Mancozeb Treatments Research Articles

Effects of pyraclostrobin rotations and tank-mixtures on Cercospora beticola sensitivity and Cercospora leaf spot control in sugarbeet

Sugarbeet production supplies approximately 50–60% of domestic sugar in the United States. One of the most economically important foliar diseases of sugarbeet is Cercospora leaf spot (CLS), caused by Cercospora beticola. Fungicide resistance is a major concern due to the frequent applications needed to control multiple infection cycles each season and the reliance on single-site fungicides. Reduced C. beticola sensitivity to multiple fungicide groups, including the quinone outside inhibitors (QoIs) has been observed. The QoI fungicide Headline (23.6% pyraclostrobin) was exceptionally effective in controlling CLS until high levels of reduced sensitivity stabilized in C. beticola populations. This study aimed to test application programs to minimize C. beticola pyraclostrobin resistance development and maximize CLS management. Rotation (high- and low-risk) and tank-mixture programs integrating pyraclostrobin (Headline™) with mancozeb (a multi-site fungicide) treatments were evaluated in 2019 and 2020 field studies. For all Headline programs, distributions of C. beticola pyraclostrobin sensitivities were not significantly different from each other but differed from the non-treated control (P < 0.05). In 2020, a significant increase in the percentage of isolates with half-maximal effective pyraclostrobin concentrations ≥5 μg/ml was noted in all Headline treatments (P < 0.05), even where a single application of Headline alone was used. Furthermore, no additional CLS control, yield, or sugar benefits from Headline were observed when compared to grower standard programs without Headline (P > 0.05). In conclusion, pyraclostrobin-based products used in chemical rotations or tank-mixtures were not more beneficial than lower-risk programs despite their historical CLS control efficacy.

Fungicide tolerance of antagonists in the management of mango anthracnose caused by &lt;i&gt;Colletotrichum gloeosporoides&lt;/i&gt;

In the present study, fungicide tolerance of antagonists (yeast and Lactobacillus) with two fungicides viz., Mancozeb and Ridomil gold were conducted using turbidometric method. Findings of study revealed that, ridomil and mancozeb treatments could inhibit the growth of yeasts and Lactobacillus to some extent but did not completely inhibit. In this study, it was found that potential yeast and Lactobacillus antagonists were tolerant to both mancozeb and ridomil fungicides up to 2000 ppm concentrations. This result implies that the antagonistic yeast and Lactobacillus isolates were not adversely affected by both mancozeb and ridomil fungicides. So, these isolates can form an important component of Integrated disease management of mango anthracnose.

Efficacy and Induction Resistance of Neem Extract and Mancozeb 80 Wp on Physoderma Brown Spot and Physoderma Stalk Rot Diseases of Corn (Zea mays) caused by Physoderma Maydis in Far North Cameroon

Corn (Zea mays) is one of the most widely spread cereals in the world. However, in the Far North Region of Cameroon, the incidence of some maize diseases progress because of farming practices and climate change (rainfall). This work aims to evaluate effect and resistance stimulation of neem extract and Mancozeb fungicide on Brown Spot (PBS) and Stalk Rot (PSR) diseases of corn due to Physoderma maydis in field condition. The experimental design was a two-factor split-plot. The treatments were a combination of Control (T), Mancozeb (Mz) at the concentration of 6g/L and aqueous extract of neem seeds (AENS) at the concentration of 50g/L with CMS 9015 and CMS 8704 varieties. Incidence, severity, rainfall, Area Under Disease Progress Curve (AUIPC, AUSiPC) were recorded. Phenol and protein rates, enzymatic activity of Polyphenol oxidase (PPO), peroxidase (POX) and glucanase were carried out. Stalk length and yield were evaluated. Incidence and severity of Physoderma Brown Spot (PBS) and Physoderma Stalk Rot (PSR) increased with time and environmental conditions (rainfall). The highest disease incidence was observed in the control treatments with both diseases, 52.39 and 37.67 % respectively for Brown Spot and Stalk Rot in CMS8704 variety and lower with AENS, 13.5 and 36.01%. AENS reduced PBS incidence and severity by 23.1 and 19.9 %, respectively and Mz by 9.3 and 18.1 %. The AUIPC and AUSiPC of PBS and PSR remained lower with AENS treatment during the growing season and higher with the other treatments. The highest phenol and proteins rates (8.81 and 25.1 mg/g/FM) were recorded for the AENS treatment in CMS9015 and CMS8704 variety, respectively. Enzymatic activity was more enhanced in CMS8704 variety with AENS. 4.22 A470/min/g, 1.55 A470/min/g and 1.15 µmole/min /g were recorded respectively for PPO, POX, and Glucane activities. Stalk length was higher in AENS and Mancozeb treatments with variety CMS8704 (125.13 and 123 cm respectively). A yield increase of 7.44% was obtained in the AENS treatment. The combination or not of aqueous neem extract and CMS8704 could be used in the integrated control of PBS and PSR of maize

Functional Impairment of Bovine Spermatozoa by Fungicide Mancozeb: an in vitro Exposure Study

Agrochemicals have been identified as endocrine disruptors affecting many bodily functions of animals, especially the fertility of males. Evidence of various agrochemicals affecting male reproductive functions are plenty. However, evidence on disruptive effects of fungicides on sperm functions is scarce. Therefore, an in vitro study was conducted to investigate acute effects of the fungicide Mancozeb on spermatozoa functions using a bovine spermatozoa model. Semen samples were obtained from fertility proven Jersey bulls and were exposed to series of Mancozeb concentrations (0.01 μg/ml to 10 μg/ml), and the changes occurred in sperm motility parameters, acrosine proteolytic activity and acrosome integrity were assessed at different time intervals. Pure and commercial forms of Mancozeb were in the study, and sperm motility parameters were measured using computer assisted sperm analysis (CASA). Mancozeb concentration of 1 μg/ml with 2 hours exposure significantly (p≤0.05) reduced the total sperm motility and the sperm progressive motility. Velocity parameters like average path, straight line, curvy linear and amplitude lateral head displacement were significantly (p≤0.05) reduced after 2 hours in both pure and commercial Mancozeb treatments of 1 μg/ml. However, the beat cross frequency and elongation of the sperm were significantly (p≤0.05) reduced only with commercial Mancozeb. Further, the acrosome integrity and proteolytic activity of the acrosome enzymes were significantly (p≤0.05) compromised by both Mancozeb treatments. The study revealed that Mancozeb (&gt;1 ug/ml) could reduce the sperm motility and impairment of acrosome activity significantly. Nevertheless, commercial Mancozeb formulation has the highest impact on the sperm functions. Thus, Mancozeb may affect the fertilization capacity of the spermatozoa under acute exposure.

The fungicide Mancozeb induces metacaspase-dependent apoptotic cell death in Saccharomyces cerevisiae BY4741.

Mancozeb (MZ), a mixture of ethylene-bis-dithiocarbamate manganese and zinc salts, is one of the most widely used fungicides in agriculture. Toxicologic studies in mammals and mammalian cells indicate that this fungicide can cause neurological and cytological disorders, putatively associated with pro-oxidant and apoptotic effects. Yeast adaptation to sub-inhibitory concentrations of MZ has been correlated with oxidative response, proteins degradation, and energy metabolism, and its main effect on yeast has been attributed to its high reactivity with thiol groups in proteins. Herein, we show that acute MZ treatments on aerobic exponentially growing yeast of wild type (BY4741) and deletion mutant strains, coupled with multiplex flow cytometry analysis, conclusively demonstrated that MZ displays the typical features of pro-oxidant activity on Saccharomyces, elevating mitochondrial ROS, and causing hyper-polarization of mitochondrial membranes leading to apoptosis. A drastic reduction of cellular viability associated with the maintenance of cell membrane integrity, as well as phosphatidyl serine externalization on yeast cells exposed to MZ, also supports an apoptotic mode of action. Moreover, abrogation of the apoptotic response in yca1 deficient mutants indicates that metacaspase-1 is involved in the programmed cell death mechanism induced by MZ in yeast.

Evaluation of tomato early blight management using reduced application rates and frequencies of fungicide applications

Field experiments were carried out to evaluate the effect of reduced rates and application intervals of the fungicides mancozeb and azoxystrobin on disease control of tomato early blight. In the spring–summer season, all fungicide treatments were significantly better than the untreated control in reducing disease severity. However, early blight disease severity was not significantly different between the two fungicides, azoxystrobin and mancozeb, treatments, nor was it different among treatment schedules within each fungicide. In the summer–fall experiment, results demonstrated significant differences between mancozeb and azoxystrobin treatments in reduction of early blight disease severity. Early blight disease severity was not significantly different among different treatments of mancozeb. However, all azoxystrobin treatments demonstrated significantly lower early blight severity than mancozeb treatments. Results suggest that lower doses of mancozeb, than currently used, can provide acceptable disease control compared to the non-treated control. In addition, results suggest that application of azoxystrobin might be beneficial in reducing disease severity under high disease pressure.

English

Late blight incited by Phytophthora infestans is a destructive disease of tomato worldwide. The plant growth-promoting antagonists, which elicit induced systemic resistance (ISR) and enhance plant growth, are being used as safe alternatives to synthetic fungicides for the management of plant diseases. In this study, a combination of Trichoderma harzianum OTPB3 and Bacillus subtilis OTPB1 and Pseudomonas putida OPf1 alone were evaluated for induction of systemic resistance in tomato against P. infestans in comparison with fungicides and growth promotion. Seed treatment with fresh suspensions of a combination of T. harzianum OTPB3 and B. subtilis OTPB1 caused significant increase in growth parameters compared to P. putida OPf1, mancozeb and untreated control due to higher production of indole-3-acetic acid (IAA) and gibberellic acid (GA3). Reduction in the incidence of late blight was positively linked to increase of phenylalanine ammonia lyase, peroxidase, polyphenol oxidase and β-1,3-glucanase, the defense-related enzymes in tomato seedlings treated with microbial consortium of OTPB3 and OTPB1 followed by foliar spray of P. putida OPf1. The effects were on par with fenamidone and mancozeb treatments. The results reveal that seed treatment with microbial consortium containing T. harzianum OTPB3 and B. subtilis OTPB1 and foliar spray of P. putida OPf1 have practical significance in the management of late blight disease and also plant growth enhancement in tomato. Key words: Trichoderma harzianum, Bacillus subtilis, Pseudomonas putida, Phytophthora infestans, Growth promotion, late blight, Growth hormones, induction of systemic resistance.

Óleo essencial de alecrim no controle de doenças e na indução de resistência em videira

O objetivo deste trabalho foi determinar as características químicas do óleo essencial de alecrim e o seu efeito na produtividade, no controle da mancha da folha e do míldio, e na indução de resistência em videira 'Isabel'. O experimento foi realizado em vinhedo comercial, em dois ciclos consecutivos. Os tratamentos consistiram das doses do óleo essencial: 0, 500, 1.000, 2.000 e 4.000 µL L-1, além dos tratamentos Tween 80%, calda bordalesa, acibenzolar-S-metil e mancozebe. Foram avaliados a severidade da mancha da folha e do míldio, a atividade das enzimas quitinase e catalase, a massa e o número de cachos e as características químicas das uvas. Houve efeito quadrático das doses do óleo essencial de alecrim, para severidade da mancha da folha e do míldio da videira, nos dois ciclos, com resultados semelhantes aos dos tratamentos com calda bordalesa, acibenzolar-S-metil e mancozeb. Também houve aumento no número e na massa dos cachos, bem como na produtividade. O óleo essencial não interferiu nas características químicas das uvas. Observaram-se aumento na atividade da enzima quitinase e redução na atividade da catalase nas folhas. O óleo essencial nas doses de 500, 1.000 e 2.000 μL L-1 é uma alternativa para o controle de doenças da videira 'Isabel'.

Synergistic interaction of tea saponin with mancozeb against Pestalotiopsis theae

Tea gray blight, caused by the fungus Pestalotiopsis theae, is one of the most destructive diseases in tea plants. In this study, we evaluated the individual and synergistic antifungal activities of tea saponin (TS) and mancozeb against P. theae, as well as the mechanisms underlying their activity. The results indicated that TS significantly inhibited both the mycelial growth of P. theae, at an EC50 value of 1.03 mg mL−1, and its spore germination, at an EC50 value of 3.68 mg mL−1. TS also significantly enhanced the antifungal activity of mancozeb, and the cotoxicity factor (CTF) assays revealed that there was a synergistic interaction between TP and mancozeb (3:7) against mycelial growth and spore germination, with CTC values exceeding 100. Our results also revealed that TS and mancozeb treatments damaged the cell membranes of P. theae, leading to a significant leakage of soluble protein, reduction of sugar and induction of a significant increase of chitinase activity in the mycelial cells; the combination treatment significantly enhanced the observed damage, leakage and induction. These findings suggested that TS had antifungal activity and a synergistic effect with mancozeb and that the mechanism of this activity might be membrane damage and the consequent cytoplasm leakage.

Impact of Vineyard Pesticides on a Beneficial Arthropod, Typhlodromus pyri (Acari: Phytoseiidae), in Laboratory Bioassays

Laboratory bioassays were conducted to evaluate the effects of six vineyard pesticides on Typhlodromus pyri Scheuten (Acari: Phytoseiidae), a key predator of the mite Calepitrimerus vitis Nalepa (Acari: Eriophyoidae), in Pacific coastal vineyards. Materials tested were whey powder, 25% boscalid + 13% pyraclostrobin (Pristine), 40% myclobutanil (Rally), micronized sulfur (92% WP), 75% ethylene bisdithiocarbamate (mancozeb; Manzate), and 91.2% paraffinic oil (JMS Stylet), all applied at three concentrations. Pesticide dilutions were directly sprayed onto T. pyri adult females and juveniles, and each treatment was assessed to determine effects on direct mortality and fecundity. Five of the six pesticides tested resulted in < 50% mortality to adult and juvenile T. pyri for all concentrations 7 d after treatment. Paraffinic oil treatments displayed direct mortality > 50% for adult and juvenile assays and resulted in significantly higher mortality. Sublethal effects were more pronounced than acute pesticide toxicity, particularly in juvenile mite bioassays. Significant decreases in fecundity were detected in the sulfur and mancozeb treatments compared with the control in juvenile tests. The relative percentage of fecundity reduction for juvenile mites was highest when applying mancozeb (> 70%), sulfur (> 25%), or myclobutanil (> 20%). Adult mites displayed the greatest reductions in fecundity from applications of paraffinic oil (> 20%) or mancozeb (> 15%) treatments. Boscalid (+ pyraclostrobin) and whey displayed the least effect on fecundity across all bioassays. These results can be used to develop management guidelines in vineyard pest management practices to help conserve and enhance predatory mite populations.

Chemical control of guava rust (Puccinia psidii) in the Northern Region of Rio de Janeiro State, Brazil

Fungicides were evaluated under field conditions for their efficacy in the control of guava rust (Puccinia psidii); five systemic fungicides (azoxystrobin, pyraclostrobin, cyproconazole, tebuconazole, triadimenol) and the protectant mancozeb. In a first trial, the fungicides were applied at two-week intervals intercalated with bi-weekly sprays of copper oxychloride. The initial incidence of rust on flower buds before treatment was 47%. Triadimenol and azoxystrobin were most effective in reducing the incidence of rust on fruit. The minimum rust incidence achieved with triadimenol was 12% compared to 84% in the control treatment (water). The initial level of rust on flower buds was particularly high for the tebuconazole treatment, which may have contributed to the ineffective control by this fungicide in the first trial. In the second trial, copper oxychloride sprays were applied when disease incidence on flower buds was low (7%). Azoxystrobin, tebuconazole, triadimenol and mancozeb treatments were started nine days after a second application of copper oxychloride. The fungicides were then applied at bi-weekly intervals and at the same concentrations as in the first trial. Triadimenol was again most effective in controlling rust, although its effect did not greatly differ from that of tebuconazole. The maximum disease incidence in all fungicide treatments was significantly lower than that observed in the control treatment.

EVALUATION OF THE NANOSILVER COLLOIDAL SOLUTION IN COMPARISON WITH THE REGISTERED FUNGICIDE TO CONTROL GREENHOUSE CUCUMBER DOWNY MILDEW DISEASE IN THE NORTH OF IRAN

ISHS VI International Postharvest Symposium EVALUATION OF THE NANOSILVER COLLOIDAL SOLUTION IN COMPARISON WITH THE REGISTERED FUNGICIDE TO CONTROL GREENHOUSE CUCUMBER DOWNY MILDEW DISEASE IN THE NORTH OF IRAN

BROWN APICAL NECROSIS (BAN): A FUNGAL DISEASE CAUSING FRUIT DROP OF ENGLISH WALNUT

Apical necroses occurring at the stigmatic end of walnut fruit are quite common on Juglans regia. The typical and specific pathogens of this culture such as Xanthomonas arboricola pv. juglandis and Gnomonia leptostyla are both able to cause black spots at the fruit apex as well as all over the husk. Amidst the apical necroses, brown apical necrosis (BAN) is caused by ubiquitous and polyphagous fungi which produce brown to dark-brown spots exclusively at the blossom end of walnut fruit. The economic importance of this disease is related to fruit drop that can cause over 20% yield loss. The presence and the severity of BAN depend upon the occurrence of conducive cultural and environmental conditions promoting the dissemination and colonization of the fungal pathogens. Previous studies highlighted several fungi associated with BAN among which Alternaria and Fusarium are the main genera. As a result of ten-years of investigation, based on isolations from flowers, fruit, catkins and artificial inoculations, it is possible to identify the fungal genera/species involved in the disease and give a picture of BAN as a complex disease. Artificial inoculations performed in planta directly on flowers and fruit, confirmed that the fungi enter trough the style, which represents the key point for BAN occurrence. Though several Fusarium species are involved in causing the necrosis of the style, endocarp and kernel, depending on site and time, F. semitectum and F. graminearum are the most aggressive with a pioneer role. Among the small-spored catenulate taxa related to Alternaria alternata, which are the agents of inner rot, A. arborescens is the most represented and aggressive species. The efficacy of tebuconazole and/or mancozeb treatments against BAN, which were also registered against anthracnose, is a further confirmation that BAN is strictly caused by fungi.

Efficacy of fungicides and a systemic acquired resistance activator (acibenzolar- S-methyl) against tobacco blue mould

Tobacco blue mould, caused by Peronospora tabacina Adam ( Peronospora hyoscyami f. sp. tabacina Skalicky 1964) can be an economically devastating leaf spot disease in shade and broadleaf cigar wrapper tobacco ( Nicotiana tabacum L.) types grown in Connecticut and Massachusetts. We investigated the effects of dimethomorph plus mancozeb and azoxystrobin fungicides as well as acibenzolar- S-methyl, a systemic acquired resistance inducer, on disease severity over 2 years in both shade-grown and broadleaf tobaccos. All fungicide and fungicide plus acibenzolar- S-methyl treatments applied were effective in reducing the number of blue mould lesions per plant. Treatments containing acibenzolar- S-methyl were the most effective, resulting in almost complete control. Substituting two or three applications of acibenzolar- S-methyl at label rates for dimethomorph plus mancozeb treatments in a spray program increased blue mould control over the same number of dimethomorph plus mancozeb applications by 28–94 percent. The effects of acibenzolar- S-methyl application on cured leaf quality were determined in commercial shade tobacco fields in 2000 and 2001. Leaves were cured, processed and commercially evaluated for quality in a blind test. Standard fungicide applications of dimethomorph plus mancozeb applied on a 14-d interval were compared to three acibenzolar- S-methyl treatments. Economic value was not different between treatments in 2000, but acibenzolar- S-methyl applied at 10-d intervals was associated with reduced value in 2001 when plants were more subject to drought and heat stress.

Statistical study of the influence of fungicide treatments (mancozeb, zoxamide and copper oxychloride) on heavy metal concentrations in Sicilian red wine

The aim was to assess the influence of mancozeb, zoxamide and copper oxychloride fungicide treatments on Mn, Zn, Cu, Cd and Pb concentrations in Sicilian red wines, grapes, marcs and grape stalks. The experimentation was carried out over two crop years: 2003 and 2004. Trace metals analysis was performed by derivative stripping chronopotentiometry, which allowed detection of concentrations lower than 1 ng g−1. The data obtained gave evidence that the levels of Mn and Zn in wines from plots treated with zoxamide–mancozeb were about threefold higher than those observed in the control. Wines treated with Cu oxychloride had a significant increase in Cu(II) concentrations with respect to the control; in particular, samples from 2004 showed a 50% increase in Cu levels. Furthermore, as shown in a previous paper, the fungicides treatments studied led to a moderate increase in Pb(II) and Cd(II) levels in treated samples with respect to the control. Wines from 2004 had higher Cu and Pb amounts than wines from 2003; but the concentrations of all the other metals were similar. Statistical analysis of the data by linear discriminant analysis (LDA) and the Kruskal–Wallis test confirmed that both zoxamide–mancozeb treatments and copper oxychloride treatments exerted a significant influence on Mn(II), Zn(II) Cu(II), Pb(II) and Cd(II) concentrations in wines, grapes, marcs and grape stalks samples from both the studied vintages.

Lack of Effect of Stone Fruit Rust on Yield of French Prune Trees and Survival of Urediniospores of the Pathogen on Leaves, Shoots, and Buds

Two prune (Prunus domestica «French» orchards, one in Tulare County and one in Yuba County, California, were treated either two or three times in summer with mancozeb or sulfur or left untreated for 3 yr. Fresh and dry fruit weights per tree, number of dry prunes per kilogram, fresh to dry weight ratio, and percent soluble solids were determined each year. Significant differences in yield parameters were few, minor, and inconsistent. Preharvest defoliation did not occur in either orchard in any year, but postharvest leaf loss was faster and leaf infection greater in control and sulfur than in mancozeb treatments. The number of urediniospores on buds declined from November through February, and the number on 1- and 2-yr-old shoots declined from November through April

Controlling potato late blight with systemic-protectant fungicide combinations of metalaxyl and mancozeb

Disease development was monitored weekly in field plots inoculated withPhytophthora infestans and treated with metalaxyl, mancozeb or metalaxyl/ mancozeb combinations. Late blight pressure was moderate to severe in 1981 and 1983 and was slight to moderate in 1982 and 1984. In 1982–84 all treated plots had significantly less foliar damage and late blight tuber rot than untreated plots. Use of metalaxyl alone resulted in the greatest increase in disease (up to 80% defoliation) in the latter part of the growing season. Under slight to moderate disease pressure, metalaxyl/mancozeb and mancozeb treatments provided significantly better disease control than metalaxyl. Under moderate to severe disease pressure, high levels of disease (65% defoliation) occurred by the end of the season with mancozeb and metalzxyl/mancozeb on 7- and 14-day spray schedules, respectively. However, significantly better control (about 20% defoliation) was obtained during early season, rapidly developing epidemic conditions when only three applications of metalaxyl/mancozeb were included in a 7-day mancozeb spray program.