Management Of Powdery Mildew Research Articles

An Effective Hybrid Fungicide Containing Tea Tree Oil and Difenoconazole for Grape Powdery Mildew Management

Grape powdery mildew caused by Erysiphe necator (Schw.) Burr. is a destructive disease in vineyards. Synthetic fungicides are the main tool to combat this disease. The search for new alternatives to reduce pesticide usage and tactical approaches for resistance management encouraged us to develop the novel strategy that we report here. We evaluated the efficacy of a new premixed hybrid fungicide containing the demethylation inhibitor (DMI) difenoconazole and essential tea tree oil (TTO), derived from the Melaleuca alternifolia plant, against grape powdery mildew in seven field trials and two large-scale demonstration trials conducted in two different regions in the world, including Chile and Israel. Foliar sprays of difenoconazole-TTO were applied as a preventive treatment in field trials at 40–80 up to 80–160 gr/ha active ingredient, and they were highly effective in controlling powdery mildew on the fruit clusters of both wine and table grapes in experimental and large-scale demonstration trials and provided up to 99% efficacy in disease incidence and severity compared with the untreated control. Difenoconazole-TTO was as or more effective than other DMI fungicides, including difenoconazole, a pre-mixed fungicide boscalid-pyraclostrobin, or treatments that included various fungicides applied in rotation or mixtures of fungicides. The results suggest that a combination of difenoconazole-TTO with a reduced synthetic chemical load can be included in powdery mildew control programs for grapevine as a strategic approach in fungicide resistance management in vineyards.

Effects of synthetic and environmentally friendly fungicides on powdery mildew management and the phyllosphere microbiome of cucumber.

Modern agricultural practices rely on synthetic fungicides to control plant disease, but the application of these fungicides has raised concerns regarding human and environmental health for many years. As a substitute, environmentally friendly fungicides have been increasingly introduced as alternatives to synthetic fungicides. However, the impact of these environmentally friendly fungicides on plant microbiomes has received limited attention. In this study, we used amplicon sequencing to compare the bacterial and fungal microbiomes in the leaves of powdery mildew-infected cucumber after the application of two environmentally friendly fungicides (neutralized phosphorous acid (NPA) and sulfur) and one synthetic fungicide (tebuconazole). The phyllosphere α-diversity of both the bacterial and fungal microbiomes showed no significant differences among the three fungicides. For phyllosphere β-diversity, the bacterial composition exhibited no significant differences among the three fungicides, but fungal composition was altered by the synthetic fungicide tebuconazole. While all three fungicides significantly reduced disease severity and the incidence of powdery mildew, NPA and sulfur had minimal impacts on the phyllosphere fungal microbiome relative to the untreated control. Tebuconazole altered the phyllosphere fungal microbiome by reducing the abundance of fungal OTUs such as Dothideomycetes and Sordariomycetes, which included potentially beneficial endophytic fungi. These results indicated that treatments with the environmentally friendly fungicides NPA and sulfur have fewer impacts on the phyllosphere fungal microbiome while maintaining the same control efficacy as the synthetic fungicide tebuconazole.

Role of new fungicide Pydiflumetofen 7.5% + difenoconazole 12.5% w/v (200 SC) in the management of powdery mildew and anthracnose diseases in grapes.

Grape is a fruit crop of commercial significance in the arena of Indian horticulture. Powdery mildew (c.o. - Erysiphe necator) and anthracnose (c.o. - Elsinoe ampelina/ Colletotrichum gloeosporioides) are the most important biotic constraints in grape. The combination fungicide Pydiflumetofen 7.5% + difenoconazole 12.5% w/v (200 SC) was evaluated for two seasons (2016-17 & 2017-18) in the vineyards of ICAR-National Research Centre for Grapes, Pune, Maharashtra against both the diseases. Different concentrations of Pydiflumetofen 7.5% + difenoconazole 12.5% w/v (200 SC) viz. 400, 500 and 600 ml/ha were compared with its component fungicides, Pydiflumetofen 7.5% and difenoconazole 12.5% w/v (200 SC) separately. Experimental results showed that Pydiflumetofen 7.5% + difenoconazole 12.5% w/v (200 SC) @ 600ml/ha manifested lowest pooled PDI of 10.00 in case of leaves and 10.31 in case of bunches respectively with a corresponding yield of 10.99 t/ha. The test fungicide was not phytotoxic to the grapevines up to the dose of 1200ml/ha. Against anthracnose, the pooled data showed that Pydiflumetofen 7.5% + difenoconazole 12.5% w/v (200 SC) @ 600 ml/ha as foliar spray showed lowest PDI of 10.81. Hence the treatment Pydiflumetofen 7.5% + difenoconazole 12.5% w/v (200 SC) @ 600 ml/ha was effective against powdery mildew as well as anthracnose.

Role of new fungicide pydiflumetofen (7.5%) + difenoconazole (12.5% w/v (200 SC)) in the management of powdery mildew and anthracnose diseases in grapes

Role of new fungicide pydiflumetofen (7.5%) + difenoconazole (12.5% w/v (200 SC)) in the management of powdery mildew and anthracnose diseases in grapes

Persistence of Combination Fungicide, Fluopyram + Tebuconazole Residues and its Risk Assessment in Kidney Bean

Background: Kidney bean is a protein rich legume crop largely cultivated in hilly tracts of India. Fungal diseases are major biotic constraints causing severe yield losses and fluopyram and tebuconazole are most commonly used for the management of powdery mildew and anthracnose diseases. Hence, studies were taken on dissipation pattern and dietary risk assessment of fungicides to establish consumer safety. Methods: A simple QuEChERS analytical method was developed and validated for the analysis of fluopyram its metabolite and tebuconazole in kidney bean immature green pods, mature pods, seeds and soil and analyzed in liquid chromatograph mass spectrometer (LC-MS). The combination fungicide was applied as foliar spray at 125+125 and 250+250 g a.i. ha-1 on kidney bean thrice at 10 days interval. Residues were determined in immature green pods, dry mature pods and soil. Immature green pods were collected on 0 (within 2 hours after last spray), 1, 3, 5, 7, 10, 15 and 20 days after third spray and in dry mature pods and soil collected at the time of harvest. Result: The average recovery and RSD were in the range of 81.63 - 95.48% and 0.55-5.10%, with 0.01 and 0.05 µg mL-1 as LOD and LOQ. The initial concentrations were 0.55 and 1.04 mg kg-1 for fluopyram and 0.57 and 1.03 mg kg-1 for tebuconazole in standard and double dose, respectively. The half-lives were 3.67-4.07 days for fluopyram and 3.86-4.18 days for tebuconazole in standard and double dose. Dietary intake risk of fluopyram and tebuconazole from kidney bean is negligible for adult men, women and children based on RQ values ( less than 1).

Management of Powdery Mildew in Cluster Bean using Fungicides, Botanicals and Bioagents

Background: Cluster bean crop is affected by various biotic and abiotic stresses which are responsible for its poor quality and low yield resulting in severe economic losses. Among the foliar diseases, powdery mildew caused by Leveillula taurica is an important disease causing the yield losses ranging from 50-55 per cent. So, there is a need to formulate suitable management practices against powdery mildew. Methods: Field experiment was laid-out in a randomized complete block design with three replications at Main Agricultural Research Station, University of Agricultural Sciences, Dharwad to determine the efficacy of economically viable and effective fungicides, botanical and bioagent against powdery mildew of cluster bean. Observation on intensity of disease was recorded using 0-9 scale. The per cent disease index and yield per hectare were taken into consideration for statistical analysis. Result: Among the thirteen combinations, two sprays of hexaconazole @ 0.1 per cent was found to be statistically significant in reducing the disease severity (11.75%) and enhancing pod yield (138.46%) upto 6.20 t ha-1 with C: B ratio of 1:3.23. The combined application of nimbecidine and Bacillus subtilis also showed significant impact on disease reduction as well as on yield of cluster bean. Relatively, the chemical, hexaconazole gave a higher benefit with minimum production cost and this approach is proposed to the cluster bean growing farmers to mitigate the powdery mildew.

Combating powdery mildew: Advances in molecular interactions between Blumeria graminis f. sp. tritici and wheat.

Wheat powdery mildew caused by a biotrophic fungus Blumeria graminis f. sp. tritici (Bgt), is a widespread airborne disease which continues to threaten global wheat production. One of the most chemical-free and cost-effective approaches for the management of wheat powdery mildew is the exploitation of resistant cultivars. Accumulating evidence has reported that more than 100 powdery mildew resistance genes or alleles mapping to 63 different loci (Pm1-Pm68) have been identified from common wheat and its wild relatives, and only a few of them have been cloned so far. However, continuous emergence of new pathogen races with novel degrees of virulence renders wheat resistance genes ineffective. An essential breeding strategy for achieving more durable resistance is the pyramiding of resistance genes into a single genotype. The genetics of host-pathogen interactions integrated with temperature conditions and the interaction between resistance genes and their corresponding pathogen a virulence genes or other resistance genes within the wheat genome determine the expression of resistance genes. Considerable progress has been made in revealing Bgt pathogenesis mechanisms, identification of resistance genes and breeding of wheat powdery mildew resistant cultivars. A detailed understanding of the molecular interactions between wheat and Bgt will facilitate the development of novel and effective approaches for controlling powdery mildew. This review gives a succinct overview of the molecular basis of interactions between wheat and Bgt, and wheat defense mechanisms against Bgt infection. It will also unleash the unsung roles of epigenetic processes, autophagy and silicon in wheat resistance to Bgt.

First Report of Powdery Mildew of American Ginseng Caused by Erysiphe heraclei in Tennessee and the United States.

American ginseng (Panax quinquefolius L.), native to the forested regions of northeast U.S is a perennial herb valued as traditional Chinese medicine. It has been cultivated in North America for several decades due to high global demand. Powdery mildew symptoms were observed on 8-year-old cultivated American ginseng leaves (Fig. 1a, b) on a residential property in Rutherford Co., TN in May 2022. Disease severity was 40 to 60% of leaf area and incidence was 33% out of 30 plants. Affected plants exhibited white fungal colonies on the leaves. Under severe infection, the leaves were chlorotic and senescing. Microscopic observation revealed masses of conidia and mycelia on symptomatic tissue. Conidiophores were cylindrical and unbranched (2- or, rarely, 3-septate), measuring 66.7 ± 12.5 μm (n=78) with a range of 24.3 to 90.7 μm. Conidia produced singly or in pseudo-chains (Fig. 1c). Conidiophore foot cells measured 23.2 ± 4.3 μm long (n=54) and the width at the foot cell septum was 5.1 ± 0.6 μm (n=54). Hyphal width was 3.3 ± 0.6 um (n=59). Fresh vacuolated spores were oblong-elliptical to oblong (Fig. 1d) and measured 31.5 × 11.9 μm (n=55), lacked fibrosin bodies. The length-to-width ratio of conidia was 1.9 to 4.4 (avg. 2.7). Superficial mycelia and germinating spores displayed lobed appressorium (Fig. 1e). Detached spore surfaces were wrinkled (Fig. 1f). Morphological characteristics of the fungus matched the description of Erysiphe heraclei (Braun and Cook, 2012) and Erysiphe sp. (Cho et al. 2016) except for conidiophore length, which was shorter in our sample. To confirm pathogen identity, total DNA was extracted directly from single spore cultures (isolates FBG1668 and FBG1728). The ribosomal internal transcribed spacer (ITS) region was amplified using ITS4 and ITS5 primers (White et al. 1990). The sequences (GenBank accession nos. OP458196 and OP469994) showed 100% identity and 100% query coverage to E. heraclei (KY073878 and LC270862). The sequences were also 100% identical to the ITS sequences of E. betae and E. malvae. Solano-Báez et al. (2022) noted that the species in the E. malvae/E. heraclei/E. betae species complex are phylogenetically undistinguishable. E. betae and E. malvae infect plants in Chenopodiaceae and Malvaceae, respectively (Braun and Cook, 2012). However, E. heraclei has been reported to infect plants in Apiaceae. American ginseng belongs to Araliaceae which is a close family to Apiaceae and both belong to Apiales. Based on morphological and molecular identification, both isolates were identified as E. heraclei. Pathogenicity was confirmed by inoculating the adaxial leaf surface of six 2-year-old American ginseng plants. Spores from detached symptomatic leaves were tapped onto the adaxial surface of healthy leaves. Six non-inoculated and inoculated plants were maintained in a greenhouse at 21 to 23°C, 70%RH, with 16-h photoperiod. After 2 weeks, powdery mildew symptoms developed on the inoculated plants. The microscopy and molecular analysis confirmed infection and all control plants remained asymptomatic. Cho et al. (2016) reported powdery mildew on Korean ginseng (P. ginseng C.A. Mey) caused by Erysiphe sp., and Sholberg et al. (1996) reported Erysiphe sp. on P. quinquefolius in Canada, but to our knowledge, this is the first report of powdery mildew caused by E. heraclei on American ginseng in Tennessee and the U.S. Identification and timely management of powdery mildew on American ginseng will be necessary to control this disease in affected growing sites.

Management of powdery mildew and aphid in organically grown Indian mustard (Brassica juncea L.) through different oils

All the cultivated Brassica species exhibited powdery mildew severity with highest (43.2%) on Brassica juncea followed by B. rapa (28.0%) which is widely cultivated in India. Yield losses from 10-90 per cent with reduction in 6.47 per cent oil content have been estimated from different Brassica species. Hence, the present study was carried out to evaluate different oils to manage powdery mildew disease and aphids in an organically grown mustard crop. Five oils (castor, groundnut, sunflower, neem and mustard oil) and ghee were evaluated against powdery mildew (Erysiphae cruciferarum) and aphid (Lipaphis erysimi) of Indian mustard (Brassica juncea). Castor oil 50 EC, neem oil 50 EC and mustard oil 50 EC and deshi ghee 50 EC (@ 100 ml/10 litre water) were effective over untreated control in reducing powdery mildew disease severity when applied as foliar spray (@ 5 ml/litre) in the experiment carried out in organic field (plot No. B-2 at Agronomy Instruction Farm, S. D. Agricultural University, Sardarkrushinagar). Maximum reduction in germinated conidia (66.0%) over control, disease severity (50.0%), area under disease progress curve (AUDPC) values (51.8%) and maximum increase over control in 1000 seed weight (16.7%) and seed yield (10.3%) was observed with neem oil. This was followed by the application of ghee which exhibited reduced disease severity (22.9%) and AUDPC values (30.6%) and increased seed yield (8.1%) and the application of castor oil 50 EC which exhibited an increased in seed yield (8.0%) and reduced powdery mildew severity (20.8%). Shortest log phase was observed with neem oil during 10th std. week. All the oils tested (castor, groundnut, sunflower, neem and mustard oil) and deshi ghee were effective in reducing aphid population (39.5 to 65.9%) and damage index (6.1 to 25.1%). A maximum reduction in aphid population (65.9%) over control and lowest aphid damage index (3.70) was observed with neem oil 50 EC 6 days after 2nd spray. Application of neem oil, castor oil and deshi ghee resulted in increased seed yield (8.1 to 10.4%). This information could be useful in devising strategies for powdery mildew and aphid management in organic cultivation, eco-friendly management and IPM of mustard.

Can Comparable Vine and Grape Quality Be Achieved between Organic and Integrated Management in a Warm-Temperate Area?

The high demand for wine in Europe has increased the impact of viticulture on the environment. In line with European objectives, more sustainable agronomic practices have spread as an alternative to traditional management. This study aimed to compare, in a vineyard of Pinot blanc and Rhine Riesling in northeast Italy, the integrated agronomic practices (INT) with two types of organic management (ORG1—cattle manure and ORG2—green manure), in terms of production, grape quality, pest susceptibility, and soil nutrient availability. The results, after the fifth, sixth, and seventh year of testing, showed that organic management obtained a yield and vegetative features comparable to INT. Grape quality also did not show considerable overall differences between the theses in the must properties, despite the higher total sugar content and lower yeast available in ORG1. In the three-year period, the management of downy mildew, powdery mildew, and rot, as well as the soil fertilization, with the products available in organic farming proved to be comparable to the INT method. The application of cattle manure contributed by enriching the soil in K and P, while a balanced green manure mix has proven to be the best agronomic practice in terms of the release of mineral N during the phenological stages of greatest need of the vine. Organic management appears as an agronomic strategy able quantitatively and qualitatively support the vineyard system.

Alternative products in the management of powdery mildew (Podosphaera xanthii) in melon

Alternative products in the management of powdery mildew (Podosphaera xanthii) in melon

A Comparative Analysis of Microbe-Based Technologies Developed at ICAR-NBAIM Against Erysiphe necator Causing Powdery Mildew Disease in Grapes (Vitis vinifera L.).

Globally, Erysiphe necator causing powdery mildew disease in grapevines (Vitis vinifera L.) is the second most important endemic disease, causing huge economic losses every year. At present, the management of powdery mildew in grapes is largely dependent upon the use of chemical fungicides. Grapes are being considered as one of the high pesticide-demanding crops. Looking at the residual impact of toxic chemical pesticides on the environment, animal, and human health, microbe-based strategies for control of powdery mildew is an emerging technique. It offers an environment-friendly, residue-free, and effective yet safer approach to control powdery mildew disease in grapes. The mode of action is relatively diverse as well as specific to different pathosystems. Hence, the aim of this study was to evaluate the microbe-based technologies, i.e., Eco-pesticide®, Bio-Pulse®, and Bio-Care 24® developed at the Plant-Microbe Interaction and Rhizosphere Biology Lab, ICAR-NBAIM, Kushmaur, against grape powdery mildew and to integrate these technologies with a safer fungicide (sulfur) to achieve better disease control under organic systems of viticulture. The experiments were conducted at four different locations, namely, the vineyards of ICAR-NRCG, Rajya Draksha Bagayatdar Sangh (MRDBS), and two farmers' fields at Narayangaon and Junnar in the Pune district of Maharashtra. A significantly lower percent disease index (PDI) was recorded on the leaves of grape plants treated with Eco-Pesticide®/sulfur (22.37) followed by Bio-Pulse®/sulfur (22.62) and Bio-Care 24®/sulfur (24.62) at NRCG. A similar trend was observed with the lowest PDI on bunches of Eco-pesticide®/sulfur-treated plants (24.71) followed by Bio-Pulse®/sulfur (24.94) and Bio-Care®/sulfur (26.77). The application of microbial inoculants singly or in combination with sulfur has a significant positive impact on the qualitative parameters such as pH, total soluble solids (TSS), acidity, berry diameter, and berry length of the grapes at different locations. Among all the treatments, the Bio-Pulse®/sulfur treatment showed the highest yield per vine (15.02 kg), which was on par with the treatment Eco-Pesticide®/sulfur (14.94). When compared with the yield obtained from the untreated control, 2.5 to 3 times more yield was recorded in the plants treated with either of the biopesticides used in combination with sulfur. Even in the case of individual inoculation, the yield per vine was approximately two times higher than the untreated control and water-treated plants across the test locations. Results suggested that microbial technologies not only protect grapevines from powdery mildew but also enhance the quality parameters with increased yield across the test locations.

Mechanisms of resistance to powdery mildew in cucumber

Podosphaera xanthii causes powdery mildew of cucumber, and is associated with significant yield and quality losses. Development of resistant or tolerant varieties is the most effective and eco-friendly strategy for powdery mildew management. An important host resistance mechanism is based on the recognition of conserved resistance genes, resulting in durable resistance. To determine powdery mildew resistance mechanisms in cucumber, total RNAs were isolated from the powdery mildew resistant cultivar Meltem, the tolerant line VT18, and the susceptible local variety Camlica. Expression levels of nine genes in these plants were analysed by Reverse Transcription Polymerase Chain Reaction (RT-PCR). The host reactions were assessed using microscope observations of stained specimens. Serine/threonine (STN7), transcription factor (WRKY22), serine/threonine-protein kinase (D6PKL1), and serine/threonine receptor kinase (NFP) genes were induced, as positive regulators in defence mechanisms against powdery mildew. Polygalacturonase Inhibitor (PGIP) did not express after P. xanthii inoculation of Camlica, resulting in susceptibility. After inoculation, callose synthase (CALLOSE) and cinnamyl alcohol dehydrogenase (CAD) gene expression levels were increased in resistant Meltem, but Hypersensitive Reaction (HR) and ROS formation were only linked in the tolerant VT18. Powdery mildew development was less in Meltem than in VT18, indicating that cell wall thickening and HR play separate roles in resistance to this disease.

Optimizing Use of DMI Fungicides for Management of Apple Powdery Mildew Caused by Podosphaera leucotricha in New York State.

Powdery mildew, caused by the ascomycete Podosphaera leucotricha, is an endemic disease found wherever apples are grown that reduces both tree vigor and fresh market yield. In the absence of durable host resistance, chemical management is the primary means of disease control. Demethylation inhibitor (DMI) fungicides are widely used to manage apple powdery mildew, but members within this fungicide class have been observed to differ in efficacy with respect to disease control. Moreover, debate exists as to the optimal timing of DMI fungicide applications for management of apple powdery mildew. In this regard, the goal of this study was to determine the best-use practices for DMI fungicides to manage apple powdery mildew in New York State. Multiyear trials were conducted to evaluate the potential differential efficacy performance of four common DMI fungicides, and additional trials were conducted to assess optimal application timing. In all years, we observed that treatments of flutriafol and myclobutanil consistently had the lowest incidences of powdery mildew compared with difenoconazole and fenbuconazole. In the 2018 and 2021 trials, the newly registered mefentrifluconazole was more comparable to the difenoconazole program with respect to powdery mildew disease incidence. We hypothesize that differences in DMI efficacy may result from each fungicide's water solubility and lipophilicity characteristics and thus their ability to move systemically in the host or more easily penetrate the surface of germinating conidia. Applications timed between petal fall and first cover resulted in the lowest incidence of powdery mildew on terminal leaves of apple shoots compared with applications timed before petal fall. These observations are contrary to previous studies conducted in regions with differing climates. We also found that the incidence of secondary powdery mildew observed 2 weeks after petal fall was influenced by applications of DMI fungicides during the previous season. For example, management programs consisting of applications of flutriafol or myclobutanil in the previous season tended to have lower incidence of apple powdery in the next spring, presumably because of reductions in overwintering inoculum. Despite reports of DMI resistance in other apple pathosystems, the DMI fungicide class is still relevant for the successful management of apple powdery mildew in New York State.

Biological Approaches Promise Innovative and Sustainable Management of Powdery Mildew in Lebanese Squash

Biological management techniques act as a promising and sustainable alternative to alleviate pathogen-induced losses, improve ecosystem functions, and reinforce the resilience of agricultural systems. Lebanese squash production has been threatened by powdery mildew disease caused by the fungus Podosphaera xanthii. Very few studies, even unpublished ones, stress the evaluation of biological control approaches in the Lebanese agriculture sector. Here, we have aimed to evaluate the effect of five safe biological treatments (olive soap, sodium bicarbonate, garlic extract, horsetail, and compost tea) in the management of powdery mildew on Lebanese squash in organic open field conditions. Plants were treated after the first spots of powdery mildew appeared on leaves. We then examined the leaves to evaluate disease incidence and severity, and to compare the ability of the five treatments to reduce powdery mildew disease and incidence, in comparison with the untreated control. Plants treated with sodium bicarbonate and garlic extract were the least affected by powdery mildew regarding disease incidence and severity, while tea compost proved to be the least effective product. Organic management of vegetable crops is extremely important in order to ensure global food security and reduce pesticide applications.

Integrating management of powdery mildew with Botrytis in protected strawberries in the UK

Powdery mildew, caused by Podosphaera aphanis, is an important disease of strawberries under protection. Botrytis fruit rot is an important cause of losses in strawberries particularly under open-field conditions. Current control of both these diseases in the UK is dependent on conventional fungicides. Recently, research in the UK demonstrated that integrating biopesticides and biostimulants with a decision-based management programme could achieve reductions in conventional fungicide use without loss in yield or fruit quality. Further field studies were conducted to extend the decision-based management programme to include control of Botrytis fruit rot on everbearer crops. In 2018, three management programmes were compared to a routine fungicide-based programme and an untreated control. In two management programmes, treatments for Botrytis and powdery mildew were either applied routinely or managed. In the third programme, treatments for both diseases were managed. Disease risks were estimated with a simple lookup table based on past and forecast weather. The results showed that the integrated management for both diseases resulted in a nearly 45% reduction in conventional fungicide use and a cost saving of £699/ha compared to a routine programme with no penalties in yield, fruit quality or disease control. There were no significant effects of treatments on Botrytis rot incidence compared to the untreated control, suggesting that the fungicides applied for controlling Botrytis gave no benefit. In 2019, two treatments based on the decision-based management system for powdery mildew and Botrytis, one of which excluded specific fungicide treatment for Botrytis, were compared to an untreated control and a routine fungicide programme. Cool chain management of the fruit post-harvest was also included to extend post-harvest fruit shelf life. The results showed that the simple decision-based system for determining treatments for mildew and Botrytis based on biopesticides and omitting Botrytis-specific fungicides resulted in a 93% reduction in fungicide use and a cost saving of £924/ha compared to a routine programme with no penalties in yield, fruit quality or disease control. Cool chain management delayed the development of both Botrytis and soft rots. In both years, detectable fungicide residues were considerably reduced in the fruit from the managed programmes.

Podosphaera leucotricha (Ellis et Everhart) Salmon - prouzrokovač pepelnice jabuke

Apple powdery mildew, caused by Podosphaera leucotricha, is one of the economically most important apple diseases. It is present in all regions where the apple is grown, and it can cause production loss of up to 50%. The appearance of white mycelium on leaves, flowers and shoots is the typical symptom of this disease. If the disease is not managed properly, fruits are not formed, causing direct yield loss. Furthermore, fruit russet appears on the infected fruit, resulting in decreased market value. Disease intensity mostly depends on ecological factors and the susceptibility of the apple variety. Nowadays, significant efforts are being made in order to develop resistant apple varieties, but this goal is yet to be achieved. Management of apple powdery mildew in commercial production is based on chemical control measures, but due to health and environmental concerns, as well as the development of fungicide-resistant populations of the pathogen, it is necessary to find effective biological control methods as an alternative to chemicals.

Suppression of Hemp Powdery Mildew Using Root-Applied Silicon

Powdery mildew (Golovinomyces spadiceus) is the most common disease of greenhouse cannabis. Most hemp grown for cannabinoid production is propagated by cuttings or started from feminized seed in greenhouses and then moved outdoors, while most marijuana and some hemp are grown entirely indoors. To determine the effects of silicon on powdery mildew in the greenhouse, silicon was applied to hemp roots in a peat-based soilless mix and evaluated for plant uptake and disease suppression over a 6-week period. This study confirmed that there was a negative linear relationship between percent silicon accumulation in leaf tissue and the percent powdery mildew per leaf area. Mildew severity in the upper canopy was significantly reduced at 300 kg/ha of silicon, while 600 kg/ha was needed for the mid canopy. Results confirmed that silicon may be a useful tool for the integrated management of powdery mildew. As the cannabis market expands, silicon can serve as a viable option for greenhouse growers, especially for plants grown in soils or soilless mixes low or limiting in soluble silicon.

Biopriming and integrated management of powdery mildew and anthracnose disease of chilli caused by Colletotrichum capsici (Sydow)

Field experiment evaluating therein the effect of integrated use of seed treatment, vermicompost enriched with Tricoderma harzianum, seedling dip and foliar application of fungicides, conducted with the aim of finding safer alternatives to chemical fungicides for management of foliar diseases of chilli powdery mildew and anthracnose/fruit rot diseases during kharif 2015 and 2016 revealed that seed treatment with T. harzianum @ 10 g kg−1 at nursery followed by seedling dip with Pseudomonas fluorescens @ 10 g L−1 and spot application of enriched P. fluorescens (1.0 kg P. fluorescens enriched in 100 kg farm yard manure) @ 250 kg ha−1 followed by spray of (tebuconazole 50% + trifloxistrobin 25% WG) @ 0.5 g L−1 recorded least per cent disease index 47.80 and 33.30 per cent for anthracnose and powdery mildew, respectively, and recorded highest dry chilli yield (12.76 q ha–1) with net returns of ₹99,598 and highest B: C ratio (1:2.74) as compared to untreated check with 73.82 and 69.10 per cent disease index and dry chilli yield of 5.37 q ha−1.

Effective Management of Cucumber Powdery Mildew with Essential Oils

This research evaluated the efficacy of essential oils in the management of cucumber powdery mildew. Essential oils of lemongrass, lemon, thyme, peppermint, abundance blend, purification blend, and thieves blend were tested in vitro and under greenhouse conditions in two separate experiments. The effects of essential oils were tested against powdery mildew disease at concentrations of 1.0–2.5 mL/L, and the consequent impact of the oils on plant growth was evaluated. Powdery mildew fungus, Podosphaera xanthii, was identified using sequencing of the ITS region. The essential oils significantly reduced disease incidence up to 77.3% compared with the positive control (p < 0.5). Moreover, the essential oils increased the plant length (up to 187 cm), leaf area (up to 27.5 cm2), fresh weight (up to 123 g), dry weight (up to 22.5 g), number of flowers (16.3), and metabolite content compared with the positive control (p < 0.5). Cell membrane injury decreased significantly in the oil-treated pants (p < 0.5), indicating the protective effect of essential oils. This study recommends the application of essential oils in an appropriate dose (2.5 mL/L) to protect cucumber plants against powdery mildew. Overdose of the oils (more than 2.5 mL/L) should be avoided due to adverse effects.