Control Of Powdery Mildew Research Articles

Sensitivity reduction in Blumeria graminis f. sp. hordei to triadimenol fungicide applied as barley seed treatment

Experiments were carried out in a growth chamber with controlled temperature and photoperiod to test two populations of Blumeria graminis f. sp. hordei from Guarapuava, Paraná State, and Passo Fundo, Rio Grande do Sul State, Brazil. Treatments consisted in application of the fungicide triadimenol (Baytan 150 SC®) at three rates of its commercial formulation: 150, 250, 350 mL/100 Kg barley seeds. The experiments were conducted separately in a growth chamber for each population, adopting the same temperature and photoperiod. For inoculation, pots containing barley seedlings colonized by the fungus were placed among the plots. After emergence of the first symptoms, the disease severity was assessed at two-day intervals. The experiments were repeated twice for each fungus population. Data were expressed as area under the disease progress curve and as powdery mildew control by comparing the severity after the fungicide treatments to that of control. Data were subjected to analysis of variance and regression analysis; the area under the disease progress curve was also calculated. Comparing the data obtained in the present study with those reported in the literature and the control, the maximum value of 26.1% is considered insufficient to prevent the damages caused by the disease. The control response to the fungicide rate was significant. We can conclude that there was a reduction in the sensitivity of both B. graminis f.sp. hordei populations to the fungicide triadimenol, which explains the control failure observed in barley farms.

Essential oils and whole milk in the control of soybean powdery mildew

This research aimed to evaluate the potential of essential oils (EOs) and cow's whole milk (CWM) in order to control soybean powdery mildew and to estimate the most effective concentrations of these natural products in reducing the disease severity on soybean plants. Three experiments were carried out: The first experiment evaluated and selected the most effective treatments to reduce the severity of soybean powdery mildew under greenhouse conditions; the second experiment evaluated the effect of CWM and EOs of citronella, lemongrass, eucalyptus, cinnamon and tea tree on the pathogen through the ultrastructure analysis of soybean leaflets infected by Erysiphe diffusa using the scanning electron microscope (SEM) and light microscope (LM) technology. In the third experiment, the most effective products were tested at several concentrations in order to define the most effective concentrations to reduce disease severity under greenhouse conditions. The treatments CWM (100mL L-1) and EOs of citronella, lemongrass and eucalyptus (1.0mL L-1), reduced the disease severity from 67 to 74%. Direct effects from all natural products tested on the structures of E. diffusa were demonstrated through the SEM and LM analysis. Concentrations at 1.5mL L-1 for EOs of citronella, lemongrass and eucalyptus and also at 180mL L-1 for the treatment CWM were the most effective against E. diffusa on soybean.

Eficiência do silicato de potássio no controle do oídio e no desenvolvimento de abobrinha de moita

A medida mais utilizada para o controle de oídio em cucurbitáceas é o uso de variedades resistentes e fungicidas sistêmicos, entretanto, a nutrição silicatada tem se mostrado uma opção. O fornecimento do silício é benéfico para muitas espécies vegetais, estimulando o crescimento, a produção, a fotossíntese e a regulação da transpiração; além disso, sua deposição na epiderme evita a invasão de fungos, bactérias e insetos sugadores. O objetivo deste trabalho foi verificar a influência do silicato de potássio no controle do oídio, e no desenvolvimento e na produção de abobrinha de moita, cultivar Caserta. O experimento foi conduzido em cultivo protegido, com delineamento inteiramente casualizado, quatro repetições e cinco tratamentos: testemunha (água); tratamento químico com fenarimol (2,4 g i.a 100 L-1) e silicato de potássio, nas doses de 1,5 L ha-1; 2,0 L ha-1 e 2,5 L ha-1. Foram avaliados a severidade da doença; trocas gasosas; crescimento e produção de frutos. Os resultados mostraram que a aplicação foliar de silicato de potássio com fenarimol controlou o oídio e não teve influência no crescimento da planta. Portanto, o silicato de potássio pode ser utilizado como alternativa para o controle desse fungo e diminuição da aplicação de produtos químicos, o que proporciona uma maior sustentabilidade ambiental. No entanto, deve-se tomar cuidado com dosagens altas, pois observou-se que a dosagem de 2,5 L ha-1 foi prejudicial à produção de frutos e às trocas gasosas, apesar de ter sido eficiente no controle do oídio. Recomenda-se o uso de 2,0 L ha-1 de silicato de potássio para o controle de oídio para abobrinha de moita, podendo substituir o uso de fenarimol, sem afetar a produção e desenvolvimento das plantas.

난황유를 이용한 단감 흰가루병 방제*

난황유를 이용한 단감 흰가루병 방제*

English

Apple scab caused by Venturia inaequalis (Cooke) wint, and apple powdery mildew, caused by Podosphaera leucotricha (Ell. and Ev.), are the most important diseases of apples in Uganda. Control of apple scab and powdery mildew require the application of fungicides in absence of resistant apple cultivars. This study was conducted to identify effective control fungicides and to document the status of these diseases in south western Uganda. The survey results of 2012 indicated that scab incidence was highest in districts of Kanungu (71.90%), followed by Kisoro (48.14%), Kabale (41.03%), Buhweju (29.23%), Mbarara (28.75%) and Rukungiri (17.80%). The severity of apple scab measured as percentage leaf area affected ranged from 20.12 to 76.19%. Powdery mildew incidence ranged from 30.00 to 70.00% with severity score ranging from 14.63 to 76.19%. Fungicides containing  propineb (70% a.i), metalazyl (4% a.i) + macozeb (64% a.i), and bupirimate (25% a.i) were found to be effective at controlling apple scab with potential to reduce the disease severity by 61.11, 61.11 and 58.33%, respectively, while fungicides containing bupirimate (25% a.i), tebuconazole (43% a.i)  and propineb (58% a.i) + cymoxanil (4.8% a.i) were more effective in the control of powdery mildew with potential to reduce the infection by 55.95, 39.12 and 20.84%, respectively.   Key words: Apple scab, powdery mildew and fungicides.

Coffee-leaf extract and phosphites on the curative control of powdery mildew in eucalyptus mini-stumps

Summary The aim of this study was to evaluate the effectiveness of a plant extract obtained from the leaves of coffee plants infected by Hemileia vastatrix (NEFID), different formulations of phosphites and the combination of the extract and phosphites in controlling powdery mildew in eucalyptus mini-stumps, as well as to study the effects on the production of mini-cuttings and their rooting percentage. The experiments were conducted on two eucalyptus hybrids (‘urocam’ and ‘urograndis’) in a clonal garden and greenhouse. First, the NEFID plant extract and phosphites of copper, zinc, potassium and potassium/manganese were evaluated to determine their effectiveness in controlling powdery mildew and their toxic effect on the fungus' morphology. Subsequently, we analysed the direct fungitoxicity, curative efficiency and anti-sporulating action of the NEFID extract and various combinations of phosphites with or without the extract, and we also evaluated their effects on shoot production and rooting in eucalyptus mini-cuttings. The NEFID plant extract and phosphites of Cu, Zn and K/Mn were more effective than the fungicide pyraclostrobin + epoxiconazole in the control of powdery mildew. Potassium phosphite was not effective in controlling the pathogen. Among the tested mixtures, the combination of 50% NEFID plant extract and 50% copper phosphite was the most effective because it exhibited direct toxicity on powdery mildew, a high curative efficiency, anti-sporulating action and no adverse effects on the production of shoots or rooting in eucalyptus mini-cuttings.

Fontes de fosfito e acibenzolar-S-metílico associados a fungicidas para o controle de doenças foliares na cultura da soja

The goal of this study was to evaluate commercial sources of phosphite and acibenzolar-S-methyl (ASM) followed by one fungicide application on the control of downy mildew, powdery mildew and asian soybean rust, reducing the number of fungicide applications and increasing the control spectrum of these soybean diseases. Two field experiments were carried out in Ponta Grossa, Parana state, Brazil, during the 2006/07 and 2007/08 growing seasons. The experimental design was of randomized blocks with four replications. Treatments consisted on five sources of potassium phosphite and one of manganese (450 g P2O5 ha-1) and ASM (12.5 g a.i. ha-1) sprayed at the V7 and R2 stages. Phosphite- and ASM-treated plants received one application of the fungicide piraclostrobine + epoxiconazol (66.5 + 25 g i.a. ha-1) at the R3 stage and were compared to plants which received two fungicide applications at the R2 and R5.1 stages, as well as to untreated plants. The use of phosphite and ASM significantly reduced the AUDPC for downy mildew. No effects were observed for powdery mildew and Asian rust. The higher number of fungicide application increased the control of biotrophic fungi under higher disease pressure.

Efficacy of Fungicides and Rotational Programs for Management of Powdery Mildew on Cantaloupe.

Powdery mildew of cucurbits, caused by Podosphaera xanthii (syn. Sphaerotheca fuliginia auct. p.p. (Schltdl.) Pollacci), is a common and often severe disease in most areas of the world. Field trials were conducted with cantaloupe to compare disease management success provided by conventional fungicides and biofungicides having different inherent efficacies and modes of action, when applied alone throughout the treatment period or as components of fungicide application programs. Additionally, the portion of total disease control provided by each component fungicide within selected rotational programs was determined. When applied alone throughout the treatment period, disease severity in 2008 and 2009 compared with nontreated plants was reduced by values of 100, 99.3, and 98.1% by wettable sulfur (Microthiol Disperss), triflumizole (Procure), and quinoxyfen (Quintec), respectively; 83.9, 76.4, and 57.4% by trifloxystrobin (Flint), pyraclostrobin (Cabrio), or azoxystrobin (Quadris), respectively; and 39.8, 31.1, 30.0, and 28.6% by thiophanate-methyl (Topsin M), potassium bicarbonate (Kaligreen), kresoxim-methyl (Sovran), and Bacillus subtilis (Serenade), respectively. Rotational application programs composed of Microthiol Disperss, Procure, and Quintec reduced powdery mildew severity on cantaloupe by 97.5 to 100% in both trials. In comparison, disease reduction of 86.0 to 100% was achieved when the first and third fungicide applications were Quintec or Procure and the second and fourth applications were Cabrio, Flint, Kaligreen, Quadris, Serenade, Sovran, or Topsin M. In field trials designed to elucidate the portion of total disease control provided by each component fungicide within a rotational program, application sequences of Procure, Streptomyces lydicus (Actinovate), Procure, and Actinovate or Procure, Kaligreen, Procure, and Kaligreen resulted in reductions in powdery mildew severity of 69.1 and 78.7%, respectively. In comparison, inclusion of only the two Procure applications brought about a mean disease reduction of 85%, whereas inclusion of only the two Actinovate or Kaligreen applications reduced the level of powdery mildew control to 17.6 and 12.9%, respectively. The usefulness of fungicides with low inherent efficacy as resistance management partners when applied with highly efficacious at-risk fungicides may be questioned; however, the importance of any fungicide as a resistance management partner should be measured by its ability to dilute the selection pressure of the at-risk fungicide and to inhibit the growth of any resistant biotypes that may arise, factors which may not be reflected by its inherent efficacy in controlling disease. Because less efficacious fungicides did not increase the overall level of disease control, encouraging growers and pest control advisors to incorporate them into powdery mildew treatment programs may be a challenge, because resistance management is not their top priority. An ongoing educational effort emphasizing the benefits of resistance management programs with respect to prolonging the effectiveness of single-site mode of action fungicides is essential.

The antagonistic strain Bacillus subtilis UMAF6639 also confers protection to melon plants against cucurbit powdery mildew by activation of jasmonate- and salicylic acid-dependent defence responses.

Biological control of plant diseases has gained acceptance in recent years. Bacillus subtilis UMAF6639 is an antagonistic strain specifically selected for the efficient control of the cucurbit powdery mildew fungus Podosphaera fusca, which is a major threat to cucurbits worldwide. The antagonistic activity relies on the production of the antifungal compounds iturin and fengycin. In a previous study, we found that UMAF6639 was able to induce systemic resistance (ISR) in melon and provide additional protection against powdery mildew. In the present work, we further investigated in detail this second mechanism of biocontrol by UMAF6639. First, we examined the signalling pathways elicited by UMAF6639 in melon plants, as well as the defence mechanisms activated in response to P. fusca. Second, we analysed the role of the lipopeptides produced by UMAF6639 as potential determinants for ISR activation. Our results demonstrated that UMAF6639 confers protection against cucurbit powdery mildew by activation of jasmonate- and salicylic acid-dependent defence responses, which include the production of reactive oxygen species and cell wall reinforcement. We also showed that surfactin lipopeptide is a major determinant for stimulation of the immune response. These results reinforce the biotechnological potential of UMAF6639 as a biological control agent.

Study on the Control of Leaf Mold, Powdery Mildew and Gray Mold for Organic Tomato Cultivation

Study on the Control of Leaf Mold, Powdery Mildew and Gray Mold for Organic Tomato Cultivation

Evaluation of dodine, fluopyram and penthiopyrad for the management of leaf spot and powdery mildew of tart cherry, and fungicide sensitivity screening of Michigan populations of Blumeriella jaapii

Field trials were conducted on the tart cherry cultivar Montmorency to evaluate the efficacy of dodine and the succinate dehydrogenase inhibitor (SDHI) fungicides fluopyram and penthiopyrad for control of cherry leaf spot (CLS) and powdery mildew (PM). The in vitro sensitivity of Blumeriella jaapii (CLS) to the same fungicides was also tested. Treatments with dodine or fluopyram were among the most effective for controlling CLS, while fluopyram or penthiopyrad treatments were among the most effective for controlling PM. In vitro studies detected a wide range of minimum inhibitory concentrations (MICs) among the isolates (0.05-400 µg AI mL(-1) ) in response to dodine. Orchard isolates showed reduced sensitivity to dodine as compared with baseline isolates. B. jaapii was more sensitive to fluopyram (0.01-10.0 µg AI mL(-1) ) than to penthiopyrad (0.01-25 µg AI mL(-1) ), and orchard isolates also showed a shift towards reduced sensitivity. The results indicate that dodine remains effective in CLS control. In addition, as penthiopyrad and fluopyram become available to growers, this research establishes baseline information that will be important for future monitoring and analysis of B. jaapii population responses to exposure to dodine and these SDHI fungicides.

Combining sanitation and disease modelling for control of grapevine powdery mildew

Chasmothecia of Erysiphe necator form in one season, survive winter and discharge ascospores that cause primary infections and trigger powdery mildew epidemics in the next season. A strategy for powdery mildew control was developed based on (i) the reduction in overwintering chasmothecia and on (ii) spring fungicide applications to control ascosporic infections timed based on estimate risk (two to five sprays per season). Several fungicides, the hyperparasite Ampelomyces quisqualis, and a mineral oil product were first tested as separate applications in a greenhouse and in vineyards. In the greenhouse, A. quisqualis suppressed chasmothecia formation by 41 %; fungicides and mineral oil suppressed chasmothecia formation by 63 % and ascospore viability by 71 %. In vineyards, application of boscalid + kresoxim-methyl or meptyldinocap once after harvest, as well as application of A. quisqualis pre- and post-harvest, delayed disease onset and epidemic development in the following season by 1 to 3 weeks and lowered disease severity (up to the pea-sized berry stage) by 56 to 63 %. Risk-based applications of sulphur and of synthetic fungicides provided the same control as the grower spray program but required fewer applications (average reduction of 47 %). Sanitation strategies were then tested by combining products and application times (late-season, and/or pre-bud break, and/or spring). Adequate disease control with a reduced number of sprays was achieved with the following combination: two applications of A. quisqualis (pre- and post-harvest), one application of mineral oil before bud break, and model-based applications of sulphur fungicides between bud break and fruit set.

Strobilurin (QoI) Resistance in Populations of Erysiphe necator on Grapes in Michigan.

Powdery mildew, caused by Erysiphe necator, is the most common and destructive disease of grapes (Vitis spp.) worldwide. In Michigan, it is primarily controlled with fungicides, including strobilurins (quinone outside inhibitors [QoIs]). Within the United States, resistance to this class of fungicides has been reported in E. necator populations in some east coast states. Among 12 E. necator isolates collected from five Michigan vineyards in 2008, one carried the G143A single-nucleotide mutation responsible for QoI resistance. This isolate was confirmed to be resistant in a conidium germination assay on water agar amended with trifloxystrobin at 0.001, 0.01, 0.1, 1, 10, or 100 μg/ml and salicylhydroxamic acid (100 mg/liter). The mutant isolate was able to germinate on media amended with 100 μg/ml trifloxystrobin, whereas a representative wild-type isolate did not germinate at concentrations higher than 0.1 μg/ml. In 2009, 172 isolates were collected from a total of 21 vineyards (juice and wine grapes): three vineyards with no fungicide application history (baseline sites), six research vineyards, and 12 commercial vineyards. QoI resistance was defined as the effective concentration that inhibited 50% of conidial germination (EC50) > 1 μg/ml. Isolates from baseline sites had EC50 values mostly below 0.01 μg/ml, while isolates that were highly resistant to trifloxystrobin (EC50 > 100 μg/ml) occurred in five research and three commercial wine grape vineyards at frequencies of 40 to 100% and 25 to 75% of the isolates, respectively. The G143A mutation was detected in every isolate with an EC50 > 1 μg/ml. These results suggest that fungicide resistance may play a role in suboptimal control of powdery mildew observed in some Michigan vineyards and emphasizes the need for continued fungicide resistance management.

Controlling powdery mildew on cucurbit rootstock seedlings in the greenhouse with fungicides and biofungicides

Powdery mildew (Podosphaera xanthii) affects seedlings of inter-specific hybrid squash (Cucurbita moschata × Cucurbita maxima) and bottle gourd (Lagenaria siceraria) used as rootstocks to graft seedless watermelon (Citrullus lanatus var. lanatus). Because powdery mildew grows primarily on the leaf surface where contact fungicides are effective, biofungicides may be effective preventative treatments for powdery mildew. The objectives of this study were to determine which biofungicides, organic fungicides, and conventional synthetic fungicides provided the best control of powdery mildew and least phytotoxicity on cucurbit rootstock seedlings in the greenhouse. Sixteen treatments (six biopesticides, four additional organic-approved fungicides, and six conventional synthetic fungicides) were tested. Four experiments were conducted and all were repeated once. Hybrid squash ‘Strong Tosa’ seedlings were used in the first three experiments, and bottle gourd ‘Emphasis’ seedlings were used in experiment four. In experiments one, two, and four, seedlings were sprayed three times at 5-day intervals and exposed to powdery mildew continuously after the first application. In the third experiment, seedlings were exposed to inoculum for 7 days, sprayed once, and held in a humidity chamber for 7 days under conditions used for healing after grafting. The most effective organic-approved fungicides were sulfur and fish oil + sesame oil, and the most effective conventional fungicides were penthiopyrad, myclobutanil, and cyprodinil plus fludioxonil. Quinoxyfen was phytotoxic to cotyledons of both species, and tebuconazole stunted both species. To manage powdery mildew, one or two preventative applications of sulfur or fish oil + sesame oil and one application of myclobutanil or penthiopyrad, if needed, are recommended.

Integration of Elicitors and Less-Susceptible Hybrids for the Control of Powdery Mildew in Organic Tomato Crops.

Powdery mildew is a serious economic problem in Mediterranean tomato production. The disease is currently controlled by fungicides (especially sulfur) in both conventional and organic production. Four factorial greenhouse experiments were conducted in successive cropping seasons (autumn 2005, autumn 2006, spring 2006, and spring 2007) to assess the main and combined effects of (i) a less-susceptible hybrid ('Elpida'), (ii) chitin soil amendment, or (iii) Milsana or chitosan elicitor foliar treatments on the severity of powdery mildew and crop performance. Analysis of variance revealed significant effects of cropping season on disease severity and crop yield. All control practices reduced disease severity; reductions of approximately 40, 30, 15, and 15% were achieved by Milsana foliar treatment, the use of a less-susceptible hybrid, chitosan foliar treatment, and chitin soil amendment, respectively. In the season with the highest disease pressure, higher yields were obtained with the less-susceptible hybrid Elpida whereas, in the three seasons with no or low disease pressure, the use of the more susceptible hybrid 'Bison' produced higher yields. Milsana and sulfur treatments did not significantly affect yield (yields were slightly lower compared with untreated control plants) and, therefore, their use cannot be recommended based on the results obtained.

Agronomic and economic effects of host resistance vs. fungicide control of barley powdery mildew in southern Sweden

Agronomic and economic effects of powdery mildew host resistance and a fungicide treatment were investigated in nine ‘Pallas’ near-isogenic barley lines. Four years of field trials and virulence surveys detected virulence against all fourteen mildew resistance genes present in the lines. In the field trials, with the exception of gene Mlra, the resistance genes were found to significantly reduce disease severity by 38–99%. The gene mlo5 had a significant negative effect on agronomic characters, while the other resistance genes were neutral. Fungicide treatment reduced powdery mildew by 50–97% and increased grain yield 11–17%, thousand grain weight 6–10%, grain volume weight 2–3% and water content 8–13%, while there was no significant effect on straw strength. From an agronomic perspective, the benefit of the fungicide treatment was greater than that of the selected host resistance. Profitability was directly related to the grain price and cost of fungicide. Net return was negative when using fungicides in years with the lowest grain price, while a higher grain price resulted in a positive net return. It thus seems unprofitable to use fungicides in years with low grain prices, especially when cultivars with effective host resistance are available.

Optimization of integrated pest management for powdery mildew (Unincula necator) control in a vineyard based on a combination of phenological, meteorological and aerobiological data

SUMMARYPowdery mildew is one of the most important vineyard diseases. Infection requires the interaction of a susceptible host (a vine in a phenological phase susceptible to the pathogen), a virulent pathogen (the fungusUncinula necator(Schw.) Burr) and an environment favourable for disease development (optimal meteorological conditions). The aim of the present study was the implementation of a system to predict powdery mildew infection periods in order to optimize and reduce the application of pesticide treatments in a vineyard. The study was conducted in a vineyard of the ‘Ribeiro’ Designation of Origin region located in north-western Spain from 2006 to 2011, during the Vitis vegetative period. The phenological study was conducted following the BBCH phenological scale and infection risk index (IRI) was calculated based on the maximum temperature. Aerobiological sampling was performed using a LANZONI VPPS-2000 volumetric trap. The results of the study show that the critical phenological stages for powdery mildew infection are 5 (inflorescence emergence), 6 (flowering) and 7 (development of fruit), as consequence of the high susceptibility of the vine. The IRI allows determination of the periods in which the meteorological conditions could facilitate fungal attacks during the aforementioned phenological phases. Finally, the aerobiological model helps to identify and predict the times of real infection risk among the possible periods described by the IRI with high accuracy, in order to avoid possible reappearance of infection symptoms in the vine. The combination of these three variables provides a valuable tool to establish an accurate, modern, integrated pest-management strategy in a vineyard.

Use of beneficial bacteria and their secondary metabolites to control grapevine pathogen diseases

Grapevine is one of the most important economic crops yielding berries, wine products as well as derivates. However, due to the large array of pathogens inducing diseases on this plant, considerable amounts of pesticides—with possible negative impact on the environment and health—have been used and are currently used in viticulture. To avoid negative impacts of such products and to ensure product quality, a substantial fraction of pesticides needs to be replaced in the near future. One solution can be related to the use of beneficial bacteria inhabiting the rhizo- and/or the endosphere of plants. These biocontrol bacteria and their secondary metabolites can reduce directly or indirectly pathogen diseases by affecting pathogen performance by antibiosis, competition for niches and nutrients, interference with pathogen signaling or by stimulation of host plant defenses. Due to the large demand for biocontrol of grapevine diseases, such biopesticides, their modes of actions and putative consequences of their uses need to be described. Moreover, the current knowledge on new strains from the rhizo- and endosphere and their metabolites that can be used on grapevine plants to counteract pathogen attack needs to be discussed. This is in particular with regard to the control of root rot, grey mould, trunk diseases, powdery and downy mildews, pierce’s disease, grapevine yellows as well as crown gall. Future prospects on specific beneficial microbes and their secondary metabolites that can be used as elicitors of plant defenses and/or as biocontrol agents with potential use in a more sustainable viticulture will be further discussed.

Microorganisms, application timing and fractions as players of the milk-mediated powdery mildew management

Milk has proven to be efficient in powdery mildew (PM) control, but little has been reported on the modulators of its efficacy. This work aimed at studying milk's preventive and curative activities on PM control, determining the changes of fungal structures after milk treatment, surveying the leaf microbial community after milk treatment and testing the milk's fractions and sources for PM control. A preventive activity of milk was only observed for plants treated with milk at 30% concentration, whilst a reduced number of mildew colonies were recorded on leaves treated with conidia exposed to milk before inoculation. Scanning electron microscopy revealed damaged hyphae and conidiophores, a deposit over conidia and abundant yeast-like microorganisms for milk-treated plants. The microbial community was higher on plants treated with milk than those either treated with a fungicide or water and a yeast isolated from milk-treated leaves controlled the disease as well as milk. Both raw and pasteurized milk were the most efficient sources, and the lactose fraction had an effect similar to ultrahigh temperature (UHT) milk. Our results shed light on important aspects that should be considered when using milk for PM management.

Molecular detection of a gene effective against powdery mildew in the wheat cultivar Liangxing 66

Since it was commercialized in 2008, Liangxing 66 is one of the most widely grown cultivars of wheat (Triticum aestivum L.) in winter and facultative wheat-producing regions in northern China. This cultivar displays broad-spectrum resistance to isolates of powdery mildew. To identify the powdery mildew resistance gene in Liangxing 66, genetic analysis and molecular mapping were conducted using the F2 populations and F2:3 families derived from the reciprocal crosses of Liangxing 66 and the susceptible cultivar Jingshuang 16. A single dominant gene, tentatively designated PmLX66, conferred resistance in Liangxing 66 to the powdery mildew isolate E09. The results of molecular mapping indicated that this gene was located on the short arm of chromosome 5D and flanked by SCAR203 and Xcfd81 at genetic distances of 0.4 and 2.8 cM, respectively, which is similar to the position of locus Pm2. However, PmLX66 and Pm2 showed different reactions to five of the 42 isolates of powdery mildew tested. Together, these results indicated that PmLX66 was most likely an allele of Pm2. Based on its superior yield and agronomic performance, in combination with powdery mildew resistance, Liangxing 66 is useful as a promising parent for control of powdery mildew and for the development of new disease-resistant cultivars.