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1.
Rice planthoppers' damage on Pusa Basmati 1 cultivar was simulated with InfoCrop, a generic crop growth simulation model. The model was calibrated and validated with two experimental data sets on planthopper population and rice yield that were generated through differential insecticide application during the rainy season 2006 and 2007. Simulated yield and total dry matter (TDM) in various treatments over the two experiments were found to be proximal to the observed yields (R2 = 0.972, RMSE = 4.61%) and TDM (R2 = 0.949, RMSE = 3.25%), respectively. Likewise, the simulated yield and TDM losses were also respectively close to observed yield losses (R2 = 0.938, RMSE = 13.53%) and TDM losses (R2 = 0.835, RMSE = 19.12%), suggesting appropriate validation of planthopper damage mechanism on Pusa Basmati 1 rice. Economic injury levels (EILs) of planthoppers were simulated with two control expenditures involving two applications with each of monocrotophos and imidacloprid, and three market prices of Pusa Basamti 1 rice. The EIL exhibited a negative relationship with market value of produce but a positive one with expenditure on control measures. Simulated EILs were comparable to earlier established empirical EILs, indicating utility of simulation models for developing location specific EILs that may help in doing away with the use of blanket EILs. Iso-loss curves, devised through validated model, depicted combinations of crop age and planthopper population that resulted in similar yield losses. Both the EILs and iso-loss curves can be useful in monitoring planthopper populations and promoting judicious pesticide applications that would avoid unwarranted control expenditure and environmental contamination. The simulation models being based on detailed crop ecological and physiological processes and pest damage mechanism can thus aid in development of location-specific decision support tools and ensure precision in pest management decisions. 相似文献
2.
Field studies were conducted during 1993 and 1994 in the Imperial Valley, California and Maricopa, Arizona to examine relationships between densities of Bemisia tabaci (Gennadius) populations and cotton (Gossypium hirsutum L.) yields, and to estimate economic injury levels (EILs) for pest management application. Populations of B. tabaci were manipulated by applying different numbers of insecticide applications in replicated plots. Resulting insect populations and cotton lint yields were used to develop damage functions and to estimate EILs for all life stages in relation to variable cotton prices, insecticide costs, and pest control efficacy. Economic injury levels declined with increasing cotton prices and increased as the cost of control increased, however, these changes were relatively small, based on typical ranges in price and control costs. In contrast, the efficacy of control provided by insecticide applications had a large influence on EILs, with lower efficacies being associated with higher injury levels. We developed a multiple regression model that accounted for the dynamic changes in the EIL in relation to crop price, control costs, control efficacy, and potential yield. Based on average prices and reasonable control costs and efficacy, EILs ranged from 5.9–15.2 adults/leaf, 6.1–19.8 eggs cm−2, and 1.7–4.7 nymphs cm−2 of leaf area. Additional research is needed to more closely relate the costs of control to the suppression of insect populations, and to define economic thresholds that will enable pest managers to maintain pest populations below EILs. 相似文献
3.
东北地区亚洲玉米螟危害损失测定模型研究 总被引：2，自引：0，他引：2
研究并建立玉米螟产量损失与不同代数(一代、二代及一二代混合发生)幼虫数量及产量损失与产量构成因子、相关生育指标间的关系,便于制定更加准确且适应种群发生规律变化的防治指标。结果表明,不同生育期的玉米螟卵量与产量损失之间呈显著相关和回归关系,仅一代幼虫和仅二代幼虫的危害具有独立性,且第二代幼虫是造成玉米产量损失的主要世代。在此基础上,分别建立仅一代、仅二代玉米螟幼虫数量与产量损失的数学模型,并根据模型特性以叠加的方式得到一二代混合发生的玉米螟幼虫数量与产量损失之间的数学模型。 相似文献
4.
Within any geographic area where pest management is to be improved or adapted to agricultural changes, there is a need for characterization to define constraints to crop production. The objective of this study was to assess pest injuries (diseases, insects and weeds) in farmers' fields in the japonica rice zone of Yunnan, China, explore characteristics of rice injury profiles, analyse the relationships between injury profiles and yield levels, and estimate yield losses caused by individual injuries. 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. Correspondence analysis based on patterns of injury profiles yielded a path of increasing yield levels associated with varying combinations of injuries. The use of principal component analysis with multiple regression generated estimates of yield reductions due to rice diseases, insects and weeds. The analysis indicated that injuries caused by weeds that are taller than the rice canopy, white heads, leaf folder, bacterial leaf blight, army worms, leaf blast and plant hoppers should be considered as potentially most damaging in this region. Results of this study will provide some foundations for developing pest management strategies and improving rice production at the regional scale. 相似文献
5.
Weeds and grain feeding birds are the two main biological causes of yield losses in irrigated rice in Africa. To quantify the single and combined effect of these biological constraints on rice yields, and to investigate whether weeds attract birds and thereby contribute to increased bird damage, a three-year factorial experiment was set-up in the Senegal River Valley. We tested two management factors (bird and weed management), each with two levels (‘complete’ and ‘absent’), and one crop cycle factor also with two levels (Sahel 202, a medium-cycle and Sahel 108, a short-cycle rice cultivar). Season-long competition from weeds resulted in high but predictable yield losses ranging from 50% to 75%, with lower yield losses for the medium-cycle cultivar Sahel 202 in two of the three seasons. Due to the nature of the pest, season-long exposure to birds resulted in less predictable yield losses ranging from 13% to as high as 94%, with high seasonal variation. In two seasons, much lower bird-inflicted yield losses were observed in the short-cycle cultivar Sahel 108, whereas in one season the medium-cycle cultivar Sahel 202 was much less damaged. When rice was exposed to both weeds and birds, the relative yield losses ranged from 80 to 99%. The yield reducing effect of weeds and birds was never additive. Bird visits to a weedy crop were more frequent compared to a weed-free crop at least in the early rice grain filling stages. This attraction of birds by weeds resulted in an additional yield loss in five of the six cases, ranging from 2 to 62%. Bird-inflicted yield losses in irrigated rice may be reduced by keeping the crop, as much as possible, free from weeds. 相似文献
6.
W.H. White R.P. Viator E.O. Dufrene C.D. Dalley E.P. Richard Jr. T.L. Tew 《Crop Protection》2008,27(9):1256-1261
The sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), is the key insect pest of sugarcane, Saccharum spp., grown in Louisiana. For more than 40 years, Louisiana sugarcane farmers have used a value of 10% internodes bored at harvest as the economic injury level (EIL). Three plant-cane studies were conducted to re-evaluate the long-standing sugarcane borer EIL level using the most recently released varieties of sugarcane. Varieties were exposed to artificially enhanced borer infestations; the experimental treatments consisted of borer control with insecticides or no control. Data were collected on infestation intensity, damage intensity, and associated yield losses. Crop yields from plots were obtained by mechanical harvesting, and losses were classified as field losses, e.g. losses of gross tonnage in the field and factory losses, e.g., losses that were realized at the factory as cane is being milled. Farm income is based on the product of these two measures of yield, i.e. cane yield×sugar yield. In our study, seasonal stalk-infestation counts did not reveal any indication of preference by the borer moths for a specific variety; infestation pressure was generally uniform within a season among the varieties that we planted. Significant differences were detected among the varieties for harvest percentage of internodes bored as well as yields between borer-controlled and non-controlled plots (P<0.05). In general, varieties were less susceptible to losses in the field (sugarcane yields) than in the factory (sugar yields). As a group, the most recent varieties released to Louisiana growers exhibit more tolerance to the borer than varieties grown 40 years ago. The percent reduction in sugar/ha loss per 1% internodes bored has decreased from an average of 0.74 for varieties grown in the 1960s to 0.61 as a mean for the newly released varieties. Although the cost associated with an insecticide application for sugarcane borer control has increased nearly 4-fold from 1971 to present, sugar yields have increased by approximately 60% allowing farmers to offset some of these increased costs. Our economic analysis indicates that the EIL of 10% internodes bored is too high, considering the high yielding potential and susceptibility of currently grown varieties. For the most at risk farmer, the tenant farmer, a more appropriate value for the EIL is 6% internodes bored. However, this EIL can be raised 12% if a resistant variety is grown. 相似文献
7.
Selecting appropriate strategies for pest control has become an issue of major concern, but research on decision making regarding this issue is limited. An analytic hierarchy process (AHP) approach for selecting strategies for the management of rice stem borer [Chilo suppressalis (Walker)] in paddy fields of Sari county of Mazandaran province in Iran was developed. Agricultural faculty members, experts of a local plant protection unit, local extension agents, and elite farmers in the study area participated in the project to determine the suitability of four common pest control methods (i.e., chemical control, cultural control, biological control, pheromone trapping) for rice stem borer management, based on 10 main criteria and 32 sub-criteria identified through pertinent literature and focus group discussions. All the examined alternatives of pest control were preferred to some extent for rice stem borer management. Control effectiveness, relative advantages, social usefulness, and technical support were the most important criteria for assessing strategies for rice stem borer management, followed by observability, ease of use, trialability, farmer's self-efficacy, compatibility, and farm characteristics. Overall, chemical control ranked first, being superior to the other three methods with respect to six main criteria of the model (relative advantages, trialability, observability, farmer's self-efficacy, farm characteristics, and control effectiveness). Biological control ranked second at the overall level, being superior to cultural control and pheromone trapping in the three remaining main criteria (i.e., technical support, compatibility, and social usefulness). Pheromone trapping ranked first only with respect to ease of use criteria. The proposed model constitutes a flexible tool for decision making in pest control with high applicability among policy makers in the government and local agricultural office and extension agents; it could greatly assist extension programs to effectively select strategies for rice stem borer management or similar pest problems in various agricultural sites. 相似文献
8.
《Crop Protection》1987,6(1):33-37
Plant damage and grain yield losses of rice cultivar IR46 under field conditions were highest when attacked by yellow stem borer Scirpophaga incertulas (Walker) larvae in the tillering and flowering stages and lowest when plants were at the panicle initiation stage of growth. A screenhouse tests indicated that S. incertulas development was most rapid on the tillering and flowering stages and lowest on the panicle initiation stage. An action threshold of one egg mass per m2 is suggested. 相似文献
9.
Avoidable losses and economic injury levels (EILs) were computed for the sorghum head bug, Calocoris angustatus Leth., on three cultivars during three rainy seasons (1985–1987) at ICRISAT. Grain yield in plots protected with 2–5 insecticide sprays (carbaryl at 500 g a.i./ha) between the half-anthesis and the dough stage was significantly higher than in untreated plots, with cost-benefit ratios > 1. Plots that were not protected at half-anthesis and/or complete-anthesis, and at milk and dough stages, suffered a significant loss in yield. Bug damage spoiled the grain quality in terms of germination, 1000-grain mass, grain hardness and percentage floaters. Three to four sprays between complete-anthesis and the dough stage prevented a significant reduction in grain quality. Head bug density at half-anthesis, complete-anthesis, milk and dough stages was significantly and negatively associated with grain yield. Bug density at different stages explained 43–94% of the variance in yield. Direct effects of bug numbers at the milk stage and the indirect effects of head bug density at other stages through the milk stage contributed towards maximum reduction in yield. Maximum avoidable losses were recorded in cultivar ICSV 1 (88·6%), followed by CSH 1 (69·9%), and CSH 5 (53·9% in 1986 and 55·0% in 1987). Loss in grain yield/ha due to one insect/panicle at half-anthesis and that based on natural increase, were 548 and 232 kg in CSH 5 during 1986 and 1987, respectively, 251 kg in ICSV 1, and 77 kg in CSH 1. EILs based on a cost-benefit ratio of 1:1 ranged from 1·3–1·4 insects/panicle for CSH 1, 0·4 for ICSV 1, and 0·4–0·6 and 0·2–0·4 for CSH 5 during 1986 and 1987, respectively. Simple cost estimates for insecticide sprays and the resultant saving in grain yield are a useful tool for decision-making in pest management. 相似文献
10.
《Crop Protection》1987,6(1):20-27
Yield loss from damage by yellow stem borer, Scirpophaga incertulas, was assessed in deep-water rice in Bangladesh and Thailand using five different methods. Because of the long stems and special growing conditions of the crop only three methods proved reliable: pot experiments in metal containers, potted plants exposed in the field, and floating exclusion cages in the field. Yields were reduced by 27–34%, and 1% yield loss was associated with 2% damaged stems at harvest. Yield loss was mainly due to a loss of bearing stems and lighter panicles borne by compensatory nodal tillers. A tentative damage threshold of 10% damaged stems at booting/flowering stage and 20% damaged stems at plant maturity is proposed. 相似文献
11.
豫南“籼改粳”理论与技术研究进展 总被引：1，自引：0，他引：1
简要介绍了豫南稻区"籼改粳"的基本情况和在理论技术方面的研究进展。高温、稻瘟病和纹枯病、三代三化螟危害是豫南粳稻产量低、品质差的三大障碍因子,而播期早是产生障碍的根源,推迟粳稻播期是"籼改粳"的关键技术;豫南"籼稻-小麦"轮作存在制度缺陷,推迟粳稻播期可以得到修复,因秧龄过长而减产、机插秧以及抛秧难以利用等问题得到解决;增产提质、机械化、轻简化、规模化生产是"籼改粳"的必然选择;"东粳西移"是解决豫南粳稻品种利用的有效途径;机插秧、抛秧有利于实现粳稻推迟播种,而"泥质法"育秧解决了高温条件下育秧的问题,提高了机插秧、抛秧的秧苗素质;粳稻晚播稻瘟病、纹枯病和三化螟已不再是豫南"籼改粳"的毁灭性病虫害,恶苗病、干尖线虫病、稻蓟马、稻曲病上升为主要病虫害;水稻两段栽培技术是根据水稻高产稳产生长发育规律,分别从群体、形态和机能构建三个方面进行栽培设计,按照营养生长和生殖生长两个阶段进行定向培育的一种栽培方法,不仅高产稳产,而且减肥减药。 相似文献
12.
13.
Yellow stem borer (YSB), Scirpophaga incertulas (Walker) has become the main rice insect pest once again along the Changjiang River sinee 1990s. Unfortunately, no rice variety with resistance to YSB has been reported so far. 相似文献
14.
Yellow stem borer (YSB), Scirpophaga incertulas (Walker) has become the main rice insect pest once again along the Changjiang River sinee 1990s. Unfortunately, no rice variety with resistance to YSB has been reported so far. 相似文献
15.
甘蔗对螟虫的抗性及其机制研究进展 总被引：1，自引：0，他引：1
甘蔗是主要的糖料作物和能源作物,螟虫是甘蔗生产中为害最严重的钻蛀性害虫,使甘蔗的产量和品质显著降低。尽管目前普遍采用化学药剂和生物防治方法,但因甘蔗的特殊性使防治效果甚微。利用品种的抗虫性是最为经济有效的防治方法。从抗性方式来看,甘蔗抗螟虫性机制主要是幼虫的排趋性和抗生性。本文从甘蔗对螟虫的田间抗性鉴定、室内抗性鉴定讨论了抗性鉴定方法,以及茎表皮硬度、纤维素含量、硅含量等物理结构特性和类黄酮、氮素和必需氨基酸等化学因子与抗性的关系,阐述了物理结构和化学因子在甘蔗对螟虫抗性机制中的作用,最后从抗性来源等方面探讨抗性机制的研究,并对今后的研究方向提出展望。 相似文献
16.
《Field Crops Research》2005,91(2-3):263-271
The effects of shortage of agricultural labour, represented by direct-seeding technologies replacing transplanting, and of water scarcity, represented by limited water supply, on rice pests (pathogens, weeds, insects) were studied. The analysis was based on a field characterisation data set covering six sites in tropical Asia and several cropping seasons. Two-way ANOVAs and MANOVA were, respectively, used to test the effects of the two factors on individual rice pest injuries, and on the profile of injuries that an individual rice crop experiences over a cropping season. Fourteen injuries were considered, which individually were significantly (P < 0.05) influenced by crop establishment (nine injuries), by water management (11 injuries), or their interaction (nine injuries). Multiple analysis of variance indicated that rice injury profiles, regionally, are altered by both factors. The results suggested that injuries caused by some pests would be enhanced (e.g., brown spot, planthoppers) or reduced (e.g., stem rot, sheath blight, rice whorl maggot) by crop establishment shifting from transplanting to direct-seeding. Water shortages, proxied in our data by poor water management, would favour some injuries (e.g., sheath rot, brown spot, neck blast, whiteheads) or suppress others (e.g., stem rot, sheath blight). Very strong increases in weed infestation were observed with both direct-seeding and poor water management. The results are discussed with respect to pest management in rice. 相似文献
17.
Alexander M. Stuart Colin V. PrescottGrant R. Singleton Ravindra C. Joshi 《Crop Protection》2011,30(2):147-154
A survey of the knowledge, attitudes and practices (KAP) of 100 rice farmers and 50 coconut farmers was conducted in the coastal lowland agro-ecosystems of the Sierra Madre Biodiversity Corridor, Luzon, Philippines to identify current rodent management practices and to understand the extent of rat damage and the attitudes of farmers to community actions for rodent management. Pests were most commonly listed as one of the three most important rice and coconut production constraints. Other major crop production constraints were typhoons and insufficient water. Farmers consider rats to be the major pest of coconut and of rice during the wet season rice crop, with average yield losses of 3.0% and 13.2%, respectively. Rice and coconut farmers practised a wide range of rodent management techniques. These included scrub clearance, hunting and trapping. Of the 42 rice farmers and 3 coconut farmers that applied rodenticides to control rodents, all used the acute rodenticide, zinc phosphide. However, only ten rice farmers (23.8%) applied rodenticides prior to the booting stage and only seven farmers (15.6%) conducted pre-baiting before applying zinc phosphide. The majority of farmers belonged to farmer organisations and believed that rat control can only be done by farmers working together. However, during the last cropping season, less than a third of rice farmers (31.2%) applied rodent management as a group. In order to reduce the impact of rodents on the farmers of the coastal lowlands of the Sierra Madre Biodiversity Corridor, integrated management strategies need to be developed that specifically target the pest rodents in a sustainable manner, and community actions for rodent management should be promoted. 相似文献
18.
Phomopsis stem canker (Diaporthe helianthi) is a worldwide fungal disease which is responsible for high yield losses in sunflower crop in the main regions of production. Field data on the influence of crop management on the incidence and severity of stem canker were reported by Debaeke et al. (2003) but a more thorough study was required to analyse step-by-step the spread of the fungus within the canopy from spore deposition on leaves to stem injury.In a 2-year study (2000–2001), the effects of crop management (plant density, N fertilization, and irrigation) and genotypic tolerance (susceptible vs tolerant cultivars) on the epidemics of Diaporthe helianthi were monitored under conditions of reinforced inoculum. The incidence and severity of leaf and stem symptoms were closely related to canopy development (leaf area index) and microclimatic conditions (relative humidity) resulting from different crop management options. Increasing plant density resulted in a greater proportion of girdling stem lesions, detrimental to yield, because of earlier infection under dense canopies. The number of girdling lesions per plant was maximal with high N fertilization but more leaves were infected without N fertilization.The field data were used to evaluate satisfactorily the epidemiological Asphodel model regarding the main periods of leaf infection. The relative humidity within the canopy (observed), the number of leaf infection events (simulated by Asphodel) and the final proportion of stem lesions (observed) were positively related which clearly demonstrated the key role of crop management in the development of stem canker in sunflower. 相似文献
19.
The yield and quality response of Russet Burbank potatoes to simulated hail damage was dependent upon the amount of damage and on the growth stage at which the damage occurred. Plots of Russet Burbank potato plants were subjected to 0%, 10%, 25%, 50%, 75%, or 100% defoliation at 3, 5, 7, 9, 11, or 14 weeks after emergence. A motorized flail was used to simulate the complex damage that occurs during a natural hail storm. Early season simulated hail damage, when the plants were mainly vegetative, caused yield losses proportional to the degree of damage. Simulated hail damage during the early phases of tuber growth caused minor yield losses (< 5%) at low defoliation levels but severe losses at the higher levels with proportional loss of tuber quality. Defoliation later in the season resulted in progressively less reduction of both yield and quality. At or near maturity, late season simulated hail damage caused insignificant losses unless the stems were damaged enough to prevent nutrition and carbohydrate translocation into the tubers. 相似文献
20.
A field experiment was conducted to investigate the impact of simulated rat damage on grain yield in irrigated lowland rice in An Giang province, in the Mekong Delta of Vietnam. Rat damage was simulated by making a 45° cut at the base of the rice tillers about 3–5 cm above the soil surface. 0% (control), 5%, 10%, 25% and 50% of the tillers were removed at the tillering (25 days after sowing, DAS), panicle initiation (43 DAS), flowering (72 DAS) and ripening (87 DAS) stages. The total number of mature tillers, immature tillers and percent filled grains, the weight of 1000 grains and grain yields were recorded. The rice crop completely compensated by increased tillering and yield for tillers damaged up to 50% at the tillering stage. However, the damage and yield loss were highly variable. The ability of the rice crop to compensate at later stages progressively reduced. The implications for managing rat damage to rice crops are (1) rodent control activities should be applied before 10% of tillers are damaged at the tillering stage, and (2) a well balanced nitrogen supply during the tillering stage could potentially assist the rice plants to better compensate for rat damage. 相似文献