共查询到20条相似文献，搜索用时 31 毫秒
1.
《Crop Protection》1987,6(5):334-340
Eight contact and three systemic insecticides, and an enriched neem extract were tested for the control of sorghum head bug, Calocoris angustatus Leth. at the ICRISAT Center. The insecticides were applied at the complete-anthesis and milk stages (at 500 1/ha) with a knapsack sprayer. On the basis of effectiveness of head bug control, grain yield and 1000-grain mass, carbaryl (at 500 g a.i./ha) was the most effective insecticide followed by fenvalerate (at 50 g a.i./ha), and chlorpyrifos (at 250 g a.i./ha). Among the systemic insecticides, demeton-S-methyl (at 250g a.i./ha), was the most effective. Demeton-S-methyl and dimethoate were also effective for the control of other head bug species—Eurystylus bellevoyei Put. and Reut. and Campylomma sp. Plots sprayed with demeton-S-methyl gave higher grain yields than those treated with carbaryl, which was the best contact insecticide. Two sprays of carbaryl (at 500g a.i./ha) applied at the complete-anthesis and milk stages have been found to be effective for head bug control. Dichlorvos, fenitrothion and monocrotophos were highly phytotoxic and resulted in burning and drying of entire leaves. Dimethoate resulted in a slight drying of leaf tips and margins. 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.
This study investigated the correlation between insect mortality and insecticide residue levels in rice grain during the developing stages and at harvest, and also determined the relative toxicities of three insecticides, monocrotophos (Azodrin 16·8 EC), lindane (Agrocide 26 DP), and carbaryl (Sevin 85 WP) to Leptocorisa oratorius (Fab.), (Hemiptera: Alydidae). The insecticides were applied on field plots at 0·75 kg a.i./ha at the start of the milk stage of the developing grains. Sampling was conducted at 2 hours and 1, 2, 3, 4 and 5 days after spraying, which covered the milk stage to the soft dough stage. Mortality of insects exposed to the treated grain, the residue analysis of the treated grain during development and at harvest, and the LD50s of the insecticides were determined. Monocrotophos was the most effective insecticide against the rice bug; lindane provided control for only one day; carbaryl was ineffective. Maximum residue levels of lindane and carbaryl in the harvested grains were below the established tolerance limits provided by FAO/WHO. There is no established tolerance for monocrotophos in rice. 相似文献
4.
Leonard B. Coop Brian A. Croft Christopher F. Murphy Stanley F. Miller 《Crop Protection》1991,10(6):485-495
A decision support system for benefit/cost analysis of chemical treatment of the Senegalese grasshopper, Oedaleus senegalensis (Krauss) (OSE), was created to assist in the training, analysis, and management of grasshopper treatment programmes. The system, known as GHLSIM, has linked simulation models, databases, and a user interface. Millet and sorghum phenology and yields are estimated by an FAO (Food and Agriculture Organization, United Nations) soil water deficit model. Outputs from the PRIFAS (Programme de Recherches Interdisciplinaire Français sur les Acridiens du Sahel) OSE biomodel, including daily grasshopper life stages and favourability for development, are converted to density estimates using survey data, oviposition rates, and natural and insecticide-caused mortality. Crop loss is estimated through crop injury units — a function of grasshopper stage densities, consumption rates, crop preference, crop stage susceptibility, and non-crop vegetation greenness. Second-year benefits of treatment are estimated from end-of-season egg-pod densities. The model was calibrated using published economic thresholds for four crop stages. Yield increases from a late-season grasshopper aerial treatment campaign, 22 September — 19 October 1987, at 13 sites in eastern Chad were estimated at 33%±20% (s.e.). Benefit/cost ratios were 2.6±0.5 for the first season, and 3.8±0.7 with second-year effects added. The analysis indicated that optimal timing was 5–10 days earlier than the actual treatments. Crop yield reports from treated and non-treated areas, a crop loss assessment conducted in Batha, Chad in October 1987 and a break-even analysis provide further evidence that the campaign was successful and cost-effective at most sites, as indicated by model results. 相似文献
5.
Field trials were conducted at Samaru in the northern Guinea and at Bakuta and Kadawa in the Sudan Savanna ecological zones of Nigeria to identify suitable herbicides for weed control in irrigated onion. The herbicides tested were chlorthal-dimethyl, fluorodifen and oxadiazon. In the trials each herbicide treatment was compared with an identical treatment which received supplementary hand-weeding. The results of these experiments show that oxadiazon at 1·0–2·0 kg a.i./ha, with or without supplementary hoe-weeding at 6 weeks after transplanting, combined effective weed control with high bulb yields in irrigated dry season onions. While fluorodifen at 1·5 kg a.i./ha followed by supplementary hoe-weeding may be effective at sites with low weed infestation, a higher rate (3·0 kg/ha) may be desirable at sites with a higher broad-leaved weed infestation. Chlorthaldimethyl at 10·0 kg a.i./ha effectively controlled weeds at all the sites and gave high onion yields at sites with 6–12% clay; the selectivity was, however, lower at Bakura with very light soil. Uncontrolled weed growth caused 49–86% reduction in the bulb yields compared with the best herbicide treatments. 相似文献
6.
Powders prepared from sweetflag Acorus calamus rhizomes collected at both high (1700 m) and low (900 m) altitude in Eastern Nepal were admixed with wheat at concentrations in the range 0.05–2% w/w and the wheat infested with Sitophilus oryzae or S. granarius adults. Following a 7 day incubation, the mortality of both species was significantly lower at 20 °C than at 30 °C, and the material collected from high altitude was slightly less toxic than that from low altitude. The moisture content of the wheat (14 or 17%) and the part of the rhizome used to prepare the powder (young or mature growth) had no apparent effect on the toxicity of the preparation. Sitophilus granarius (L.) adults were more tolerant of the material than S. oryzae (L.), while the converse was true for larvae developing in treated grain. An admixture rate of approximately 2% w/w admixed rhizome powder was required to give complete kill of adults of both species following 7 days exposure at 20 °C, while a concentration of 1% w/w either prevented the emergence of adults or killed them rapidly following emergence when wheat containing eggs of either species was incubated for 7–8 weeks at 30 °C.
The β-asarone content of the rhizome powders was determined by GC-MS as 6.4 and 4.7% w/w (mature section of rhizomes collected at high and low altitudes, respectively) and 3.6 and 4.0% w/w (young sections of rhizomes collected at high and low altitudes, respectively). It is anticipated that, under field conditions and in the temperature range 20–30 °C, the initial residue of approximately 1300 mg/kg β-asarone required to disinfest wheat containing these weevil species would decline rapidly due to evaporation. 相似文献
7.
InfoCrop, a generic crop–pest simulation model, was used to validate yellow stem borer, Scirpophaga incertulas Wlk., damage mechanism on two rice cultivars, Pusa Basmati 1 and Ratna. Data sets consisted of three experiments, one under natural infestation of the pest and two involving artificial detillering. The simulated yields showed less than 10% variation from the observed yields, except in one treatment, where the difference was 10.5%. The simulated yield losses were also proximal to respective observed yield losses (R2=0.922, RMSE=3.825), indicating proper validation of damage mechanism of the stem borer. As the model simulated the pest damage appropriately under natural injury, as well under artificial detillering; artificial detillering seemed comparable to natural injury of the stem borer in its effect on rice growth and yield. Validated InfoCrop was used to simulate economic injury levels (EILs) of the stem borer at different rice growth stages for varied control expenditure, incurred on two and three sprays of monocrotophos and one granular application of carbofuran, and for three market prices of produce. The EIL consistently decreased with advancing crop age and it exhibited a positive relationship with control expenditure and a negative relationship with market value of the produce. The simulated EILs were observed to be comparable to empirical injury levels that were previously established. The validated model was also used to devise iso-loss curves that depicted same yield loss for different combinations of the stem borer injury and crop age. Crop simulation model-based EILs and iso-loss curves are useful in monitoring the stem borer injury and in need assessment for pesticide application, thereby avoiding unnecessary expenditure and environmental contamination. Due to their mechanistic nature, crop models can be used to formulate location-specific decision support tools and therefore, help improve decision making in pest management. 相似文献
8.
Soil-incorporated and foliar-applied insecticides, alone and in combination, were tested in two different tropical sites of Peru. At San Ramon (altitude 800 m) major pests during the wet season were Diabrotica spp. and Myzus persicae. Soil-incorporated insecticides gave protection against Diabrotica but not M. persicae, and yields were significantly lower with these compared with the foliar-applied insecticide, carbofuran. Mean yield was inversely and significantly correlated with mean number of Diabrotica individuals per plant (r=0·989; 0·01 <P<0·05). The foliar-applied insecticide, season, major pests were Phthorimaea operculella, M. persicae and Feltia spp. Mean yield was inversely correlated with mean number of larval mines by P. operculella on foliage (r=0·976;0·02 <P<0·05). The foliar-applied insecticide methomyl, reduced pest damage and increased yields significantly. The major pests during the dry season at Yurimagus (altitude 180m) were Diabrotica spp. Foliar application of carbaryl alone, or in combination with soil-incorporated insecticides, was equally effective in reducing damage and yield loss. An inverse significant correlation (r=0·985; 0·01<P<0·02) for yield vs. damage from Diabrotica spp. was observed. 相似文献
9.
10.
Field trials were conducted in 1997 and 1998 wet seasons to determine the effect of seed treatment of different sorghum varieties with brine (NaCl) on the control of Striga hermonthica in sorghum. The varieties of sorghum used were ICSV 1002, ICSV 1007 (improved resistant varieties from ICRISAT, Mali), BES (a local improved variety), and War-warabashi (a local susceptible variety). Different concentrations of brine at 0.5, 1.0, 1.5, and 2.0 M were used. The results show that the varieties, ICSV 1002 and ICSV 1007 had significantly higher establishment count than the BES and War-warabashi varieties, but had shorter plants. Similarly, the ICSV 1002 and ICSV 1007 and War-warabashi varieties had significantly larger LAI values than the BES variety, although the BES significantly out yielded them. The susceptible War-warabashi variety supported the highest number of Striga emergence than the improved varieties. The effect of brine treatments on plant establishment, growth and yield of sorghum under Striga infestation shows that there was a decrease in crop stands with increase in brine concentration, with the least value at 2.0 M brine treatment, which was damaging at this rate. Plant height and, leaf area index (LAI) of sorghum increased with increasing concentration of brine to a maximum at 1.5 M and declined at 2.0 M brine treatment. The 1.5 M brine treatment produced the highest grain yield. Striga shoot emergence significantly declined with increasing brine concentration reaching the lowest values at 1.5 and 2.0 M brine treatments. The interaction between sorghum varieties and brine concentrations shows that War-warabashi with 1.5 M brine treatment had the tallest plants and largest LAI, while BES and 1.5 M brine produced the highest grain yield. In general, the interaction between the varieties and all the brine concentrations significantly reduced Striga emergence. Irrespective of the sorghum varieties the use of brine at 1.5 M was found optimal for controlling Striga emergence resulting in increased crop growth and grain yield. This implies that which ever variety farmers are using either resistant, tolerant or susceptible, they could easily use brine at 1.5 M to effectively control Striga and increase in grain yield. The mechanism by which brine successfully controlled Striga, is, however, not clear and needs to be investigated. 相似文献
11.
Melon collapse caused by the heat-tolerant soil-borne fungus Monosporascus cannonballus is not controlled by current solarization technology applied to large soil volumes because the temperatures achieved are not high enough to kill the pathogen's ascospores. The efficacy of improved solarization achieved by mulching a shallow layer of growth medium in containers was studied in terms of disease control and yield increase over two growing seasons. Compared to solarization of a regular container, solarization of a shallow layer (5–6 cm) of growth medium resulted in a 3–5°C elevation in maximal temperature at a depth of 3 cm, and in a 7–10°C increases at the bottom of the shallow layer. This led to a higher disease reduction and higher yields in the 1996 experiment. In 1997, both methods of solarization were highly effective. Yield was highly correlated with disease reduction in both experiments. In the 1997 experiment, ascospore viability declined faster in the shallow container treatment than in the regular container. This study demonstrates the potential of an additional approach for improving solarization of containerized plant growth medium and improving its reliability, with the aim of controlling heat-tolerant pathogens. 相似文献
12.
The effects of relative humidity (RH) and temperature on tomato powdery mildew (Leveillula taurica) were studied in controlled environments to define conditions that affect disease development in fresh market tomatoes in California. Gradients of RH (20–90%) at constant temperatures (20–30°C) were generated in single growth chambers to determine their effect on mildew development on mature tomato plants. Temperatures of 30°C and above were deleterious for spore germination, germ tube elongation, and disease development. Lesion growth and rate of disease progress were significantly higher at 20°C than at 25°C. Low RH levels (20–40%) reduced spore germination and lesion growth, accelerated host tissue death and reduced disease progress. Intermediate RH levels (50–70%) increased spore germination and optimized disease development, provided temperatures were maintained within favorable limits. High RH levels (80–90%) were favorable for spore germination but continued exposure to these conditions led to a limited lesion growth and disease progress. Short daily periods (two or three daily exposures of at least 2 h) of high temperatures (35°C) suppressed disease development by 70–92%. 相似文献
13.
The genus Lesquerella is a promising source of hydroxy fatty acids (HFA). Several species such as Lesquerella fendleri and Lesquerella mendocina are candidate crops for arid and semi-arid cropping systems. Several reports are available on the environmental effects on growth and yield in Lesquerella, but information on the effect of temperature on plant growth and development specifically during the reproductive period in Lesquerella is limited. The objective of this work was to determine the effect of two contrasting thermal regimes after flowering on time to maturity, plant growth and biomass allocation to the different organs in L. fendleri and L. mendocina. A greenhouse experiment was conducted with plants grown at a range of 11–23 °C during the vegetative phase. After this stage, 50% of the plants of each species remained under the same temperature regime until maturity, whereas the other 50% was transferred to another module subjected to a range of 17–31 °C until maturity. The duration of the reproductive phase was reduced by 23 days in plants of both species in the 17–31 °C treatment compared to those at 11–23 °C, although no differences were observed when the length of the reproductive phase was measured in thermal-time units. Total plant biomass for both species was 20% greater in the 11–23 °C treatment. In L. fendleri, this increment occurred due to more vegetative shoot biomass, whereas in L. mendocina it was associated with greater reproductive and root biomass. No changes in biomass allocation were produced by temperature in L. fendleri, while in L. mendocina the lower temperature regime increased allocation to the reproductive organs, at the expense of a lower allocation to vegetative shoot. These results could be used to predict the specific temperature effects after flowering on yield under field conditions, and suggest that L. mendocina might be a promising perennial alternative for cooler sites. 相似文献
14.
Leland C. Dickey Michael J. Kurantz Nicholas Parris 《Industrial Crops and Products》2008,27(3):303-307
The many recent dry-grind plants that convert corn to ethanol are a potential source of substantial amounts of corn oil, if an economical method of separating it can be developed. Oil separation from corn germ by aqueous extraction (AE) was studied. Batches of 5–20% germ in a buffer solution were preheated in a pressure cooker, ground in a blender or colloid mill, churned in an incubator/shaker and centrifuged to separate a free oil fraction. The highest oil yields were obtained when the germ mass fraction was between 0.1 and 0.16. Addition of an enzyme solution to the ground germ suspension prior to churning, aqueous enzymatic extraction (AEE) gave an oil yield twice as high as the AE yield, carried out using similar conditions. Both types of extraction produced the most oil after a 122 °C cook followed by churning at 160 rpm and 70 °C. Oil yield increased linearly with dispersion loading, from 0.5 up to 1.0 g/cm2 based on beaker cross-section (0.09–0.12 germ mass fraction). Over a several month period the germ used for the extractions became more difficult to extract, despite storage at 4 °C. 相似文献
15.
不同生育时期叶面喷施奇善宝对冬小麦产量及品质的效应 总被引：1，自引：0，他引：1
为了解海洋寡糖复合制剂奇善宝在小麦上的应用效果,2011-2013年以小麦品种中麦349为材料,研究了返青、拔节和孕穗期叶面喷施奇善宝对冬小麦产量及品质的影响。结果表明,叶面喷施奇善宝使冬小麦增产2.9%~11.3%,效果明显,增产的主因是显著增加了穗粒数和千粒重。喷施奇善宝对冬小麦部分品质性状影响显著,其中使籽粒容重、硬度、蛋白质含量和面粉湿面筋含量分别较对照提高0.1%~0.8%、1.0%~5.3%、0.3%~3.3%和0.4%~5.1%,使面团稳定时间和延展性分别下降3.5%~5.8%和2.3%~5.2%。增产效果以返青期和拔节期喷施最佳,返青期喷施对改善品质效果最佳。 相似文献
16.
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
17.
Richard A. Creager 《Crop Protection》1989,8(6):443-446
Four herbicides, monthly handweeding and a 15 cm deep straw mulch were evaluated for weed control during 1982 to 1987 on rhubarb (Rheum rhabarbarum L. ≡ R. rhaponticum L. ‘Victoria Red’). The straw-mulched plots produced larger plants, provided higher yields and had fewer weeds than all other treatments during the five years of these field trials. Yields in 1987 were 29·42, 17·65 and 13·06 tonnes/hectare for straw, handweeded and herbicide treatments, respectively. Monthly handweeding produced large plants and high yields, but required much more hand labour than mulching, making straw mulch the most cost-effective treatment. The four herbicides evaluated (glyphosate, fluazifop, sethoxydim and propyzamide) provided weed control for up to 1 month and would require reapplication during the growing season. 相似文献
18.
Wheat grain damaged by wheat bug (Eurygaster spp.) contains the bug salivary secretion which hydrolyses the gluten needed for the dough quality of breadmaking due to its proteolytic activity. Since the protease inhibitors are widespread throughout the plant kingdom, the possibility of using some plants, especially food and feed legumes to decrease the proteolytic activity of flours milled from bug damaged wheats was investigated. The proteolytic activity was considerably inhibited by pefabloc-SC and EDTA-Na2, suggesting that bug protease(s) included serine and metallo proteases. Extracts from cones of hops, seeds of grass pea, red kidney bean and sunflower caused reduction in the activity of bug protease(s). Effects of hop extract on electrophoretic, rheological properties of high protease activity flours milled from different bread wheat cultivars damaged by the bug were also studied. The dough development time and stability values of high protease activity flours increased considerably with hop extract at the lowest addition level (10:1, flour to hop extract ratio). The doughs supplemented with the hop extract had higher maximum resistance and lower extensibility values as compared to their controls. These results suggested that hop extract had improving effects on high protease activity flours due to the bug damage. 相似文献
19.
水氮互作对小麦籽粒蛋白质组分和品质的影响 总被引：1，自引：0，他引：1
为了给强筋小麦高产优质高效栽培提供理论依据,以高产强筋小麦品种济麦20为材料,研究了施氮量和灌溉量对小麦籽粒蛋白质组分和品质的影响.结果表明,施氮量由120 kg*ha-1(N1)增加至240 kg*ha-1(N2),籽粒蛋白质含量、清蛋白和球蛋白含量增加,(醇溶蛋白+麦谷蛋白含量)/(清蛋白+球蛋白含量)比值(谷醇/清球比值)降低,面团稳定时间缩短.同一施氮量条件下,由不灌水(W0)到灌2水(W1),籽粒蛋白质含量增加,谷醇/清球比值降低,面团稳定时间缩短;由灌2水(W1)到灌3水(W2)和5水(W3),籽粒蛋白质含量降低,蛋白质组分中清蛋白和球蛋白含量升高,醇溶蛋白和麦谷蛋白含量降低,谷醇/清球比值降低,面团稳定时间亦缩短.以上结果表明,在本试验条件下,增加施氮量和灌水量导致面团稳定时间缩短,原因是清蛋白和球蛋白占总蛋白含量的比例,即谷醇/清球比值降低. 相似文献
20.
Grain yields of a soft white winter wheat cultivar, cv. Ionia, susceptible to cereal leaf beetle (Oulema melanopus (L.)), were determined when the crop was subjected to four controlled infestation levels of the beetle in caged plots over a 3-year period in Michigan. Although identical infestation procedures and insect numbers were used each year, the intensity of larval infestation and feeding damage varied with the year. Significant (P < 0·01) grain losses occurred in plots that had at least 9·0 larvae per stem. The greatest yield loss was 45% and occurred with 15 larvae per stem and 85% feeding damage. Beetle damage had a greater effect on kernel weight than on the other yield components. Although economic thresholds should be conservative to allow for environmental variations, it appears that soft white winter wheat can often withstand beetle infestation levels greater than the current economic threshold of three or more eggs and largae per stem before the boot stage or one or more large larvae per flag leaf during heading. 相似文献