Side Effects Of Fungicides Research Articles

Effect of L-cysteine treatment to induce postharvest disease resistance of Monilinia fructicola in plum fruits and the possible mechanisms involved

Plum is an important stone fruit in China, but the fruit is easily perishable and susceptible to infection by pathogens. Traditionally, synthetic fungicides are used to control diseases. However, the side effects of fungicides should not be ignored. Cysteine, generally recognized as safe (GRAS) amino acid, has been reported to play roles in the plant abiotic stress response, but little is known about the role of cysteine to control postharvest diseases in fruits. Therefore, this study was designed to investigate the effect of L-cysteine treatment on control of postharvest brown rot in artificially inoculated plum fruits and the possible biocontrol mechanisms involved. Postharvest plum fruits were inoculated with 1, 10, 100 and 1000 mg L−1 L-cysteine. 100 mg L−1 L-cysteine treatment effectively controlled brown rot in artificially inoculated plum fruits by inducing resistance. Furthermore, 100 mg L−1 L-cysteine treatment increased the activities of glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH), enhanced the content of NADPH of the pentose phosphate pathway, as well as improved the contents of H2O2 and some amino acids in the artificially inoculated plum fruits. 100 mg L−1 L-cysteine treatment also elevated the antioxidant content (AsA, GSH) and the antioxidant enzymes activities (APX, GR, MDAR, DHAR) of the ascorbate-glutathione (AsA-GSH) pathway. The protective effects of L-cysteine treatment on postharvest plum fruits likely be due to activating some defense-related responses of the fruit against infection. L-cysteine treatment is a safe promising method for controlling postharvest brown rot in plum fruits.

Screening antagonistic yeasts against citrus green mold and the possible biocontrol mechanisms of Pichia galeiformis (BAF03).

Penicillium digitatum is one of the most important pathogens causing citrus green mold, leading to significant economic losses. Traditionally, synthetic fungicides are used to control diseases. However, the side effects of fungicides should not be ignored. Thus, antagonistic yeasts were proposed to be safe and effective alternatives for managing diseases. Orchards are excellent sources of naturally occurring antagonists against pathogens. Therefore, in the present study, antagonistic yeasts obtained from orchards were screened, and the possible biocontrol mechanisms of the most promising yeast were investigated. Seventy-eight isolates of yeasts (15 species of 10 genera) were obtained from citrus orchards. In in vitro assays, 16 strains showed antifungal activity against Pichia digitatum and 15 strains showed biocontrol potential against green mold on Olinda oranges. Pichia galeiformis (BAF03) exhibited the best antagonistic activity against P. digitatum during 6 days storage at 25 °C and a good antagonistic activity during 29 days at 4 °C. Pichia galeiformis (BAF03) could colonize and amplify quickly in wounded citrus. Scanning electron microscopy results showed that the citrus wound was colonised by the yeast. A total of eight volatile organic compounds (VOCs) were identified by gas chromatography-mass spectrometry The VOCs produced by P. galeiformis (BAF03) efficiently inhibited P. digitatum. Pichia galeiformis (BAF03) isolated from a citrus orchard showed potential to control postharvest green mold of citrus. The possible mechanisms of action likely include competition for space and nutrients as well as production of VOCs.

Side effects of fungicides and insecticides on entomopathogenic fungi in vitro

Abstract Products based on different strains of entomopathogenic fungi are now being used in Integrated Pest Management (IPM) programs. Compatibility studies of chemical and biological control agents are necessary to be able to give proper recommendations for their integrated use. The effect of three insecticides based on imidacloprid, spinosad and abamectin, and three fungicides based on chlorothalonil, azoxystrobin and thiophanate-methyl on the activity of the following entomopathogenic fungi: Metarhizium anisopliae (Metschn.) sensu lato, Beauveria bassiana (Bals.-Criv.) Vuill., Acremonium sp. was tested under laboratory conditions. Tests of the influence of the pesticides on growth and production of conidia were performed. From this study, we concluded that all tested insecticides can be applied together with fungus B. bassiana products in IPM programs. They even stimulate sporulation of this fungus at the recommended dose, 0.5 of the recommended dose and 1.5 times the recommended dose. In the case of fungicides we observed inhibition of growth and sporulation of B. bassiana and reduction of growth and sporulation of other species of fungi.

Side effects of fungicides and insecticides on predatory mites, in laboratory conditions

Abstract Experiments were carried out on the toxicity of selected insecticides and fungicides to the predatory mites species: Amblyseius swirskii, A. andersoni, and Phytoseiulus persimilis. Among the tested active substances: abamectin, hexytiazox, and spinosad were safe to the predators. The mortality level of the tested predator was comparable to the control treatment, seven days after application. The percentage values of these predatory mites’ mortality caused by these insecticides, applied at one and a half of the recommended dose did not exceed a low toxicity – 25% (referring to International Organisation for Biological and Integrated Control (IOBC) classification on the toxicity to beneficial organisms). The results of the tests revealed that imidaclopryd, lambda-cyhalothrin, and fenpyroksymat were highly toxic to the predatory mites. It was found that toxicity of fungicides to the tested predatory mite species depended on the date of the chemical treatment and the date the predators were introduced. The fungicide Topsin M 500 SC – thiophanate-methyl, appeared to be selective to the species A. swirskii and it could be used in the Integrated Pest Management (IPM) programs for greenhouse grown crops.

Side effects of fungicides on the abundance and the species diversity of the natural populations of Drosophila and their hymenopterous parasitoids in orchards

Within entomophagous insects, hymenopterous parasitoids are important regulators of natural populations of insects including pests. Pesticide treatments are largely used in orchards for economic reasons. These treatments allow for greater productivity, but they may also impact upon non-target insect populations. Drosophila and their hymenopterous parasitoids are abundant in orchards and are not direct targets of pesticide treatments. In this work, natural populations of Drosophila and their parasitoids were monitored from June to November, and their abundance was reported from two types of orchards. One type was under conventional pesticide treatments, mostly fungicides (“Treated plot”), and the other was under low-input treatments (“Low-input plot”). Five Drosophila species and five parasitoid species were present in both types of orchards. A time effect on abundance was found with two peaks of abundance, one in August and the other in autumn (October), corresponding to a fluctuation of numbers depending on the availability of resources. When comparing insect abundance between the two types of plots, the abundance in the Treated plot was found to be lower than or equal to that in the Low-input plot. Furthermore, a significant decrease in the abundance of two scarce parasitoid species (Leptopilina heterotoma and Asobara tabida) that could lead to their disappearance was also observed. The results are discussed in the context of the diverse lethal and sub-lethal effects of pesticides on the development and reproduction of natural populations of insects and their importance as natural enemies.

Side effects of some fungicides on phytoseiid mites (Acari, Phytoseiidae) in north‐Italian vineyards

AbstractThe effects of fungicides containing mancozeb or copper oxychloride, as principal active ingredients, on phytoseiid mites were investigated in a vineyard comprising four varieties (Prosecco, Cabernet Franc, Pinot gris and Merlot) and located in north‐eastern Italy. Phytoseiid colonisation was different among the four varieties: Amblyseius andersoni and Kampimodromus aberrans were dominant on Pinot gris and Merlot, respectively, while Typhlodromus pyri was more common than the above species on Prosecco and Cabernet Franc. Applications of mancozeb fungicides significantly affected K. aberrans populations. Concerning T. pyri, a significant effect was observed on Cabernet but not on Prosecco. The effects of mancozeb fungicides on A. andersoni were less clear. The response of phytoseiids to fungicides containing mancozeb appeared to be mediated by the variety. Therefore, the choice of one or two varieties as a standard reference for field tests is recommended. These results also suggest that the side effects of fungicides on predatory mites should be studied on different phytoseiid species and, possibly, on susceptible and resistant strains in order to gain useful insights.

Effects of the fungicides benomyl, captan and chlorothalonil on soil microbial activity and nitrogen dynamics in laboratory incubations

The use of fungicides in agriculture, to protect plants from soil-borne pathogens, is a common practice. However, there is a dearth of information on the side-effects of fungicides on key soil ecological processes. We investigated the effects of three fungicides, benomyl, captan and chlorothalonil, on soil microbial activity (substrate-induced respiration and dehydrogenase activity), and nitrogen dynamics (NH 4–N and NO 3–N) in two laboratory experiments, one with captan and chlorothalonil and another with captan. In each laboratory batch incubation, soil was treated with a fungicide at approximately recommended field application rates (benomyl, 51 mg a.i. kg −1, captan,125 mg a.i. kg −1 and chlorothalonil, 37 mg a.i. kg −1) and incubated at 30°C for 8 weeks. Some soils were amended with either ground alfalfa leaves or ground wheat straw to provide additional substrates for soil microorganisms and to alter rates of nitrogen mineralization/immobilization. All three fungicides suppressed the peak soil respiration in unamended soil by 30–50%, but the three fungicides had different effects in the amended soils. Soil dehydrogenase activity was stimulated by benomyl (18–21%) and chlorothalonil (8–15%) except in the alfalfa amended soil, but was decreased by captan (40–58%) in both the straw-amended and unamended soils. The fungicide-treated soils in general had less microbial biomass N concentrations than the untreated soils. Captan-treated soils had much higher NH 4 N concentrations than the control soils, with or without the organic amendments. Benomyl and chlorothalonil had little influence on soil NH 4 N concentrations. Net N mineralization and nitrification rates were influenced by all fungicide treatments as well as by the addition of organic materials. N mineralization rates were significantly higher in captan-treated soils than in untreated soils. N dynamics were influenced by chlorothalonil in a similar pattern to captan but reached peak nitrification rates earlier (day 7), in the alfalfa-amended soil. The effects of the three fungicides on soil microbial activity and nitrogen dynamics depended on the quality of the organic materials added to the soil. The patterns of effects of the fungicides on soil nutrient cycling processes were not large and were specific to each fungicide. Captan appeared to have more pronounced overall effects on soil microbial activity and nitrogen dynamics than either benomyl or chlorothalonil.

Possible side effects of fungicides on banana and coffee diseases.

EXPERIENCE suggests that excessive application of fungicidal sprays to crops has not had as many undesirable biological side effects as the excessive application of insecticides. Nor has there been much evidence, at least at the level of field application, of acquired resistance to fungicides1.