共查询到20条相似文献,搜索用时 31 毫秒
1.
P.T. WALKER 《EPPO Bulletin》1981,11(2):13-17
In an attempt to standardize methods of assessment of Eurygaster spp. and Aelia spp., some methods published in USSR, Romania and Turkey are reviewed and details given. These are: 1) counting overwintering adults in quadrats or along a line; 2) counting old adults in quadrats or by sweep net after migration; 3) counting nymphs in quadrats. Methods of assessing crop loss caused are: 1) counting attacked stems of young wheat; 2) counting attacked ears; 3) identification and counting of attacked grain at harvest; 4) caging different numbers of nymphs and adults, and taking yields, grain weight, germination etc.; 5) assessing the effect on baking quality of flour etc. The effects of different numbers of insects per m2 on yield are given. It is suggested that standardization of such methods would lead to improved cooperative studies between different countries. 相似文献
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M. Calderon 《Phytoparasitica》1981,9(2):157-167
The grain bulk in its environment is presented as an ecosystem, comprising biotic (grain, insects, microflora) and abiotic (dockage, intergranular air, water vapors, storage structure) elements. The effect of the stored grain bulk environment and microenvironment on each of the system components is analyzed, and the possible implications of these effects in the cause or prevention of grain storage losses are discussed. The interrelation of the biotic and abiotic elements (variables) of this ecosystem, interacting with each other in causing storage losses, is also considered. It is suggested that the ecosystem approach for evaluating the potential loss of stored grain in a given storage site can be used not only to assess the present status of damage and the storability of grain, but also to indicate the steps needed to prevent losses. 相似文献
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T. Hashimoto 《国际虫害防治杂志》2013,59(3):325-329
Abstract A survey of termite damage to groundnuts and an estimation of loss in yield was made between 1977 and 1979 in northern Nigeria. The foliage was attacked by Odontotermes. Damage was restricted to the Sudan savanna and loss in yield was less than 5%. Much more important was the damage caused by Microtermes lepidus Sjöstedt which attacked the pods, the tap root and the haulms. There was a linear relationship between the percentage of stands with the tap root invaded by Microtermes and the loss in yield. Damage varied from year to year, but the higher yield losses (up to 40%) were consistently recorded in the Sudan savanna. There was a significant relationship between the level of Microtermes damage and rainfall, the latter having a marked influence on foraging behaviour and the level of foraging activity. The chemical control of termites is economically viable on mechanised farms in the Sudan savanna, but cannot be justified on peasant farms, where yields are too low. 相似文献
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A pest risk assessment was performed according to the EPPO Standard PM 5/3 to determine the probability of introduction of Monilinia fructicola into the countries of the European Union (EU) and its potential economic impact. Data on the biology of the pathogen were combined with trade pathways and information on the use of commodities in order to quantify risk. On the basis of the EPPO Standard, we concluded that there is a serious risk that M. fructicola could become established in the EU, with significant economic losses as a result. This justifies the phytosanitary measures currently in place in the EU. 相似文献
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R. Rabbinge E. M. Drees M. van der Graaf F. C. M. Verberne A. Wesselo 《European journal of plant pathology / European Foundation for Plant Pathology》1981,87(6):217-232
Laboratory and field studies on aphid damage in wheat are described. Both direct and indirect effects of aphids on the behaviour of the crop were studied. In the laboratory a clear effect of honeydew and yeasts on photosynthesis was found. This effect could not be demonstrated under field conditions, since even at yield loss levels of 700 kg ha–1 the size of this effect may be undetectable with crop enclosures reaching an accuracy of 10%. The effect of honeydew on ageing, measured in the laboratory trials was also found in the field and may form a major cause of the yield losses found in the field. Yield losses under field conditions reached 700 kg ha–1 and were for 72% due to direct sucking damage of the 35 aphids, found maximally per culm, and direct and indirect honeydew effects. Saprophytic and possibly also some necrotrophic fungi caused 28% of the yield losses. The exact contribution of each of the damage factors was not revealed but it was demonstrated that direct and indirect effects contribute to the final yield losses.Samenvatting Laboratorium- en veldproeven over de schade door bladluizen in tarwe worden beschreven. Een analyse van de directe en indirecte effecten van bladluizen op de groei van het gewas werd verricht. In het laboratorium werd een duidelijk effect van honingdauw en gisten op de fotosynthese gevonden. Dit effect kon niet worden gedemonstreerd in het veld, hetgeen waarschijnlijk wordt veroorzaakt door de orde van grootte van dit effect dat valt binnen de meetfout van de gewasfotosyntheseapparatuur.Het effect van honingdauw op veroudering, dat in het laboratorium werd vastgesteld, kon ook worden aangetoond in het veld en is waarschijnlijk een van de hoofdoorzaken van de oogstverliezen. Deze oogstverliezen in het veld bedroegen 700 kg ha–1 bij een maximale dichtheid van 35 bladluizen per halm en werden voor 72% veroorzaakt door direct zuigsschade en honingdauweffecten. Van de totale schade werd 28% veroorzaakt door saprofytische en wellicht ook door enige necrotrofe schimmels. De precieze bijdrage van ieder van de schadefactoren tot de schade werd niet vastgesteld, maar de wijze waarop directe en indirecte effecten hun bijdrage leverden aan de uiteindelijke oogstverliezen werd zichtbaar gemaakt. 相似文献
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J. M. Williams 《国际虫害防治杂志》2013,59(4):379-391
Abstract The amount of rat damage to immature coconuts was assessed by two methods. The first involved fortnightly recordings of all coconuts produced, including those rat damaged, at representative sites for up to three years. The second method attempted to utilise decay characteristics of rat damaged coconuts as a basis for projecting spot counts of damaged coconuts to long term estimates of damage. Damage was concentrated on coconuts aged three to six months with most of the damage being inflicted by Rattus rattus. Damage varied considerably from month to month with seasonal trends in damage being apparent at only one site. Rats clearly favoured particular palms in all plantations, resulting in over 75% of the damage being confined to 30% of the palms. Those selectively attacked were randomly distributed within the survey plots and did not produce significantly fewer harvestable coconuts than those palms seldom attacked. Tall palms, i.e. over 15 m incurred less damage than those under 10 m. Decay characteristics of rat damaged coconuts proved to be of limited value as a basis for projecting spot counts to long term losses, but counts of green damaged coconuts accurately reflected the previous 33–35 days damage. Overall production losses (derived after adjustments for known palm compensation for damage) were relatively low; being 2.7, 2.0 and 1.3 nuts per palm per year during 1970, 1971 and 1972. 相似文献
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The brown planthopper (BPH) is an important pest in rice. Rice losses due to BPH's damage are often more than 10% of yield. Assessments on loss rates from BPH are now basically dependent on experiential indices. However, early assessments on rice yield losses using hyperspectral data are still rare. In this study, reflectance from rice canopy was measured in net cages after different densities of BPH release. Results showed that reflectance in the near-infrared region (750–1000 nm) from milk grain stage, and in 400–531 nm and 567–705 nm from mature grain stage was closely related to BPH density. These spectral indices: red-edge parameters (λr, Dλr, Sλr), ratio of the maximal reflectance in green (490–560 nm) to minimal reflectance (640–740 nm) in red (RGREEN/RRED), ratio of the near-infrared peak (RNIR) to RRED, normalized difference vegetation index between RNIR and RRED and soil-adjusted vegetation index (SAVI) from both milk and mature grain stages, indicated BPH densities well. As expected, rate of loss in rice grain was higher with increasing BPH density. SAVI, Dλr, Sλr and reflectance at 760 nm (R760) from milk grain stage were significantly correlated with rates of loss in panicle, and 1000-grain weight and multiple-linear regression models for detecting loss rate were established. The hyperspectral reflectance from rice at milk grain stage can be used to assess rice yield losses due to BPH and improve management policies. 相似文献
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Abstract The African rice gall midge, Orseolia oryzivora Harris and Gagne (Diptera: Cecidomyiidae), is an important pest of rice, Oryza sativa, in Burkina Faso as well as other countries in West and East Africa. In spite of its importance, little is known regarding the relationship between gall midge populations and grain yield losses. To determine yield losses the gall midge was reared in cages and adult midges were placed on caged plants of the rice variety ITA 123 at different population levels. The seven treatments consisted of different numbers of insects infested on the plants; 0 insect pairs (non‐infested check), and 1, 5, 10, 15, 20 or 25 midge pairs/cage. The loss in yield in relation to the non‐infested control was highly positively correlated (R2 = 0.81) with the percentage of gall midge damaged tillers. The infestation by the insect on the plants resulted in the compensatory production of tillers which developed in response to the gall midge damage but the compensation was not sufficient to make up for the loss of yield due to the damaged tillers. Yield loss ranged from 0% in the control to 65.3% in the treatment with 25 pairs of adults. One per cent of tillers damaged resulted in 2% grain yield loss. 相似文献
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Radivoje Jevtić Vesna Župunski Mirjana Lalošević Novica Mladenov Branka Orbović 《European journal of plant pathology / European Foundation for Plant Pathology》2018,152(2):469-477
Thousand kernel weight (TKW) is a yield component associated with grain quality. It is reported in the literature that TKW is significantly influenced by varieties, agro-ecological conditions and disease indices, but the influence of their interactions on TKW loss has rarely been taken into consideration. The main objective of this study was to examine the combined effects of multiple diseases and climatic conditions on TKW losses in winter wheat. Leaf rust, powdery mildew, and Septoria tritici blotch were considered biotic predictor variables in regression models explaining TKW losses. Monthly averages of temperature, relative humidity and total rainfall in May and June in the 2006–2013 growing seasons were used as abiotic predictor variables. The results of this study indicated a significant low positive correlation between yield loss and TKW loss in the two varieties. TKW losses were less influenced by leaf rust, powdery mildew, and Septoria tritici blotch than yield losses. The significant influence of the interaction between variety and the environmental conditions on TKW loss was confirmed from the general linear model function. The results of this study indicated that factors influencing yield and yield component losses are part of the complex environment, and the relationship between them should be investigated with respect to their interactions. 相似文献
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Joseph Aubert Mouen Bedimo Daniel Bieysse Ibrahim Njiayouom Jean Pierre Deumeni Christian Cilas Jean Loup Nottéghem 《European journal of plant pathology / European Foundation for Plant Pathology》2007,119(4):391-400
In the high altitude regions of Africa, coffee berry disease (CBD), caused by Colletotrichum kahawae, is the main constraint for arabica coffee (Coffea arabica) production. However, certain agricultural practices can reduce losses caused by the disease and thereby promote optimum
production. On small family farms in Cameroon, mixed cropping with fruit trees, intercropping with food crops and maintenance
pruning of coffee trees are very widespread agricultural practices that can affect CBD epidemics. Consequently, an epidemiological
study was conducted to assess how cultural practices affected the disease in an arabica coffee smallholding in Cameroon. The
disease was monitored on a weekly basis over four successive years (2002–2005) on coffee trees in diverse cultural situations.
Cultural practices likely to reduce losses due to CBD were identified. The infection rate was significantly lower on coffee
trees grown intensively than on coffee trees grown in the traditional manner. Coffee trees located under the shade of fruit
trees were significantly less attacked than those located in full sunlight. In addition, berries on the leafless parts of
branches, near the main trunk of the coffee tree, were less infected than those on leafy sections. These results show that
maintenance pruning, removal of mummified berries, and mixed cropping with shade plants are cultural practices which create
environmental conditions that limit CBD development. 相似文献
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Hiroyuki Ura Naruto Furuya Kazuhiro Iiyama Masatomo Hidaka Kenichi Tsuchiya Nobuaki Matsuyama 《Journal of General Plant Pathology》2006,72(2):98-103
Rice plants with bacterial leaf-sheath browning and grain rot were observed in Fukuoka Prefecture in Japan during the autumn
seasons of 1995 and 1996. Burkholderia spp. were consistently isolated from the infected leaf sheaths and grains. These isolates were pathogenic and induced symptoms
of seedling rot, grain rot, and leaf-sheath browning in rice plants, as well as in some orchidaceous plants (cymbidium, dendrobium,
and oncidium leaves), gladiolus leaves, and onion bulbs. On the basis of morphological, physiological and pathological tests,
and species-specific polymerase chain reaction, the isolates were identified as belonging to either Burkholderia glumae or Burkholderia gladioli. B. gladioli, as well as B. glumae, attacked rice plants after artificial inoculation and reproduced the symptoms similar to those after natural infections.
We confirmed that rice is an additional natural host of B. gladioli. It is clarified that bacterial grain rot of rice is caused not only by B. glumae but also by B. gladioli. 相似文献
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辽宁省主要粮食作物产量灾损风险评估 总被引:5,自引:0,他引:5
从产量灾损风险的角度,利用1971~2008年辽宁省主要粮食作物玉米和水稻的产量资料,构建了辽宁省粮食产量灾损风险评估模型,从历年平均减产率、灾年减产率变异系数、产量灾损风险指数等角度综合评估了辽宁省粮食产量的灾损风险.结果表明:辽宁大部都是玉米生产的低风险区,高风险区主要分布在朝阳和锦州地区,大连、鞍山和葫芦岛为中风... 相似文献
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In this article, we review studies of the ecology of the larger grain borer, Protephanus
truncatus, both outside and within the maize storage systems. Laboratory studies have shown that P. truncatus can breed on a wide range of woody substrates (branches, roots, and seeds). Pheromone trap catches in different habitats strongly suggest that P. truncatus is well-established in certain non-agricultural environments, presumably breeding in dead or dying wood. In Meso-America, West and East Africa, P. truncatus reproduction in the field has been documented in branches ring-barked by cerambycid beetles. Within a maize store, P. truncatus densities can increase from very small initial colonies of probably less than 200 individuals to densities in excess of 1000 beetles per kg after about 4–6 months of storage. Insect parasitoids are very often found in smallholders' grain stores attacked by P. truncatus, but they do not contribute significantly to population regulation. Declines in maize store population levels in Benin from 1993 to 1996, and in adult abundance in pheromone traps in the natural environment in Kenya, have been attributed to predation by the introduced predator, Teretrius
nigrescens, but in recent years pheromone trap catches in West Africa suggest that the situation may be complex. Several environmental factors, notably temperature, humidity, and daylength, and their interactions, have been correlated with P. truncatus flight activity, as well as, in West Africa, the emptying of maize stores. Laboratory experiments have shown food quality also affects flight activity. Factors terminating dispersal and flight are most likely attraction to the male-released aggregation pheromone. Short range attraction to plant volatiles has also been recorded. In Africa the highest densities of P. truncatus tend to occur in humid lowlands, which contrasts with the situation in meso-America where P. truncatus tend to occur in greatest numbers in cooler upland regions. Pheromone trap catches can be significant predictors of the risk of stores becoming infested. Coupled with the development of a rule-based model of flight activity, these studies may offer the prospect of predicting the risk of store infestation based upon temperature and humidity measurements. 相似文献
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实蝇类害虫是世界性检疫害虫,对福建省农作物造成为害的主要包含橘小实蝇、南亚寡鬃实蝇、瓜实蝇、具条实蝇4种。这4种实蝇类害虫给福建省水果、蔬菜带来较为严重的经济损失,并且由于防治过程中农药的使用,造成生态环境问题。本研究选取实蝇类害虫为害较为严重的福建省主要水果和蔬菜作为研究对象,从直接经济损失、防治费用和间接经济损失3个层面建立评估模型,并对2016年4种实蝇类害虫造成的经济损失进行评估,旨在通过评估经济损失情况,为今后防治政策的制定提供思路。研究结果显示,这4种实蝇类害虫对福建省造成的经济损失约为313.48亿元,其中直接经济损失约为221.74亿元,防治费用约为84.24亿元,间接经济损失约为7.5亿元。最后,本研究提出了重视有害生物灾情评估、完善经济损失评价方法,开展农户专业培训、提升防控技术水平,加强环境规制力度、发展绿色生态农业等政策建议。 相似文献
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Stem rust, or black rust, of wheat, caused by Puccinia graminis f. sp. tritici, has recently re-emerged in several parts of the world, with epidemics occurring in eastern Africa, as well as northern and southern Europe. Damage mechanisms from disease dynamically affect the physiology of the crop as it grows and develops, and as the epidemic progresses, leading to yield losses in the stem rust-diseased wheat stand. Process-based agrophysiological models that include disease-induced damage mechanisms can help to better understand the physiological processes leading to yield losses, and to inform strategic decisions such as breeding strategies. Such models have not been developed for wheat stem rust so far. Two damage mechanisms for stem rust, light stealing and assimilate diversion, were incorporated in the agrophysiological simulation model WHEATPEST. The model, tested from experimental field data retrieved from the literature, provides a satisfactory representation of the system, although consistently underestimates relative yield losses by about 6.9%, resulting in relative yield losses between 17% and 56%. Analyses highlight the importance of the diversion of assimilates toward the pathogen in the magnitude of yield loss. Considering only the reduction of green leaf area would underestimate damage from stem rust by at least threefold. The analysis also shows the importance of the dynamic interplay between disease and crop growth, especially the dynamics of leaf area, on yield loss. Directions to consider additional damage mechanisms are proposed, and perspectives for future research, especially in relation to plant breeding strategies under climate change, are offered. 相似文献