Documents about Powdery Mildew

  • 2 Pages


    University of Florida, PLP 3002

    Excerpt: ... Laboratory 9 Study Guide (video: 1 hour 3 minutes) Study Questions 1. Compare and contrast the mechanics of infection by downy and powdery mildew s. 2. What are powdery mildew haustoria and how do they contribute to the process of causing disease? 3. What are cleistothecia and how do they enhance the survival of powdery mildew s in temperate climates? 4. Almost all powdery mildew s found in tropical climates are known by the generic name of Oidium. Why? 5. How was Bordeaux mixture discovered? Also, Downy mildew was not a problem in Europe until about the 18th century. Why not? 6. What are some of the general characteristics of downy mildews with respect to a) host range, b) parasitism (facultative or obligate), and c) types of damage induced by each? 7. What are sooty molds and what is the best ways to control them? 8. What is honeydew, and how does this relate to damage by sooty molds? Are sooty molds parasitic? 9. Disease forecasting (used to control potato late blight) is of no concern when dealing with the p ...

  • 2 Pages


    Arizona, AZ 1252

    Excerpt: ... Reaction of Different Cultivars of Lettuce to Development of Powdery Mildew on Lettuce in 2001 Michael E. Matheron and Martin Porchas Abstract Seven different cultivars of lettuce were seeded and watered on Dec 1, 2000 at the Yuma Valley Agricultural Center. Cultivars were rated for severity of powdery mildew caused by Erysiphe cichoracearum at plant maturity (Mar 21). The highest levels of powdery mildew were found on the cultivars Winterhaven and Silverado, whereas lower disease severity was observed on Jackel, Cibola, RC-74 and Accolade. All tested cultivars would have required application of fungicides to reduce the amount of powdery mildew to acceptable levels. On the other hand, planting of lettuce cultivars with some disease tolerance may require less fungicide inputs to achieve acceptable disease control compared to planting susceptible cultivars. Introduction Powdery mildew , caused by the fungus Erysiphe cichoracearum, is becoming an increasing concern for lettuce growers in the desert southwest. T ...

  • 2 Pages


    Arizona, AZ 1323

    Excerpt: ... Evaluation of Lettuce Cultivar Susceptibility to Powdery Mildew in 2003 Michael E. Matheron and Martin Porchas Abstract Powdery mildew , caused by the fungus Golovinomyces cichoracearum (formerly known as Erysiphe cichoracearum), can cause economic losses in lettuce fields harvested in March and April, the last months of the production season in western Arizona. A field study was conducted to evaluate 14 different cultivars of lettuce for potential resistance to this disease. Cultivars Two Star and Big Green COS were very resistant to powdery mildew . All other tested cultivars would have required application of fungicides to reduce the amount of powdery mildew to acceptable levels. On the other hand, planting lettuce cultivars with some disease tolerance may require less fungicide inputs to achieve acceptable disease control compared to planting very susceptible cultivars. Among tested cultivars, Slugger was most susceptible to powdery mildew . Introduction Powdery mildew , caused by the fungus Golovinomyces c ...

  • 3 Pages


    Cornell, PROJ 06

    Excerpt: ... A Practical Model for Control of Grapevine Powdery Mildew in the Northeast Region David M. Gadoury, Robert C. Seem, Wayne F. Wilcox, and Michelle M. Moyer New York State Agricultural Experiment Station, Geneva, NY 14456. _ A B S T R A C T : Powdery mildew causes extensive losses at the farm level. Loss of the most highly-effective fungicides to resistance has caused a shift towards soft and/or organically-acceptable options. Maintaining control with innately less-effective materials will require near-perfect timing with respect to seasonal changes in host susceptibility and environmental conditions. Our objective was to begin the development of a forecasting system that will answer questions (identified by stakeholders themselves) that are commercially relevant to decisions made in disease management. In 2006, we found an important piece of the puzzle: the fungus may occasionally discharge nearly all of it's overwintering spores ...

  • 2 Pages


    Arizona, AZ 1177

    Excerpt: ... Effect of Cultivar and Actigard on Development of Powdery Mildew on Lettuce Michael E. Matheron and Martin Porchas Abstract Nine different cultivars of lettuce were planted at the Yuma Valley Agricultural Center. Plants were treated four times with two different rates of Actigard. Control plants were not treated. Near plant maturity (Mar. 23, 2000) the severity of powdery mildew was recorded. Among nontreated plants, Cibola, Conquistador, and Coolguard had the lowest levels of powdery mildew . On the other hand, Bos 9003 and Mohawk had significantly higher levels of powdery mildew than all other tested cultivars. Four applications of Actigard at a rate of 14 g. of active ingredient per acre significantly reduced the level of powdery mildew on all nine tested cultivars of lettuce. On two lettuce cultivars, powdery mildew was significantly lower when treated with Actigard at the 28 g. a.i./A rate when compared to the 14 g. a.i./A rate. No evidence of phytotoxicity was apparent on plants treated with Actigard. T ...

  • 7 Pages


    Arizona, AZ 1143

    Excerpt: ... New Fungicides Evaluated for Control of Powdery Mildew of Cantaloupe in 1998 Michael E. Matheron and Martin Porchas Abstract Powdery mildew of cucurbits, which include cantaloupe, honeydew, watermelon, cucumber and squash, occurs every year in Arizona. Moderate temperatures and relative humidity, succulent plant growth and reduced light intensity brought about by a dense plant canopy are factors that promote development of powdery mildew , which is caused by the pathogenic fungus Sphaerotheca fuliginea. Potential new fungicides were evaluated and compared to existing chemicals for control of powdery mildew of cantaloupe in a field trial conducted during the spring of 1998 at the Yuma Agricultural Center. A high level of disease had developed by crop maturity (June 23). On the upper leaf surface where spray coverage was good and disease severity on nontreated leaves was moderate (24% of upper leaf surface infected), all treatments significantly reduced the severity of powdery mildew . These treatments included ...

  • 48 Pages


    Berkeley, LECTURE 110

    Excerpt: ... Mold, Capnodiaceae, www.hortipm.tamu Dothidiomycetes Pseudothecial with fissitunicate asci Capnodium sp. Pycnidium, mitospores Pseudothecium, meiospores Apothecial Pezizomycotina The other Pseudothecial fungi Chaetothyriales Spatafora et al. 2006 Chaetotheriomycetes = Loculoascomycetes Exophiala sp. Apothecial Pezizomycotina Apothecial Pezizomycotina Erysiphales ? Spatafora et al. 2006 Leotiomycetes Erysiphales Wang et al. 2006 Erysiphales Wang et al. 2006 Spatafora et al. 2006 Erysiphales = powdery mildew s Pezizomycetes that look like Eurotiomycetes and behave like Sordariomycetes, but are truly Leotiomycetes! Obligate plant parasites. Erysiphales - Powdery Mildew s, Sphaerotheca Erysiphales - Powdery Mildew s, Blumeria Erysiphales - Powdery Mildew s, Blumeria Erysiphales - Powdery Mildew s, Blumeria Erysiphales Powdery Mildew s Erysiphales, Erysiphe Erysiphales - Powdery Mildew s, Sphaerotheca Erysiphales - Powdery Mildew s, Uncinula Erysiphales Microsphaera Er ...

  • 19 Pages


    University of Florida, PLP 3002

    Excerpt: ... Powdery Mildew s, Phytophthora, Downy Mildews, and Sooty Molds Phyllactinia and other Powdery Mildew s Early, mild symptoms of powdery mildew , caused by Erysiphe cichoracearum, on the lower surface of a chrysanthemum leaf. 1 Late, severe symptoms of powdery mildew , caused by Erysiphe cichoracearum, on the lower surface of a chrysathemum leaf. Extensive growth of the powdery mildew fungus, Erysiphe cichoracearum, on a chrysanthemum stem. Powdery mildew on cineraria, caused by Sphaerotheca spp. and Erysiphe cichoracearum. 2 Powdery mildew on a begonia flower, caused by Erysiphe spp., Oidium spp., and Microsphaeria begoniae. Powdery mildew on an African daisy, caused by Erysiphe spp. and Sphaerotheca fusca. Powdery mildew on poinsettia, caused by Leveillula clavata, Erysiphe spp., and Oidium spp. 3 Powdery mildew caused by Sphaerotheca pannosa var. rosae; note leaf curl and distortion symptoms. Powdery mildew on a bean plant, caused by Erysiphe polygoni. Whi ...

  • 2 Pages


    Purdue, BTNY 518

    Excerpt: ... Plant Health Brief Special Interest Articles: Powdery Purdue University BTNY 518: Diseases of Landscape Trees and Shrubs/ A Purdue University Service Learning Project by: Daniel Mudd Powdery Mildew The fungus that causes powdery mildew has a wide variety of host plants. While a wide range of plants that are affected, the disease itself is very host specific. So the type of powdery mildew that infects your ash tree is different from the one that infects your roses or lilacs. Powdery mildew is mostly a cosmetic disease and doesn't cause much damage, but there are a few plants in which it can damage such as, roses, zinnias and phlox. The disease usually occurs during periods of high relative humidity and in shady areas. Powdery Mildew is very easy to diagnose. The leaves are usually covered with white "powder". The first signs of the disease are white blotches which will eventually spread to cover the whole leaf and spread to others. The disease sometimes causes leave to fall prematurely. Again the disease i ...

  • 9 Pages

    3 - Copy

    N.C. State, PP 315

    Excerpt: ... PP 315/590J Laboratory 3 Diseases Caused by Fungi - II True Fungi Introduction Phyllum Ascomycota (Ascomycetes) Class Hemiascomycetes: asci without an ascocarp Class Plectomycetes: asci in a closed ascocarp - cleistothecium Objectives of lab 3 1) To become familiar with vegetative and reproductive structures of the Hemiascomycete and Plectomycete classes within Ascomycota, and their role in disease development. 2) To observe symptoms and signs of representative diseases caused by pathogens in the Ascomycota phyllum. Description Ascomycetes, or sac fungi, make up the largest group of fungi, having 50,000 species including yeasts, licens, and truffles. These fungi are about 75% of all known species. Ascomycetes are also responsible for many plant diseases such as Dutch elm disease and powdery mildew s. Vegetative hyphae are septate The ascomycete sexual stage is characterized by the ascocarp fruiting body, which may be absent, closed, disk-shaped, or flask shaped. The ascocarp bears sac-like re ...

  • 1 Pages


    Ohio State, B 780

    Excerpt: ... Table 17. Spray Schedules for Pest Control on Grapes. Time to spray Pesticide Required Insects and diseases most likely to be a problem at the specific time (first column) during growing season. Insecticide needed only if flea beetles or climing cutworms are usually a problem (e.g., swollen buds have holes or are eaten). Bud swell, before buds show green Insecticide Sevin or methoxychlor or rotenone Fungicide mancozeb or myclobutanil or ferbam or captan Fungicide same as above Fungicide same as above Insecticide Sevin or Imidan or methoxychlor or diazinon* New growth 4 to 6 inches long Fungicide for control of black rot, Phomopsis cane and leaf spot, powdery mildew , and downy mildew. Myclobutanil is excellent for control of black rot and powdery mildew , but will not control Phomopsis or downy mildew. Mancozeb, Ferbam and Captan are good for black rot, downy mildew and Phomopsis control, but will not control powdery mildew . Diseases same as above New growth 10-15 inches long or 7-10 day after first spray. ...

  • 4 Pages


    Arizona, AZ 1275

    Excerpt: ... Effect of fungicide treatments on incidence of powdery mildew of pecan and on pecan nut quality M. Olsen, S. Rasmussen and C. Nischwitz Abstract Powdery mildew of pecan, caused by Microsphaera ulni, was observed on pecan shucks by the latter part of June 2000 in a commercial pecan orchard near Sahuarita, Arizona. Results of 1999 studies indicated that infection does not reduce nut quality. In order to determine effects of fungicide treatments and to substantiate results from 1999, preventive applications of micronized sulfur and azoxystrobin were initiated on June 8, 2000 in selected clusters in both Wichita and Western varieties. Trials were established in plots that had a high incidence of powdery mildew in 1999. Whole nut weights, kernel weights, or color ratings were not significantly different among clusters of nuts that were treated with fungicides and untreated nuts that were infected with powdery mildew . Percent disease incidence was 100% in untreated clusters, 0% in clusters treated with azoxystrobi ...

  • 8 Pages


    Wisconsin, BOTANY 130

    Excerpt: ... member one of these three subgroups. You should be able to recognize all structures and terms in bold. Domain: Eukarya - Organisms with nucleated cells Kingdom: Fungi Phylum: Chytridomycota (Chytrids) no examples Phylum: Zygomycota (Zygomycetes) Genus Rhizopus Phylum: Ascomycota (Ascomycetes) Genus Sordaria Yeasts Genus Penicillium Powdery Mildew s Genus Morchella Phylum: Basidiomycota (Basidiomycetes) Common woodland fungi Rusts and Smuts I. Zygomycota (The Zygomycetes). Members with bodies made up of coenocytic hyphae and produce zygosporangia during sexual reproduction. The group is important as saprophytic decomposers and as mycorrhizal symbionts. 2 Ia. Sexuality in the Zygomycota. See the sexual cultures of Phycomyces on the side bench. Take one of these to your seat. Note the two points of inoculation on either side of the plate. Phycomyces is heterothallic - that is it has genetically determined mating types which must out-cross with strains of a different type. In this case there are two strains, ...

  • 2 Pages


    University of Illinois, Urbana Champaign, IB 471

    Excerpt: ... IB 371 GENERAL MYCOLOGY THE EUROTIALES AND ERYSIPHALES Thursday, November 6, 2003 By the completion of today's lecture and after reading the text, you should be able to: 1. Describe the distinguishing characteristics of the Eurotiales and Erysiphales. 2. Discuss anamorph/teleomorph relationships in the Eurotiales and Erysiphales. 3. Tell your children the story of the development of penicillin and why the city of Peoria is important in this story. 4. Explain the economic and biological importance of members of the Eurotiales to a high school biology class. 5. Describe how the life history of powdery mildew s relates to their role as obligate pathogens. I. Distinguishing characteristics of the Eurotiales. II. Talaromyces lineage. A. Morphology of the anamorph and teleomorph. B. Habitat and biological role. C. Human pathogens. D. Economic importance. http:/ myces.html III. Eupenicillium lineage. A. Morphology of the anamorph an ...

  • 4 Pages


    Rutgers, IR 4

    Excerpt: ... IR-4/EPA Demonstration Research Grant Report 2004 BLUEBERRY APPLES PASTURE GRAPE APPLES PUMPKIN SWEET CORN LETTUCE TURF 2004 Demonstration Research Results Table of Contents Title Page Executive Summary.3 Efficacy of Mycotrol ES Against Blueberry Flea Beetle in Lowbush Blueberry. F. Drummond 5 Evaluation of Serenade for Management of Apple Diseases. B. Turechek .12 Evaluation of biofungicides for managing powdery mildew of pumpkin, 2004. M. McGrath.16 Evaluation of biofungicides used with compost tea for managing powdery mildew of pumpkin, 2004. M. McGrath.19 Biopesticide-based area-wide approach to managing codling moth in Michigan Apple L. Gut ...

  • 2 Pages

    lab_quiz3 - Copy

    N.C. State, PP 315

    Excerpt: ... Lab Quiz #3 Date_ Name_ Section_ 1. (3 pts) List three distinguishing characteristics of fungi in the phylum Ascomycota. Septate vegetative hyphae, Conidia, Ascus. 2. (1 pt) In the Ascomycota, what structure is used to distinguish among classes? Ascocarp 3. (2 pts) Name two diseases caused by pathogens in the Hemiascomycetes. Would you attempt to control these diseases? Why or why not? Peach leaf curl and Oak leaf blister. These diseases can only be prevented before they infect the leaf buds. Control is only effective before the buds open. 4. (1 pt) In the class Plectomycetes, how are the genera distinguished? The genera are distinguished by the host they infect because they are host-specific. 5. (2 pt) What is the role of conidia in epidemics of powdery mildew ? How are they dispersed? Conidia are asexual spores that are polycyclic and function as the secondary inoculums. They are carried by the wind to other hosts. 6. (2 pts) On a dogwood severely infecte ...

  • 5 Pages


    Ohio State, B 861

    Excerpt: ... to control black rot fruit infections with fungicide is from immediately prior to bloom through three to four weeks after bloom. An infected berry rst appears light brown in color. Soon the entire berry turns dark brown, and then black pycnidia develop on its surface. Infected berries eventually turn into shriveled, hard, black mummies (Figure 156). These mummies also serve as a source of secondary inoculum later in the growing season and are the primary means by which the fungus overwinters. growing season. The most critical period to control black rot with fungicide is from immediate prebloom through three to four weeks after bloom. Powdery Mildew Powdery mildew is caused by the fungus Uncinula necator. If not controlled on susceptible cultivars, the disease can reduce vine growth, yield, quality, and winter hardiness. Cultivars of Vitis vinifera and its hybrids (French hybrids) are generally much more susceptible to powdery mildew than are native American cultivars such as Concord (see Table 5-2). On ...

  • 10 Pages


    Rutgers, IR 4

    Excerpt: ... approach(es) to disease, insect and weed management. General Results As in previous surveys, participants were asked to provide their top three disease, insect, and weed issues. For 2007, the question was written For the following questions, consider your product arsenal and provide answers based on where you have limited product choices. This was an attempt to filter out those chronic problems which have a constant impact on crops or maintained plants but where multiple control options are available. 2007 Top Diseases Each of the diseases or pathogens listed by participants was given a weighted ranking based on the order written. Each was also assigned to a disease group such as Botrytis, Crown & Root Rot, Leaf Spots & Anthracnose and Phytophthora. The top diseases listed by survey participants are shown in Table 2. Table 2. Top Five Disease Groups Identified in the 2007 Survey Disease Group Powdery Mildew Leaf Spots & Anthracnose Phytophthora Crown & Root Rot Botrytis Weighted Ranking 318 318 259 237 ...

  • 9 Pages


    Ohio State, B 861

    Excerpt: ... crown gall. If winter injury is reduced, crown gall may not become an important problem. Practices such as hilling or burying vines of coldsensitive cultivars are benecial. Proper pruning practices and proper crop loads for maximum vine vigor will result in stronger plants that are less susceptible to winter injury. Controlling other diseases, such as downy and powdery mildew , is also important in preventing winter injury and crown gall. Practice Sanitation (Removal of Overwintering Inoculum) Vineyard sanitation is an extremely important part of the disease-management program. Most pathogens overwinter (survive from one season to the next) in old diseased plant material, such as mummied fruit, leaves, and infected canes or trunks, within the Identify the Disease Correctly If you do not know what disease or diseases are present in the vineyard, you cannot choose the most effective fungicide or fungicides for their control. Correct disease identication is essential for selecting the proper fungicide ...