Fungicides For Management Research Articles

Status of Alternaria leaf blight in cotton and its fungicidal management

Surveys were carried out in the three districts of North Gujarat, viz., Aravalli, Sabarkantha, and Banaskantha to investigate the severity of Alternaria leaf blight in cotton, The disease was found to be quite severe and with a mean PDI of 23.77, the Banaskantha district had the highest disease intensity of Alternaria leaf spot disease; in contrast, the average disease intensity in the Aravalli and Sabarkantha districts was 17.94 and 20.44 per cent, respectively. Further, to manage the disease, research was conducted to evaluate the in vitro and in planta bioefficacy of fungicides against Alternaria macrospora of cotton at the Department of Plant Pathology and Alternaria leaf blight in cotton at Agronomy Instructional farm, S D Agricultural University Sardarkrushinagar, Gujarat, respectively. Under in vitro condition, among five systemic fungicides, Carbendazim showed the highest per cent growth inhibition, while Propiconazole showed the lowest. Among different non-systemic fungicides, Mancozeb inhibited the radial growth of A. macrospora the most, while Chlorothalonil inhibited the least. Further, among five combined fungicides, Tebuconazole 50% + Trifloxistrobin 25 WG inhibited the most growth and Captan 70% + Hexaconazole 50 WP inhibited the least. Thereafter, the bio-efficacy of the two most effective fungicides from each group (two systemic, two non-systemic, and two combined fungicides) was tested under field conditions, and the mean disease intensity ranged from 12.28 to 36.43 per cent, with the lowest being Tebuconazole 50% + Trifloxystrobin 25 WG and the highest being untreated control. The highest percentage of illness control (66.29%).. KEYWORDS :Alternaria macrospora, cotton, fungicides

Economic analysis of crop protection strategies: comparing the value of increased fungicide inputs and crop genetic improvement in managing Ascochyta blight in Australian chickpeas.

Genetic improvement of crop varieties requires significant investment. Therefore, varieties must be developed to suit a broad range of breeding targets, such as yield and suitability to rainfall zones, farm management practices and quality traits. In the case of breeding for disease resistance, breeders need to consider the value of genetic improvement relative to other disease management strategies and the dynamics of pathogen genetic and phenotypic diversity. This study uses a benefit-cost analysis framework to assess the economic value of fungicide management and crop genetic improvement in disease resistance for Australian chickpea varieties. When assessing the likelihood of growers switching to new crop varieties with improved genetic resistance to disease, the simulation results reveal that adopting these varieties yielded higher net benefit values compared to implementing current fungicide strategies across all rainfall zones. On average, the increase in net benefit varied between 2.6% and 3.5%. Conversely, when we examined the scenario involving modifying the current fungicide strategy, we observed that, on average, switching from the current fungicide management strategy to one which involved additional fungicides was beneficial in about 73% of the cases. Our analysis reveals the importance of factors such as commodity prices, production costs, disease-related variables and risk aversion in determining the economic benefits of adopting new crop protection strategies. Furthermore, the research reveals the need for accessible information and reliable data sources when evaluating the benefits of new agricultural technologies. This would assist growers in making informed and sustainable disease management decisions. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Desempenho agronômico de genótipos de trigo em manejo de fungicidas

The aim of this work was to demonstrate the agronomic response of wheat genotypes to fungicide management. The experiment took place at Escola Fazenda of the Regional University of the Northwest of the State of Rio Grande do Sul, located in the municipality of Augusto Pestana, RS, Brazil. The experimental design used was randomized blocks, organized in a factorial scheme, with four fungicide managements (Management I: no application; Management II: one fungicide application; Management III: two fungicide applications and Management IV: three fungicide applications) x seven cultivars of wheat (TBIO Audaz, ORS Madre Pérola, BRS Bela Joia, TBIO Ponteiro, TBIO Trunfo, OR Agile, TBIO Toruk), in two replications. Three meters wide and five meters long formed the experimental units, totaling 15 m2 per plot. Evaluation of each plot, morphological and productive wheat traits. Use of Tukey's test at 5% probability for analysis of variance and linear correlation analysis to verify linear relationships between pairs of characters. Application of principal component analysis and euclidean distance to verify associations between treatments. The TBIO Trunfo cultivar enhances ear length with two fungicide applications. The management of fungicides did not influence the grain yield of wheat cultivars. The cultivars TBIO Trunfo and ORS Madre Pérola present the highest productive performance. Ear weight and number of grains per ear can select wheat cultivars with higher grain yield indirectly.

Kinetic and Mechanistic Modelling of Pyrimethanil Fungicide Adsorption onto Soils of Varying Physico-chemical Properties.

Pesticide transport in the environment is impacted by the kinetics of its adsorption onto soil. The adsorption kinetics of pyrimethanil was investigated in ten soil samples of varying physicochemical properties. The highest adsorption was in the soil having the maximum silt and CaCO3 contents, pH and electrical conductance but the lowest amorphous Fe oxides and CaCl2 extractable Mn. Pseudo-second order kinetics and intra-particle diffusion model best accounted the adsorption kinetics of pyrimethanil. The equilibrium adsorption estimated by pseudo-second order kinetics (q02) was significantly and positively correlated with CaCl2 extractable Cu content (r = 0.709) while rate coefficient (k02) had a negative correlation with crystalline iron oxides content (r = -0.675). The intra-particle diffusion coefficient (ki.d.) had inverse relationship with CaCl2 extractable Mn content in soils (r = -0.689). FTIR spectra showed a significant interaction of pyrimethanil with micronutrient cations. Adsorption kinetic parameters of pyrimethanil could be successfully predicted by soil properties. The findings may help to evolve fungicide management decisions.

Effects of reduced pesticide use on winter wheat production in the Canadian Prairies

Winter wheat (Triticum aestivum L.) is a highly competitive crop with the potential to enhance on-farm revenue and reduce reliance on crop protection inputs. The adoption of winter wheat in the Canadian Prairies has varied significantly over recent decades; however, improved weed and disease management practices could facilitate stability of hectares cultivated. To assess current and alternative pesticide management practices, we conducted a study across 15 site-years at four locations over four years (2018-2022). Experimental treatments included pre-plant weed management (glyphosate vs. glyphosate mixed with pyroxasulfone+carfentrazone-ethyl), in-crop weed management (no in-crop herbicide vs. fall-applied 2,4-D vs. fall-applied 2,4-D+spring-applied site-year-specific herbicides) and in-crop fungicide management (no in-crop fungicide vs. one prothioconazole+tebuconazole application at ZGS60 vs. two prothioconazole+tebuconazole applications at ZGS32 and ZGS60). Pre-plant glyphosate alone and glyphosate tank-mixed with pyroxasulfone+carfentrazone-ethyl exhibited comparable effects on grain yield, quality parameters, and agronomic characteristics. In-crop weed management had no significant influence on these factors compared to the no in-crop herbicide control, suggesting that in-crop herbicide applications are unnecessary due to the high competitiveness of winter wheat against weeds. However, disease mitigation was prudent as single and double application of fungicide increased grain yield while maintaining grain protein concentration levels. A high-yielding, stable system for optimal grain yield typically required pre-plant weed management coupled with two fungicide applications. These observations confirm herbicide inputs can be reduced in a winter wheat cropping system but disease pressure requires careful cultivar selection with an emphasis on disease resistance as multiple applications of fungicides were needed to optimize grain yield.

Management Efficacy and Response to Post-Application Precipitation of Fungicides for Southern Stem Rot of Peanut and Evaluation of Co-Application with Micronized Sulfur

Southern stem rot (SSR) is caused by Athelia rolfsii and is an economically important disease of peanut (Arachis hypogaea L.). Application of protectant fungicides is an effective management component for reducing levels of this soil-borne disease. The majority of peanut hectarage in South Carolina and Mississippi is rainfed. Timely precipitation has the potential to aid the movement of foliar-applied fungicides through the canopy and into contact with soil interfaces where SSR infections occur. Questions have arisen as to the quantitative relationship of post-application precipitation and fungicide-active ingredient efficacy in managing SSR and protecting associated pod yield potentials. To examine this, fungicide efficacy experiments were screened for inclusion in a meta-analysis, from which eleven experiments conducted from 2015 to 2023 were selected and paired with environmental data from nearby weather stations. Precipitation during the two days following fungicide application was associated with significant reduction in SSR incidence (logit rate of −0.0039/mm) and increased pod yield (log slope of 0.0028/mm). Active ingredient interactions with precipitation among pod yield but not SSR incidence data were present for benzovindiflupyr plus azoxystrobin, flutolanil, and tebuconazole. Fungicides with the greatest levels of control per application at maximum label rates were inpyrfluxam (18.8%), benzovindiflupyr plus azoxystrobin (15.4%), flutolanil (12.3%), and prothioconazole plus tebuconazole (10.5%). Micronized sulfur neither contributed to SSR control nor pod yield increase. Tebuconazole was associated with the greatest % SSR control per fungicide product cost (0.47%/$/ha/application) but was also the treatment with the least amount of control (3.5%) at its maximum label rate. Maximum label rates of benzovindiflupyr plus azoxystrobin (USD 637) and inpyrfluxam (USD 548) were estimated as conferring the greatest returns over the chlorothalonil-only control. Results serve as a helpful reference for farmers and practitioners in selecting fungicide management options and targeting application times, as feasible, to utilize natural precipitation to improve management outcomes.

Fungicide strategies for Ramularia Leaf Spot control recommended in Uruguay and its residues in barley grains

Ramularia leaf spot (RLS) is primarily managed by foliar fungicide spraying, which can result in residues in the grain. In recent years, increasing attention has been paid to the risks these residues pose to consumers. This study aimed to evaluate the efficacy of fungicide management used for RLS control and their fungicide residues in barley grain. Four different alternatives of fungicide mixtures: fluxapyroxad + pyraclostrobin + epoxiconazole; pyraclostrobin + epoxiconazole + chlorothalonil; prothioconazole + trifloxystrobin, and isopyrazam + azoxystrobin, in three spray timings: GS33, GS47 and GS33+GS47, were evaluated in five field experiments. An untreated and a fully protected treatment were included. Fungicide residues, disease severity, control efficacy, area under the disease progress curve, and plump grain yield were calculated. All fungicide strategies adhered to food safety, complying with the Maximum Residue Limits established by Codex and the European Union. Effectiveness varied based on RLS development, application time, and number of applications. Fungicide treatments applied at GS33+GS47 were the most effective as the highest severity levels were observed at the stage after GS47 under the conditions studied. Plump grain yield only showed minimal differences in the late epidemic. The study emphasized the low risk of fungicide presence in grains, favoring efficacy when selecting RLS management options. Any changes in management or regulations should be carefully reviewed to maintain findings. The research underscored the compatibility of recommended fungicide treatments with food safety standards, highlighting the balance between disease control efficacy and consumer safety.

Adaptabilidade e estabilidade de híbridos de milho pelas metodologias de Eberhart e Russell e AMMI em ambientes subtropicais

ABSTRACT Brazil boasts a vast variety of environmental conditions conducive to maize cultivation. Given the various maize hybrids available in the Brazilian market, properly selecting and positioning different genetic materials are critical for successful grain production. Thus, this study aimed to determine the adaptability and stability of different maize hybrids, comparing the Eberhart and Russell and AMMI models, to guide the positioning of these maize hybrids in subtropical regions. A randomized block experimental design with six hybrids and three replicates was used. The experimental environments were defined by combinations of factors such as location, sowing time, fungicide management and irrigation, resulting in 12 distinct environments. Notably, the two models largely agree. For instance, the AG 9025 PRO3 hybrid showed a high yield during early sowing under favorable conditions, whereas the AS 1730 PRO3 and DKB 230 PRO3 hybrids had good yields even under unfavorable conditions. The main limitation of the Eberhart and Russell model is its limited ability to interpret stability, classifying hybrids only as having high or low predictability, limiting the detailed interpretation of stability. Conversely, the AMMI model offers a more detailed analysis of stability, allowing the interpretation of hybrid stability within a broader set and presenting information graphically, which facilitates understanding and enables a more comprehensive and accurate analysis for the appropriate positioning of maize hybrids.

Effect of Bio-Agents and Fungicides in Management of EAF Spot of Chilli (Capsicum annuum L.) Caused by Alternaria alternata (Fr.) Keissler

The study entitled “Effect of bio-agents and fungicides in management of leaf spot of chilli (Capsicum annuum L.) caused by Alternaria alternata (Fr.) Keissler” was carried out during the rabi season of 2022-2023 at the Central Research Field, Department of Plant Pathology, Sam Higginbottom University of Agriculture, Technology & Sciences, Prayagraj. The experiment was carried out in Randomized Block Design (RBD). Among the treatments taken up for research Mancozeb (1g/L)+Carbendazim (1g/L for foliar spray) was found most effective against Alternaria alternata. The minimum disease intensity (11.21, 14.42 and 18.97) was obtained in Mancozeb (1g/L)+Carbendazim (1g/L as foliar spray). It can be concluded that foliar spray treatment of chilli with Mancozeb (1g/L)+Carbendazim (1g/L as foliar spray) recorded higher plant height (61.63), number of leaves per plant (184.60), number of branches per plant (12.07), number of fruit per plant (55.93), fruit weight (g) (4.61), fruit yield (g) per plant (258.70), fruit yield (g) per plot (1293.49) and fruit yield (t ha-1) (6.47).

Identification of Fungicide Combinations Targeting Plasmopara viticola and Botrytis cinerea Fungicide Resistance Using Machine Learning.

Downy mildew (caused by Plasmopara viticola) and gray mold (caused by Botrytis cinerea) are fungal diseases that significantly impact grape production globally. Cytochrome b plays a significant role in the mitochondrial respiratory chain of the two fungi that cause these diseases and is a key target for quinone outside inhibitor (QoI)-based fungicide development. Since the mode of action (MOA) of QoI fungicides is restricted to a single active site, the risk of developing resistance to these fungicides is deemed high. Consequently, using a combination of fungicides is considered an effective way to reduce the development of QoI resistance. Currently, there is little information available to help in the selection of appropriate fungicides. This study used a combination of in silico simulations and quantitative structure-activity relationship (QSAR) machine learning algorithms to screen the most potent QoI-based fungicide combinations for wild-type (WT) and the G143A mutation of fungal cytochrome b. Based on in silico studies, mandestrobin emerged as the top binder for both WT Plasmopara viticola and WT Botrytis cinerea cytochrome b. Famoxadone appeared to be a versatile binder for G143A-mutated cytochrome b of both Plasmopara viticola and Botrytis cinerea. Thiram emerged as a reasonable, low-risk non-QoI fungicide that works on WT and G143A-mutated versions of both fungi. QSAR analysis revealed fenpropidin, fenoxanil, and ethaboxam non-QoIs to have a high affinity for G143A-mutated cytochrome b of Plasmopara viticola and Botrytis cinerea. Above-QoI and non-QoI fungicides can be considered for field studies in a fungicide management program against Plasmopara viticola- and Botrytis cinerea-based fungal infections.

SDHI resistance in Pyrenophora teres f teres and molecular detection of novel double mutations in sdh genes conferring high resistance.

Net blotch (NB), caused by Pyrenophora teres f. teres (Ptt), is an important disease of barley worldwide. NB control is commonly achieved through the use of fungicide mixtures including strobilurins, triazoles and carboxamides. Succinate dehydrogenase inhibitors (SDHI) are important components of fungicide management programs of barley diseases. However, during the last growing seasons in Argentina, barley fields sprayed with mixtures containing SDHI fungicides have shown failures in NB control. Here, we report the isolation and characterization of Argentine Ptt strains resistant to SDHI fungicides. Compared against a sensitive (wild-type) reference strain collected in 2008, all 21 Ptt isolates collected in 2021 exhibited resistance to pydiflumetofen and fluxapyroxad both in vitro and in vivo. Concordantly, all of them presented target-site mutations in any of the sdhB, sdhC and sdhD genes. Although the mutations detected have been previously reported in other parts of the world, this study documents for the first time the occurrence of double mutations in the same Ptt isolate. Specifically, the double mutation sdhC-N75S + sdhD-D145G confers high resistance to SDHI fungicides, while the double mutations sdhB-H277Y + sdhC-N75S and sdhB-H277Y + sdhC-H134R confer moderate levels of resistance in Ptt. SDHI-resistance in Argentine Ptt populations is expected to increase. These findings emphasize the urgent need to perform a wider survey and a more frequent monitoring of SDHI sensitivity of Ptt populations and to develop and implement effective antiresistance tactics. © 2023 Society of Chemical Industry.

The influence of temperature and vapour pressure deficit on conidia germination and germ tube production in an Australian Podosphaera xanthii isolate

Powdery mildew of cucurbits, caused by Podosphaera xanthii, is an economic constraint in cucurbit production worldwide. This study examined the influence of temperature and vapour pressure deficit (VPD) on the rate of conidial germination and the formation of germ tubes in an Australian P. xanthii isolate 12 – 48 h after inoculation. Two experiments were prepared by inoculating cucumber, cv. crystal salad, leaf-discs using a spore settling tower. The first experiment incubated inoculated cucumber leaf-discs at eight temperatures between 8 and 35 °C under saturated vapour pressure (SVP), the second compared 18 VPD conditions between 0.038 and 1.797 kPa, in six humidity chambers (33% – 99% relative humidity) and three temperatures (22 °C, 25 °C, 28 °C). Leaf-discs were cleared, stained and microscopically inspected for conidial germination and the number of germ tubes. The optimal temperature for germination was 28ºC at SVP, where more than 50% of conidia had germinated by 12 h, and 85% by 48 h. Fewer germinated conidia were recorded after 12 h at other temperature treatments between 17 °C and 31 °C. The germination percentage and germination rate were significantly lower when vapour pressure was between 0.13 and 2.5 kPa, with germination in response to VPD varying by approximately 10%, indicating difficulty associating conidial germination to VPD above 0.13 kPa. Germ tube production was highest between 25 ºC and 28 ºC at the lowest VPD treatment at near SVP, with more than 50% of the germinated conidia producing at least three germ tubes. Germination and formation of germ tubes significantly reduced when VPD increased. P. xanthii conidia were able to produce a primary germ tube under relatively dry conditions, such as 2.53 kPa, but these results show infection would be less likely and require longer incubation. This study provides the first crucial step in simulating powdery mildew infections on cucurbit plants and may lead to a model capable of providing risk forecasts or fungicide management decision support tools.

Artificial Intelligence in the Simulation of Fungicide Management Scenarios for Satisfactory Yield and Food Safety in oat Crops

Purpose: The objective of the study is to analyze the management of the fungicide that seeks a longer interval between the last application and the harvest of oat grains, with an indication of the cultivars with the highest satisfactory productivity without application in the grain filling. Validate artificial neural network models in the expectation of satisfactory productivity with food security, through the interaction between management, pathogen, genotype, and environment. Method/design/approach: The study was conducted in 2015, 2016, 2017, in a randomized block design, in a 22 x 4 factorial scheme, for 22 white oat cultivars (recommended and no longer present in the current Brazilian recommendation) and 4 fungicide application conditions (no application; one application at 60 days after emergence (DAE); two applications, 60 and 75 DAE; and three applications, at 60, 75, 90 DAE), with three repetitions. Results and conclusion: The oat cultivars URS Altiva, URS, Guará, URS Charrua, FAEM 4 Carlasul, IPR Aphrodite, and UPFPS Farroupilha showed satisfactory yields in absence of fungicide applications. URS Altiva, FAEM 4 Carlasul, and IPR Aphrodite showed significant yield increases with fungicide application before grain filling. Artificial neural networks are efficient in predicting productivity and are a reliable alternative for simulating scenarios to validate more sustainable management practices. Originality/value: An unprecedented study seeking more sustainable managements to reduce the use of fungicides in the control of oat diseases and development of simulation models by artificial intelligence, providing opportunities for analysis of different scenarios of the complex interaction plant, pathogen, and environment.

Economically viable fungicidal management for powdery mildew of wheat

Economically viable fungicidal management for powdery mildew of wheat

USE OF DIFFERENT FUNGICIDES IN WHEAT UNDER WATER DEFICIT CONDITIONS

The study aimed to evidence the efficiency of fungicides in disease control and the economic and productive effects under water deficit conditions in wheat. In addition, it sought to list the best management of fungicides so that the active principles can be more efficient in controlling diseases and, therefore, in the production of wheat grains. The experiment was carried out in São Borja – RS, in a randomized block design, with twenty treatments (fungicide management), in four replications, in 80 plots. The management composed by Versatilis + Versatilis potentiated the expression of cob length, number of grains per plant, leaf rust. Fusão + Fusão treatment promoted the lowest cob weight and grain weight per plant, similarly to Cypress + Mancozeb treatment. Orkestra + Fusão treatment enhanced grain yield and showed the best cost benefit, close to the value of the control treatment, proving to be the most profitable.

ECONOMIC AND AGRONOMIC POSITIONING OF FUNGICIDES IN CONDITIONS OF WATER DEFICIT IN SOYBEAN CULTURES

<p><strong>Background. </strong>The management of diseases in soybean crops demands a great economic cost with fungicide applications. Therefore, unnecessary or excessive applications can promote negative environmental results. Therefore, understanding the weather conditions and the development of diseases in the crop is essential to avoid the unnecessary use of fungicides, consequently reducing costs and ensuring the sustainability of the activity. <strong>Aim.</strong> The aim is to identify which yield components are quantitatively affected, and which aspects of the chemical composition of the grains are qualitatively influenced by fungicide management, in addition to relating the cost-benefit rate of sequential applications or previously stipulated management in the soybean crop, as well as their economic effects under water deficit conditions. <strong>Methodology. </strong>The trial was carried out using a randomized block design composed of 4 replications. The trial consisted of 5 kinds of fungicide management, defined by the time and number of applications, during the development cycle of the Lança cultivar, in the 2019/2020 crop season. Soybean agronomic traits and nutritional attributes were evaluated. <strong>Results. </strong>Unfavorable climate conditions contributed to the low rate of Asian rust infection during the soybean development cycle. The different kinds of fungicide management influenced soybean performance for the main agronomic variables studied. For the chemical composition of the grains, there was no statistical difference in relation to the different kinds of fungicide management. <strong>Implications. </strong>The results indicate that the management of fungicides must be carried out according to the meteorological conditions of the year of cultivation. <strong>Conclusion.</strong> Management without fungicide application maximized grain yield and promoted the highest economic return.</p>

Changes in Activity of Phenylalanine Ammonia Lyase (PAL), Phenols and β 1, 3 Glucanase in Crossandra Plants affected by Fusarium incarnatum (Desm.) Sacc and treated with Bioagents, Organic Amendments, Silver Nanoparticles and Fungicide in Pot Culture

Laboratory and pot culture experiments were carried to study the effect of different bioagents, organic amendments, silver nanoparticles and fungicide in management of crossandra wilt caused by Fusarium incarnatum and nematode Pratylenchus. delattrei During the study observations are made on changes in activity of phenylalanine ammonia lyase (PAL), phenols and β 1, 3 Glucanase in crossandra plants. All the treatments applied recorded increased levels of phenylalanine ammonia lyase (PAL), phenols and β 1, 3 Glucanase in treated plants, but among all soil application (SA) of T.viride @ 2.5 kg/ha at 20 DAP plus soil drenching (SD) of carbendazim @ 0.1% at 30 DAP plus SA of T.viride @ 2.5 kg/ha at 50 DAP plus Foliar application (FA ) of P. fluorescens@ 1.0 kg/ha at 70 DAP plus Foliar application (FA ) of B. subtilis @ 1.0 kg /ha at 90 DAP was found to be significantly higher in induction of phenylalanine ammonia lyase (PAL), phenols and β 1, 3 Glucanase in crossandra. The same results are also noticed in later stage in reducing disease incidence compare to control and other treatments.

Identification and Management of Phytophthora Aerial Blight Caused by Phytophthora nicotianae on Catharanthus roseus.

Phytophthora nicotianae is the most common pathogen in nurseries and gardens, infecting both woody and herbaceous ornamental plants. Phytophthora aerial blight symptoms such dull water-soaked lesions on shoot tips and leaf petioles, girdling on the main stem, necrosis, and wilting of annual vinca were observed in a commercial greenhouse in Warren County, TN, U.S.A., in May 2016. The objective of this study was to identify the causal agent of Phytophthora aerial blight and develop a fungicide management recommendation for ornamental producers. Attempts to isolate the pathogen from symptomatic leaf tissue were conducted, and excised leaf pieces were embedded in V8 agar medium. Morphological characterization, PCR, sequencing, and pathogenicity test of the isolate FBG2016_444 were conducted to confirm the pathogen identification. The sequence identity was 100% identical to P. nicotianae, and a combined phylogenetic tree (internal transcribed spacer, large subunit of rDNA, and ras-related protein gene) grouped isolate FBG2016_444 within the clade of P. nicotianae. In the pathogenicity study, all inoculated annual vinca plant showed Phytophthora aerial blight symptoms, and P. nicotianae was reisolated, whereas noninoculated annual vinca plant remained symptomless. These findings confirmed P. nicotianae as the causal agent of Phytophthora aerial blight of annual vinca. In addition, two rates (0.078 and 0.156 ml·liter-1) and three application intervals (7, 14, and 21 days before inoculation [DBI]) of oxathiapiprolin (Segovis) were evaluated for their ability to reduce the Phytophthora aerial blight severity on annual vinca plants. The control groups were positive (nontreated inoculated) and negative (nontreated noninoculated) plants. Both rates and application timings of oxathiapiprolin significantly reduced Phytophthora aerial blight severity and disease progress (area under disease progress curve [AUDPC]) on annual vinca plants compared with the positive control. However, 0.078 and 0.156 ml·liter-1 of oxathiapiprolin applied at 7 or 14 DBI were the most effective treatments in reducing the disease severity and AUDPC on annual vinca plants. The plant growth parameters such as increase in height and width, total plant weight, and root weight were not influenced by the application of oxathiapiprolin. The findings reported in this study will help ornamental producers with better management of Phytophthora aerial blight of annual vinca.

A New Approach: Determining cyt b G143A Allele Frequency in Zymoseptoria tritici by Digital Droplet PCR.

Simple SummaryDroplet digital polymerase chain reaction (ddPCR) is an innovative technique for quantifying a target DNA in a diluted target sample, based on the partition of PCR reaction in a large number of sub-reactions (droplets). In recent years there has been an increase in digital PCR (dPCR) utilization in several different fields, and the application of ddPCR in fungicide resistance studies is very recent. Zymoseptoria tritici is the causal agent of Septoria Tritici Blotch (STB), one of the most devasting foliar diseases of wheat grown in temperate climates. STB control relies mostly on fungicide applications and mutations conferring fungicides resistances are concerning phenomena. G143A substitution in fungal cytochrome bc1 confers resistance toward Quinone outside Inhibitor (QoIs) fungicides. In Italy, QoIs are currently sprayed in STB control programs. To the best of our knowledge, we have developed the first ddPCR assay for G143 and A143 alleles detection in samples of gDNA from Z. tritici monocondial cultures. We have also investigated G143 and A143 alleles frequency in Italian Z. tritici populations representative of different fungicide management strategies. The detection of very low G143A substitution percentages in Z. tritici populations is essential for monitoring the emergence of QoIs resistance in field and effectively control STB.Z. tritici first appeared in Italy later than in northern-central European countries. QoIs fungicides currently play a role in STB control, used in combination with Demethylation Inhibitors (DMIs) or Succinate dehydrogenase Inhibitors (SDHIs). In this study, we set up a fast, sensitive, and accurate ddPCR protocol in order to investigate the presence and frequency of G143A substitution, causing a reduction in strobilurins’ efficacy in Z. tritici. The best PCR conditions for the clear separation of positive and negative droplets were identified. The lowest wild-type and resistant alleles frequencies were accurately determined on samples consisting of mixed DNAs from monoconidial cultures of Z. tritici and were expressed as fractional abundance. The protocol was tested by determining the copy number and frequency of alleles on gDNA purified in three Italian Z. tritici field populations representative of different fungicide management strategies. For the first time, the determination of allele concentration and the frequency of a mutation involved in Z. tritici fungicide resistance was carried out by employing digital PCR. This new approach provides a diagnostic tool that is rapid and able to detect very low G143A substitution percentages, which is very useful for fungicide resistance detection at early stages, thus, informing field management strategies for contrasting STB disease.

Evaluation of Different Fungicides in Management of Early Blight Disease of Tomato Caused by Alternaria Solani

Ten fungicides, including five systemicat, 50, 100 and 200 μg mL−1 concentrations and five non-systemic fungicides at 500, 1000 and 2000 μg mL−1 concentrations were evaluated for their efficacy against Alternaria solani under in vitro conditions. Among non-systemic fungicides, both mancozeb 75 WP and propineb 50 WP proved highly toxic in inhibiting the mycelial growth. Among systemic fungicides, propiconazole 25 EC and tebuconazole 25 EC proved highly toxic. Two each of most effective, systemic and non-systemic fungicides under in vitro studies were evaluated under field conditions for managing the early blight disease. Under field conditions, the application was integrated with different planting dates in two cropping seasons of 2016 and 2017. The study revealed significant disease reduction in all treatments over control. The treatment combination 1st spray of mancozeb 75 WP @ 0.3% followed by 2nd spray of propiconazole 25 EC @ 0.05% was found to be most efficient in reducing the disease incidence and intensity from 46.0 and 21.8% in unsprayed check to 7.6 and 4.4% at all planting dates. Amongst different planting dates, disease progression was less when planted on 1st May followed by 20th May and 10th June.