جستجوی مقالات مرتبط با کلیدواژه « قارچکش » در نشریات گروه « گیاهپزشکی »

Due to the process of quality control of agricultural products and accurate assessment of pesticide residues in products exported to destination countries, the application of biological control has become essential. In order to use biological control, biological agents must either be purchased from countries with the technology of mass production of natural enemies, or to meet the needs of the country, the technology of mass production of predators and parasitoids must be developed. In the case of mass rearing of predatory mites, which are mostly used to control spider mite, the problem of mass prodaction has been partially resolved and some companies are rearing, but in mass rearing of these predators, destructive effects on non-target natural enemies and mold growth on the rearing media of predatory mites are problematic. The predatory mite, Amblyseius swirskii (Athias-Henriot) is one of the most common biological agents for control of two-spotted mite, whitefly and onion thrips in greenhouses, which is widely used in greenhouse crops worldwide. The importance of this study is to facilitate the mass production of this predatory mite. In mass production of this predator, a medium with eggs, nymphal stages, and mature mites of Carpoglyphus lactis Linnaeus was used at 25 ± 1 ° C, 70 ± 5% RH and L: D 16: 8. One of the most important limitation in the production of this predator is infection with some fungi such as Rhizopus spp., Aspergillus spp,and Penicillium spp., which caused the deterioration of the medium and consequently the death of dried fruit mites and predatory mites in the production environment.
To investigate the efficacy of five componds on fungal control, an experiment was achieved with twelve treatments in a completely  randomized design in three replication. From the culture medium (800 g of elm flour, 195 g of wheat bran and 5 g of palm pollen) plus 1g/kg of compounds: tebuconazole, baking soda (sodium bicarbonate), Caliban® (potassium bicarbonate), Chitosan®, and carbendazim and in treatments where two compounds were mixed, 0.5 g/kg was used.
The analysis of variance for the treatments revealed significant differences in fungal infection reduction and the population dynamics of the mites. The treatments that showed the highest reduction in fungal infection compared to the control were treatments 1 (tebuconazole®), 3 (Caliban®), and 6 (Trichocara®), with reductions of 66.33%, 63.25%, and 28.62%, respectively.
In terms of the population increase of the prey mite C. lactis, the treatments that exhibited the highest increases were treatments 1 (tebuconazole®), 10 (Chitosan = tebuconazole), and 6 (Trichocara®), with population increases of 80.22%, 65.75%, and 65.15%, respectively.
Regarding the population increase of the predatory mite A. swirskii, the treatments that showed the highest increases were treatments 1 (tebuconazole®) and 6 (Trichocara®), with population increases of 76.33% and 72.66%, respectively, in the first group. In the second group, treatments 3 (Caliban®), 2 (soda), and 10 (Chitosan + tebuconazole) exhibited population increases of 56.33%, 54.66%, and 53.66%, respectively.
These results demonstrate the effectiveness of treatments 1 (tebuconazole®) and 6 (Trichocara®) in reducing fungal infection and promoting the population growth of both prey and predatory mites. Treatments 3 (Caliban®), 10 (Chitosan = tebuconazole), and 2 (soda) also showed positive effects on the population dynamics of the mites.
The predator mite population of A. swirskii is able to complete its growth on growth substrates with prey mite C. lactis. This predator has a high potential in feeding on dry fruit mite C. lactis. Therefore, this bait can be a suitable food for the mass production of A. swirskii mites. The most important problem in rearing large numbers of predatory mites is saprophytic fungi, which cause the destruction of a large number of predatory mites and their prey due to their sudden expansion. In general, according to the results of our study, the use of tebuconazole fungicide at a rate of one per thousand of commercial material and also the biological compound of Trichocara® (Trichoderma virens) with a concentration of one per thousand are recommended to control saprophytic fungi in mass production environment of predatory mite,A. swirskii,. Each of these two compounds has its advantages and disadvantages. In terms of availability, tabuconazole is more readily accessible compared to Trichocara®, which is a biological compound and considered more environmentally safe. However, Trichocara® may darken the color of the culture medium slightly due to the growth of Trichoderma virens in the medium. Considering the economic aspect and cost reduction in mass production of predatory mites, baking soda and Caliban®, which were part of the second group of effective treatments, offer economic value and are much cheaper than other compounds. They can effectively reduce the severity of fungal infections at minimal cost. Among the different compounds tested, the use of tebuconazole fungicide at a rate of one gram per thousand grams of substrate showed the most significant effect in controlling fungi. Although sodium bicarbonate and potassium bicarbonate were found to be less effective, they are still viable options due to their non-toxic nature.

Tomato (Solanum lycopersicum L.) belongs to the Solanaceae family and is economically one of the most important vegetable crops in Iran after the potato, cultivated all year but threatened by a large number of plant pathogens. One of the most significant diseases affecting this plant is tomato early blight, caused by various species of Alternaria. To date, chemical fungicides have been the only effective method of controlling this disease. Given the damaging effects of chemical pesticides on human and environmental health, as well as food safety, this study aimed to compare the inhibitory effects of savory, garlic, thyme, fennel, and rosemary essential oils on tomato early blight disease to that of a fungicide, Mancozeb+Metalaxy, under laboratory and greenhouse conditions.

Plant essential oils were extracted using a Clevenger apparatus and, after dehydration, utilized at 50, 150, and 250 μL/L concentrations by mixing with cultural media in Petri dishes. The growth inhibitory effect of plant essential oils was assessed by measuring the fungal colony’s growth diameter and calculating the amount of Minimum Inhibitory Concentration (MIC) and Minimum Fungicidal Concentration (MFC) associated with each essential oil. Moreover, the effect of plant essential oils on tomato early blight control was evaluated at a 750 μL/L concentration by spraying tomato plants with 3 to 5 leaves under greenhouse conditions. A chemical mixture containing Mancozeb and Metalaxyl was used as a positive control to compare its antifungal effects versus plant essential oils.

Statistical analysis using Duncan’s multiple-range test revealed a significant difference in all treatments at the 5 percent level. A. alternata growth diameter measurements showed that the lowest colony growth diameter was associated with 250 μL/L of savory essential oil with 100% inhibition. At a concentration of 50 μL/L, rosemary essential oil inhibited fungus growth by 6.35%, resulting in the highest average growth diameter. Accordingly, among the studied essential oils, savory exhibited the strongest inhibitory effect, while rosemary yielded the weakest. However, MFC determination revealed that garlic essential oil demonstrated the highest fungicidal properties and the lowest amount of MFC (700 μL/L). On the other hand, fennel essential oil yielded the highest amount of MFC (2000 μL/L). In general, all essential oils were able to deteriorate and disrupt the structure and morphology of A. alternata mycelium, leading to sedimentation and granulation of cytoplasmic contents and its organelles. This fungus showed the least and most sporulation in the savory and rosemary treatments, respectively, compared to the control. In greenhouse studies, unlike laboratory tests, the highest control rate of tomato early blight was related to the application of a fungicide with an average leaf surface contamination of 1.6%, which demonstrated the highest control rate in greenhouse conditions compared to other essential oil treatments. Compared to the infected control, savory essential oil and rosemary essential oil, with disease severity of 16.66% and 35.0%, respectively, had the greatest effect on the appearance of symptoms following fungicide application.

Numerous plant compounds have been studied for their antifungal and antibacterial properties thus far. Using the antifungal effect of plant essential oils is undoubtedly one of the newest techniques for controlling plant pathogens. The current study compares plant essential oils to a chemical fungicide for controlling tomato early blight in vitro and under greenhouse conditions and demonstrates that plant essential oils are more effective than chemical fungicides. Consistent with this finding, previous research has demonstrated the potential of plant essential oils to control early blight in tomatoes.

Blight disease caused by Mycosphaerella rabiei is the major constraint for chickpea production worldwide. Pathogenicity of pathogen and the analysis of its genetic diversity in pathogen population are necessary for management of the disease. Different strategies such as seed treatment, application of resistant cultivars, adjustment sowing date and integration of resistant genotype with post-infection application of fungicides have been recommended to reduce the losses caused by the disease. The use of resistant cultivars is the best management strategy to minimize yield losses due to blight. But because of the considerable variation in pathogenicity of the fungal population and partial resistance in germplasm of chickpea the effectiveness of resistant cultivars is limited. Different aspects of the biology, pathogenic and genetic diversity, resistance inheritance and the management options are discussed in this paper.

Nesidiocoris tenuis Reuter (Hemiptera: Miridae) is a zoophytophagous mirid known as a potential biological control agent of whiteflies and Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae). This predator is widely used in integrated pest management programs in greenhouses. In this study, side effects of four pesticides including pymetrozin, abamectin chlorantraniliprole, mancozeb and iprodion carbendazim on survival and number of offspring N. tenuis were evaluated. Adults of predators exposed to the pesticides through residual and oral routes simultaneously. None of the pesticides except abamectin chlorantraniliprole cause significant mortality on predator but all of them were affected the number of offspring. The highest reduction in fertility was related to abamectin chlorantraniliprole (92.5%). Iprodion carbendazim (43.22%), pymetrozin (37.44%) and mancozeb (17.14%) were next in rank, respectively. Toxicity of pesticides was calculated based on the reduction coefficient, Ex. According to IOBC classification abamectin chlorantraniliprole was moderately harmful, pymetrozin and iprodion carbendazim were slightly harmful and mancozeb was harmless.

The Colorado potato beetle (CPB) is the most important pest of potato. Adults and larvae feeding on potato leaves cause economically damage to host. Since this pest overwinters as adults in soil, any disturbance in assimilation and storage of the energy resources may weaken the overwintering adults and lessen their resistance to environmental stresses during the winter. In this research, effects of sublethal concentrations of Chlorothalonil 72% SC were studied on lipid, carbohydrate and protein contents in CPB adults under field conditions. The experiments had a complete randomized four-factor factorial design. The four factors were the concentration (0, 2000, 3000 and 4000 μl/l), sex (male and female), time (3, 6 and 12 day) and number of treatment (first and second). The sugar, glycogen and lipid quantities were determined in milligram per gram of fresh weight. Results showed that Chlorothalonil affected significantly the lipids, glycogens, sugars, proteins and caloric content (p<0.01). The most reductions in bioenergetic resources were observed in adults retreated with the concentration of 3000 μl/l 12 days after second Spraying. After taking into account the control, %61.07, %21.58, %57.22 and %54.46 reduction were found in lipid, glycogen, sugar and energy content, respectively. Also in concentration of 3000 μl/l protein increased as much as 39.94%. So the chlorthalonil reduced the outcome of energy in CPB.

Esca of grapevine is a serious and injurious disease in grape-growing all over the world، for which no effective control exists. The presented research، in two separate experiments، thirteen fungicides (benomyl، thiophanate-methyl thiram، mancozeb، fosetyl-Al، metalaxyl mancozeb، caboxin thiram، ortiva، topas، penconazole، tebuconazole، propiconazole، sodium arsenate، agri-fos) were evaluated for their in vitro effects on conidial germination and mycelia growth of Phaeoacremonium iranianum (Phi)، Phaeomoniella chlamydospora (Pch) and Fomoitiporia mediterranea (Fmed)، the most causal agents of esca diseases of grapevine in north Khorassan province. Those experiments were tested in a completely randomized design with factorial arrangement and three replications. For each fungicides eight concentrations (0،0. 1،0. 2،1،2،3،10،100) were assessed. The different fungicides were added to MEA in order to achieve the experimental concentrations. Mycelial plugs of each pathogen were transferred to the center of the fungicide amended plates. After 10 days، the daily growth rate relative to the unamended control was estimated. The results showed that sodium arsenate was found to be the most effective fungicide in inhibiting the colony growth of three associated fungi of esca followed by carboxin thiram and benomyl against Fmed and two other pathogens respectively. Meanwhile Agri-fos and ortiva were less effective. Additionally، Conidial suspensions (5x105 conidia ml-1) of both pathogens Pch and Phi were exposed to 3ppm concentration of the different fungicides. After 24 hours، the percent conidia germination relative to the control treatment was assessed. Sodium arsenate (87. 51%) and thiophanate-methyle thiram (85. 93%) were highly effective on suppression spore germination. Meanwhile Agri-fos (20. 55%) showed less performance in reducing spore germination of two pathogens.

Thirty seven isolates of Erysiphe necator were collected from different vineyards from three regions and nine cities of Khorasan Razavi province within two time periods i. e. May to June and August to September 2009. Their resistance to azoxystrobin + difenconazole (Ortiva®) fungicide as well as cross resistance to penconazole and hexaconazole fungicides registered in Iran for the control of powdery mildew was investigated. A leaf disk bioassay was carried out to determine the resistance of powdery mildew isolates on the basis of EC50 values derived from log-logistic dose-response curves. These subcultures were analyzed for resistance to azoxystrobin + difenconazole. The mean EC50 values of azoxystrobin + difenconazole on E. necator subcultures from vineyards was 0. 279 mg L-1. The highest and the lowest EC50 values were found in Mashhad (0. 622 mg L-1) and Khalilabad (0. 143 mg L-1)، respectively. Frequency distributions were skewed most toward higher resistance to azoxystrobin + difenconazole. The present study demonstrated a steady and significant increase in EC50 values for azoxystrobin + difenconazole during the growing season after multiple applications. Also، there was no cross resistance (P> 0. 05) among fungicides.