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1.
The synergistic effect of a range of ergosterol-biosynthesis-inhibiting (EBI) fungicides and a pyrethroid insecticide was studied in the honeybee (Apis mellifera L.). Various EBI fungicides were combined separately with the pyrethroid lambda-cyhalothrin at ratios derived from their recommended application rates to represent tank-mixing in the field. The mixture was then applied topically to the thorax of honeybees, and mortality assessed 24 h post-treatment. All the fungicides tested increased the toxicity of lambda-cyhalothrin to honeybees. The fungicide propiconazole was found to have the strongest synergistic effect, decreasing the LD50 of lambda-cyalothrin from 68.0 ng bee?1 to 4.2 ng, thus having a synergistic ratio of 16.2. Hazard ratios were calculated for lambda-cyhalothrin and fungicide mixtures using a recommended application rate of 7.5 g a.i. ha?1. The hazard ratio for lambda-cyhalothrin alone was 110, but when mixed with fungicide synergists, the hazard ratio ranged from 366 with flutriafol to 1786 with propiconazole. A blank formulation of a fungicide (without the active ingredient prochloraz) had little effect on the toxicity of lambda-cyhalothrin, indicating that it is primarily the fungicide active ingredient that is responsible for the synergistic effect. The results are discussed in terms of the potential hazard posed by pesticide synergism to honeybees in the field. 相似文献
2.
Laboratory studies on the formation of bound residues and on the degradation of the triazole fungicide propiconazole were conducted in two different soils. Soils treated with 14C-propiconazole were incubated at 22 degrees C and extracted exhaustively with a solvent at each sampling date until no further propiconazole was extracted. The solvent-extractable residues were used to measure propiconazole remaining in the soil, and the extracted soils were used to investigate bound residues of propiconazole. Mineralization of propiconazole was investigated by measuring [14C]carbon dioxide evolved from the soil samples. Formation of bound residues of propiconazole was higher in silty clay loam soil than in sandy loam soil, giving approximately 38 and 23% of the applied 14C, respectively. In contrast, the rates of degradation and mineralization of propiconazole were lower in silty clay loam soil than in sandy loam soil. Decreased extractability of the 14C residues with incubation time was observed with increased formation of bound residues. When the propiconazole remaining in the solvent-extractable residues was quantitatively measured by high-pressure liquid chromatographic analysis, the half-life value in sandy loam soil was about 315 days, while the half-life in silty clay loam soil exceeded the duration of the 1 year experimental period. Increased formation of bound residues was observed as propiconazole degraded with incubation time, suggesting that degradation products are involved in the formation of bound residues. Our study suggests that the formation of bound residues of propiconazole contributes to the persistence of this fungicide in soil. 相似文献
3.
ABSTRACT Gray leaf spot, caused by the fungus Cercospora zeae-maydis, causes considerable yield losses in hybrid maize grown in the north-central United States and elsewhere. Nonchemical management tactics have not adequately prevented these losses. The probability of profitably using fungicide application as a management tool for gray leaf spot was evaluated in 10 field experiments under conditions of natural inoculum in Iowa. Gray leaf spot severity in untreated control plots ranged from 2.6 to 72.8% for the ear leaf and from 3.0 to 7.7 (1 to 9 scale) for whole-plot ratings. In each experiment, fungicide applications with propiconazole or mancozeb significantly reduced gray leaf spot severity. Fungicide treatment significantly (P 相似文献
4.
E. Ann Slade Robert A. Fullerton Alison Stewart Harry Young 《Pest management science》1992,35(1):95-100
An enhanced rate of degradation of the dicarboximide fungicides iprodione and vinclozolin was induced in the laboratory in Patumahoe clay loam soil by adding three successive applications of fungicide. Enhanced degradation of the dicarboximide fungicide procymidone could not be induced. Following the first fungicide treatment, the time to 50% loss of iprodione was greater than 35 days; for vinclozolin the time to 50% loss was 22 days. The rate of degradation accelerated with successive applications until, after a third successive application of fungicide, the time to 50% loss of iprodione was only two days and none was detectable at seven days. For vinclozolin, after the third successive application of fungicide, 50% loss occurred after 35 days. By comparison, minimal loss of procymidone was detected after 35 days following each of two successive soil treatments. The induction of enhanced degradation of iprodione and vinclozolin in this soil in the laboratory may explain the observed loss of field control of onion white rot disease. Degradation of iprodione occurred in non-sterile soil but not in sterile soil, indicating that microbial involvement may be responsible for the degradation of iprodione and vinclozolin in soil. 相似文献
5.
In field and laboratory experiments, enhanced degradation of the dicarboximide fungicides, iprodione and vinclozolin, was stimulated by only one application of the fungicides in a soil with no previous history of any pesticide input. Field and laboratory studies demonstrated the ease of stimulation by pre-treatment with even very low concentrations of the fungicides (0·5 μg g−1 soil) and at a range of temperatures and soil moisture conditions. Soils that had acquired full enhanced degradation could rapidly degrade fungicide applied at 30 times the recommended field rate. Cross-enhancement of degradation was noted with both fungicides, but not with their common metabolite, 3,5-dichloroaniline. Application of the antibiotics chloramphenicol or rifampicin to soil reduced enhanced degradation to control levels; cycloheximide had no effect. This, together with the inhibitory action of azide, mercuric chloride and repetitive microwaving, indicated that the agent(s) of enhanced degradation was probably bacterial. 相似文献
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7.
ABSTRACT The fitness and the dynamics of demethylation inhibitor fungicide (DMI) sensitivity in isolates of Monilinia fructicola sensitive (no growth at 0.3 mg/liter propiconazole) and resistant (>/=50% relative growth at 0.3 mg/liter propiconazole) to propiconazole were investigated. Overall, there was no considerable compromise in the fitness of resistant isolates compared to sensitive isolates of M. fructicola at the time of collection. Resistant and sensitive isolates differed in their sensitivity to propiconazole (P < 0.001) and incubation period (P = 0.044), but not in latent period, growth rate, spore production, and spore germination frequency (P > 0.05). Consecutive transferring on potato dextrose agar had an impact on conidia production, conidial germination, and growth rate (P < 0.0001). Consecutive transferring also had an impact on propiconazole sensitivity in resistant isolates. In the resistant isolates, sensitivity to propiconazole increased (R(2) = 0.960, P = 0.0034) within the first eight transfers. Similarly, sensitivity to propiconazole increased by 273% over the course of 34 months in cold storage in propiconazole-resistant isolates. Our results show that propiconazole resistance is unstable in vitro and that standard subculturing and cold storage procedures impact propiconazole sensitivity of resistant isolates. The instability of propiconazole resistance in M. fructicola may have important implications for disease management in that a reversion to propiconazole sensitivity could potentially occur in the absence of DMI fungicide pressure in the field. 相似文献
8.
In a 2-year investigation, the dissipation of residues of the fungicide propiconazole from winter wheat straw and leaves was measured by periodic sampling of the green plant material from several plots that had been sprayed with ‘Tilt 2.50EC’ at three different rates. The fungicide deposits on straw and leaves at day 0 were approximately one-quarter of the dose applied on all treatment plots, and this fraction did not differ significantly between three dosage rates. The fungicide residues disappeared rapidly, and the half-life of the fungicide on straw and leaves was approximately 5 days. At harvest time, the fungicide residues in grain and soil were negligible, but the residues remaining on straw and leaves were considerable, especially at higher spraying rates than the recommended dosage. 相似文献
9.
Dolar Pak Ming Pei You Vincent Lanoiselet Martin J. Barbetti 《European journal of plant pathology / European Foundation for Plant Pathology》2017,148(2):247-259
Fungicides are the preferred rice blast (Pyricularia oryzae) control option by farmers. However, no fungicides are yet registered for this purpose in Australia. Hence, it is important to test the baseline sensitivity of P. oryzae isolates collected from blast-affected regions across northern Australia, which have not yet been exposed to the fungicides, as part of a resistance management strategy. Further, it is also important to investigate and compare effect of application timing of fungicides on conidial development, including germination and germ tube growth, and penetration on susceptible rice. The EC50 of a collection of fungicide-sensitive blast isolates were within the range of 0.02–2.02 and 0.06–1.91 mg L?1 for azoxystrobin and propiconazole, respectively. Azoxystrobin was shown to have greater inhibitory effect on conidial germination than propiconazole. In addition, for pre-inoculation application, only germ tubes in the presence of external nutrients continued to grow from 24 to 48 hpi. On susceptible seedlings, both fungicides completely controlled blast disease when applied the same day as inoculation. However, for pre- or post-inoculation application of fungicide, the extent of disease control was reduced, with azoxystrobin more efficacious than propiconazole. A stimulatory effect of both fungicides at low dose was observed on certain P. oryzae isolates. This is the first study to assess the baseline sensitivity of the P. oryzae population in Australia and the first to report a stimulatory effect of low azoxystrobin concentration on growth of P. oryzae. The study highlights, for the first time, the critical role of external nutrients in promoting germ tube growth under fungicide stress conditions. Lastly, it demonstrates the high degree of efficacy of the fungicides and their potential for future rice blast management in Australia. 相似文献
10.
秸秆还田及施肥对小麦复种油菜农田土壤呼吸的影响 总被引：2，自引：0，他引：2
在甘肃省石羊河绿洲灌区连续3 a的小麦复种油菜田间定位试验的基础上,采用EGM-4密闭式土壤呼吸测量系统,测定了不同施肥水平和不同秸秆还田方式下小麦复种油菜农田的土壤呼吸速率。结果表明：在整个观测期内, 土壤呼吸速率最高值出现在8月下旬（152.06~199.58 mg•m-2•h-1）,最低值出现在10月中旬（12.67~19.01 mg•m-2•h-1）。土壤呼吸速率日变化呈单峰曲线,最高值出现在12:00-14:00, 4:00左右达最低值;不同秸秆还田方式下, 高茬收割免耕播种油菜的处理明显降低了土壤呼吸速率,且在秸秆处理后的油菜生育期内降低效果更加明显;不同施肥水平下,在N、P减量15%的情况下,土壤呼吸速率显著下降;各试验处理措施下, 土壤呼吸速率与5 cm和10 cm土壤温度、30 cm各层土壤含水量均呈极显著正相关,并且土壤呼吸速率与0~30 cm土壤水分的相关性较土壤温度高;不同处理下土壤呼吸速率与土壤孔隙度基本上呈负相关,但是两者之间相关性并不显著。 相似文献
11.
Paul PA Madden LV Bradley CA Robertson AE Munkvold GP Shaner G Wise KA Malvick DK Allen TW Grybauskas A Vincelli P Esker P 《Phytopathology》2011,101(9):1122-1132
The use of foliar fungicides on field corn has increased greatly over the past 5 years in the United States in an attempt to increase yields, despite limited evidence that use of the fungicides is consistently profitable. To assess the value of using fungicides in grain corn production, random-effects meta-analyses were performed on results from foliar fungicide experiments conducted during 2002 to 2009 in 14 states across the United States to determine the mean yield response to the fungicides azoxystrobin, pyraclostrobin, propiconazole + trifloxystrobin, and propiconazole + azoxystrobin. For all fungicides, the yield difference between treated and nontreated plots was highly variable among studies. All four fungicides resulted in a significant mean yield increase relative to the nontreated plots (P < 0.05). Mean yield difference was highest for propiconazole + trifloxystrobin (390 kg/ha), followed by propiconazole + azoxystrobin (331 kg/ha) and pyraclostrobin (256 kg/ha), and lowest for azoxystrobin (230 kg/ha). Baseline yield (mean yield in the nontreated plots) had a significant effect on yield for propiconazole + azoxystrobin (P < 0.05), whereas baseline foliar disease severity (mean severity in the nontreated plots) significantly affected the yield response to pyraclostrobin, propiconazole + trifloxystrobin, and propiconazole + azoxystrobin but not to azoxystrobin. Mean yield difference was generally higher in the lowest yield and higher disease severity categories than in the highest yield and lower disease categories. The probability of failing to recover the fungicide application cost (p(loss)) also was estimated for a range of grain corn prices and application costs. At the 10-year average corn grain price of $0.12/kg ($2.97/bushel) and application costs of $40 to 95/ha, p(loss) for disease severity <5% was 0.55 to 0.98 for pyraclostrobin, 0.62 to 0.93 for propiconazole + trifloxystrobin, 0.58 to 0.89 for propiconazole + azoxystrobin, and 0.91 to 0.99 for azoxystrobin. When disease severity was >5%, the corresponding probabilities were 0.36 to 95, 0.25 to 0.69, 0.25 to 0.64, and 0.37 to 0.98 for the four fungicides. In conclusion, the high p(loss) values found in most scenarios suggest that the use of these foliar fungicides is unlikely to be profitable when foliar disease severity is low and yield expectation is high. 相似文献
12.
Studies on the effect of a pesticide spray sequence on the behaviour of terbutryn residues and on soil microbial activity. Part II. Influence on microbial activity In laboratory incubation experiments (at 10 and 20°C and 30 and 60% soil water-holding capacity) soil microbial activities (dehydrogenase, respiration after glucose amendment and nitrogen transformations) were scarcely affected by 20·9 and 28·0 mg kg?1, respectively, of terbutryn in two soils of different sorption properties. In contrast, dinosebacetate, alone or mixed with terbulryn, triadimefon or parathion, inhibited dehydrogenase activity and respiration even at a low rate of application (2·87 mg kg?1). Following application of a 10 times higher rate to a highly adsorbent soil there was an initial inhibition of nitrification followed by an enhanced rate of nitrogen mineralization. Triadimefon and parathion, alone and in combination with other pesticides, caused both stimulation and inhibition of microbial activity; the reason is not clear. The effects on dehydrogenase and respiration were confirmed in field experiments. Dehydrogenase activity was the most sensitive and so could be a useful test for the side-effects of pesticides on soil micro-organisms. Additional work on nitrogen transformations is needed to interpret the results. 相似文献
13.
依据鉴别浓度检测了中国不同地理来源的114株草坪草币斑病菌对甲基硫菌灵的敏感性,并采用菌丝生长速率法测定了供试菌株对异菌脲和丙环唑的敏感性。结果显示:对甲基硫菌灵敏感的菌株共98株,占总数的85.96%,抗性菌株16株,占总数的14.04%;在8个有甲基硫菌灵施药历史的采样点中,5个点检测到了抗性菌株。异菌脲和丙环唑对草坪草币斑病菌的EC50值分别在0.012 1~1.264 4和0.000 4~0.100 4 μg/mL之间,平均EC50值分别为（0.525 6 ± 0.207 7）和（0.015 2 ± 0.020 1）μg/mL,最大EC50值和最小EC50值分别相差104.7和251.0倍。敏感性频率分布结果显示,币斑病菌对异菌脲和丙环唑已出现敏感性下降的亚群体。与从未施过相关药剂地区的币斑病菌群体相比,分离自8个有施药历史地块的菌株群体对异菌脲的敏感性均显著降低,4个有施药历史地块的群体对丙环唑的敏感性显著降低。相关性分析显示,对丙环唑最不敏感的10株币斑病菌对异菌脲的敏感性均呈现下降趋势,且两者间存在一定的正相关关系（ρ = 0.755 4,P < 0.000 1）,推测这部分菌株可能存在多药抗药性。本研究结果可为杀菌剂的合理使用及币斑病的有效防治提供理论支持。 相似文献
14.
C. Abdul Jaleel 《Pesticide biochemistry and physiology》2008,90(2):135-139
An investigation was carried out to estimate the salt stress ameliorative effect of propiconazole (a triazole group of fungicide cum plant growth regulator) on the NaCl stressed Catharanthus roseus. The experiment was conducted in pots. All the pots were irrigated to the field capacity with ground water up to 30 days after sowing (DAS). The treatments were given as 80 mM NaCl, 80 mM NaCl + 20 mg l−1 propiconazole and 20 mg l−1 propiconazole alone on 30, 50 and 70 DAS. The samples were collected on 60 and 80 DAS. NaCl stress inhibited the root and stem length, total leaf area, fresh and dry weight, and antioxidant enzymes superoxide dismutase (SOD), peroxidase (POX) and polyphenol oxidase (PPO) activities. Plants treated with NaCl with propiconazole increased these parameters to a larger extent when compared to NaCl stressed plants. The propiconazole treatment increased the root length, fresh and dry weight, and SOD, POX and PPO activities, but decreased the stem length and leaf area when compared to control. The results showed that the propiconazole could significantly ameliorate the effect of NaCl stress in Catharanthus roseus. 相似文献
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16.
Tom Hsiang Lin Yang Wayne Barton 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(2):163-169
Isolates of Sclerotinia homoeocarpa were collected from across southern Ontario from areas where demethylation inhibiting fungicides reportedly had never been used. Forty of these isolates with propiconazole EC50 values ranging from 0.003 to 0.069 µg ml-1 were inoculated onto creeping bentgrass (Agrostis palustris) in summer 1995 and summer 1996 to assess virulence. Each isolate was grown on mixed cereal grains, dried, ground up and applied separately at a rate of 10 g m-2 to 0.25 m2 plots with three replicates per isolate. For both years, no spots were visible on the plots at time of inoculation; however, by the end of each experiment, there were up to 180 spots per plot with significant differences between isolates. Growth rate in culture was not significantly related to fungicide sensitivity (log-EC50 values). Statistically significant negative relationships were found in both years between AUDPC and log-EC50 values. These significant relationships imply that in the absence of propiconazole use, isolates that are more sensitive to propiconazole may out-compete isolates that are less sensitive. However, further study is required to determine the time frame for this to occur, and whether DMI-resistance prevention strategies can feasibly be based on the existence of resistance-related fitness costs. 相似文献
17.
Dissipation of the fungicide pencycuron was examined under controlled laboratory conditions in clay loam soils from rice cultivated fields of alluvial soil (Typic udifluvent) and coastal saline soil (Typic endoaquept) at field rate, twice the field rate and 10 times the field rate with and without decomposed cow manure maintained at 60% of maximum water-holding capacity (WHC) and waterlogged soil condition. The half-life values depended on the initial concentrations of pencycuron. Pencycuron, in general, degraded fastest in coastal saline soil and in soil amended with decomposed cow manure at 60% of maximum WHC of soil. 相似文献
18.
S. Pivonia Z. Gerstl A. Maduel R. Levita R. Cohen 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(2):201-209
Sudden wilt (vine decline) of melon caused by Monosporascus cannonballus is a problem in arid and semiarid regions worldwide. Preplanting soil disinfestation with methyl bromide, a common treatment
for disease management, has been banned in many countries, raising the need for alternative disease-control measures. Soil
fungicide application during the growing season is one possible treatment. Twelve fungicides were evaluated in vitro for M. cannonballus suppression, seven of those were evaluated under field conditions. The fungicides azoxistrobin, prochloraz and pyraclostrobin
+ boscalid exhibited high and similar efficacies in controlling sudden wilt disease under field conditions. Fludioxonil applied
at high rates was also effective but was phytotoxic. Fluazinam, the first fungicide found capable of suppressing sudden wilt
and one which has been used in Israel since 2000, was less effective. The results indicate that two applications of a fungicide
during the short fall season should be sufficient for effective control of the disease. In the long spring season, at least
three applications are needed to protect the melon crop. Melon fruits were examined for fungicide residues and only boscalid
residues were found. This fungicide was therefore limited to the first application before fruit set. 相似文献
19.
Three pesticides, dimethoate, pirimicarb and fenpropimorph, had a negative impact on the colonization of a sterilized soil by a natural population of soil protozoa. Fenpropimorph has an effect at the lowest concentration applied; 25 mg litre?1. Dimethoate reduced the soil respiration significantly for about 10 days after application. In single species cultures of soil protozoa in liquid media, a flagellate Cercomonas sp., was a better test organism than a ciliate, Colpoda sp., or an amoeba, Acanthamoeba sp., with respect to interpretation of dose-response curves and ease of observation. 相似文献
20.
The fate of fenpropimorph and its metabolite fenpropimorphic acid was investigated in a silty sand soil and in a clayey silt soil. In laboratory and field experiments fenpropimorph disappeared without a lag phase. A few days after application fenpropimorphic acid was detected. Additional laboratory experiments with [14C]fenpropimorph emphasized the significance of mineralization and the formation of non-extractable residues. The determination of soil/water distribution coefficients of parent compound and metabolite yielded a higher leaching potential for fenpropimorphic acid due to its higher polarity. This was confirmed by performing a laboratory column test under worst-case conditions. Under field conditions, however, fenpropimorphic acid was detected only in the superficial soil layers (0–5 cm) of both investigation sites at very low concentrations. 相似文献