Efficacy Of Fungicides For Control Research Articles

Efficacy of fungicides for control of powdery mildew on grapevines in Chott Sidi Abdel Salam oasis, southeastern Tunisia

Grapevine is an important fruit crop grown in the Chott Sidi Abdel Salam oasis in south eastern Tunisia. It provides great economic potential for the oasis population due to its higher yield and monetary returns. It, also, has a good nutritional value and is consumed fresh or in dried form. Powdery mildew represents one of the most destructive diseases affecting viticulture, especially in temperate-humid climate. It is an economically important fungal disease in the grapevine farms. This pathogen is able to differentially attack leaves and grapes, and is currently controlled with repeated applications of fungicides. This research aimed to use chemical control in order to assess the ability of contact, systemic and the combination of both routes of fungicides’ administration, at three different sampling moments to manage powdery mildew infestation of grapevines (Cv. Bazzoul Kalba), under field conditions. The experiments were conducted in the oasis of Chott Sidi Abdel Salam in southeastern Tunisia. Both Pristine WG and Vectra 10 SC allowed controlling the disease intensity of powdery mildew compared to Talendo® showing a highly significant augmentation of the inhibitory growth potential (84.26% and 88.94%, respectively at 21 days after the first fungicide application) and the protective potential (73.11% and 76.92%, respectively at 21 day). This information can be used to help grapevines growers to improve powdery mildew control and enhance marketable yields.

Evaluating the efficacy of fungicides for wheat scab control by combined image processing technologies

Wheat scab, a major disease in wheat worldwide, is primarily controlled by fungicide application. Traditional methods used to evaluate fungicide efficacy are involved with manual counting of infected wheat heads in the field, which is time-consuming and laborious, and requires professional knowledge. This study developed a new method that could automatically and effectively assess the efficacy of fungicides in the field. Unet++ network and Fuzzy C-Means algorithm combined with R-G method (subtracting the green band from the red band in each image) were used to segment whole wheat ears and associated diseased areas, respectively. Proposed convolutional neural network (CNN) and connected domain method were then used to count all wheat ears and diseased wheat ears, respectively. The disease incidence of wheat ear groups was graded and the efficacy of five fungicides was evaluated. The results of these analyses show that the efficacy of all the five different fungicides was predicted accurately. The errors between predicted and measured levels of diseased wheat ears are less than 5%. The new method developed here can effectively assess the efficacy of fungicides for control of wheat scab under field conditions.

Evaluating the efficacy of potential fungicide-adjuvant combinations for control of myrtle rust in New Zealand

Myrtle rust is a serious fungal disease caused by Austropuccinia psidii affecting a number of Myrtaceae species in New Zealand and elsewhere. Control with fungicides or biologicals provides a mechanism to reduce the build-up of inoculum in the short-term while other strategies are being developed or deployed for long-term management. This study evaluated the efficacy of fungicides for control of myrtle rust under controlled conditions and identified adjuvants that would promote spreading of fungicidal active ingredients across the leaf surface. The spread of fungicide on detached M. excelsa leaves was assessed by applying three different adjuvants in combination with seven fungicides. Subsequently, M. excelsa plants were treated with three fungicides/mixes, (azoxystrobin + epoxiconazole, triademinol or a natural tea-extract) at a single rate followed by inoculation with A. psidii urediniospores on day 0, 7, 14 or 21 days after spraying. The response to infection in M. excelsa plants based on different inoculation timings at days 0, 7 and 21 significantly differed among fungicide treatments. The fungicide azoxystrobin + epoxiconazole was the most effective with infections significantly lower on the adaxial leaf surface than abaxial, despite good surface coverage of fungicide being achieved on both leaf surfaces. There were significant differences among fungicides based on the proportion of infected leaves on M. excelsa plants. Day 21 post-spray inoculation indicated a significant interaction between inoculation time and fungicide on leaf disease ratings. However, this was not the case at either 28 or 35 days post-inoculation. This research contributes to fungicide options for myrtle rust control in New Zealand.

Evaluation of Efficacy of Fungicides for Control of Wheat Fusarium Head Blight Based on Digital Imaging

Fusarium head blight (FHB) is one of the most important diseases in wheat worldwide. Evaluation and identification of effective fungicides are essential for control of FHB. However, traditional methods based on the manual disease severity assessment to evaluate the efficacy of fungicides are time-consuming and laborsome. In this study, we developed a new method to rapidly assess the severity of FHB and evaluate the efficacy of fungicide application programs. Enhanced red-green-green (RGG) images were processed from acquired raw red-green-blue (RGB) images of wheat ear samples; the images were transformed in color spaces through K-means clustering for rough segmentation of wheat ears; a random forest classifier was used with features of color, texture, geometry and vegetation index for fine segmentation of disease spots in wheat ears; a newly proposed width mutation counting algorithm was used to count wheat ears; and the disease severity of the wheat ears groups was graded and the efficacy of six fungicides was evaluated. The results show that the segmentation algorithm could segment wheat ears from a complex field background. And the counting algorithm could effectively solve the problem of wheat ear adhesion and occlusion. The average counting accuracy of all and diseased wheat ears were 93.00% and 92.64%, respectively, with the coefficients of determination (R 2 ) of 0.90 and 0.98, and the root mean square error (RMSE) of 10.56 and 7.52, respectively. The new method could accurately assess the diseased levels of wheat eat groups infected by FHB and determine the efficacy of the six fungicides evaluated. The results demonstrate a potential of using digital imaging technology to evaluate and identify effective fungicides for control of the FHB disease in wheat and other crop diseases.

Efficacy of fungicides for control of rosette and fruit diseases of ‘Kiowa’ and ‘Chickasaw’ erect blackberries grown in the southeastern United States

Efficacy of fungicides for control of rosette and fruit diseases of ‘Kiowa’ and ‘Chickasaw’ erect blackberries grown in the southeastern United States

Mowing Frequency and Plant Growth Regulator Effects on Dollar Spot Severity and on Duration of Dollar Spot Control by Fungicides.

Management of dollar spot (incited by Sclerotinia homoeocarpa) on golf course fairways is increasingly challenging. The objectives of this study were to determine the influence of mowing frequency and plant growth regulators (PGRs) on dollar spot severity and on the residual efficacy of fungicides for control of dollar spot. Two 4-month-long studies were conducted on 'Putter' creeping bentgrass (Agrostis stolonifera) maintained as a fairway at the University of Connecticut. Treatments were arranged in a three-by-three-by-five factorial that assessed the influence of mowing frequency (2, 4, or 6 days week-1) and PGRs (paclobutrazol, trinexapac-ethyl, or none) on dollar spot control by five fungicide treatments (boscalid, chlorothalonil, iprodione, propiconazole, or none). Turf was mowed in the afternoon hours to minimize the confounding effect of mowing frequency on leaf wetness duration. Treatments were initiated in the late spring of 2007 and 2008, and each fungicide treatment was reapplied only when dollar spot exceeded a threshold of five infection centers plot-1. In the absence of fungicides, dollar spot severity was reduced by 63 to 90% in plots treated with paclobutrazol and by 13 to 55% in plots treated with trinexapac-ethyl. Dollar spot severity was 23 to 50% lower in plots mown 2 days week-1 compared with those mown 6 days week-1. In cases where a significant interaction was observed between mowing frequency and PGRs, dollar spot was reduced on most rating dates in plots treated with trinexapacethyl that were mown 2 days week-1 compared with those mown 6 days week-1. Survival analysis of days until threshold was met revealed that duration of control of fungicides in plots receiving paclobutrazol were 28 to 84% longer compared with plots not receiving PGR. Duration of control by fungicides was generally similar between plots treated with trinexapac-ethyl and no PGR. In general, mowing frequency did not influence duration of control. Results from this study indicate that paclobutrazol could be used to increase the treatment interval of fungicides and that mowing frequency in the absence of dew is likely to have little influence on fungicide residual efficacy. When used without fungicides, PGRs and less frequent mowing may reduce dollar spot in situations where fungicide use is limited.

Efficacy and effects on yield of different fungicides for control of wet bubble disease of mushroom caused by the mycoparasite Mycogone perniciosa

Carbendazim, iprodione, prochloraz-Mn, thiabendazole and thiophanate-methyl were tested in vitro and in vivo for their effect on Mycogone perniciosa, the mycoparasite that causes wet bubble disease of white button mushroom. In vitro experiments showed that prochloraz-Mn (ED 50 = 0.006–0.064 μg ml −1) and carbendazim (ED 50 = 0.031–0.097 μg ml −1) were the most effective fungicides for inhibiting the mycelial growth of M. perniciosa, while iprodione (ED 50 = 1.90–3.80 μg ml −1) was the least effective. The resistance factors calculated for the five fungicides were between 1.4 and 2. The results obtained suggest that there is very little risk that M. perniciosa will develop resistance to the fungicides assayed. The in vivo efficacy of fungicides for control of wet bubble was studied in two mushroom cropping experiments, which were artificially infected with two doses of M. perniciosa, 10 6 and 10 7 spores m −2, respectively. There was, in the low dose inoculum experiment, a very high degree of effectiveness (96.5–100.0%) with all the fungicides assayed. However, iprodione performed poorly (20.5–24.4%) compared with the other fungicides (88.7–100.0%) in the high concentration inoculum experiment. The most effective treatments for controlling wet bubble did not improve the biological efficiency of Agaricus bisporus.

Comparison of the effectiveness of standard and drift-reducing nozzles for control of some winter wheat diseases

Field experiments were conducted over three consecutive growing seasons (20042–2006) to determine the effect of use of drift-reducing nozzles (ISO 03 code) on biological efficacy of fungicides for control of winter wheat diseases and their effect on grain yield. Four drift-reducing flat fan nozzles (VMD 270–440 μm) were compared with three standard nozzles (VMD 170–210 μm) at 300 l ha−1 spray volume. Commercial fungicide mixtures based on 12 different active substances were applied twice a season (BBCH 36–38 and 61–63). When controlling powdery mildew (Blumeria graminis) and wheat brown rust (Puccinia recondita) differences in efficacy of fungicides applied by standard or drift-reducing nozzles were small and mostly non-significant. The differences noticed at control of leaf blotch (Septoria tritici) depended a lot on the combination of growing season and fungicides applied. No general rule could be made regarding to the efficacy of fungicides for control of septoria leaf blotch. The greatest differences were observed by control of fusarium head blight (Fusarium spp.) and septoria glume blotch (Septoria nodorum) where the decrease (5–15%) of fungicide efficacy was determined when using drift-reducing nozzles. Decrease of biological efficacy of fungicides due to the use of drift-reducing nozzles however did not have a significant effect on the grain yield in most of the fungicide programs. According to our results the use of drift-reducing nozzles could be recommended without limitations to wheat producers applying wheat production systems similar to those in our experiment.

Efficacy of Fungicides for Control of Sclerotinia Stem Rot of Canola.

Sclerotinia stem rot (SSR), incited by Sclerotinia sclerotiorum, causes yield reductions to canola (Brassica napus) grown in North Dakota and Minnesota. Field trials were conducted in North Dakota and Minnesota from 2000 to 2004 to evaluate the effect of foliar fungicides on SSR and canola yield. Levels of SSR varied among years and location. In general, fungicides that consistently reduced SSR incidence compared with an untreated control were azoxystrobin, benomyl, boscalid, iprodione, prothioconazole, tebuconazole, thiophanate-methyl, trifloxystrobin, and vinclozolin. Significant reductions in SSR incidence with fungicides did not always translate into differences in canola yield, however. Inconsistent results were observed with different timings of applications based on percent bloom. This indicates that application timing should be based on factors in addition to percent bloom.

Residual Efficacy of Fungicides for Control of Dollar Spot on Creeping Bentgrass.

The duration of effective concentrations of fungicides for control of dollar spot on creeping bentgrass fairways was investigated using a bioassay technique. In each of three runs of the experiment, fungicide treatments were applied once to turf in replicated field plots; then, the plots were sampled periodically over 3 weeks by removing turf plugs from the field. The sampled plugs were placed in incubation containers and inoculated with sections from a 4-day-old colony of Sclerotinia homoeocarpa growing on potato dextrose agar. After a 96-h incubation period, the extent of pathogen growth on the turf plugs was measured. Results described a precipitous decline in effective concentration for all fungicide treatments beginning 7 to 10 days after application. The fungicides were only marginally effective at 14 days after application, and none provided any disease suppression at 21 days after application. The efficacy half-life (EHL) associated with four of the fungicides (chlorothalonil, iprodione, propiconazole, and thiophanate methyl) was estimated with two models. EHL estimates ranged from 6.1 to 15.2 days depending on the fungicide and the model. This research contributes to our knowledge of the duration of effective fungicide concentrations on creeping bentgrass and can provide insight for scheduling fungicide sprays for golf course fairways.

Influence of Wheat Cultivar, Species of Fusarium, and Isolate Aggressiveness on the Efficacy of Fungicides for Control of Fusarium Head Blight.

Attempts to control Fusarium head blight (FHB) with fungicides have been highly variable. Variability is caused by cultivar resistance, fungicide efficacy, fungicide coverage, timing, and pathogen aggressiveness. In this research, fungicides were tested on winter wheat cultivars with different levels of resistance to FHB using different isolates of Fusarium graminearum and F. culmorum to evaluate the role of host resistance and isolate aggressiveness on severity of FHB. Fungicides were applied to groups of wheat heads to provide full coverage. Incidence and severity of FHB was measured by the severity of head symptoms, percentage of Fusarium-damaged kernels (FDK), yield loss, and deoxynivalenol (DON) contamination. Development of FHB was affected by fungicides, cultivars, fungal isolates, and most of the two-way interactions of these variables. Among the fungicides tested, those containing tebuconazole tended to be more effective in reducing FHB. Reduction of disease in susceptible cultivars may not be adequate to produce marketable yields under conditions of high disease pressure. In most cases, if a fungicide reduced FHB visual symptoms, similar decreases were detected in yield loss, DON concentration, and FDK reaction. In 1998, an increase in DON contamination compared with the Fusarium check was observed with azoxystrobin and carbendazim on the more susceptible cultivar. This increase in DON with some fungicide requires additional research. Research to develop more resistant cultivars, better spraying technology, and more effective fungicides is also needed.

Efficacy of fungicides for control of rice tungro disease

Tungro is considered an important disease of rice in Southeast Asia and in the southeastern states of India. Tungro virus disease can be managed through vector control (Bae and Pathak 1969, Shukla and Anjaneyulu 1980, Satapathy and Anjaneyulu 1984). Dubey (1980) reported that Bavistin, a fungicide, was effective in controlling leaf crinkle virus of urdbean. This prompted us to test fungicides for the therapeutic recovery of tungro on rice. We tested 12 fungicides (three granular, three EC formulations, and six wettable powders) under net-house conditions for therapeutic recovery of plants that were previously infected with tungro disease. One-month-old Jaya seedlings were planted in four rows of 10 seedlings per tray. Ten seedlings were healthy and 10 seedlings each of three replications were inoculated with three viruliferous hoppers per seedling in galvanized iron-mesh cages. The top of the cage was covered with muslin cloth and tightened with a rubber band. After symptoms were expressed (about 10–12 d after inoculation), each tray was sprayed with the fungicide at recommended doses at weekly intervals. Five such sprays were given. Virus quantification and symptomatology before the treatments showed a yellow color of the youngest leaf, which is a typical tungro symptom. After treatment with effective fungicides, the yellow color gradually fades away and the plant is able to recover. Two trays were not sprayed with fungicide (each tray has 20 healthy seedlings and 20 inoculated seedlings) and these served as a control. The height of the plants and number of tillers were observed and plant yield determined.

Efficacy of Fungicides for Control of Entomosporium Leaf and Berry Spot of Saskatoon.

Studies were conducted to identify non-phytotoxic fungicides that would effectively control Entomosporium leaf and berry spot of saskatoon. Of 13 fungicides tested, benomyl, imazalil, myclobutanil, propiconazole, and thiophanate-methyl completely restricted in vitro radial growth of a monoconidial Entomosporium mespili isolate. Chlorothalonil, imazalil, propiconazole, and thiophanate-methyl completely inhibited conidiospore germination in vitro at 1 ppm a.i., the lowest concentration tested. In 1995, chlorothalonil and propiconazole provided the best control of Entomosporium leaf and berry spot at three orchard test sites in Alberta, Canada, while benomyl was also effective at two of these sites. Multiple applications of chlorothalonil (970 g ha-1) and propiconazole (125 g ha-1) effectively reduced disease severity at two of three test sites in 1996.

Abstracts, The Canadian Phytopathological Society, Annual Meeting, Saskatoon, Saskatchewan, June 1996

Abstracts, The Canadian Phytopathological Society, Annual Meeting, Saskatoon, Saskatchewan, June 1996

Factors affecting the efficacy of post‐harvest fungicide applications for the control of blue mould (Penicillium expansum) in stored apples

The effects of apple fruit maturity, temperature of fruit or dip solution, period of time in fungicidal dip, storage conditions, and spore inoculum concentration, on the efficacy of fungicides for control of blue mould (Penicillium expansum) were examined in various experiments.Iprodione and imazalil were only effective when inoculum concentration was low, whilst prochloraz was highly effective in controlling rot on fruit inoculated with 3 × 106 spores/ml. There was no consistent effect of dip temperature or fruit maturity on the efficacy of the fungicides. Iprodione was more effective on warm fruit (19°C) than cold fruit (6°C) whilst the reverse was true of imazalil. Extended periods of immersion in the fungicides slightly reduced the incidence of rotting but not to any useful degree.The incidence of rotting in fruit treated with prochloraz and etaconazole was less in fruit stored under controlled‐atmosphere cold storage conditions than in fruit stored in air cold‐storage. Both fungicides were also effective for short‐term storage at 20 C in air. Captan, benomyl, captan plus benomyl or vinclozolin were either ineffective or of poor efficacy under all storage conditions.

Effect of environment on efficacy of seed-treatment fungicides for control of common bunt in spring and winter wheat

The effectiveness of protectant and systemic seed-treatment fungicides for control of common bunt caused by Tilletia caries (DC.) Tul. and T. foetida (Wallr.) Liro. in spring and winter wheats was evaluated at different locations from 1981 to 1987. The fungicides, tested at two rates (I and II), were of three types: (1) fungicides which were effective in all years and locations at levels approaching 100%; (2) fungicides which provided uniform bunt control in all years and locations at levels less than 100%, and (3) fungicides which were sensitive to environmental conditions within years and locations. Fungicides which were effective in all years and locations at levels approaching 100% were triadimenol II, myclobutanil I and II, diniconazole I and II, and flutriafol II, on spring wheat, and etaconazole and furmecyclox in the seed-(SD), and seed- and soil- (SS) inoculation treatments, and triadimenol in the SD-inoculation treatment on winter wheat. Fungicides which provided uniform bunt control in all years and locations at levels less than 100% included flutriafol I and triadimenol I in spring wheat, applied at rates below optimal, and carboxin dust and nuarimol on winter wheat, in SS- and SD-inoculation treatments. Fungicides which were sensitive to environmental conditions within years and location included maneb, carboxin I and II on spring wheat, and carboxin solution and dust in the SD- and SS-inoculation treatments on winter wheat. Comparisons of bunt levels in fungicide treatments with those in the infested controls revealed that some fungicides did not perform consistently across years and locations. Variation in efficacy of fungicides was classified into three types: (1) random environmental variation which occurred with all fungicide treatments tested; (2) non-random environmental variation which occurred with maneb and carboxin fungicides, and (3) variation attributed to increasing bunt severity which occurred with the SS and SD carboxin fungicides used to control bunt in winter wheat. The implications of inadequate protection from currently registered seed-treatment fungicides on wheat varieties that are highly susceptible to bunt are discussed.

Resistance of African Violet to Powdery Mildew and Efficacy of Fungicides for Control of the Disease

Resistance of African Violet to Powdery Mildew and Efficacy of Fungicides for Control of the Disease

Efficacy of Fungicides for Control of Phytophthora Leaf Blight of Taro

Efficacy of Fungicides for Control of Phytophthora Leaf Blight of Taro

Título en español.

En este trabajo se presentan datos en relación con la eficacia de los nuevos fungicidas para combatir el tizón tempranero (Alternaria solani) y el tizón tardío (Phytophthora infestans) respectivamente, que atacan a las papas (Solarium tuberosum) en Puerto Rico.