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1.
In the last fifteen years many grapevine have been destroyed in vineyards in Germany by Eutypa dieback, esca (“black measles”) and Petri disease (“black goo disease”). These diseases caused by one ore more phytopathogens. So far a directly combat is not possible. Well-known data of the literature about biology, epidemiology and disease symptoms on grapevine are summarized and indirectly recommendations of combat are proposed. A stocktaking of a field attempt on biological control of fungi diseases with antagonistic microorganisms of Trichoderma ssp. in grapevine from 2003 in the framework of project “Preventive plant protection methods for biological control of three important fungal disease pathogens in organic viticulture” is given. The content of nutrition elements in grapevine leaves of healthy and diseased grapevines is determined. The analyzed contents of mineral elements in the leaves of the infected plants differentiate to the recommended values of sufficiently nutrition of grapevine leaves. Microorganisms of Trichoderma ssp. are able to antagonise the inhibition of the reception of manganese. 相似文献
2.
L. Hallau M. Neumann B. Klatt B. Kleinhenz T. Klein C. Kuhn M. Röhrig C. Bauckhage K. Kersting A.‐K. Mahlein U. Steiner E.‐C. Oerke 《Plant pathology》2018,67(2):399-410
Cercospora leaf spot (CLS) poses a high economic risk to sugar beet production due to its potential to greatly reduce yield and quality. For successful integrated management of CLS, rapid and accurate identification of the disease is essential. Diagnosis on the basis of typical visual symptoms is often compromised by the inability to differentiate CLS symptoms from similar symptoms caused by other foliar pathogens of varying significance, or from abiotic stress. An automated detection and classification of CLS and other leaf diseases, enabling a reliable basis for decisions in disease control, would be an alternative to visual as well as molecular and serological methods. This paper presents an algorithm based on a RGB‐image database captured with smartphone cameras for the identification of sugar beet leaf diseases. This tool combines image acquisition and segmentation on the smartphone and advanced image data processing on a server, based on texture features using colour, intensity and gradient values. The diseases are classified using a support vector machine with radial basis function kernel. The algorithm is suitable for binary‐class and multi‐class classification approaches, i.e. the separation between diseased and non‐diseased, and the differentiation among leaf diseases and non‐infected tissue. The classification accuracy for the differentiation of CLS, ramularia leaf spot, phoma leaf spot, beet rust and bacterial blight was 82%, better than that of sugar beet experts classifying diseases from images. However, the technology has not been tested by practitioners. This tool can be adapted to other crops and their diseases and may contribute to improved decision‐making in integrated disease control. 相似文献
3.
4.
Sugarcane yields have been severely reduced by white leaf and grassy shoot phytoplasma diseases in many parts of Asia. Australian sugarcane crops are not known to be affected by these diseases, but plant pathogenic phytoplasmas found in other introduced and native grasses in northern Australia could pose a serious threat to the Australian sugarcane industry. To further evaluate this threat, leaves from plants of 20 grass species, with and without symptoms, were collected during field surveys in northern Australia and tested to determine whether phytoplasmas were present and whether symptoms were reliable indicators of phytoplasma presence. Molecular tools were used to detect and characterize phytoplasmas. Four different phytoplasmas were found in seven grass species known to grow near healthy sugarcane crops. All the phytoplasmas were closely related to sugarcane white leaf phytoplasma (SCWL), one of the phytoplasmas that causes disease in sugarcane in Asia. Four of the host plant species and two of the phytoplasmas were new records. The relationship between symptoms and phytoplasma presence was poor. Because some plants with symptoms tested negative for phytoplasmas, a series of surveys was carried out in which flowers, leaves, roots and stems of two known host plant species, Whiteochloa cymbiformis and Sorghum stipoideum, were tested separately on nine occasions during two wet seasons. This was done to investigate the distribution of phytoplasmas within plants over time. Results showed that spatial and temporal variation of phytoplasmas occurred in these two host plant species. Hence, evaluation of disease distribution within a region requires repeated testing of all plant parts from plants without symptoms, as well as those with symptoms. To date, there is no report of a vector capable of transmitting to Australian sugarcane the phytoplasmas found in grasses in this study. If one is present, or occurs in the future, then native and introduced grasses could constitute a large reservoir of phytoplasma for vectors to draw on. This work provides an early warning for the sugarcane industry that the potential for infection exists. 相似文献
5.
Identification of plants against a soil background using colour images is discussed, and a technique is presented for finding plant segments consisting of crop or weed plants, or both. The problems of overlapping plants and image border effects are explored using techniques developed in stereology. An automatic weed density estimation method is proposed, based on a non–linear regression model and features of the plant segments in an image. The method is applied to a set of images from five barley fields. At present two features of the segments are used: segment area and whether a segment cuts the image border or not. Further, a method is suggested for evaluating the automatic weed density estimation by comparison with an interactive weed density estimator including human judgement. Critical factors and ways of improving the automatic method by including additional features are discussed. 相似文献
6.
《Physiological and Molecular Plant Pathology》2003,62(2):65-72
There are relatively few bacterial diseases of roots, in comparison to those of aerial plant tissues. Numerous species and pathovars of Pseudomonas,Erwinia and Xanthomonas are important pathogens of leaf and stem tissue on dozens of plant families but these bacterial genera only infrequently attack roots or other underground plant structures. In contrast, there is a growing list of Streptomyces species that are very effective root pathogens. These filamentous, Gram-positive bacteria can cause scab, rot and gall diseases of plant roots and other underground plant structures. The best known pathogenic Streptomyces species is S. scabiei. Horizontal transfer of pathogenicity genes among diverse scab-causing streptomycetes appears to explain the emergence of several new plant pathogens over the last half century. It is proposed that the ability to penetrate plant tissue is essential for successful root infection as there are few natural openings in roots. In contrast, leaves have many natural openings that allow bacteria access to the interior tissues. Thaxtomin, a phytotoxin produced by many plant pathogenic streptomycetes, appears to aid penetration of developing plant tissues by inhibiting primary cell wall development. 相似文献
7.
I. K. Toth J. M. van der Wolf G. Saddler E. Lojkowska V. Hélias M. Pirhonen L. Tsror J. G. Elphinstone 《Plant pathology》2011,60(3):385-399
Dickeya species (formerly Erwinia chrysanthemi) cause diseases on numerous crop and ornamental plants world‐wide. Dickeya spp. (probably D. dianthicola) were first reported on potato in the Netherlands in the 1970s and have since been detected in many other European countries. However, since 2004–5 a new pathogen, with the proposed name ‘D. solani’, has been spreading across Europe via trade in seed tubers and is causing increasing economic losses. Although disease symptoms are often indistinguishable from those of the more established blackleg pathogen Pectobacterium spp., Dickeya spp. can initiate disease from lower inoculum levels, have a greater ability to spread through the plant’s vascular tissue, are considerably more aggressive, and have higher optimal temperatures for disease development (the latter potentially leading to increased disease problems as Europe’s climate warms). However, they also appear to be less hardy than Pectobacterium spp. in soil and other environments outside the plant. Scotland is currently the only country in Europe to enforce zero tolerance for Dickeya spp. in its potato crop in an attempt to keep its seed tuber industry free from disease. However, there are a number of other ways to control the disease, including seed tuber certification, on‐farm methods and the use of diagnostics. For diagnostics, new genomics‐based approaches are now being employed to develop D. dianthicola‐ and ‘D. solani’‐specific PCR‐based tests for rapid detection and identification. It is hoped that these diagnostics, together with other aspects of ongoing research, will provide invaluable tools and information for controlling this serious threat to potato production. 相似文献
8.
Effect of temperature on symptom expression and accumulation of tomato spotted wilt virus in different host species 总被引：2，自引：0，他引：2
M. E. Llamas-Llamas E. Zavaleta-Mejia V. A. Gonzalez-Hernandez L. Cervantes-Diaz J. A. Santizo-Rincon & D. L. Ochoa-Martinez 《Plant pathology》1998,47(3):341-347
The effect of two temperature regimes (daytime, 29 ± 2°C, night-time, 24 ± 3°C; and daytime, 23 ± 1°C, night-time, 18 ± 2°C) on the symptoms caused by tomato spotted wilt virus (TSWV), and the accumulation of TSWV virions, was compared in Datura stramonium , Nicotiana tabacum cv. White Burley and Physalis ixocarpa . Tobacco plants were more severely affected by TSWV at the high temperature regime, but the incidence (percent of plants with symptoms) was 100% for both regimes. In P. ixocarpa and D. stramonium the higher temperature caused an increase in both incidence and rate of development of symptoms. At high temperature, all three species showed both local and systemic symptoms; however, at low temperature only P. ixocarpa consistently developed systemic symptoms. In general, virus accumulation in the inoculated leaves (presumably the combined effect of virus replication and local movement) of all plants was higher at the lower temperature. Long distance movement in tobacco, leading to virion accumulation in other plant organs, was favoured by high temperature; but there was relatively little effect in P. ixocarpa and D. stramonium . 相似文献
9.
The development of plant diseases is associated with biophysical and biochemical changes in host plants. Various sensor methods have been used and assessed as alternative diagnostic tools under greenhouse conditions. Changes in photosynthetic activity, spectral reflectance and transpiration rate of diseased leaves, inoculated with Cucumber mosaic virus (CMV), Cucumber green mottle mosaic virus (CGMMV), and the powdery mildew fungus Sphaerotheca fuliginea were assessed by the use of non‐invasive sensors during disease development. Spatiotemporal changes in leaf temperature related to transpiration were visualized by digital infrared thermography. The maximum temperature difference within a leaf was an appropriate parameter to differentiate between healthy and diseased plants. The photosynthetic activity of healthy and diseased cucumber plants varied as measured by chlorophyll fluorescence and compared to the actual chlorophyll content. Hyperspectral imaging data were analysed using spectral vegetation indices. The results from this study confirm that each pathogen has a characteristic influence on the physiology and vitality of cucumber plants, which can be measured by a combination of non‐invasive sensors. Whereas thermography and chlorophyll fluorescence are unspecific indicators for plant diseases, hyperspectral imaging offers the potential for an identification of plant diseases. In a sensor data fusion approach, an early detection of each pathogen was possible by discriminant analysis. Although it still needs to be validated under real conditions, the combination of information from different sensors seems to be a promising tool. 相似文献
10.
Botrytis cinerea is an ubiquitous pathogen which causes severe losses in many fruit, vegetable and ornamental crops. The pathogen infects leaves, stems, flowers and fruits. The complexity of diseases caused by B. cinerea in greenhouses makes this pathogen one of the most important diseases of vegetable crops in greenhouse in many countries. In general, epidemics occur in cool and humid conditions, which favour infection and may also predispose the host to become susceptible. High relative humidity in the greenhouse and free moisture on plant surfaces are considered the most important environmental factors which influence infection by B. cinerea. In this review we specify the factors affecting the development of diseases incited by B. cinerea and discuss different approaches for its suppression. Chemical and non-chemical controls are outlined and their integration is discussed. Finally, achievements, gaps in knowledge, and future needs are indicated. The most common means for disease management is by application of chemical fungicides. Both spraying of fungicides and application of fungicides directly to sporulating wounds is practiced. However, high activity of several fungicides is being lost, at least in part, due to the development of resistance. As fungicides still remain an important tool for control of epidemics caused by B. cinerea, it is important to monitor populations of the pathogen for their resistance towards potential fungicides. Cultural measures can be a powerful means to suppress plant diseases in greenhouses where the value of crops is high and the farmers make considerable efforts during long cropping seasons. Such measures are usually aimed at altering the microclimate in the canopy and around susceptible plant organs, prevention of inoculum entrance into the greenhouse and its build up, and, rendering the host plants less susceptible to diseases. Calcium loading of plant tissues and alteration of nitrogen fertilization reduce susceptibility to Botrytis. Cultivars resistant to B. cinerea are not available. Another alternative methods to control B. cinerea is by means of biological control agents. At least one preparation is already available in the market and in many cases it was as effective as the conventional fungicides. A decision support system was recently developed for integration of chemical and biological controls. Adaquate suppression of B. cinerea diseases in greenhouse crops is an attainable goal. In our opinion this goal can be reached by considering the ecology of the pathosystem in its broader sense and by integration of all possible control measures. This implies optimization of plant nutrition, microlimate and control (cultural, biological, physiological and, if necessary, chemical) measures. Moreover, Botrytis management must be incorporated in a more holistic system that is compatible with insect control, crop production systems and profitability of the crop. 相似文献
11.
Emily R. Grace Mojgan Rabiey Ville-Petri Friman Robert W. Jackson 《Plant pathology》2021,70(9):1987-2004
Trees and woody plants can be attacked by many pests and pathogens either individually or as polymicrobial infections. In particular, infections caused by tree-specific bacterial pathogens have become more common during the last decade, causing serious concern for important tree and woody plant species in horticulture, urban environments, and forests. For example, Xylella and Pseudomonas bacteria are causing significant economic and ecological devastation throughout Europe in olive, cherry, and other stone fruits, mainly because of lack of efficient control methods and the emergence of bacterial resistance to traditional antimicrobial compounds such as copper and antibiotics. Hence, there is an urgent need for innovative approaches to tackle bacterial plant diseases. One way to achieve this could be through the application of biological control, which offers a more environmentally friendly and targeted approach for pathogen management. This review will explore recent advances in use of pathogen-specific viruses, bacteriophages (or phages), for the biocontrol of bacterial tree diseases. Phages are an important component of plant microbiomes and are increasingly studied in plant pathogen control due to their highly specific host ranges and ability to selectively kill only the target pathogenic bacteria. However, their use still poses several challenges and limitations, especially in terms of managing the bacterial diseases of long-lived trees. A particular insight will be given into phage research focusing on controlling Pseudomonas syringae pathovars, Erwinia amylovora, Xanthomonas species, Ralstonia solanacearum, and Agrobacterium tumefaciens. Recent milestones, current challenges, and future avenues for phage therapy in the management of tree diseases are discussed. 相似文献
12.
植物对土壤水分变化的响应与控制性分根交替灌溉 总被引：8，自引：0，他引：8
在土壤水分减少的情况下,植物可以感知并利用脱落酸(ABA)作物信号传递物质,将水分胁迫信号传至叶片,进而调节气孔导度,减少蒸腾耗水。同时,植物蒸腾耗水与气孔导度为线性关系,而光合作用与气孔导度为渐趋饱和关系,如果适当降低气孔导度,可以在显著降低蒸腾耗水的基础上,对光合没有影响或影响很小。在此理论基础上,提出了一种新的灌溉技术——控制性分根交替灌溉。其核心是通过一定的灌溉措施,形成土壤水分的不均匀分布,使作物的根系处于不同的水分状态：处于湿润部分的根系吸收水分,保证作物光合,处于干燥土壤的根系产生ARA,调节叶片气孔导度。这样,在不降低或少量降低光合作用的前提下,更多地减少作物的蒸腾耗水,提高作物的水分利用率。它是一种以内涵为主的节水灌溉技术,具有坚实的理论基础和良好的应用前景。 相似文献
13.
E. Bertolini R. T. A. Felipe A. V. Sauer S. A. Lopes A. Arilla E. Vidal F. A. A. Mourão Filho W. M. C. Nunes J. M. Bové M. M. López M. Cambra 《Plant pathology》2014,63(5):1149-1158
Huanglongbing (HLB) disease is seriously threatening and/or damaging the citrus industry worldwide. Accurate detection of the three species associated with HLB disease, ‘Candidatus Liberibacter asiaticus’, ‘Candidatus Liberibacter africanus’ and ‘Candidatus Liberibacter americanus’, is essential for the preventive control of the disease. Real‐time PCR is a useful tool for bacterial detection. However, nucleic acid purification steps limit the number of samples that can be processed by PCR. Universal detection of ‘Ca. Liberibacter’ species was achieved by direct tissue‐printing and spotting of plant leaf petiole extracts or squashing of individual psyllids onto paper or nylon membranes. Primers were designed and used with TaqMan chemistry for accurate detection of the bacterium in immobilized targets (prints of 10 overlapping leaf pedicels per tree, or squashed single vectors), by extraction with water and direct use for real‐time PCR. This simplified method was validated and could detect HLB‐liberibacters in 100% of leaves with symptoms and 59% of symptomless leaves collected from HLB‐infected trees. The use of direct assays as template showed good agreement with use of purified DNA (κ = 0·76 ± 0·052). The squash assay allowed detection of the bacterium in 40% of mature Diaphorina citri that fed on leaves of HLB‐infected trees with or without symptoms. A commercial ready‐made kit based on this technology showed 96% accuracy in intra‐laboratory performance studies. The simplified direct methods of sample preparation presented herein can be effectively adopted for use in rapid screening of HLB agents in extensive surveys, certification schemes or for epidemiological and research studies. 相似文献
14.
M. T. Kuska A.-K. Mahlein 《European journal of plant pathology / European Foundation for Plant Pathology》2018,152(4):987-992
Protection of crops against plant diseases is crucial in crop production. Agricultural practice and scientific research is confronted with new challenges. Environmentally friendly and sustainable solutions are increasingly demanded. Therefore, the precise detection of primary infection sites and disease dynamics is fundamental to make a decision for a subsequent management practice. In this context, optical sensors can provide an accurate and objective detection of plant diseases. This has awoken the interest and expectation from the public, farmers, and companies for sophisticated optical sensors in agriculture, providing promising solutions. Nevertheless, the application of optical sensors in a practical context in the field is still challenging, and sophisticated data analysis methods have to be developed. In general, the entire system pipeline, consisting of the type of sensor, the platform carrying the sensor, and the decision making process by data analysis has to be tailored to the specific problem. Here, we briefly recount the possibilities and challenges using optical sensors in research and practice for plant disease protection. Optical sensor-based approaches are considered as a key element in plant phenotyping. This overview addresses mainly hyperspectral imaging as it determines several plant parameters that represent the basis for more specific sensors in the future. 相似文献
15.
M. M. Mohd Nadzir F. M. Vieira Lelis B. Thapa A. Ali R. G. F. Visser A. W. van Heusden J. M. van der Wolf 《Plant pathology》2019,68(1):42-48
Clavibacter michiganensis subsp. michiganensis (Cmm) is a quarantine organism in Europe and in many other countries. It is one of the most severe bacterial pathogens affecting tomato. Screening tomato plants for their resistance level to Cmm requires a large amount of space under quarantine conditions and is therefore costly. This project developed a new inoculation protocol on in vitro tomato plants to facilitate a more economic and higher throughput disease screening. A new method using the PathoScreen system was tested to localize green fluorescent protein-tagged Cmm in planta and to quantify the pathogen based on the percentage of corrected GFP (cGFP%). The system was sensitive in detecting the GFP-tagged Cmm in the shoots, but in the roots a high autofluorescence masked detection and thus sensitivity of the assay. The in vitro protocol was tested on several wild relatives of tomato, which were previously screened in a greenhouse assay. The correlation between wilt symptoms in vitro and wilt symptoms in the greenhouse was overall moderate (r = 0.6462). The protocol worked well in differentiating the two parents that were used in the mapping studies. This study shows that the in vitro protocol can be efficiently used for resistance breeding in many tomato genotypes. 相似文献
16.
Paula S. Coelho Luísa Valério António A. Monteiro 《European journal of plant pathology / European Foundation for Plant Pathology》2009,125(2):179-188
Downy mildew caused by the oomycete Hyaloperonospora parasitica (formerly Peronospora parasitica) is a worldwide foliar disease of Brassica vegetables, which may cause seedling loss in the nurseries and damage to adult
plants in the field. Disease symptoms start from the lower leaves and progress upwards. Three experiments were conducted under
controlled environment conditions, using inoculated leaf discs, to determine the influence of leaf position, plant age, and
leaf age on the expression of resistance to downy mildew in various Brassica oleracea genotypes. The upper leaves were more resistant than the lower leaves when 7–19 week-old plants of broccoli and Tronchuda
cabbage were tested. Broccoli lines ‘PCB21.32’ and ‘OL87123-2’ were fully susceptible at the cotyledon stage, showed a clear
resistance increase from lower to upper leaves at 6 weeks and ‘PCB21.32’ was fully resistant 16 weeks after sowing. Immature
leaves were more resistant than adjacent fully expanded mature leaves. Susceptibility increased with leaf age when the same
leaf was tested at two to 4-week intervals. Leaf age and upper-leaf position on the stem had opposite effects on disease score,
since younger leaves collected from lower positions and older leaves collected from upper positions tended to score similarly
in compatible interactions. The progression of downy mildew from the base of the plant upwards on B. oleracea in the field could be due to differences in leaf resistance in addition to environmental variation. To maximise the expression
of a compatible reaction in adult plants lower leaves of Brassica plants that are at least 12 weeks-old should be used. 相似文献
17.
Rajaâ Jebbouj Brahim El Yousfi 《European journal of plant pathology / European Foundation for Plant Pathology》2009,125(2):303-315
This paper evaluates, in the greenhouse and under natural conditions, barley yield losses due to defoliation treatments of
the upper three leaves either healthy or infected at the boot stage by Pyrenophora teres f. teres. Defoliation was assumed as a loss of a similar leaf area caused by net blotch disease severity of 100%. Contribution to
grain yield was defined herein as a difference between defoliation treatments and a treatment where plants lost all their
upper three leaves. In contrast, yield losses referred to differences in yield between defoliations and the control. In the
greenhouse, removal of the antepenultimate leaf did not affect any yield component. For main stems, defoliating upper three
leaves reduced grain yield by 30% and this was mainly due to flag leaf removal. These losses were similar to those induced
by net blotch disease under natural conditions, but were of 42% for all tillers. Grain yield losses due to disease severity
were not equivalent to the defoliation effect of a similar healthy leaf area. On the other hand and for a significant contribution
to grain yield, flag leaf was dependent on the presence of the other two leaves. Inoculation and defoliation of 21 cultivars
induced similar grain yield losses of 32%. However, biotic stress reduced by 40% the contribution of their upper three leaves.
Under field conditions, yield losses were not significant until barley plants lost more than one upper leaf and flag leaf
contribution was equivalent to that of the remaining leaves. Characteristic roots, defined as leaf coefficients for plant
performance, were 0.13, 0.06 and 0.01 for the flag, penultimate and antepenultimate leaves, respectively. Because antepenultimate
leaves become trivial at the boot stage, we propose that coefficients of the remaining leaves should be used when modelling
yield losses due to barley foliar diseases. 相似文献
18.
S. Mahadevakumar C. Chandana Y. S. Deepika K. S. Sumashri Vandana Yadav G. R. Janardhana 《European journal of plant pathology / European Foundation for Plant Pathology》2018,151(4):1081-1087
A severe outbreak of southern blight disease of China aster was observed during the post rainy season (September–November 2015) in the Mysore and Mandya Districts of Karnataka, Southern India. The disease incidence ranged between 12 and 47%. The typical disease symptoms include water-soaked lesions on leaves, stems and on the lower stem surfaces followed by quick wilting of the whole plant with abundant production of sclerotia near the stem-soil interface. The associated fungal pathogen was isolated on potato dextrose agar (PDA) medium, on which numerous reddish-brown sclerotia were seen. A total of 26 fungal isolates were isolated and studied for the mycelial compatibility. Isolate SrCCM 1 was used for pathogenicity analysis. The results of the study showed that, there was no variation among the isolates tested. Molecular identification of the pathogen by ITS-rDNA sequences of S. rolfsii showed 100% similarity with reference sequences. Based on the cultural, morphological and molecular characteristics, the fungal pathogen was identified as Sclerotium rolfsii Sacc. (Sexual morph: Athelia rolfsii (Curzi) C.C. Tu & Kimbr). Pathogenicity tests were performed on healthy leaves, roots and stems. Typical disease symptoms on leaves, stems and roots were evident after 5, 8 and 10 days of post-inoculation. Sclerotium rolfsii is known to cause diseases in economically important crop plants. However, no reports are available on the occurrence of S. rolfsii on China aster in India. 相似文献
19.
ABSTRACT We investigated the use of computer-assisted image analysis techniques for the objective quantification of maize streak virus (MSV) symptoms in Zea mays. We compared independent duplicate evaluations of chlorotic lesion areas occurring on MSV-infected leaves using visual assessment, a commercial image analysis system, and a custom image analysis system employing software developed in our laboratory. Relative to visual assessments of disease severity, computer-assisted image analysis employing both the commercial and custom systems provided significant enhancements in the accuracy and precision of chlorotic area estimations. The commercial image analysis system afforded no significant improvement in precision or accuracy over the custom system. An important advantage of examining images using the custom-written software was that the software permitted a high degree of analysis automation. Digitized images of maize leaves could be automatically analyzed by the custom software five times faster than, and with the same precision and accuracy as, when the same images were analyzed with the commercial software. Because of the flexibility of the image analysis techniques described, they should be applicable to the measurement of symptom severity in other plant host-pathogen combinations. 相似文献