Phytophthora megasperma drechsler, journal of the washington academy of sciences 21. Chilling 7 c, heating 40 c, and sonication were evaluated as meth infest soil at 0, 10, 100, 250, 500, and 1,000 opg, percentages of soybean. Phytophthora ramorum affects a wide range of woody, perennial plants including forest, landscape, and nursery plants. Evaluation of chemical agents for the control of phytophthora ramorum and other species of phytophthora on nursery crops robert g. Phytophthora species root and crown rots of woody plants. There were only about 50 identified species when the last key was published in 1990, but now that species. Phytophthora medicaginis is part of a species complex with phytophthora megasperma. Phytophthora root and stem rot prsr is a destructive soybean disease in major soybeangrowing countries across the world.
Alfalfa seedling resistance to phytophthora megasperma jag irwin. Phytophthora diseases worldwide davison 1998 plant. Phytophthora root and crown rot in the gardenuc ipm. The disease is characterized by a reddish discoloration of the older leaves followed. Phytophthora megakaryaone of the species causing black pod of cacoa, and is probably responsible for the greatest cocoa crop loss in africa. Phytophthora species identified through sequencing its 0 20 40 60 80 100 120 140 160 p. In total, nine phytophthora species were isolated from rhizosphere soil. The external surfaces and internal tissues of roots infected with phytophthora are dark in color and are rotted. Phytophthora medicaginis is an oomycete plant pathogen that causes root rot in alfalfa and chickpea. The pathogen was identified as phytophthora megasperma based on.
But unlike true fungi, their cell walls contain cellulose instead of chitin, their hyphae lack. An average annual yield loss caused by prsr was estimated as 1. In partial fulfillment of the requirements for the degree of master of science in the graduate college. The genus phytophthora, known as the plant destroyer, is one of the most important group of disease causing organisms.
We evaluated several chemicals that target oomycete pathogens, inoculating detached rhododendron or lilac leaves. Examination of the inheritance of resistance to phytophthora megasperma var. Phytophthora megasperma isolates are less sensitive to the fungicide metalaxyl than are isolates of p. On rose plants, several species of phytophthora, such as p. Phytophthora megasperma is a species of water mould in the family peronosporaceae. Phytophthora kernoviaepathogen of beech and rhododendron, also occurring on other trees and shrub species including oaks, and holm oak. Baiting, pathogenicity, and distribution of phytophthora. Multiple new phenotypic taxa from trees and riparian ecosystems in phytophthora gonapodyidesp. Various enzymic and chemical treatments of the released elicitor indicated that the activity resided in a carbohydrate moiety, and gel filtration disclosed the presence of at least two active.
The disease is caused by phytophthora megasperma drechsler. Identifying species by morphology and dna fingerprints, enables diagnosticians and regulatory personnel as well as researchers to identify phytophthora species with speed and confidence. A study on the growth and sporulation of phytophthora. They also grow 12 mm day faster at 5 c than the other species hansen and hamm, 1983. Consult the documents andor contact the holder for additional rights questions and requests. Temperature effects on growth, survival, and pathogenicity of. The name phytophthora is derived from greek and literally means plant destroyer. It is the cause of several plant diseases, including ramorum leaf blight, ramorum dieback, andthe most widely. It is a major disease of these plants and is found wherever they are grown. Kansas state university libraries encourages the fair use of ed material, and you are free to link to content here without asking for permission.
Ho and others published behavior of phytophthora megasperma var. Phytophthora root and crown rots sometimes called collar rot are common and destructive diseases of fruit trees throughout the world. During the course of an investigation into the occurrence and distribution of pink rot of the potato in northern ireland, a species of phytophthora other than p. This is a poorly defined species which is generally called a species complex. Pathogenicity of the isolates was tested by stem inoculation to sour cherry seedlings. Identification of new isolates of phytophthora sojae and the. Falloon crop research division, dsir private bag, christchurch, new zealand abstract tendayoldasparagus seedlings floated over flooded soil were used as a bait to isolate and identify phytophthora megasperma var.
Currently the latter species is classified as invasive, and a second one, phytophthora kernoviae, is about to be placed in this category. It is the cause of several plant diseases, including ramorum leaf blight, ramorum dieback, andthe most widely knownsudden oak death. In ohio, apple, cherry, and peach trees are usually attacked. Its name applies to water moulds of many forms, functions, and host preferences. Pear and plum trees appear to be relatively resistant. Its aim is to contribute to a deeper understanding of factors affecting diversity, adaptation and hybridization processes in the important oomycete genus phytophthora through the application and implementation of innovative technologies based on microbiology, bioinformatics, biology. Examination of the inheritance of resistance to phytophthora.
Phytophthora root rot can result in leaf chlorosis, wilting,and dieback of canes fig. Leaves, especially older ones, turn purple red and wilt. Herbaceous perennials, bedding plants, pot plants and even bulbs can be affected, in addition to woody plants. There are a number of different phytophthora species, all causing very similar symptoms. Pdf almond decline caused by phytophthora megasperma in. Hansen and others published morphological differentiation of hostspecialized groups of phytophthora megasperma find, read and cite all the research you need on.
Phytophthora species are widespread, relatively abundant, very diverse. Phytophthora megasperma translation englishfrench dictionary. Preparation protocols and effects of mtt vital staining and permanganate pretreatment by g. In partial fulfillment of the requirements for the degree of master of science in the graduate college the university of arizona 19 7 2.
Ridley growing near forbes in the lachlan valley, new south wales, was classified as. Survival, and pathogenicity of phytophthora megasperma by dhansukh maganlal naik a thesis submitted to the faculty of the. Pdf phytophthora megasperma sensu lato was a conglomeration of morphologically similar but phylogenetically unrelated species. What is phytophthora phytophthora pronounced fytoffthoruh is a genus of microorganisms in the stramenopile kingdom which includes water molds, diatoms and brown algae. This disease is caused by the fungus phytophthora megasperma f. This genus contains the potato blight pathogen, phytophthora infestans, and the sudden oak death pathogen, phytophthora ramorum. Almost all fruit and nut trees, as well as most ornamental trees and shrubs including many california natives, can develop phytophthora rot if soil around the base of the plant remains wet for prolonged periods, or when planted too deeply. Phytophthora megasperma an overview sciencedirect topics. Alfalfa seedling resistance to phytophthora megasperma j. A soluble elicitor of glyceollin accumulation was released from insoluble mycelial walls of phytophthora megasperma var. The oospores are then stimulated to germinate in the presence of free water. Rapid assessment of the need for a detailed pest risk analysis for phytophthora austrocedrae.
After honey fungus, phytophthora root rot is the most common cause of root and stem base decay of a wide range of trees and shrubs. Phytophthora megasperma causing pink rot of the potato nature. Erwin and tali kuan, personal communica were investigated. Phytophthora basics forest phytophthoras of the world. In the hr interaction of tobacco leaves with phytophthora megasperma. Release of a soluble phytoalexin elicitor from mycelial. The project objective is to create an excellence research team focused on research of phytophthora diseases. Anne davis, biological laboratory technician, usdaars horticultural. Phytophthora megasperma causing pink rot of the potato. Pdf morphological differentiation of hostspecialized.
Multiple new phenotypic taxa from trees and riparian. Diagnosis and control of phytophthora diseases pacific. Several species of soilborne pathogens in the genus phytophthora cause crown and root rot diseases of herbaceous and woody plants. It is well known as a plant pathogen with many hosts. Phytophthora root rot of alfalfa medicago sativa l. Phytophthora species emerging as pathogens of forest trees. Phytophthora sojae is a soilborne pathogen, which forms a parasitic relationship with soybean, glycine max. Phytophthora root rot on cole cropsphytophthora megasperma. Diversity of phytophthora species from declining mediterranean.
Morphological characteristics of phytophthora species. Phytophthora morindae, a new species causing black flag disease on noni morinda citrifolia l in hawaii. Pdf decline symptoms were observed on young almond trees in. The pathogens were identified as phytophthora chlamydospora and p. Temperature effects on growth, survival, and pathogenicity. Hyphal lysis and formation of new hyphae unsterile soil maintained at different levels of temperature 4, 15, and 24 c occurred concurrently in soil at all three temperatures. O1brasier biodiversity icpp turin phytophthora database. The effects on seedling resistance by phytophthora megasperma drechs. In nurseries, potting mixes should be steamed to kill phytophthora inoculum, and only certified phytophthora free planting material should be used chapter 7. Phytophthora megasperma phytmeoverview eppo global database. Pdf phytophthora porri from stored carrots in alberta. Although phytophthora is a recognized disease problem in the pacific northwest, it has been misdiagnosed half the time in oregon.
Phytophthora root and crown rot of fruit trees ohioline. Ridley growing near forbes in the lachlan valley, new south wales, was classified as race 4 after hypocotyl inoculation on a united states differential set consisting of harosoy, harosoy 63, sanga, wells ii, pi 103091, pi 869721 and altona. Ultrastructure of mature oospores of phytophthora megasperma. Noteworthy examples of phytophthora include the infamous p. We explore the conditions leading to and the consequences of the emergence of some phytophthora species from their presumptive coevolved roles in undisturbed forest ecosystems to destructive agents as invasive forest pathogens. As against singlecycle pathogens, phytophthora has a devastating potential because it is multicyclic and can produce inoculum continuously after the initial infection, as long as conditions remain favorable. The current identification of the pathogen is phytophthora megasperma drechs. Phytophthora medicaginis is an oomycete plant pathogen that causes root rot in alfalfa and.
Metalaxyl is one of the main fungicides used to control pepper blight caused by phytophthora capsici. Lack of host specificity among isolates of phytophthora megasperma. Genus phytophthora 1phytg species phytophthora megasperma phytme. Trees declining and dying from phytophthora root and crown rots are frequently misdiagnosed as suffering from wet feet root asphyxiation.
O16geoffrey denton phytophthora diversity in uk gardens 15. Isolates of phytophthora from alfalfa and soybean and the type isolate of phytophthora megasperma drechsler from hollyhock were compared morphologically, for temperature response, and pathogenically. Kaufmann and gerdemann 1958 proposed the name of the pathogen as phytophthora sojae. Phytophthora species resemble true fungi because they grow by means of fine filaments, called hyphae, and produce spores. Evaluation of chemical agents for the control of phytophthora. In this paper we continue the segregation of species from the old p. Phytophthora root rot is a major cause of seedling death in newly established alfalfa and causes a progressive decline of established stands in nebraska. Microorganisms free fulltext differential potential. The water mold phytophthora ramorum is an invasive pathogen that recently became established in the united states.
Phytophthora megakarya was first reported as the causal agent of black pod disease in 1979 after the reclassification of phytophthora. Time spent collecting all the information for an accurate diagnosis will aid management efforts in the long run. Phytophthora vignae phytophthora stem rot of cowpea. Species of phytophthora are prominent in lists of emerging threats to forest ecosystems. Phytophthora species phytophthora species post 2000 pre 2000 described or under construction phylotypes or virtual taxa p. Phytophthora diseases occur frequently in nurseries, and the recent incidence of ramorum blight, caused by p. Microorganisms free fulltext differential potential of. Almond decline caused by phytophthora megasperma in southeastern anatolian region of turkey article pdf available april 2016 with 230 reads how we measure reads. Erwin department of plant pathology, university of california, riverside, ca.
Phytophthora megasperma translation in englishfrench dictionary. Notes on taxonomy and nomenclature top of page phytophthora vignae was first described in 1957 purss, 1957 and is an accepted species of phytophthora, being readily distinguishable from related taxa through being homothallic, producing nonpapillate persistent sporangia, and having all of its antheridia amphigynous, placing it in group vi stamps et al. As a professional plant pathologist i particularly liked the detailed explanations that were given for taxonomic and nomenclatural changes. Below the soil, the crown tissue and roots become dark brown and necrotic fig. Baiting, pathogenicity, and distribution of phytophthora megasperma var. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Phytophthora sojae is a soilborne pathogen, which forms a parasitic relationship with soybean, glycine max, causing severe economic damages.
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