most conditions to cause a problem if proper control measures were not used, especially with continuous cropping. When a weed problem occurs under conditions as in this study, the results indicate that it could be reduced by growing winter and summer crops in rotation, which permits controlling weeds with tillage and/or herbicides when a crop is not growing. Other possibilities for controlling weeds under conditions as in this study are to alternate between dicotyledonous and monocotyledonous crops, which would permit use of a wider range of herbicides, and to use selective in-crop herbicides. 相似文献
10.
Ginseng ( Panax quinquefolius ) is an important cash crop in various regions of North America, but yields are often reduced by various root pathogens. A quantitative real-time PCR (qPCR) assay for Cylindrocarpon destructans f. sp. panacis (CDP), the cause of a root rot and replant disease which discourages successive cropping of ginseng on the same site, was developed to quantify the levels of this pathogen in soils previously cropped with ginseng. DNA was extracted from 5-g samples of soil. In pasteurized soils which were re-infested with varying levels of the pathogen, qPCR estimates of pathogen DNA were significantly correlated with disease severity ( r = 0·494) and with counts of colony-forming units ( r = 0·620) obtained with an agar medium. In several naturally infested field soils, qPCR estimates of CDP-DNA concentration were significantly correlated with disease severity ( r = 0·765) and these concentrations were estimated to range from 0 to 1·48 ng g−1 dried soil. A principal components analysis did not show any strong relationships between soil chemistry factors and the concentration of pathogen DNA. The approach outlined here allows the quantification of current populations of CDP in soil many years after ginseng cultivation and the prediction of disease severity in future crops. The method should be generally applicable to root diseases of many crops. 相似文献
11.
不同水稻品种花期耐旱性评价 总被引：1，自引：0，他引：1
以我国96个主导水稻品种为材料,于水稻开花期进行水分处理10d,研究水分胁迫下不同水稻品种与
水稻产量构成因子的关系。结果表明,开花期水分胁迫对水稻每穗粒数影响不显著,结实率和千粒重有着不同程
度的下降。根据水分胁迫指数将供试品种分为耐旱型(WSI<0.0599)、中间型(0.06000.2600)3类。筛选出9个耐旱型品种,其中粳型常规水稻1个、籼型常规水稻1个、籼型两系杂交水稻2
个、籼型三系杂交水稻5个。籼稻品种的酎旱性明显优于粳稻品种,来源于同一母本冈46A的冈优527、冈优188和
冈优725在本试验中都表现出良好的耐旱性。 相似文献
12.
Substantial reductions in winter wheat diseases caused by addition of straw but not manure to soil 总被引：2，自引：0，他引：2
Over a period of 3 years, five agronomically distinct crops of winter wheat were grown in plots in which straw (1 kg m−2 ), manure (4 kg m−2 ) or nothing were incorporated into the soil. Plant establishment and height, but not leaf area per tiller, were lower in straw-treated plots. Fertilizer regimes differed between years. Soil and leaf nitrogen were recorded; there was no obvious link between N and any disease or soil amendment. The numbers of leaf layers scorable for disease were similar in all treatments. At the end of the season, plants from straw-treated plots had consistently reduced septoria tritici blotch (caused by Mycosphaerella graminicola ), powdery mildew [caused by Erysiphe ( Blumeria ) graminis ], brown rust (caused by Puccinia recondita ) and foot rot (caused by Fusarium spp.). Early on, M. graminicola was worse in straw-treated plots. In manure-treated plots, P. recondita was reduced but effects on other diseases were inconsistent and slight. A fungicide, chlorothalonil, was applied in one crop; its effects did not interact with those of other treatments. Mycosphaerella graminicola was not suppressed by straw in outdoor pot experiments. Late in the season, straw-treated plants had significantly higher leaf silica ( P < 0·01). In a glasshouse experiment, plants supplied with silicon had less E. graminis infection ( P < 0·001) and higher leaf silica, but effects on M. graminicola were inconsistent. A prior inoculation of M. graminicola primed plant defences against a subsequent attack of E. graminis , but only in the presence of adequate Si. It is postulated that straw acts in the field by increasing Si availability. 相似文献
13.
The effect of pea canopy structure on epidemics of Mycosphaerella pinodes was investigated in four spring pea cultivars (Bridge, Obelisque, Solara and Athos) in two field experiments. These cultivars had similar levels of susceptibility to ascochyta blight and presented different architectural features (branching, standing ability and stem height). Stem height ranged from 77 to 95 cm in 1999 and from 72 to 92 cm in 2000, while leaf area index (LAI) ranged from 3·8 to 5·1 in 1999 and from 3·8 to 4·7 in 2000. Internode lengths varied from 4·6 to 6·0 in 1999 and from 3·8 to 4·7 in 2000. Mean distance between nodes in the canopy (MDN) ranged from 12·2 to 15·3 cm in 1999 and from 11·2 to 13·9 cm in 2000. Canopies with different architecture differed in disease progression on stipules and mainly on pods. The levels of disease on stipules and pods were strongly correlated. Moreover, if disease was considered as a function of stipule height up the stem, large differences in vertical disease distribution were observed between cultivars. Three architectural features acted on disease development: cumulative LAI above the node on which disease was assessed (LAIcum) and large MDN favouring disease development, and large internode length reducing disease severity. Modifying LAI distribution and plant organization could be one way to reduce the impact of ascochyta blight, by direct or indirect effects on environmental and dispersal conditions. 相似文献
14.
H. Wang S. F. Hwang F. Eudes K. F. Chang R. J. Howard G. D. Turnbull 《Plant pathology》2006,55(2):224-230
Greenhouse trials conducted in 2003 and 2004 investigated the impact of trichothecenes on the severity of seedling blight and root rot in common wheat ( Triticum aestivum ), durum wheat ( Triticum turgidum var. durum ), barley ( Hordeum vulgare ) and triticale (× Triticosecale 6x ) using two trichothecene-producing and two trichothecene-nonproducing Fusarium graminearum strains. In 2003 seedling emergence and survival following soil infestation of the trichothecene-producing strain (Gz3639) were significantly reduced compared with the trichothecene-nonproducing strain (GzT40), while root-rot incidence and severity were increased significantly. In 2004, two trichothecene-producing strains (Gz3639 and GzT106) reduced seedling emergence and survival ( P ≤ 0·01) in eight of 10 crops/cultivars based on single-degree-of-freedom contrasts. However, when results from all strains were combined no significant differences were observed between two trichothecene-producing and two trichothecene-nonproducing F. graminearum strains. Inoculation with GzT106, a trichothecene-producing 'add-back' strain, resulted in more severe root rot symptoms in eight of 10 cultivars ( P ≤ 0·01–0·05) and lower seedling emergence and survival in seven of 10 cultivars ( P ≤ 0·01–0·10), compared with the wild-type parental strain Gz3639. The presence of trichothecenes may play an important role in the aggressiveness of F. graminearum . 相似文献
15.
This study reviews 52 field experiments, mostly from the UK, studying the effects of cultivation techniques, sowing date, crop density and cultivar choice on Alopecurus myosuroides infestations in cereal crops. Where possible, a statistical meta‐analysis has been used to calculate average responses to the various cultural practices and to estimate their variability. In 25 experiments, mouldboard ploughing prior to sowing winter cereals reduced A. myosuroides populations by an average of 69%, compared with non‐inversion tillage. Delaying drilling from September to the end of October decreased weed plant densities by approximately 50%. Sowing wheat in spring achieved an 88% reduction in A. myosuroides plant densities compared with autumn sowing. Increasing winter wheat crop density above 100 plants m?2 had no effect on weed plant numbers, but reduced the number of heads m?2 by 15% for every additional increase in 100 crop plants, up to the highest density tested (350 wheat plants m?2). Choosing more competitive cultivars could decrease A. myosuroides heads m?2 by 22%. With all cultural practices, outcomes were highly variable and effects inconsistent. Farmers are more likely to adopt cultural measures and so reduce their reliance on herbicides, if there were better predictions of likely outcomes at the individual field level. 相似文献
16.
Chen L Zhang SJ Zhang SS Qu S Ren X Long J Yin Q Qian J Sun F Zhang C Wang L Wu X Wu T Zhang Z Cheng Z Hayes M Beer SV Dong H 《Phytopathology》2008,98(7):792-802
Harpins of phytopathogenic bacteria stimulate defense and plant growth in many types of plants, conferring disease resistance and enhanced yield. In a previous study, we characterized nine fragments of the harpin protein HpaG(Xooc) from Xanthomonas oryzae pv. oryzicola for plant defense elicitation and plant growth stimulation activity relative to the intact protein. In plants grown under controlled conditions, the fragment HpaG10-42 was more active in both regards than HpaG(Xooc). Here, we demonstrate that the activity of HpaG10-42 in rice under field conditions significantly exceeds that of HpaG(Xooc), stimulating resistance to three important diseases and increasing grain yield. We carried out tests in 672 experimental plots with nine cultivars of rice planted at three locations. Application protocols were optimized by testing variations in application rate, frequency, and timing with respect to rice growth stage. Of the concentrations (24, 24, 12, and 6 microg/ml), and number and timing of applications (at one to four different stages of growth) tested, HpaG10-42 at 6 microg/ml applied to plants once at nursery seedling stage and three times in the field was most effective. Bacterial blight, rice blast, and sheath blight were reduced 61.6 and 56.4, 93.6 and 76.0, and 93.2 and 55.0% in indica and japonica cultivars, respectively, relative to controls. Grain yields were 22 to 27% greater. These results are similar to results obtained with typical local management practices, including use of chemicals, to decrease disease severities and increase yield in rice. Our results demonstrate that the HpaG10-42 protein fragment can be used effectively to control diseases and increase yield of this staple food crop. 相似文献
17.
Abstract Grassy stunt disease, ragged stunt virus and rice tungro virus, are among the most widespread and damaging rice diseases in Indonesia. Yield losses due to grassy stunt and the brown planthopper (Nilaparvata lugens) in the period 1974–77 were more than US$510 million. Ragged stunt virus is a new disease which is widespread in Indonesia and has been reported in several rice growing countries in Asia since 1977. Loss figures for ragged stunt are not available, however, individual farmers have suffered 100% yield loss in infected fields. Tungro and grassy stunt are controlled by resistant varieties but there are no commercially available varieties with resistance to ragged stunt. 相似文献
18.
利用分子标记提高筛选普感水稻抗病突变体的准确性 总被引：1，自引：0，他引：1
水稻丽江新团黑谷(LTH)是一个云南地方粳稻普感品种,对全球近2 800多个稻瘟病菌生理小种均表现为感病表型。本研究为利用60Co-γ射线辐照处理LTH种子,分单株收获M1代种子。对M2和M3代植株分别进行稻瘟病的自然诱发筛选和人工喷雾接种筛选,以期从LTH中筛选获得抗性提高的突变体。在突变体筛选过程中,我们发现突变体的遗传背景受到零星异交或混杂干扰,这种情况在其他本底抗性水平较高的抗性突变体筛选中往往容易被忽略。为了确保突变体遗传背景的真实性,我们利用分布在水稻12条染色体上的在粳稻LTH与籼稻品种间存在多态性的In/Del标记,分析候选抗性植株是否为LTH纯合背景,以排除杂合假抗性个体。通过两种不同的筛选策略,最终从M3代植株中分别鉴定出1份和4份抗性突变体,为进一步研究LTH普感特性奠定基础。将其中一个LTH抗病突变体分别与野生型LTH和籼稻普感品种CO39进行杂交,获得的F2群体人工喷雾接种稻瘟病菌后调查抗、感植株的分离情况,分析结果显示,该突变体性状符合单个显性基因控制的遗传规律。另外,本研究结果表明:在水稻诱变育种工作中,不仅要做到充分隔离,还需借用分子标记辅助剔除零星意外串粉造成的杂合假突变体,以提高水稻突变体筛选的准确率。 相似文献
19.
The Effects of Cultural Measures on Cereal Pests and Their Role in Integrated Pest Management 总被引：1，自引：0，他引：1
David M. Glen 《Integrated Pest Management Reviews》2000,5(1):25-40
The influences of cultural control measures on invertebrate pests and their natural enemies in cereals (wheat, barley and oats) are described and discussed, with emphasis on the major pests in north-west Europe. Possibilities for additive and synergistic combinations of cultural measures are identified, together with opportunities for integrating cultural measures with chemical and biological control where appropriate. Recent studies confirm the central role of cultural control measures in integrated pest management and integrated production of cereal crops. However, cultural measures often have opposing effects on different pests as well as diseases and weeds, so that appropriate measures must be selected on the basis of an assessment of the risks from key pests, diseases and weeds. Crop rotation is not an important means of controlling cereal pests, but its use is recommended for control of cereal diseases and weeds, as well as pests of crops grown in rotation with cereals. Diversification of crops and non-crop habitats in predominantly cereal growing areas is thought to increase numbers of certain parasitoids and polyphagous predators of cereal pests. The presence of weeds or an intercrop in a field together with cereals may reduce the severity of aphid and slug damage to cereals. Trap cropping has not yet been adequately tested in wheat, barley or oats. Cover crops reduce damage by wheat bulb fly in a following wheat crop, but increase the risk of slug damage. Resistance to a wide range of cereal aphid species has been identified in wheat and barley, but in Europe, more emphasis is placed on selecting cultivars with resistance to cereal diseases rather than pest resistance. Resistance in wheat to wheat bulb fly and wheat blossom midge is recorded, and resistance to slug damage has been reported in some laboratory studies. Early sowing of winter cereals results in more damage by certain dipterous pests and increased numbers of the aphid vectors of barley yellow dwarf virus (BYDV), but early sowing results in less damage by wheat bulb fly and slugs in autumn/winter and by late infestations of aphids in summer. Avoidance of ploughing results in reduced incidence of wheat bulb fly, yellow cereal fly and aphids, but increased numbers of slugs, wheat blossom midge and bibionid larvae. Avoidance of ploughing can result in greater numbers of certain polyphagous predators, particularly in the first weeks following crop establishment. The presence of straw residues results in increased slug populations, but reduced incidence of yellow cereal fly and wheat blossom midge. Preparation of fine, firm seedbeds discourages attack by slugs and wheat bulb fly on cereals. Drilling at slightly greater depth in rough cloddy seedbeds helps to protect wheat seeds from slug damage. Nitrogen fertiliser applied in spring can help cereal plants compensate for losses by wheat bulb fly or slugs. However, nitrogen applications tend to result in increased summer infestations of aphids. 相似文献