Estimated Yield Loss Research Articles

First Report of Leaf Spot Disease Caused by Epicoccum nigrum on Lablab purpureus in India.

Lablab purpureus (L.) Sweet (Indian bean) is an important pulse crop grown in arid and semi-arid regions of India. It is one of the most widely cultivated legume species and has multiple uses. During a September 2010 survey, we recorded a new leaf spot disease on L. purpureus in and around Mysore district (Karnataka state) with 40 to 80% disease incidence in 130 ha of field crop studied, which accounted for 20 to 35% estimated yield loss. The symptoms appeared as small necrotic spots on the upper leaf surface. The leaf spots were persistent under mild infection throughout the season with production of conidia in clusters on abaxial leaf surface. A Dueteromyceteous fungus was isolated from affected leaf tissues that were surface sterilized with 2% NaOCl2 solution then washed thrice, dried, inoculated on potato dextrose agar (PDA) medium, and incubated at 28 ± 2°C at 12 h alternate light and dark period for 7 days. The fungal colony with aerial mycelia interspersed with dark cushion-shaped sporodochia consists of short, compact conidiophores bearing large isodiametric, solitary, muricate, brown, globular to pear shaped conidia (29.43 to 23.92 μm). Fungal isolate was identified as Epicoccum sp. based on micro-morphological and cultural features (1). Further authenticity of the fungus was confirmed by PCR amplification of the internal transcribed spacer (ITS) region using ITS1/ITS4 universal primer. The amplified PCR product was purified, sequenced directly, and BLASTn search revealed 100% homology to Epicoccum nigrum Link. (DQ093668.1 and JX914480.1). A representative sequence of E. nigrum was deposited in GenBank (Accession No. KC568289.1). The isolated fungus was further tested for its pathogenicity on 30-day-old healthy L. purpureus plants under greenhouse conditions. A conidial suspension (106 conidia/ml) was applied as foliar spray (three replicates of 15 plants each) along with suitable controls. The plants were kept under high humidity (80%) for 5 days and at ambient temperature (28 ± 2°C). The appearance of leaf spot symptoms were observed after 25 days post inoculation. Further, the pathogen was re-isolated and confirmed by micro-morphological characteristics. E. nigrum has been reported to cause post-harvest decay of cantaloupe in Oklahoma (2). It has also been reported as an endophyte (3). Occurrence as a pathogen on lablab bean has not been previously reported. To our knowledge, this is the first report of the occurrence of E. nigrum on L. purpureus in India causing leaf spot disease.

1961—2010年潜在干旱对我国夏玉米产量影响的模拟分析

PDF HTML阅读 XML下载 导出引用 引用提醒 1961-2010年潜在干旱对我国夏玉米产量影响的模拟分析 DOI: 10.5846/stxb201305060937 作者: 作者单位: 中国农业科学院农业环境与可持续发展研究所,中国农业大学资源与环境学院,中国农业科学院农业环境与可持续发展研究所,中国农业科学院农业环境与可持续发展研究所,中国农业科学院农业环境与可持续发展研究所,中国农业大学资源与环境学院 作者简介: 通讯作者: 中图分类号: 基金项目: 973资助项目（2012CB9559-04，2010CB951599-04）；国家自然科学基金资助项目（41171094）；中央高校基本科研业务费专项资金资助项目（2013BH038） Simulation of summer maize yield influenced by potential drought in China during 1961-2010 Author: Affiliation: Institute of Environment and Sustainable Development for Agriculture,Chinese Academy of Agricultural Sciences,College of Resources and Environmental Sciences, China Agricultural University,,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:玉米是我国重要的粮食和饲料作物，旱灾是玉米生产中常见的气象灾害。采用CERES-Maize作物模拟模型，模拟了1961-2010年潜在干旱对我国夏玉米产量影响的时空变化趋势，并分析了其与大气环流因子间的关系，以期了解我国50年来夏玉米受旱的变化情况，并为干旱的研究方法提供一些参考。结果表明：（1）1961-2010年我国夏玉米的潜在产量损失呈略微下降的趋势，不同时期表现不同，其中20世纪60年代、90年代表现为上升趋势。（2）在过去50年里，我国夏玉米潜在旱灾损失中心有向东北移动的趋势，华北地区受旱程度的减轻和东北地区受旱程度的增强是造成损失中心移动的主要原因。（3）我国夏玉米潜在旱灾产量损失中心的经纬度和影响我国夏季降水的北极涡、副热带高压系统的部分指数具有显著的相关关系。当北极涡在生长季前期或同期偏小、偏弱时，我国夏玉米潜在旱灾产量损失中心将偏东、偏北，而副热带高压系统影响更为复杂。 Abstract:Maize is one of the most important crops in China, both as human food and livestock feed. However, drought has become the key climate disaster affecting the maize production recently, particularly in northern part of the country, a primary maize cultivation area in China. The temporal and spatial changes of drought impact on maize have therefore aroused more and more concerns. Most previous studies investigated the drought impacts through climate indices methods, such as SPI, which usually neglected the crop responses to different degrees of drought stresses and the different drought-resistant characteristics between crop genotypes. This study assessed the potential impacts of past drought anomaly (1961-2010) on yield of summer maize, using a process-based crop model, CERES-Maize. The model was drove with the daily weather data and soil data based in every 50 km ×50 km grid. The output of model included the rainfed yield and irrigated yield in grid, if and only if which grew summer maize. The yield difference between the irrigated and rainfed was defined as the potential yield loss caused by drought. And we used the anomaly percentage of potential yield loss to reflect the interannual and interdecadal variation of estimated impact of drought on summer maize yield. Then we calculated the location of the drought affecting center from 1961 to 2010,which were divided in 5 decades (1960s:1961-1970, 1970s:1971-1980, 1980s:1981-1990, 1990s:1991-2000, 2000s:2001-2010). At last, we examined the relationships between estimated yield impacts and recorded indices of atmosphere circulation, to understand the underlying drivers of past drought risks. The indices were averaged over the summer maize prior growing-season (Nov-Apr) and growing-season (May-Oct) respectively. Our results demonstrate: (1) the irrigated yield exhibited a slight and insignificant (P>0.05) decrease from 1961 to 2010, while the rainfed yield exhibited a slight and insignificant (P>0.05) increase. So the potential yield loss in summer maize due to past drought anomaly exhibited a slight and insignificant (P>0.05) decrease, suggesting a decreased drought risk for summer maize production in China. But the potential yield loss experienced a significant increase (P<0.05) in the past two decades (1960s, 1990s), indicating a temporal fluctuation of the risk. (2) The cultivation area with a largest estimated loss in production due to drought experienced a clear northeastern move during the past 50 years, because the production loss decreased in north China while increased in northeast China with the changes in precipitation and temperature patterns. Besides, the period of 1960s-1970s and 1990s-2000s had the largest drift of the drought affecting center. (3) Estimated yield loss and location of the main drought affecting area demonstrated significant (P<0.05) correlations to a few atmosphere indices related to North Pole Vortex and subtropical high system. A weaker North Pole Vortex before or during the maize growing season associated with a less serious drought effect with affecting center located in further northern and eastern areas, vice versa. Subtropical high system also affected the drought risk for summer maize, but differed with indices. 参考文献 相似文献 引证文献

Occurrence, Estimating Yield Loss from The Rate of Diseased Hills at Maturing Stage and Control of Rice Sheath Blight in Shonai Area of Yamagata Prefecture

Occurrence, Estimating Yield Loss from The Rate of Diseased Hills at Maturing Stage and Control of Rice Sheath Blight in Shonai Area of Yamagata Prefecture

水稻多元有害生物为害特征及产量损失量化

PDF HTML阅读 XML下载 导出引用 引用提醒 水稻多元有害生物为害特征及产量损失量化 DOI: 10.5846/stxb201301280183 作者: 作者单位: 云南农业大学农业生物多样性与病虫害控制教育部重点实验室，云南农业大学农业生物多样性国家工程中心，云南农业大学植物保护学院;云南农业大学食品科技学院,云南农业大学资源与环境学院,黑龙江农业经济职业学院农学院,云南农业大学农业生物多样性与病虫害控制教育部重点实验室，云南农业大学农业生物多样性国家工程中心，云南农业大学植物保护学院,云南农业大学农业生物多样性与病虫害控制教育部重点实验室，云南农业大学农业生物多样性国家工程中心，云南农业大学植物保护学院;云南农业大学基础与信息学院,云南农业大学农业生物多样性与病虫害控制教育部重点实验室，云南农业大学农业生物多样性国家工程中心，云南农业大学植物保护学院,云南农业大学农业生物多样性与病虫害控制教育部重点实验室，云南农业大学农业生物多样性国家工程中心，云南农业大学植物保护学院 作者简介: 通讯作者: 中图分类号: 基金项目: 云南省自然科学基金(2011FB051); 云南省教育厅重点基金(2011Z037, 2011Y449); 国家自然科学基金(31060277, 31160363); 国家重大基础研究计划(973)项目(2011CB100404) A characterization of rice multiple-pest injuries and quantification of yield losses Author: Affiliation: Key Laboratory of Agricultural Biodiversity for Pest Management of Education Ministry of China,The National Center for Agricultural Biodiversity,College of Plant Protection,Yunnan Agricultural University,Kunming;College of Food Science and Technology, Yunnan Agricultural University, Kunming,College of Resources and Environment,Yunnan Agricultural University,Kunming,College of Agriculture,Heilongjiang Agricultural Economy Vocational College,Mudanjiang,Key Laboratory of Agricultural Biodiversity for Pest Management of Education Ministry of China,The National Center for Agricultural Biodiversity,College of Plant Protection,Yunnan Agricultural University,Kunming,Key Laboratory of Agricultural Biodiversity for Pest Management of Education Ministry of China,The National Center for Agricultural Biodiversity,College of Plant Protection,Yunnan Agricultural University,Kunming;College of Basic Science and Information Engineering, Yunnan Agricultural University, Kunming,Key Laboratory of Agricultural Biodiversity for Pest Management of Education Ministry of China,The National Center for Agricultural Biodiversity,College of Plant Protection,Yunnan Agricultural University,Kunming,Key Laboratory of Agricultural Biodiversity for Pest Management of Education Ministry of China,The National Center for Agricultural Biodiversity,College of Plant Protection,Yunnan Agricultural University,Kunming Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:收集了云南粳稻主产区沾益、寻甸两县106块稻田水稻有害生物为害和产量等信息,并用两种方法对其分析.第一种方法应用聚类分析和对应分析描述水稻有害生物为害类型和产量水平之间的关系,第二种方法应用主成分分析和多元逐步回归估计各为害的产量损失.聚类分析确定了7种有害生物为害类型,其中IN1、IN2和IN3为害水平较低,而IN5、IN6和IN7为害水平较高.有害生物为害类型和水稻产量水平之间的对应分析,在前两个轴构成的因子空间内绘出了各为害类型和产量水平的位置,并给出了一条与为害类型紧密联系的产量水平增加路线.该分析暗示与位于该因子平面右边的有害生物为害类型(IN1、IN2和IN3)相比,位于左边的为害类型(IN5、IN6和IN7)将引起水稻更大的产量损失.主成分多元回归分析评估了水稻各种病、虫、草害所造成的减产量及其相对重要性.分析结果表明,高于水稻冠层杂草、蛀茎害虫(白穗)、稻纵卷叶螟、白叶枯病、粘虫、叶瘟病和稻飞虱是该稻作区对水稻产量影响较大的为害因子. Abstract:A total of 106 individual farmers' fields were surveyed in Zhanyi and Xundian counties (the main japonica-rice-producing areas of the Yunnan plateau) of Yunnan province. The data pertaining to pest injuries and yields was collected and analyzed using two analytical approaches. The first approach was intended to characterize relationships between injury profiles and yield levels using cluster and correspondence analyses, while the second approach was aimed at generating yield loss estimates using combinations of principal components and step-wise multiple regressions. Seven pest injury profiles (abbreviated as IN) were determined using cluster analysis; IN1, IN2, and IN3 were lower injury levels of pest combinations in seven profiles, while IN5, IN6, and IN7 were higher injury levels. Clusters of injury profiles (IN1-IN7) and yield levels (Y1-Y5) are plotted on the two first axes of correspondence analysis between patterns of injury profiles (IN) and yield levels (Y). The correspondence analysis yielded a path of increasing yield levels (Y1 to Y5) associated with varying combinations of injuries in the plane defined by axes 1 and 2. This would suggest that injury profiles (IN5, IN6 and IN7) located on the left in the factorial plane may cause more considerable damage than others (IN1, IN2 and IN3) located on the right. The principal component analysis with multiple regressions generated estimates of yield reductions due to rice diseases, insects and weeds. The results showed that injuries caused by weeds above rice canopy, stem borers (white heads), leaf folder, bacterial leaf blight, army worms, leaf blast and plant hoppers were the most damaging factors in this region. Results of this study will provide some foundations for developing pest management strategies and improving rice production level at the regional scale. 参考文献 相似文献 引证文献

Survey of Plant-Parasitic Nematodes in Kansas and Eastern Colorado Wheat Fields

Observations on the prevalence and abundance of plant-parasitic nematodes were made from soil and root samples collected from 2,640 wheat fields in Kansas and Colorado during 2007-2010. Stunt nematodes (predominately Merlinius brevidens and Quinisulcius acutus), root-lesion nematodes (predominately Pratylenchus neglectus), and pin nematodes (Paratylenchus projectus) were the most commonly encountered taxa. Maximum soil population densities of 6,520 and 1,880 nematodes/100 cm3 soil were observed for pin and stunt nematodes, respectively, while a maximum root population density of 90,309 nematodes/g dry root was observed for root-lesion nematodes. Lower nematode densities were associated with wheat following corn, grain sorghum, or soybean for pin and stunt nematodes, and with wheat following fallow for root-lesion nematodes. Based on the results of this survey, 6% and 8% of wheat acreage in the central Great Plains are estimated to be at risk for significant (&gt;5%) yield loss due to stunt nematodes and root-lesion nematodes, respectively. The number of fields with high population densities of both stunt and root-lesion nematodes was negligible (1%); therefore, the total wheat acreage with nematode populations above provisional economic thresholds is estimated to be ∼13%. Damage relationships with greater accuracy, precision, and relevance are necessary to establish reliable yield loss estimates for this region. 3 June 2014. 11 August 2014.

First Report of Pseudocercospora angolensis Causing Fruit and Leaf Spot of Citrus in Ghana

Citrus is one of the most important crops in Ghana, representing a large proportion of the fresh fruit consumed in the country. In 2004, symptoms consisting of necrotic leaf spots of about 1 cm in diameter with light brown centers and dark brown margins surrounded by a yellow halo were first observed in sweet orange (Citrus sinensis) and mandarin (C. reticulata) orchards in the Eastern Region of Ghana. Fruits with raised corky lesions of up to 3 to 4 cm in diameter with yellow halos were also observed. Affected fruit had longitudinal and transversal cracks in the rind with the internal locules exposed. Juice content in diseased fruit was strongly reduced, making them unsuitable for fresh consumption or processing. The disease expanded to the Central and Ashanti Regions, with incidences over 95% and estimated yield losses of about 50 to 90%. Symptomatic leaves and fruit collected in Kade in the Eastern Region were surface disinfested with 0.5% NaOCl for 5 min and small fragments from lesions were plated onto malt extract agar (MEA). Slow-growing fungal colonies were isolated from about 5% of the affected tissues plated after 5 days of incubation at 24 to 26°C, and were transferred to V-8 juice agar and MEA. Plates were incubated for 30 days at 24 to 26°C with 12 h of fluorescent light and 12 h of dark for morphological examination. Colonies were gray in the upper side and dark green on the underside. Conidia produced in culture were mostly solitary or in short chains of 2 to 6 spores, hyaline to pale brown, cylindrical, with rounded apex and base truncated. Conidia were 24 to 82 × 4 to 6 μm, with up to 3 to 5 transverse septa and no longisepta. The 5.8S, ITS2, and 28S ribosomal RNA (rRNA) regions were amplified using the primers ITS1 and ITS4 (3) and sequenced from DNA extracted from the isolate MC-39, obtained from sweet orange leaves in Kade (GenBank Accession No. KF111755). The sequence had 99% identity (total score 819, 85% coverage) with that of Pseudocercospora angolensis (T. Carvalho & O. Mendes) Crous & U. Braun epitype strain CBS 112933 (GU269836) (1). Pathogenicity tests were performed twice on 12-week-old detached fruit of sweet orange cv. Valencia Late of about 4 to 5 cm in diameter. Inoculations were performed using a conidial suspension (3.0 × 105 conidia/ml water) by spraying fruit to run off, brushing the rind, dipping for 6 min, or injecting 2 ml in the albedo. Twenty-two isolates were evaluated and 18 fruit were used for each inoculation technique, isolate and experiment. Fruit treated with sterile distilled water were used as controls. Inoculated fruit were maintained in humid chambers at 24 to 26°C. Disease incidence on inoculated fruit varied from 40.7% to 92.6% and severity from 2 to 3 to 3 to 11 lesions per fruit, depending on the isolate and inoculation technique. No symptoms were observed on control fruit. Fungal colonies morphologically identified as P. angolensis were reisolated from lesions on inoculated fruit, but not from asymptomatic control fruit. Based on these results, the disease was identified as Pseudocercospora fruit and leaf spot of citrus caused by P. angolensis. Until this present report, Ghana was considered one of the few countries in Central Africa that was still free of this citrus disease (2).

Within-plant distribution of an invasive mealybug, Phenacoccus solenopsis, and associated losses in cotton

The cotton mealybug Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae), an invasive pest species, has appeared on a large scale on cotton in India since 2006. Its distribution within the plant, and associated yield losses in cotton, were studied over 2 years. Distribution of P. solenopsis was observed within the cotton plant from vegetative to boll formation stage. In the vegetative and square formation stages, the highest mealybug population was recorded on the upper portion of the stem, followed by the middle leaves of the plant. In the boll formation stage, there was no significant difference in distribution of the insect among plant parts. Losses in cotton due to the mealybug varied between 14.9% at Grade 1 and 53.6% at Grade 4, on a 0 to 4 severity index, with a mean reduction of 35% and 32%, during 2008 and 2009, respectively. There was a significant relationship between severity of infestation and decrease in seed cotton yield. The information generated from this study will help in the early detection of mealybug infestation and estimation of yield losses corresponding to the severity grade of the damage.

A Visual Rating Scale for Quantifying the Severity of Greasy Spot Disease on Grapefruit Leaves

Accurate quantitative assessment of greasy spot of grapefruit, caused by Mycosphaerella citri Whiteside, is crucial for designing appropriate disease management strategies and estimating yield losses. A visual rating scale was developed by measuring the total leaf area of 143 ‘Rio Red’ grapefruit leaf samples, and calculating the percent diseased area. The mean severity of the entire sample was 23.1%, but many leaves on the orchard floor exhibited symptoms on more than 50.0% of the leaf area. This rating scale should be highly useful to growers and researchers for field assessments of greasy spot severity.

First Report of Corynespora cassiicola-Incited Target Spot on Cotton in Alabama.

Target spot symptoms were first observed on dryland and irrigated cotton (Gossypium hirsutum L.) statewide in Alabama in 2011. Leaf spots first appeared in the lower canopy and spread upward through the canopy toward the shoot tips. Individual leaf spots were roughly circular, formed concentric rings of alternating light and dark brown bands, and were up to 10 mm in diameter. Leaves with multiple lesions senesced prematurely. In 2012, target spot symptoms were observed as early as 68 days after planting in Tallapoosa County, Alabama. The possible combination of early disease onset and frequent showers/irrigation triggered rapid premature defoliation in some fields in excess of 75% in susceptible cultivars (Phytogen 499). Estimated yield losses in select cultivars (Deltapine 1050 and Phytogen 499) exceeded 336 kg/ha seed cotton. In 2012, symptomatic leaves were obtained from two separate locations in Alabama (Baldwin and Tallapoosa counties). The fungus was isolated from lesions by single spores plated on antibiotic V8 agar (1) and incubated at 21°C for 2 weeks under 12-h light cycles. Conidiophores arising from the gray, flocculose colonies were simple, erect, cylindrical, brown or olivaceous, unbranched, with two to seven septa. Conidia were borne singly, ranging from subhyaline to olivaceous, obclavate to cylindrical, straight to slightly curved, contained 4 to 15 pseudosepta, and were 50 to 209 μm long and 7 to 15 μm wide. These characteristics were consistent with the original description of Corynespora cassiicola on cotton (2). The internal transcribed spacer region (ITS) of two isolates, one representing each location, was amplified using primers 2234c and 3126t targeting a 550-bp region of the ITS1, 5.8S rRNA gene, and ITS2 (3). Sequences revealed 99% similarity to C. cassiicola in NCBI (Accession Nos. AY238606 and JQ717069). In greenhouse pathogenicity tests, 10 cotton seedlings (Phytogen 499) were inoculated by spraying a fungal suspension (2 × 104 spores/ml) of each of the two isolates prepared from 2-week-old cultures until runoff. Controls were inoculated with sterile water. Cotton seedlings were incubated in a moist chamber at 21°C for 72 h. All plants inoculated with the fungus developed leaf spot symptoms in 6 days. The fungus was reisolated from five inoculated plants. DNA was extracted from each isolate, amplified using primer pair 2234c/3126t, and sequenced. Sequences (550-bp) from all isolates shared 99% similarity to other C. cassiicola sequences in GenBank (Accession Nos. AY238606 and JQ717069). Nucleotide sequence data reported are available in GenBank under Accession Nos. KC544017 to 23. This pathogen has been reported previously to be economically important on a number of other hosts. To our knowledge, this is the first report of C. cassiicola on cotton in Alabama. Given the increasing prevalence of this disease in Alabama, its confirmation is a significant step toward developing management recommendations for growers.

Plant‐parasitic nematodes of potential phytosanitary importance, their main hosts and reported yield losses

The potential phytosanitary importance of all named plant‐parasitic nematode species was determined by evaluating available information on species characteristics, association with economically‐important crop hosts, and ability to act as vectors of viruses or form disease complexes with other pathogens. Most named species of plant‐parasitic nematodes (PPN) are poorly known, recorded from a single location only, not associated with economically‐important crops, and not known to be associated with other plant disease organisms. However, 250 species from 43 genera fulfilled one or more of the criteria to be considered to present a phytosanitary risk. The genera and number of species (in parentheses) considered as posing phytosanitary risk included: Achlysiella (1), Anguina (8), Aphasmatylenchus (1), Aphelenchoides (12), Aphelenchus (1), Belonolaimus (2), Bitylenchus (3), Bursaphelenchus (4), Cactodera (3), Ditylenchus (8), Dolichodorus (1), Globodera (3), Helicotylenchus (7), Hemicriconemoides (3), Hemicycliophora (3), Heterodera (25), Hirschmanniella (5), Hoplolaimus (5), Ibipora (3), Longidorus (10), Macroposthonia (2), Meloidogyne (38), Merlinius (3), Nacobbus (1), Neodolichodorus (2), Paralongidorus (2), Paratrichodorus (11), Paratylenchus (3), Pratylenchus (24), Punctodera (3), Quinisulcius (3), Radopholus (5), Rotylenchulus (3), Rotylenchus (1), Scutellonema (5), Sphaeronema (1), Subanguina (3), Trichodorus (5), Tylenchorhynchus (8), Tylenchulus (2), Vittatidera (1), Xiphinema (15) and Zygotylenchus (1). For each of the 250 species main hosts and yield loss estimates are provided with an extensive bibliography. Of the 250 species, only 126 species from 33 genera are currently listed as regulated pests in one or more countries worldwide. Almost all of these 250 species were also associated with economically important crops and some also acted as vectors for viruses.

Sorghum Seed Maturity Affects the Weight and Feeding Duration of Immature Corn Earworm,Helicoverpa zea, and Fall Armyworm,Spodoptera frugiperda, in the Laboratory

Corn earworm, Helicoverpa zea Boddie (Lepidoptera: Noctuidae), and fall armyworm, Spodoptera frugiperda J.E. Smith, are occasional pests in sorghum, Sorghum bicolor L. Moench (Poales: Poaceae), and can be economically damaging when conditions are favorable. Despite the frequent occurrence of mixed-species infestations, the quantitative data necessary for developing yield loss relationships for S. frugiperda are not available. Although these species share similar biological characteristics, it is unknown whether their damage potentials in developing grain sorghum panicles are the same. Using no-choice feeding assays in the laboratory, this study examined larval growth and feeding duration for H. zea and S. frugiperda in the absence of competition. Each species responded positively when exposed to sorghum seed in the soft-dough stage, supporting evidence for the interactions between host-quality and larval growth and development. The results of this study also confirmed the suitability of using laboratory-reared H. zea to develop sorghum yield loss estimates in the field, and provided insights into the biological responses of S. frugiperda feeding on developing sorghum seed.

Bird damage to select fruit crops: The cost of damage and the benefits of control in five states

Fruit loss to birds is a long-standing and costly problem for many producers. We conducted a survey of Honeycrisp apple, blueberry, cherry, and wine grape growers in California, Michigan, New York, Oregon, and Washington to estimate costs of bird damage and benefits of bird damage management. We also assessed grower perceptions of impacts on profits and effectiveness of bird management techniques. Current yield-loss estimates provided by growers and market price data were used to monetize current bird damage in each crop and growing region. Data on expected damage without management were used to estimate the benefits of bird damage management as it is currently being employed in the different crops and growing regions. We estimated that current bird damage costs per hectare ranged from $104 in Oregon tart cherries to $7267 in Washington Honeycrisp apples. Estimated benefits of bird management ranged from $299 per hectare in Oregon tart cherries to $36,851 in California blueberries. Aggregate bird damage in the five crops and states was estimated at $189 million, and the aggregate benefits of managing that damage were estimated at $737 million to $834 million. Growers viewed most techniques for bird damage management as ineffective, or only slightly effective, and a majority of blueberry and sweet cherry growers viewed bird damage as having a significant impact on profits. Enhancing the effectiveness of bird damage management would increase both the efficiency and profitability of fruit production.

Toxicity of three insecticides and tobacco extract against the fungus gnat, Lycoriella auripila and the economic injury level of the gnat on button mushroom

Lycoriella auripila (Winnertz) (Diptera: Sciaridae) is one of the most frequently seen pests of cultivated mushrooms, Agaricus bisporus (Lange) Imbach. The effects of different concentrations of diazinon, imidacloprid and deltamethrin, and tobacco extract were tested against L.auripila on varieties 737 and A15 of button mushroom. Also, economic injury level (EIL) of fungus gnat was evaluated on variety 737. Different varieties of button mushroom were cultured and weight of harvested mushrooms was recorded to provide an estimate of yield loss. A linear regression analysis was used to determine the relationship between pest density and mushroom yield. Imidacloprid was the most effective insecticide against L.auripila on both varieties and caused 100 % control at the highest tested concentration. The lowest concentration of diazinon (500 ppm a.i.) increased pest emergence on 737 and A15. This is possibly due to the hormoligosis. Deltamethrin and tobacco extract were ineffective against fungus gnat between both varieties. High levels of adults of L.auripila were associated with significant reduction in mushroom yield. EIL were calculated according to the number of L. auripila required to cause the critical yield loss from the predictive model and by control costs, mushroom price, and the reduction of injury due to spraying by imidacloprid and diazinon. The lowest values of EIL were related to imidacloprid compared with diazinon. This is due to the different efficiency of these two insecticides, for it causes mortality in population of L. auripila. Based on this research, for the first time clear EILs are introduced to the button mushroom growers for treatment of L. auripila.

Rice Whitefly (Aleurocybotus occiduus Maria), a new emerging threat of rice production and its natural control in Chitwan, Nepal

An intensive field study was carried out to identify the problem causing reddish yellowing of the rice plants, access potential natural control of the suspected pests, estimate yield losses and to suggest an immediate, environmentally safe, possible control measures. Whitefly (Aleurocybotus occiduus Maria) was outbreak on main season rice in Chitwan valley, which affected a total of 20561 ha (Severly 177.3 ha, medium 2787.6 ha, low 6945.4 ha and mild 10691.7 ha) land, losing 9448 mt rice yield in 2003. Use of monoculture, susceptible varieties (Sabitri) and improper cultural operations, excess use of agrochemicals and unconsciousness on the population build up of pest and natural enemies were the causes of outbreak. A maximum of 1000 Whitefly nymphs /tiller were counted. Parasitoid, Encarsia sp was fond most functional natural enemy in the field. However, the population build up of the parasitoid was observed quite late. Rice plants recovered in some extent after heading when the Whiteflies were found naturally controlled. Higher the population of Whitefly proportionally decreased the tillers number/hill, fertile tillers/hill, grain weight/panicle and the grain yield/ha. Rice plants infested with high population of Whitefly (898/tiller) failed to gave rice yield, where medium population (335 / tiller) gave 1287 kg and low population (103 Whitefly/tiller) gave 3456.0 kg (30.8% less than of last year) /ha. Kanchhi Mansuli (4200 kg/ha) and Mansuli (3960 kgs/ha) were comparative tolerant varieties than the Sabitri. DOI: http://dx.doi.org/10.3126/ajn.v2i0.7521 Agronomy Journal of Nepal (Agron JN) Vol. 2: 2011 pp.56-74

Stream Water Quality and Quantity Effects from Select Timber Harvesting of a Streamside Management Zone

A naturally regenerated, even-aged, mixed pine/hardwood, streamside management zone (SMZ) was selectively harvested in May 2006. The 27.8-ha SMZ buffered an intermittent headwater stream draining a 98-ha watershed. The harvest complied with Texas, US best management practices (BMP) by maintaining a minimum SMZ width of 15 m on either side of the channel, retaining a minimum basal area (BA) greater than 11.47 m2 ha-1, and minimizing forest floor and stream channel disturbance. No changes in soil bulk density were measured with only a slight increase in bare soil. No changes in water quality or quantity were detectable after harvest, in part because of dry posttreatment conditions. The Agricultural Environmental/Policy Extender (APEX) model was used to simulate treatment effects under different harvesting and weather conditions. APEX provided reasonable estimates of water yield, sediment, and nutrient losses and was found to be an effective tool for estimating the relative impacts of alternative BMP scenarios. Results indicate that maintaining a minimum BA of 11.47 m2 ha-01 and SMZ width of 15 m on intermittent streams will protect water quality even in wet years and that not retaining any residual BA can result in over 10 times more sediment loss.

Aislamiento, identificación y daños asociados al síndrome de la muerte súbita en el cultivo de soja en Argentina

Isolation, identification and yield losses associated with sudden death syndr ome in soybeans in Argentina The main objectives of this work were to isolate and identify the causal agents of sudden death syndrome (SDS) from samples collected in different Argentinean localities, to quantify its incidence, and to estimate yield losses. Two hundred and fifteen roots from plants with typical SDS foliar symptoms were analyzed. In order to perform pathogenicity tests, two bioassays were conducted in the greenhouse. Yield losses were estimated in a field trial located in Pergamino by quantification and comparison of yield of paired samples. Thirty-six percent of total roots (78 roots) presented signs of Fusarium, compatible with signs caused by SDS. Morphological studies allowed the identification of 35 isolates as F. tucumaniae and 18 as F. virguliforme. Other eight isolates could not be identified. All isolates that were inoculated reproduced typical SDS foliar symptoms. Significant differences were observed between healthy and diseased plants for 1000-grain weight and between potential and real yield (p<0.05). Average yield loss was 1514 kg/ha (range 192-3770 kg/ha). These results corroborated the distribution and predominance of F. tucumaniae and F. viguliforme in the area under study and its destructive potential.

Outbreak of Bacterial Spot (Xanthomonas cucurbitae) in Pumpkin Fields in Illinois.

About 10,000 ha of pumpkins [Cucurbita pepo L. and Cucurbita moschata (Duchesne) Duchesne ex Poir] are produced annually in Illinois. In 2010 and 2011, severe leaf and fruit symptoms typical of bacterial spot caused by Xanthomonas cucurbitae (ex Bryan) Vauterin et al. were observed in pumpkin fields in Illinois, resulting in estimated yield losses of 3 to 90%. Leaf infection was observed from the time of spreading vines until harvest, and infection of fruit occurred from when fruit weights were 0.25 kg until harvest. Leaves had small (2 to 4 mm), angular, yellow spots (1). Fruit had small (1 to 3 mm in diameter), slightly sunken, circular spots, each with a beige center and dark brown halo (1). A survey in 2010 showed that bacterial spot occurred in 40 of 50 pumpkin fields with symptoms on 3 to 94% of fruit in a field (average 34%). A survey in 2011 showed fruit with bacterial spot symptoms in 57 of 65 pumpkin fields, with lesions on 3 to 87% of the fruit in a field (average 24%). Six to twelve symptomatic pumpkins were collected from each field, and X. cucurbitae was isolated from the fruit by surface-disinfesting an area of the fruit with lesions with paper tissue soaked in 95% ethanol. One or two lesions/fruit were cut out with a sterile blade, inserted into an eppendorf tube containing 1 ml of sterile distilled water (SDW), the tubes shaken manually, and a loopful of the bacterial suspension from each tube streaked onto nutrient agar (NA). The plates were incubated at 24°C for 3 to 4 days. Single colonies of each of the isolated bacterium were prepared by streaking isolated colonies onto additional plates of NA and selecting well-separated colonies. The colonies were identified as X. cucurbitae by culturing on yeast extract-dextrose-CaCO3 (YDC) agar, on which xanthomonas-like yellow colonies with mucoid growth developed. The isolates were gram-negative, O+ and F- in the oxidative and fermentative test, oxidase negative, and motile. The isolates hydrolyzed starch and esculin, but did not hydrolyze nitrate, and grew on YDC agar at 33°C. Confirmation of the species identity was achieved using primers RST2 (5'AGGCCCTGGAAGGTGCCCTGGA3') and RST3 (5'ATCGCACTGCGTACCGCGCGCGA3') in a conventional PCR assay (2), which produced a 1,500-bp band. Koch's postulates were carried out for 40 isolates of X. cucurbitae from 40 different fields on pumpkin cv. Howden in a greenhouse. Koch's postulates for five of the isolates were also conducted in a field. Bacterial inoculum was cultured on Luria Broth agar medium and a suspension of 108 cfu/ml prepared in SDW. Pumpkin leaves and fruit were spray-inoculated. In the greenhouse test, each isolate was inoculated onto five leaves of each of four plants. In the field, each isolate was inoculated onto 10 leaves and one fruit of each of 10 plants. A positive control treatment consisted of inoculating pumpkin leaves and fruit with a known X. cucurbitae isolate. A negative control treatment entailed using SDW for inoculation. Lesions developed on leaves and fruit of plants inoculated with the positive control and suspected X. cucurbitae isolates. X. cucurbitae was reisolated from symptomatic leaves and fruit and identified by culturing on YDC agar, and using the PCR assay. No symptoms developed on leaves or fruit sprayed with SDW, and attempts to isolate X. cucurbitae from these plants did not result in development of any bacterial colonies.

Genetic parameters for paratuberculosis infection and effect of infection on production traits inIsraeliHolsteins

Paratuberculosis (Johne's disease) is an infectious enteric disease in dairy cattle and other species that causes substantial economic loss worldwide. In this study, two recursive Gaussian-threshold models were employed in order to infer the effects of Johne's disease on milk yield, fat yield, and protein yield while simultaneously estimating genetic parameters (i.e. heritability and genetic correlation) in an Israeli Holstein population. Disease diagnosis was based on ELISA serum antibody tests. Data were available for 4694 daughters of 361 sires; 3.5% were positive; and 1.6% were suspect for the disease test. Disease status was coded either as a binary character (negative vs. positive) or as an ordered categorical trait (negative, suspect, and positive) in the two recursive models and as a binary trait in a linear model. Among sires with ≥ 50 daughters, predicted probability of Mycobacterium avium ssp. paratuberculosis (MAP) infection in future daughters ranged from <1% to 16.5%. Heritability estimates for Johne's disease were near 0.15, confirming a genetic contribution to disease susceptibility. Genetic correlation estimates for Johne's disease with the three yield traits were 0.15-0.22. Residual correlations for Johne's disease with the yield traits were between -0.01 and -0.10. For the linear regression model, yield losses associated with a positive disease diagnosis during 305 days of lactation were 300 kg milk and around 10 kg for fat and protein. Yield loss estimates from the recursive models were 25-50% less than linear model estimates. Recursive modeling has theoretical advantages over linear models for these phenotypes, but the estimated genetic parameters in this study did not differ significantly between the two types of models.

Utilization of the cropgro-soybean model to estimate yield loss caused by Asian rust in cultivars with different cycle

In recent years, crop models have increasingly been used to simulate agricultural features. The DSSAT (Decision Support System for Agrotechnology Transfer) is an important tool in modeling growth; however, one of its limitations is related to the unaccounted-for effect of diseases. Therefore, the goals of this study were to calibrate and validate the CSM CROPGRO-Soybean for the soybean cultivars M-SOY 6101 and MG/BR 46 (Conquista), analyze the performance and the effect of Asian soybean rust on these cultivars under the environmental conditions of Viçosa, Minas Gerais, Brazil. The experimental data for the evaluation, testing, and adjustment of the genetic coefficients for the cultivars, M-SOY 6101 and MG/BR 46 (Conquista), were obtained during the 2006/2007, 2007/2008 and 2009/2010 growing seasons. GLUE (Generalized Likelihood Uncertainty Estimation) was used for the estimation of the genetic coefficients, and pedotransfer functions have been utilized to estimate the physical characteristics of the soil. For all of the sowing dates, the early season cultivar, M-SOY 6101, exhibited a lower variance in yield, which represents more stability with regard to the interannual climate variability, i.e., the farmers who use this cultivar will have in 50% of the crop years analyzed, a higher yield than a late-season cultivar. The MG/BR 46 (Conquista) cultivar demonstrated a greater probability of obtaining higher yield in years with favorable weather conditions. However, in the presence of the Asian soybean rust, yield is heavily affected. The early cultivar, M-SOY 6101, showed a lower risk of being affected by the rust and consequently exhibited less yield loss considering the scenario D90 (condensation on the leaf surface occurs when the relative humidity is greater than or equal to 90%), for a sowing date of November 14.

Predicting and partitioning ozone fluxes to maize crops from sowing to harvest: the Surfatm-O&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; model

Abstract. Terrestrial ecosystems represent a major sink for ozone (O3) and also a critical control of tropospheric O3 budget. However, due to its deleterious effects, plant functioning is affected by the ozone absorbed. It is thus necessary to both predict total ozone deposition to ecosystems and partition the fluxes in stomatal and non-stomatal pathways. The Surfatm-O3 model was developed to predict ozone deposition to agroecosystems from sowing to harvest, taking into account each deposition pathways during bare soil, growth, maturity, and senescence periods. An additional sink was added during senescence: stomatal deposition for yellow leaves, not able to photosynthesise but transpiring. The model was confronted to measurements performed over three maize crops in different regions of France. Modelled and measured fluxes agreed well for one dataset for any phenological stage, with only 4% difference over the whole cropping season. A larger discrepancy was found for the two other sites, 15% and 18% over the entire study period, especially during bare soil, early growth and senescence. This was attributed to site-specific soil resistance to ozone and possible chemical reactions between ozone and volatile organic compounds emitted during late senescence. Considering both night-time and daytime conditions, non-stomatal deposition was the major ozone sink, from 100% during bare soil period to 70–80% on average during maturity. However, considering only daytime conditions, especially under optimal climatic conditions for plant functioning, stomatal flux could represent 75% of total ozone flux. This model could improve estimates of crop yield losses and projections of tropospheric ozone budget.