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1.
Chemical fumigants are routinely used for soil disinfestation of high value crops. Good agricultural practices (GAPs) are needed to reduce their human health risks, environmental impacts, and improve their cost-effectiveness. This study investigated the effect of fumigant application methods on soil persistence and emission of 1,3-dichloropropene (1,3-D) and chloropicrin (CP). Field experiments were conducted to measure the individual and combined effects of pre-application tillage practices, fumigant application technology, and plastic films on 1,3-D soil concentrations to obtain a numerical index (CT value) to estimate their potential for pest control efficacy and to compare soil persistence, atmospheric flux rate, and cumulative emission of CP and 1,3-D under two diverse application scenarios. Greater 1,3-D soil vapor concentrations were observed by combining a pre-application soil seal with low soil disturbance application technology when compared to pre-application soil tillage and the use of back-swept application shanks. Under high density polyethylene plastic, the low disturbance scenario resulted in time weighted exposure concentration (CT) values ranging from 6.8 to 12.2 μg h cm−3 of soil as compared to CT values ranging from 2.9 to 5.4 μg h cm−3 under the conventional application scenario. Cumulative atmospheric emission of 1,3-D was decreased by 18% under the low disturbance scenario and atmospheric emission of CP by 21% when compared to a conventional application scenario. This study identified GAPs that can be readily implemented in the field to reduce the human and environmental impacts of soil fumigants and improve their cost-effectiveness under solid-tarp (broadcast) applications.  相似文献   

2.
A gelatin capsule (gel cap) formulation of the mixture of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) has been developed to reduce environmental emissions and potential human exposure from the use of 1,3-D/CP as a soil fumigant. The objective of the present study was to evaluate the biological efficacy of 1,3-D/CP gel cap formulations under greenhouse trial conditions. The current results indicate that a 1,3-D/CP gel cap formulation at 30 or 50 g a.i. m−2 can reduce the soil populations of Fusarium spp., Phytophthora spp., Pythium spp. and Meloidogyne spp.. In all tested crops, the 1,3-D/CP gel cap formulation provided marketable yields that were significantly higher than untreated controls and equal to the methyl bromide and 1,3-D/CP liquid injection treatments. Yields of tomato and a subsequent melon crop in plots treated with 1,3-D/CP gel cap were 93% and 87% greater, respectively, than the control. The yields of grafted cucumber and the subsequent balsam pear crop were increased by 16% and 201% respectively, compared to the control. The present study confirms that the tested 1,3-D/CP gel cap formulation provides a promising method for soil pest and disease control and reducing environmental emissions and potential human exposure in greenhouse vegetable cultivation.  相似文献   

3.
Preplant soil fumigation is commonly used to control soilborne pathogens and weeds in forest seedling nurseries of Oregon and Washington. However, lower chemical inputs are desired to meet state and federal application regulations, to minimize buffer zone size requirements, and to help protect the environment. Therefore, the objectives of this research were to evaluate the efficacy of three reduced rate soil fumigants under totally impermeable film (TIF) in managing soilborne diseases and weeds, and to determine if combined applications of up to four biocontrol agents improved soilborne disease control. Reduced rates of methyl bromide, metam sodium, and 1,3-dichloropropene, all applied in combination with chloropicrin, were effective in decreasing soil populations of Pythium and Fusarium as well as the presence of Pythium in root debris from the previous crop. The roots of Douglas-fir (Pseudotsuga menziesii) seedlings transplanted into each fumigant treatment were also colonized less by Pythium and Fusarium than those transplanted into nonfumigated control plots. However, biocontrol treatments were not effective against either pathogen. Weed biomass and weeding times were also significantly reduced by fumigation. Application costs were similar for all three fumigant treatments, but seedling size was largest from the methyl bromide and metam sodium treatments followed by the 1,3-dichloropropene treatment. Based on the results of this study, reduced rates of methyl bromide, metam sodium, and 1,3-dichloropropene show promise in managing soilborne diseases and weeds in forest nurseries.  相似文献   

4.
Small-plot research and large-field validations were conducted to determine the effect of 1,3-dichloropropene (1,3-D)+chloropicrin (Pic) application methods in combination with the herbicides pebulate and napropamide on pest control in fresh market tomato (Lycopersicon esculentum Mill.). In both the small-plot trials and the large-validation fields, various treatments compared the efficacy of soil fumigants and herbicides based on methyl bromide, in-bed and broadcast applications of 1,3-D+Pic, pebulate, and napropamide. The results consistently indicated that either in-bed or broadcast applications of 1,3-D+Pic in combination with pebulate and napropamide are equally effective against the weed Cyperus spp., the nematodes Tylenchorhynchus spp., Belonolaimus longicaudatus, and Meloidogyne spp., and the soilborne disease Fusarium oxysporum f.sp. lycopersici in fresh market tomato. Therefore, broadcast 1,3-D+Pic application can reduce personnel exposure and poisoning risks, without losing pest control efficacy.  相似文献   

5.
The soil fumigant 1,3-dichloropropene (1,3-D) has been used in the UK for the control of potato cyst nematodes (PCN), Globodera pallida (Stone) and Globodera rostochiensis (Wollenweber), but its potential herbicidal activity has not been extensively investigated in this country. Field and glasshouse studies were therefore conducted to evaluate the potential of 1,3-D for the control of weeds in potatoes, and observations were made on the severity of potato stem canker, caused by the fungus Rhizoctonia solani Kühn [teleomorph: Thanatephorus cucumeris (Frank) Donk]. Autumn application of 1,3-D at 211.5 L active substance (a.s.) ha−1 significantly suppressed the number of germinating weeds and the percentage of weed ground cover by 83% and 79%, respectively, relative to controls. There were also species-specific significant decreases (field pansy, Viola arvensis, in particular) in the number of weed seeds germinating in field soil in the glasshouse post-1,3-D treatment. The effect of 1,3-D declined in time and single (autumn or spring) or combined application produced a slight, but not significant, reduction in the number of weeds germinated on potato ridges relative to those recorded in untreated soil. The severity of stem canker on potato plants was not significantly reduced by 1,3-D but both mean number and weight of stems per plant were significantly increased compared with plants from untreated plots. These studies demonstrated that 1,3-D, in addition to giving PCN control, has efficacy against weeds; implications are the potential for reduced herbicide input in the crop rotation with accompanying economic and environmental benefits.  相似文献   

6.
Concentrations in soil and efficacy of 1,3-dichloropropene (1,3-D)+chloropicrin and methyl isothiocyanate (MITC) against the survival of Phytophthora capcisi, Rhizoctonia solani and yellow nutsedge (Cyperus esculentus L.) were studied in plastic-mulched Southern Georgia sandy soil beds. Beds were treated with InLine (60.8% 1,3-D+33.3% chloropicrin) at 93.5, 187, and 280.5 l ha−1 and Vapam (42% metam sodium) 233.8, 467.5 and 701.3 l ha−1. 1,3-D+chloropicrin and MITC concentrations in soil were monitored after drip application for 7 d and 240 h, respectively, from pre-selected sites in beds. 1,3-D+chloropicrin and MITC concentrations decreased with time and distance from the emitter. Survival of P. capsici, R. solani and yellow nutsedge in treated beds was higher with distance from the emitter. These methyl bromide alternatives did not diffuse laterally at effective concentrations beyond the point of application. Improved application techniques are required to improve the lateral distribution of these alternatives.  相似文献   

7.
Two application methods, single- and double-chisel injection of the fumigant nematicide 1,3-dichloropropene (1,3-D) were evaluated for efficacy and environmental fate in pineapple field experiments. The objectives were to compare the 1,3-D soil distribution between injection methods, evaluate volatile losses to the atmosphere, and to determine efficacy with each method. In a small-plot field experiment, 1,3-D (224, 337, and 393 1 ha−1) was manually injected 30 cm deep with fumiguns to simulate the commercial practice of a single- or double-chisel injection per planting bed. 1,3-D concentrations in the soil atmosphere and in soil samples were determined and compared to nematode control. In two large-scale field experiments, 1,3-D (224 1 ha−1) was applied with commercial injection equipment with and without polyethylene mulch. Air monitoring for 1,3-D showed a reduction in 1,3-D air emissions with single-chisel injection compared with double-chisel injection. In all experiments, the two injection methods resulted in equivalent 1,3-D concentrations in the plant line. Single-chisel injection resulted in improved retention of 1,3-D within the planting bed as shown by low 1,3-D soil concentrations in the interbed. Nematode counts and bioassay studies found equivalent nematode control in the planting bed with either injection method. The single-chisel method, however, resulted in reduced nematode control in the interbed region.  相似文献   

8.
Application and crop safety parameters for soil fumigants   总被引：2，自引：0，他引：2  
Metam sodium alone and in combination with 1,3-dichloropropene plus 17% chloropicrin (1,3-D+C-17) were evaluated under polyethylene mulch film as alternatives for methyl bromide in tobacco and tomato transplant production for both efficacy against pests and crop safety. Eight different weed species, 10 genera or species of fungi and several agronomic criteria were evaluated at three different sites. In general both the metam sodium alone and in combination with 1,3-D+C-17 were highly efficacious when compared to methyl bromide. Short polyethylene film retention times and short aeration times resulted in poor stands and poor crop vigor while relatively long polyethylene film retention times and long aeration periods at the same rates typically resulted in high stand counts and vigor. Combination treatments were more phytotoxic to germinating seed of tobacco and tomato. Vigor and stand counts of the seedlings were higher as aeration time increased, suggesting phytotoxic residues dissipate with time. Method of application of metam sodium, either injected with chisels or sprayed onto the soil surface and incorporated with a tractor-powered tiller alone or co- applied with 1,3-D+C-17 chisel injected, did not affect the efficacy of the treatments. Caution regarding phytotoxicity must be exercised when seeding into soil fumigated with metam sodium alone or combined with 1,3-D+C-17. Additional work will be required to establish safety periods required prior to transplanting crops into fumigated soil.  相似文献   

9.
Two field trials were conducted to examine the efficacy of methyl bromide (MBr) alternatives in the control of Cyperus rotundus L. (purple nutsedge) and Fusarium oxysporum Schlecht. f.sp. lycopersici (Sacc.) Snyder & Hansen (Fusarium wilt) in fresh market tomato (Lycopersicon esculentum Mill.). Various treatments compared combinations of soil fumigants and herbicides based on methyl bromide, chloropicrin, 1,3-dichloropropene, metam sodium, dazomet, and pebulate. The data show that consistently 1,3-dichloropropene plus chloropicrin at both doses in combination with the herbicide pebulate can be considered alternatives to methyl bromide in fresh market tomato. These treatments had excellent purple nutsedge and Fusarium wilt control, and marketable tomato yields were similar to that for methyl bromide plus chloropicrin.  相似文献   

10.
In California, USA, agricultural fumigant use regulations hinder the complete transition from methyl bromide (MB) to alternative fumigants. Alternative fumigants such as 1,3-dichloropropene (1,3-D) and chloropicrin (Pic) are being used on approximately half of California conventional strawberry production fields. Geographic use limits and buffer zones set by the California Department of Pesticide Regulation for 1,3-D + Pic restrict a more complete replacement of MB. Due to the regulatory constraints and public resistance to fumigant use, it is necessary to develop fumigant-free strawberry production systems. Trials were conducted during the 2007/2008 and 2008/2009 strawberry growing seasons at Salinas and Watsonville, California. Non-fumigant treatments including steam, mustard seed meal (MSM), Muscodor albus, and furfural, fertilizers including Mustard Products & Technologies fertilizer and stabilised urea, and fungicide treatments including AG3(NP), fludioxonil + mefenoxam (mfx), and mfx + thiophanate-methyl were evaluated for weed control and strawberry fruit yield, and compared to MB + Pic (MBPic) standard soil fumigation and an untreated control. Steam treatment applied pre-plant to achieve soil temperature of ≥70 °C for 20 min up to 25 cm soil depth consistently provided weed control similar to the MBPic standard soil fumigation. Use of oxyfluorfen herbicide prior to fungicide applications in 2008/2009 also controlled weeds similar to the MBPic standard soil fumigation. Strawberry yields in steam-treated plots with the exception of steam alone in 2007/2008 at Salinas, were comparable to MBPic. At Watsonville in 2008/2009, treatment effect on strawberry yields was insignificant. Yields in furfural and MSM treatments were comparable to MBPic only in some years or sites. With the exception of steam, none of the treatments can be considered viable replacement to MB.  相似文献   

11.
Paradox (Juglans hindsii × J. regia), the dominant rootstock used in the California walnut industry, is susceptible to crown gall caused by Agrobacterium tumefaciens. In practice, soil fumigation has been a common pre-plant management strategy for crown gall, but even the industry standard, methyl bromide (MeBr), results in inconsistent disease control. To examine MeBr efficacy and identify potential alternatives, combinations of 1,3-dichloropropene (1,3-D), chloropicrin, iodomethane, dazomet, and metam-sodium were examined. Except for 1,3-D alone, all treatments reduced A. tumefaciens and Phytophthora cactorum populations below detection limits. MeBr eliminated A. tumefaciens populations in buried gall tissue, but a combination of 1,3-D and chloropicrin (TC35) did not. An additional 280 kg/ha of chloropicrin in addition to TC35 eliminated A. tumefaciens populations in buried gall tissue. Of the treatments tested, TC35 was the best alternative to MeBr given its efficacy on soil populations of A. tumefaciens and P. cactorum and potential suppressiveness to soil recolonization by A. tumefaciens. MeBr reduced general aerobic bacterial populations below detection limits producing a temporary biological vacuum. A. tumefaciens reintroduced in soils treated with MeBr and TC35 reached significantly higher populations than in non-fumigated soil. However, A. tumefaciens populations in TC35-treated soil were 100-fold lower than MeBr-treated soil 110 d after reintroduction. Increased recolonization rates resulting in higher subsequent soil populations could be a mechanism underlying the observed inconsistent crown gall control after MeBr application.  相似文献   

12.
为了揭示覆膜滴灌对稻田CH_4综合排放的影响,采用比较分析法分析了覆膜滴管条件下稻田甲烷的排放变化。试验采用覆膜滴灌Ⅰ、覆膜滴灌Ⅱ和漫灌3个处理,分别对当地高产主栽品种吉旱1号进行CH_4排放通量的测定。结果表明,覆膜滴灌稻田CH_4排放通量显著高于漫灌稻田;覆膜滴灌处理条件下,土壤含水率高的覆膜滴灌Ⅰ稻田CH_4排放通量高于覆膜滴灌Ⅱ,说明土壤水分是稻田CH_4排放的主要影响因素之一;3个处理下CH_4的排放趋势大体一致,排放高峰均出现在水稻分蘖的前中期和拔节孕穗期,说明覆膜滴灌未改变稻田CH_4排放的进程。  相似文献   

13.
Fumigation in the 21st century   总被引：9，自引：0，他引：9  
C. H. Bell 《Crop Protection》2000,19(8-10):563-569
The last quarter of the 20th century has seen the withdrawal of many compounds formerly used as fumigants. Methyl bromide, the fumigant with the widest range of applications is scheduled for worldwide withdrawal from routine use as a fumigant in 2015 under the directive of the Montreal Protocol on ozone-depleting substances. Phosphine, the only other commodity fumigant available worldwide, used principally on bulk grain but also on dried fruit, nuts, cocoa, coffee and bagged rice, is currently under regulatory review in the USA and Europe. The prospects for the continued use of fumigants to protect plant and animal health and commodity trading are discussed in the context of mounting pressures on compounds due to registration requirements, atmospheric emission controls, fears on safety or health grounds, the incidence of resistance, and the need to achieve increasingly high standards of pest control in international trade. Some recent research results relating to fumigant toxicity and gas application technology are presented which indicate ways in which the use of some of the few remaining fumigants can be extended in the 21st century.  相似文献   

14.
In the low-input rice–wheat production systems of Nepal, the N nutrition of both crops is largely based on the supply from soil pools. Declining yield trends call for management interventions aiming at the avoidance of native soil N losses. A field study was conducted at two sites in the lowland and the upper mid-hills of Nepal with contrasting temperature regimes and durations of the dry-to-wet season transition period between the harvest of wheat and the transplanting of lowland rice. Technical options included the return of the straw of the preceding wheat crop, the cultivation of short-cycled crops during the transition season, and combinations of both. Dynamics of soil Nmin, nitrate leaching, nitrous oxide emissions, and crop N uptake were studied throughout the year between 2004 and 2005 and partial N balances of the cropping systems were established. In the traditional system (bare fallow between wheat and rice) a large accumulation of soil nitrate N and its subsequent disappearance upon soil saturation occurred during the transition season. This nitrate loss was associated with nitrate leaching (6.3 and 12.8 kg ha−1 at the low and high altitude sites, respectively) and peaks of nitrous oxide emissions (120 and 480 mg m−2 h−1 at the low and high altitude sites, respectively). Incorporation of wheat straw at 3 Mg ha−1 and/or cultivation of a nitrate catch crop during the transition season significantly reduced the build up of soil nitrate and subsequent N losses at the low altitude site. At the high altitude site, cumulative grain yields increased from 2.35 Mg ha−1 with bare fallow during the transition season to 3.44 Mg ha−1 when wheat straw was incorporated. At the low altitude site, the cumulative yield significantly increased from 2.85 Mg ha−1 (bare fallow) to between 3.63 and 6.63 Mg ha−1, depending on the transition season option applied. Irrespective of the site and the land use option applied during the transition season, systems N balances remained largely negative, ranging from −37 to −84 kg N ha−1. We conclude that despite reduced N losses and increased grain yields the proposed options need to be complemented with additional N inputs to sustain long-term productivity.  相似文献   

15.
The current revision of pesticides in the EU, including those for soil disinfection, will necessitate the introduction of alternative integrated methods for the control of weeds and parasites in tobacco production in Italy. The present study compared the effect of some soil fumigants, biocontrol agents, cover crops and mulching for the control of tobacco weeds and root parasites. The results show that the different soil fumigants had an important role in increasing tobacco yield, due to their ability to control weeds and the nematodes Meloidogyne incognita and Meloidogyne javanica. In particular, a typical nematicide like 1,3-dichloropropene did not control only nematodes but also Portulaca oleracea, a common weed in Italian tobacco fields. Fenamiphos, although showed a certain efficacy in controlling root-knot nematodes, did not generally have a satisfactory activity at the dose of 40 g m−1; cover crops like Trifolium squarrosum and Eruca sativa and a commercial formulation composed by the endomycorrhizal fungi Glomus spp., the antagonistic fungi Trichoderma spp. and bacteria including Pseudomonas, Bacillus and Streptomyces (Micosat F, CCS Aosta, Italy), were not able to control root tobacco diseases. The investigations confirmed that a prolonged monoculture causes a reduction of black root rot. Soil fumigation and the use of Good Agricultural Practices (GAP), influencing the inoculum density of Chalara populations, can contribute to the maintenance or to the establishment of particularly unfavourable conditions for the saprophytic growth of the pathogen, leading to a lower development of the disease.  相似文献   

16.
Two field studies were conducted in the San Joaquin Valley (SJV) of California in order to describe the association of arthropods and possible virus diseases with the plant canopy of early-season, bush-trained, fresh-market tomato (Lycopersicon esculentum L. cv. Shady Lady) over three soil surface microenvironments. The experimental treatments were based on alterations to planting bed surfaces, as follow: 1) soil covered with silver metalized, light-reflective plastic mulch; 2) soil covered with biological mulch consisting of killed, chopped, cool-season cover crop residues [mixture of triticale (X Triticosecale Wittm.), rye (Secale cereale L. cv. Merced), and common vetch (Vicia sativa L.)]; or 3) bare soil (not covered) – the SJV standard tomato production practice. In both studies, the predominant arthropods encountered in all treatments were the aphid species Aphis craccivora Koch, Macrosiphum euphorbiae Thomas, and Myzus persicae Sulzer; the western flower thrips (Frankliniella occidentalis Pergande), and the false chinch bug (Nysius raphanus Howard). These are all considered to be pests of cultivated tomato plants. Spiders were the most prevalent arthropod predator group recovered from foliage samples. All monitored arthropods, except spiders, were most abundant in tomato plants grown over the conventional, bare soil surface, and least abundant (P < 0.05) in plants grown over the silver plastic mulch. Spider numbers were highest in plant foliage over the biological mulch. Other arthropods commonly found on tomato plants in the SJV, including leafhoppers, whiteflies, various caterpillars, and predaceous taxa, were not commonly nor consistently encountered. This was likely due to the early-season timeframe of these studies. Similarly, foliar virus disease symptoms, which were originally targeted for monitoring, were virtually nonexistent. The only arthropod pest species encountered which consistently caused economically important damage to tomato fruit was N. raphanus. In both experiments, tomato fruits grown over the reflective plastic mulch had significantly less (69.5% and 39.7%, respectively) damage due to this pest than those over bare soil. The biological mulch gave inconsistent, intermediate damage reductions. Results from these two field studies showed that reflective plastic bed mulch suppressed populations of a variety of tomato canopy-associated arthropod taxa in early-season plantings, as compared to conventional, bare-soil beds. The biological bed mulch results were more inconsistent, but gave indications that killed cover crop residues, as well as the light-reflective plastic, may be of value in integrated pest management programs for fresh-market tomato production.  相似文献   

17.
In a mature Vitis labrusca L. “Niagara” vineyard, we compared an airblast sprayer and an air-assisted rotary atomizer (AARA) low-volume sprayer for coverage of grape clusters and control of grape berry moth, Paralobesia viteana. In addition, the effect of spray volume on control of fungal diseases was evaluated using the fungicides ziram and azoxystrobin applied with an airblast sprayer. For evaluation of coverage, sprayers applied kaolin clay at 28 kg/ha to grapevines while operating at low, medium and high water volumes. Kaolin residues on grape clusters were analyzed to compare the total amount of spray material deposited, percent of fruit surface covered, number of deposits, size of deposits and distance between deposits. There were no significant differences between sprayers or water volumes in the total amount of kaolin deposited on clusters, but the percent surface coverage was much greater on outside-facing berry surfaces (facing the sprayer) than inside-facing surfaces (facing the rachis). On the outside-facing berry surfaces, the airblast sprayer at 468 L/ha of water (medium volume) provided the highest percent coverage, the greatest density of deposits, the largest deposit diameter, and the smallest distance between deposits. On the inside-facing berry surfaces, the same sprayer–volume combination provided the highest percent coverage and greatest deposit diameter, but deposits from the airblast sprayer operating at 935 L/ha (high volume) had the smallest distance between deposits. No significant differences between sprayers or among water volumes were detected in the deposit density on the inside-facing berry surfaces. Bioassays of grape clusters sprayed with fenpropathrin or methoxyfenozide using the airblast or AARA sprayers at two water volumes revealed the greatest fruit protection from P. viteana at the higher volume for the airblast sprayer, but at the lower volume for the AARA sprayer. Spray volume of the airblast sprayer also affected disease control by the protectant fungicide ziram more than by the systemic fungicide azoxystrobin, with 468 L/ha providing better control than 187 L/ha. However, for most diseases, fungicide type was more influential than spray volume in determining the disease control outcome. The results of this study emphasize the need for appropriate water volumes relative to the sprayer and pesticide being used to optimize pest and disease control in juice grape vineyards.  相似文献   

18.
Telone C-35, a commercial formulation of 1,3-dichloropropene (1,3-D) and chloropicrin (CP), is one of the potential replacements to methyl bromide (MB) for soil fumigation. A laboratory dose–response study and two field trials in tomato were conducted to evaluate their weed control efficacy and their effect on tomato yield. Laboratory studies found that the seeds of Digitaria chinensis were the most sensitive to soil fumigation with Telone C-35, followed by Eleusina indica, Portulaca oleracea and Stellaria media with the LC50 values between 3.35 and 11.68 mg kg−1 soil. Field trials revealed that Telone C-35 applied to the field at 327, 243 and 164 L ha−1 could suppress the percentage of germination weed seeds while maintaining high tomato marketable yields, with no significant differences between MB + CP and the higher two Telone C-35 rates. The yield data from both seasons indicated that all Telone C-35 treatments had a positive effect on tomato yield; there was a 32%–62% increase the mean marketable tomato yield. Our results indicated that Telone C-35 was an excellent MB alternative and could provide acceptable weed control efficacy. Based on our results, Telone C-35, in combination with other alternatives to MB, is recommended to achieve integrated pest management.  相似文献   

19.
The equilibrium moisture content of agricultural products is necessary to optimize drying process and helps to keep the quality of the product during the period of storage. The main aim of this research was to find the best model which could define well, the exchange of moisture between alfalfa (Medicago sativa) and the surrounding air. The desorption isotherms of alfalfa (stem and leaf) were determined separately by using the saturated salt solutions method at three temperatures (25, 50 and 70 °C) within a range of 5-90% relative humidity. Experimental curves of desorption isotherms were fitted to modified equations of Henderson, Halsey, Oswin and Chung-Pfost as well as the GAB model and then evaluated visually by using residual plots and also by some statistical error parameters. The modified Halsey model was found to be the most suitable for describing the relationship between equilibrium moisture content, relative humidity and temperature.  相似文献   

20.
Attractants and pheromones are commonly used in integrated pest management programs in crop systems. However, pheromone dispensers employed in monitoring traps and lure and kill devices are not usually well studied and attractants are released at uncontrolled rates leading to low treatment efficacies and misleading monitoring estimations. Fruit flies are pests of economic importance and monitoring is essential in order to program insecticidal treatments. Moreover, lure and kill techniques are being increasingly used, but the cost of these techniques depends on the number of required traps and, therefore, on the efficacy of the attractants. Ceratitis capitata and Bactrocera oleae are the two main fruit flies in Mediterranean countries, and the effect of different doses of trimedlure and spiroacetal on fly attraction has been studied. Results showed that a release rate over 1.28 mg/day of spiroacetal reduces B. oleae attraction and emission values over 2.4 mg of trimedlure per day did not increase C. capitata catches. Under the environmental conditions of our study, an optimum release rate for pheromone attraction in B. oleae was determined. Emission values over this optimum level reduced B. oleae attraction. However, when a parapheromone was used with C. capitata, a fruit fly of the same family, the optimum emission value was not found and higher quantities of parapheromone attracted the same number of flies. The saturation effect of high concentrations of pheromone and parapheromone is discussed.  相似文献   

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