Systemic Fungicides Research Articles

Efficacy of Propiconazole for Prevention of Sassafras Mortality from Laurel Wilt Disease Using a Tree Micro-Injection and Micro-Infusion Delivery System

Laurel wilt is a lethal disease of American Lauraceae caused by Harringtonia lauricola. Propiconazole is a systemic fungicide which arrests fungal growth among a variety of plant hosts. Propiconazole as a preventive treatment against laurel wilt in sassafras (Sassafras albidum) has not been evaluated. We treated sassafras trees with propiconazole using the Arborjet QUIK-jet® Micro-InjectionTM and TREE I.V. Micro-InfusionTM systems (Arborjet,Inc., Woburn, MA, USA) and challenged trees by inoculating them with H. lauricola. Out of 7 trees treated using the QUIK-jet Micro-Injection system, 6 (86%) survived 52 or more weeks following inoculation with H. lauricola, while only 11% of inoculated control trees (1 of 9) survived over this period. All trees not damaged by hurricanes (n = 13) treated with propiconazole using the TREE I.V. Micro-Infusion system survived signifi cantly longer than untreated control trees after inoculation with H. lauricola; 10 of 13 trees (77%) survived with < 50% crown loss, and 8 of 13 trees (62%) appeared entirely healthy 54 weeks post-inoculation. In the TREE I.V. Micro-Infusion system trial, 15 of 19 control trees (79%) had either died or lost ≥ 50% of living crown 54 weeks post-inoculation with H. lauricola. Results indicate sassafras trees treated with propiconazole using the Arborjet QUIK-jet Micro-Injection and TREE I.V. Micro-Infusion systems are significantly less likely to die within one year of infection with H. lauricola; however some trees may exhibit signifi cant crown decline (≥ 50%) over this period.

Effects of Peganum harmala extracts and synthetic chemical fungicides on controlling early blight of tomato in the central shaanxi plain of China

Peganum harmala, also known as wild rue, is a perennial herbaceous plant that occurs in semi-arid parts of Asia, the coastal Mediterranean region, Mexico, and the southern United States. Extracts from P. harmala are toxic to aphids and mites, and also possess antifungal activity. P. harmala extracts and four systemic commercial fungicides were initially investigated for their in vitro toxicity to Alternaria solani, the fungal pathogen of early blight of tomato. The P. harmala extracts inhibited mycelial growth and conidial germination of A. solani, but inhibition was less than for the commercial fungicides prothioconazole and iprodione. Tests in a commercial greenhouse near Jingyang County, Shaanxi Province, China, during 2020, 2021, and 2022 compared efficacy of P. harmala, alone and in combination with commercial fungicides, for suppression of early blight on tomato cv. Provence. Three applications of iprodione or prothioconazole at 7- to 10-day intervals resulted in <10% incidence of foliar symptoms on naturally inoculated plants. When a spray of P. harmala extract + prothioconazole was followed at 15-day intervals by P. harmala extract + iprodione and P. harmala extract alone incidence of foliar symptoms remained <10%. These results indicate that alternating tank mixes of prothioconazole or iprodione with P. harmala, followed by the extract alone, can extend the interval between sprays by 7–10 days and reduce dependency on synthetic chemical pesticides for control of early blight in greenhouse-grown tomatoes.

Electroanalytical overview: the sensing of carbendazim.

Carbendazim is a broad-spectrum systemic fungicide that is used to control various fungal diseases in agriculture, horticulture, and forestry. Carbendazim is also used in post-harvest applications to prevent fungal growth on fruits and vegetables during storage and transportation. Carbendazim is regulated in many countries and banned in others, thus, there is a need for the sensing of carbendazim to ensure that high levels are avoided which can result in potential health risks. One approach is the use of electroanalytical sensors which present a rapid, but highly selective and sensitive output, whilst being economical and providing portable sensing platforms to support on-site analysis. In this minireview, we report on the electroanalytical sensing of carbendazim overviewing recent advances, helping to elucidate the electrochemical mechanism and provide conclusions and future perspectives of this field.

Биологическая эффективность фунгицидов нового поколения против листостебельных болезней озимой пшеницы

The article presents the data on the research of biological effectiveness of two-component fungicides Altrum Super, SE and Alkor Super, SE in crops of winter wheat variety Alekseich in the phase of the end of earing - beginning of flowering in the climatic conditions of the Central part of the Non-Chernozem region. The field experiment was carried out in 2021-2022 at the All-Russian Research Institute of Agrochemistry named after D.N. Pryanishnishnitsky. D.N. Pryanishnikov, Agricultural Engineering Department, sod-podzolic-loam soil, 1st agroclimatic zone, Domodedovo Microdistrict, Moscow Region. Barybino. Combined systemic fungicides Altrum Super, KE and Alkor Super, KE with the same active substance, but different manufacturers and winter soft wheat variety Alekseich were the objects of research. The investigations were carried out by generally accepted methods. As a result of studies, it was found that the first manifestations of diseases in wheat crops were observed in the second decade of June. Depending on the date of registration, application of new generation fungicides in winter crops provided biological effectiveness against pyrenophrosis 62,1-84,5%, powdery mildew 63,1-83,3%, stem rust 63,0-83,0%, brown rust 65,3-84,0%, septoriosis 62,4-85,9% and yellow rust 62,7-81,4%. The maximum yield in the experiment was achieved with a single treatment of the crop fungicides Altrum Super, KE and Alkor Super, KE at a rate of 0.5 l/ha. In relation to the control, Altrum Super, SE (250 + 80 g / l) -0.4 l / ha, Altrum Super, SE (250 + 80 g / l) - 0.5 l / ha and Alkor Super, SE (250 + 80 g / l)- 0.5 l / ha allowed to increase the yield by 11.80%, 15.80% and 14.10%, respectively.

Powdery Mildew A Disease of Grapes And The Fungicides Mode of Action: A Review

Powdery mildew caused by Uncinula necator (Schw.) Burr. is one of the widespread fungal diseases of grapes that have caused economic losses through poor fruit set and low yield substantially. To decrease the inoculum potential, a disease management program must be undertaken early in the season which is imperative to reduce late-season disease problems. Because, without early control of the infection of powdery mildew, often lead to severe problem in the late season. Elemental sulfur was the foremost antifungal utilized for the control of powdery mildew which is still in use as an effective and cheap fungicide for vineyards. Sterolbiosynthesis inhibitors (SI), also called SI fungicides, are the latest products to control powdery mildew effectively. For efficient use of fungicides with no or less resistance to the pathogen, it is appropriate to spray fungicides having different mechanisms of action which are specific in function, and for more efficacy, use a mixture of such fungicides that have no harmful impact on plant growth and environment. So, for effective control of powdery mildew, a protective spray of fungicide before bloom and a subsequent spray of systemic fungicides at the time of berry formation ensure healthy and higher grapes yield. This paper reviewed the powdery mildew infection in grapevines and its effect on yield losses with details of fungicides’ mechanism of action and newly developed fungicides having broad spectrum activities.

Environmental fate and metabolism of the systemic triazolinthione fungicide prothioconazole in different aerobic soils

As a best-selling triazolinthione fungicide, prothioconazole (PTZ) has been widely used worldwide and has aroused concern about its environmental effect. This study used phenyl-UL-14C-labeled PTZ and an improved fate model to investigate the fate and metabolism of this fungicide in aerobic soil. During 120 d of incubation, PTZ rapidly transformed into metabolites and bound residues, with a half-life (DT50) of less than 1 d. After 120 d, approximately 45–55% of PTZ formed bound residues, and the extractable metabolite residues were gradually degraded over time. Approximately 19%, 44% and 27% of phenyl-UL-14C-PTZ was mineralized in red soil, fluvo-aquic soil and cinnamon soil, respectively, but only approximately 3% was mineralized in black soil. Five metabolites were identified and confirmed, and a possible metabolic pathway for phenyl-UL-14C-PTZ in soil was proposed. Based on the correlation analysis between soil properties and model rate constants, soil properties exerted important effects on PTZ transformation. These results will provide basic data for environmental risk assessments and removal of the PTZ pollutant and suggest that the soil type should be considered in the selection and application of pesticides.

Эффективность применения регулятора роста растений Сетар, КС* при выращивании рапса ярового на чернозёме выщелоченном Краснодарского края

The productivity of spring rapeseed plants is significantly affected by the weather conditions of the growing season and the phytosanitary condition of the sowings. Plant growth regulators can increase crop resistance to environmental stress factors and pathogens. Combined application of plant growth regulators and fungicides is also an effective technique in rapeseed cultivation. In 2020–2021, on leached chernozem of the Krasnodar region, we studied the effectiveness of plant growth regulator Setar, SC during the cultivation of a spring rapeseed variety Tavrion. Setar, SC is a combination of a plant growth regulator paclobutrazol and a systemic fungicide difenoconazole. Spraying of rapeseed plants with Setar, SC preparation at the budding stage in doses 0.3, 0.4, and 0.5 l/ha has increased the preservation of the plant density by the harvesting time by 3.2–6.5 %, number of pods on plants – by 6.0–13.6, seeds – by 5.8–8.5, and thousand-seed weight – by 3.4–4.3 %. The application of preparation did not significantly affect the oil content of seeds of spring rapeseed. Due to the positive impact on the yield structure elements, the treatment of plants with the growth regulator Setar, SC resulted in the increase of seed yield of spring rapeseed by 0.15–0.22 t/ha and oil yield by 61–93 kg/ha on av-erage during the two years of research. The multiple correlation and regression analysis revealed the dependence of the yield of spring rapeseed variety Tavrion on the number of plants per 1.0 m2 and the number of seeds on the plants per 1.0 m2 with the impact proportions of 69.4 and 21.4 %, respectively. The optimal dose for spraying the spring rapeseed plants at the budding stage with Setar, SC preparation in the conditions of the central natural and climatic zone of the Krasnodar region was 0.4 l/ha.

Evaluation of Sprays in the Management of Black Sigatoka in Banana Crop

The main phytosanitary problem of commercial bananas is black Sigatoka, caused by the fungus Mycosphaerella fijiensis Morelet. This pathogen causes loss of leaf area, loss of exportable quality and low crop yields. The objective of the research was to evaluate four systemic fungicides applied in mixtures in different combinations and to determine percentages of severity, total leaves, and old leaf free of streaks in the two zones established for data collection. This work was carried out in Rivas, Nicaragua, municipality of Potosí, in the farms El Trapiche, El Espíritu and La Granja. In an area of 5 ha-1 of the cultivar CEMSA ¾, 50 plants were selected in the border zone and 50 in the center, with four treatments: T1 (Triazole + Amine), T2 (Pyrimethanil + Spiroxamine), T3 (Difenoconazole + Amine), T4 (Amine + Pyrimethanil) each with three replications, the frequency of application was 14 days, disease severity was recorded in percentage using the Stover scale on leaves 3, 4 and 5. The experimental design was randomized blocks and the data were analyzed using a two-way ANOVA. It was determined that the percent severity on leaf 4 in the center and border zone was High (&gt; 30 and &lt; 50%) and on leaf 5 in both zones was severe (&gt; 60 to 70%) in all farms. The T4 fungicide mixture (amine + pyrithamethanil) had the lowest percentages of black Sigatoka severity, the best average number of old leaves free of streaks and the highest number of total leaves.

Integration of host resistance and fungicides reduced ascochyta blight pressure and minimised yield loss in field pea (Pisum sativum L.) in southern Ethiopia

ABSTRACT Ascochyta blight complex causes substantial yield losses and deteriorates seed quality of field pea worldwide. Field experiments were conducted to determine the effectiveness of an integrated approach consisting of host resistance and fungicides to reduce ascochyta blight progression and enhance yield performances of field pea for two seasons at Bonke and Chencha, Southern Ethiopia. Three field pea (Bursa, Burqitu and Tegegnech) varieties and three systemic (Carbonchlor, Matico and Othello-Top) fungicides, along with unsprayed controls, were arranged in a factorial randomised complete block design with three replications. Results showed that fungicide treated plots of each variety recorded the lowest progress rate, while control plots of Bursa, Burqitu and Tegegnech recorded the highest rate parameter (0.67, 0.60 and 0.451 units day−1), respectively at Bonke. Terminal mean severities were reduced by up to 24.6–43.7% and 20.1–43.7% due to fungicide applications over unsprayed plots at Chencha and Bonke, respectively. Moreover, triple applications of Othello-Top enhanced grain yield by 211% (Bursa), 204% (Burqitu) and 140% (Tegegnech) as compared to control plots at Bonke. A related pattern was noticed at Chencha areas. Economically, Burqitu with Othello-Top showed the highest net benefit and benefit–cost ratio of $2.35 × 103 ha−1 and 4.77 (Bonke) and 2.27 × 103 ha−1 and 3.76 (Chencha) in that order of presentation, followed by Matico, and found to be the most profitable management option due to monetary advantage; and it could be suggested for field pea growers.

Comparative evaluation of the genotoxicity of carbendazim technical grade active ingredients in the Ames test and micronucleus in vivo test

Introduction. Carbendazim is a systemic benzimidazole fungicide used against a wide range of crop diseases. The ability of carbendazim to induce the incidence of chromosomal aberrations and micronuclei in mammalian cells by influencing the processes of mitotic spindle formation in the cell cycle have been shown in various in vitro and in vivo tests. Contradictory data were obtained in the bacterial test system Salmonella/microsomes, indicating both the absence and the presence of mutagenic activity of carbendazim. The discrepancy in the results may stem from the presence of impurities. The aim of the study was a comparative evaluation of the genotoxicity of various technical products of carbendazim. Materials and methods. The genotoxicity of carbendazim was studied using the plate incorporation version of the Ames test on 5 strains of Salmonella typhimurium in the presence and the absence of metabolic activation system (+S9/-S9) and in a micronucleus test in CD-1 mice. Two technical grade active ingredients (TGAI) and an analytical standard for carbendazim were tested. Results. In the Ames test, the analytical standard of carbendazim possessed no mutagenic activity (±S9) on any of the strains. The most pronounced mutagenic effect was observed for the TGAI I in TA98 strain, the number of revertants at the maximum concentration was 5-7 times higher than that in the negative control. The positive effects of carbendazim TGAIs in the Ames test are likely mediated by the presence of impurities. Under in vivo conditions, all tested TGAIs of carbendazim induced a statistically significant and dose-dependent formation of micronuclei in polychromatic erythrocytes (PCE) of mouse bone marrow. The mean frequency of PCE with micronuclei at the maximum dose exceeded this rate in the negative control by 21-24 times. Research limitations. The study is limited to testing the mutagenic activity of two samples of carbendazim technical products and one sample of its analytical standard in both in vivo and in vitro tests. Conclusion. Taking into account the high content of the active substance in the tested TGAIs, the bacterial reverse mutation test is a highly sensitive method for assessment of the equivalence of carbendazim generic products. The use of a micronucleus test for evaluating of the equivalence of carbendazim TGAIs to the original substance is inappropriate due to the pronounced aneugenic effect.

Bio-efficacy of new fungicide, Tebuconazole- 430SC against coffee leaf rust disease, Hemileia vastatrix Berk and Broome

Coffee is an important plantation crop cultivated worldwide and used as stimulating drink. Coffee leaf rust (CLR) disease is one of the devastating disease affecting foliage of Coffee, limiting Coffee production worldwide. It is caused by an obligate parasite Hemileia vastatrix, which reduce photosynthetic area in turn results in heavy defoliation and die-back of branches. In India CLR management is accomplished with one contact fungicide spray (Bordeaux mixture @ 0.5%) and effective systemic fungicide spray during pre and post monsoon periods respectively. However, to find an alternative to the recommended fungicide the studies were conducted to know the efficacy of new fungicide Tebuconazole 430 SC against CLR. The results revealed that, in the laboratory conditions, complete inhibition of the uredospore germination was observed in Tebuconazole 430 SC @ 0.5 ml/L and 0.75 ml/L and Hexaconazole 5 EC @ 2 ml/L. However, in lower concentration Tebuconazole 430 SC @0.25 ml/L there was 98.97 per cent inhibition and in Copper Oxychloride 50 WP @ 5.5 g/L 87.49 per cent inhibition was observed over control. Field trials indicated that, at all the locations, Tebuconazole 430SC @ 0.75ml/L was found very effective which recorded maximum disease reduction followed by Tebuconazole 430SC @ 0.5ml/L which was found on-par with the currently recommended fungicide Hexaconazole 5 EC @ 2 ml/L and minimum disease reduction was observed in Copper oxychloride 50 WP @ 5.5g/L.

Potential of Pseudomonas and Trichoderma from the Brazilian Amazon as Biocontrol Agents against the Wheat Blast Disease

Blast is one of the most significant wheat diseases, causing high yield losses in susceptible varieties under favorable conditions in Latin America, Southeastern Asia and Eastern Africa. The disease is caused by the ascomycetous fungal pathogen Pyricularia oryzae Triticum lineage (PoTl). Chemical control with fungicides has been used as a management strategy; however, the effectiveness of the major classes of high-risk site-specific systemic fungicides has been reduced due to the widespread prevalence of resistance, especially in Brazil. Biological control is seen as a highly important and sustainable strategy to minimize the impact of yield losses associated with wheat blast in areas where fungicides are ineffective. In our study, we specifically aimed to determine the biological control potential of the three isolates of fluorescent Pseudomonas and three of Trichoderma as the antagonists of PoTl, both in in vitro and under greenhouse conditions. Additionally, we aimed to describe the ultrastructural interactions among the biocontrol agents and the pathogen in vitro by means of scanning electron microscopy (SEM). Fluorescent P. wayambapalatensis ‘Amana’ or Pseudomonas sp. nov. ‘Yara’, both from the P. putida group, and Trichoderma koningiopsis ‘Cachara’ significantly reduced PoTl in vitro mycelial growth and the blast disease severity on wheat plants. The SEM analyses revealed ultrastructural antagonistic mechanisms: biofilm formation, direct antagonism and mycoparasitism. Further research on the topic should include the development of stable formulations of the Pseudomonas- and Trichoderma-based biocontrol agents selected in our study for managing the wheat blast disease and the field tests of the biofungicide formulations obtained thereafter.

Integrating a Bacillus-based product with fungicides by foliar application to protect soybean: a sustainable approach to avoid exclusive use of chemicals.

Biological control is widely applied against soybean (Glycine max L.) soil-borne pathogens by furrow or seed treatments. The efficiency of bioproducts and timing of application by foliar sprays against soybean pathogens needs to be more fully understood. This work investigated the efficiency of foliar application with a Bacillus subtilis-based product (BBP) to protect soybean from multiple pathogens and the best moment to apply it considering its compatibility with fungicides. Foliar applications (from stages V6 to R4) with BBP, mancozeb (M) and systemic fungicides (S) applied against Asian rust (Phakopsora pachyrhizi), BBP followed by S (BBP-S), BBP along with S (S + BBP), S along with M (S + M) or water were carried out in a soybean field for two years. The treatments S + BBP, S + M and BBP-S reduced the severity of Asian rust by 82% compared to the control. Except for M, all treatments reduced the severity of other foliar diseases by >60%. The defoliation was reduced by BBP and BBP-S, whereas the yield was 25% higher than control by using BBP, S + M, S + BBP or BBP-S. Also, the incidence of Fusarium sp. was significantly reduced on seeds from treatments BBP and BBP-S. The compatibility tests in Petri dishes demonstrated that all fungicides decreased the bacterial growth when applied along with BBP, whereas previous applications of BBP did not reduce the bacterial growth. The BBP protected soybean against multiple pathogens, reduced defoliation and promoted soybean yield similarly to conventional fungicides, but in general, the early application of the BBP was the most efficient protection. © 2022 Society of Chemical Industry.

Management of Tomato Diseases in Plastic House at Lamjung

An experiment was conducted in plastic houses at three farmers’ field, each farmer as a replication, in three local levels (Sundarbazar, Gaunsahar and Besisahar) in Lamjung district during July to December 2017, to identify and manage major diseases of tomato (variety: Srijana) using chemicals and bio-pesticides. The treatments Bio-cure-B (Pseudomonas fluorescens: bio-fungicide) Bavistin Carbendazim, systemic fungicide) and Dithane M-45 (Mancozeb, contact fungicide) were applied as foliar spray. Control plot was maintained without application of any treatment. Mainly four fungal diseases, early blight (Alternaria solani), late blight (Phytopthora infestans), powdery mildew (Leveillula taurica), septoria leaf spot (Septoria lycopersici) and one bacterial disease (Xanthomonas campestris pv. Vesicatoria) were recorded. Mancozeb showed the best to control the disease incidence and severity of early blight (25%, 6.33%), late blight (18.0%, 14.34%) and septorial leaf spot (11.67%, 11.55%) repectively followed by Carbendazim, and P. fluorescens over control. However, Carbendazim was the best to control powdery mildew (6.0%, 2.0%), followed by Mancozeb and P. fluorescens over control. There were no significant effect of pesticides on bacterial leaf spot, plant height, and leaf number butconsiderable variation in fungal diseases, yield and average fruit weight.

Evaluation of Fungicides and Bio-Agents against Ascochyta Blight (Ascochyta rabiei) of Chickpea under Dryland Conditions of Kashmir, India

Five non-systemic fungicides: chlorothalonil, carbendazim (12%) + mancozeb (63%), captan 50WP, dodine 65WP and copper oxychloride 50WP and four systemic fungicides viz., difenoconozole 25EC, carbendazim 50WP, hexaconozole 5EC and mycobutanil 10WP were evaluated against Aschochyta blight of chickpea caused by Ascochyta rabiei. The in-vitro evaluation of non-systemic fungicides through poisoned food technique at five different concentrations: 50,100, 250, 500 and 1000 µg ml-1 fungicides showed that carbendazim (12%) + mancozeb (63%) proved most effective and resulted in highest mycelial growth inhibition (82.27%) of the pathogen followed by dodine with mycelial growth inhibition of 67.99%. The least efficacious fungicide was copper oxychloride with only 29.81% mycelial growth inhibition. Among the systemic fungicides evaluated at concentrations of 25, 50, 100, 200 and 500 µg ml-1, carbendazim proved to be the most effective and caused highest mycelial growth inhibition of 90.23% followed by difenconozole (71.24%). Myclobutanil 10WP was least efficacious among the systemic fungicides and resulted in only 52.76% of mycelial growth inhibition. Among the three methods used for evaluation of efficacy of fungicides and bio-agents, revealed that the seed treatment with carbendazim (12%) + mancozeb (63%) proved most effective with lowest disease incidence (15.0%) and disease intensity (4.02%). Among the biological control agents used, seeds treated with Bacillus subtilis proved the most effective which resulted in disease incidence and intensity of 32.25 and 20.04%, respectively. Combination treatment comprising of seed treatment with Bacillus subtilis at concentration of 109spores ml-1 and foliar spray with mancozeb 63% WP+ carbendazim12%WP at the concentration of 2.5% was most efficacious and resulted in lowest disease incidence (7.80%) and disease intensity of (4.82%) while seed treatment with Bacillus subtilis at the concentration 109 spores ml-1alone was least efficacious and resulted in highest disease incidence of 53.80% with disease intensity of 37.25%. It was, however superior than control where disease incidence and intensity was 80.00% and 51.34 %, respectively.

Genome-wide association mapping identifies common bunt (Tilletia caries) resistance loci in bread wheat (Triticum aestivum) accessions of the USDA National Small Grains Collection

Key messageAssociation mapping and phenotypic analysis of a diversity panel of 238 bread wheat accessions highlights differences in resistance against common vs. dwarf bunt and identifies genotypes valuable for bi-parental crosses.Common bunt caused by Tilletia caries and T. laevis was successfully controlled by seed dressings with systemic fungicides for decades, but has become a renewed threat to wheat yield and quality in organic agriculture where such treatments are forbidden. As the most efficient way to address this problem is the use of resistant cultivars, this study aims to broaden the spectrum of resistance sources available for breeders by identifying resistance loci against common bunt in bread wheat accessions of the USDA National Small Grains Collection. We conducted three years of artificially inoculated field trials to assess common bunt infection levels in a diversity panel comprising 238 wheat accessions for which data on resistance against the closely related pathogen Tilletia controversa causing dwarf bunt was already available. Resistance levels against common bunt were higher compared to dwarf bunt with 99 accessions showing le 1% incidence. Genome-wide association mapping identified six markers significantly associated with common bunt incidence in regions already known to confer resistance on chromosomes 1A and 1B and novel loci on 2B and 7A. Our results show that resistance against common and dwarf bunt is not necessarily controlled by the same loci but we identified twenty accessions with high resistance against both diseases. These represent valuable new resources for research and breeding programs since several bunt races have already been reported to overcome known resistance genes.

A new highly effective hybrid fungicide containing difenoconazole and tea tree oil for managing scab of apple, pecan and almond trees and as a tool in resistance management

AbstractManagement of scab diseases of apple, pecan and almond is mostly based on fungicide applications according to host phenological stage and wetness events. Resistance to widely used locally systemic fungicides including the methyl benzimidazoles, demethylation inhibitors (DMIs) and quinone outside inhibitors (QoIs) has been reported. We evaluated the activity of a new premixed hybrid fungicide containing the DMI difenoconazole and essential tea tree oil (TTO) against mycelial growth of Venturia inaequalis in vitro and against scab of apple, pecan and almond in field trials. Mycelial growth of 24 isolates of V. inaequalis collected from commercial apple orchards varied in their sensitivity to difenoconazole (EC50 values of 0.0002–1.29 mg/L). Difenoconazole–TTO was significantly more inhibitory to some of the isolates than difenoconazole alone, primarily to those that were less sensitive to difenoconazole. Protective foliar applications of difenoconazole–TTO in field trials were highly effective in controlling scab of apple and generally provided significantly higher disease control than difenoconazole alone. On apple and almond, difenoconazole–TTO treatments were similarly or more effective than applications with other synthetic fungicides belonging to the DMI, QoI and succinate dehydrogenase inhibitor (SDHI) groups, or their mixtures. Difenoconazole–TTO completely prevented scab on pecan trees. Results suggest that difenoconazole–TTO can be integrated into scab control programmes for these crops and be used as a strategic approach in fungicide resistance management in orchards.

In vitro evaluations of fungicides against Sclerotium rolfsii Sacc. Causing collar rot of chickpea

Collar rot of chickpea is caused by Sclerotium rolfsii. In vitro evaluation of fungicides for the management of collar rot was carried using contact, systemic and combi fungicides. Among contact fungicides tested Mancozeb showed cent per cent inhibition at 0.20 %. Among systemic fungicides tested Hexaconazole (0.05 %) and Propiconazole (0.15 %) showed cent per cent inhibition. Among the combi fungicides evaluated Carbendazim 12 % + Mancozeb 63 % (0.15 %) and Hexaconazole 4 % WP + Zineb 68 %, Carboxin 37.5 % + Thiram 37.5 %, Tricyclazole18 % + Mancozeb 62 % WP, Captan70 % + Hexaconazole 5 % WP at 0.05 per cent concentration showed cent per cent inhibition. Among allthe fungicides tested combi products were found to be effective (Hexaconazole 4 % + Zineb 68 % at 0.05 %) in inhibiting the pathogen.

Using a bio-economic farm model to evaluate the economic potential and pesticide load reduction of the greenRelease technology

CONTEXTPolicies and strategies at EU and national level aim at a reduced use of pesticides in agriculture, such as the Farm to Fork Strategy of the EU Commission. Technological progress can lower pesticide application and contribute to a sustainable bioeconomy. As an example, the greenRelease technology increases the attachment of the active ingredient of plant protection products to the leaf surface and slowly releases the active ingredient from a microgel container. Experiments under both controlled and field conditions have demonstrated the potential of the greenRelease technology to reduce pesticide use. As a so-called platform technology, the greenRelease concept can be applied to various crops and plant protection chemicals. OBJECTIVETo guide further development, this study analyses the greenRelease technology regarding its economic potential and its possible contribution to the reduction of environmental and health risks from pesticide use. METHODSTo do so, we use a bio-economic farm model to assess the technology potential for a typical farm and spraying sequences of various crops in northwestern Germany. RESULTS AND CONCLUSIONSThe results reveal that the economic potential of the greenRelease technology is highest for systemic fungicides in all assessed crops as well as for herbicides for potato cultivation. It is lowest for insecticides in winter barley and potato as well as for contact fungicides, due to the small doses and low product costs. The potential to lower possible environmental and health risks of pesticide use, indicated by the Danish pesticide load indicator, is highest for fungicides in potato, winter wheat, and winter barley as well as for herbicides in sugar beet cultivation. Relative to overall costs in arable farming, the cost changes induced by the greenRelease technology are minor, such that the environmental benefits will be key for promoting its application. However, the economic competitiveness of the technology increases if agri-environmental policies progressively internalize the negative externalities of pesticides use. SIGNIFICANCEThis research is the first comprehensive economic and environmental assessment of the technology greenRelease which can contribute to lower the environmental burden of pesticide use in agriculture.

Phenotypic and Genotypic Characterization of Phytophthora infestans Isolates Associated with Tomato and Potato Crops in Colombia.

Late blight disease, caused by the plant pathogen Phytophthora infestans, is one of the major threats for tomato and potato crops. Monitoring the populations of P. infestans is important to determine if there are changes in the sensitivity to fungicides and host preference. In this study, microsatellite markers and mitochondrial haplotypes were used to assess the genotype of isolates of P. infestans collected from tomato and potato plants in Colombia. Furthermore, sensitivity to the three fungicides cymoxanil (penetrant fungicide), mefenoxam, and fluopicolide (systemic fungicides), and tomato-potato host preference, were evaluated. Mitochondrial haplotyping showed that isolates collected on tomato were from the genetic groups Ia and Ib, while isolates collected on potatoes belonged to group IIa. Microsatellite analyses showed that isolates from tomato form two groups, including the Ib mitochondrial haplotype (which is genetically close to the US-1 clonal lineage) and the Ia haplotype (related to the EC-3 lineage), whereas Colombian isolates from potato formed a separate group. Furthermore, differences in sensitivity to fungicides were observed. Eighty-one percent of the isolates tested were resistant to mefenoxam with an EC50 >10 μg ml-1. Forty-two percent of the isolates showed an intermediate resistance to cymoxanil. The EC50 values ranged between 1 and 10 μg ml-1. For fluopicolide, 90% of the isolates were sensitive, with EC50 <1 μg ml-1. Host preference assays showed that potato isolates infected both host species. Thus, isolates that infect potatoes may pose a risk for tomato crops nearby.