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Journal ArticleDOI: 10.1080/07060661.2021.1954695

Several Pythium species cause crown and root rot on cannabis (Cannabis sativa L., marijuana) plants grown under commercial greenhouse conditions

Abstract: Cannabis (Cannabis sativa L., marijuana) plants with symptoms of crown rot, root decay, wilting and plant death were sampled during 2018 and 2019 from seven production greenhouses. Affected tissues... more

Topics: Pythium (57%), Root rot (56%), Wilting (52%)

Open access
25 Sep 1980-

28 Citations

Open access
01 Jan 2015-
Abstract: Turfgrasses have been widely used in many residential areas and sport fields for many years. Pythium species can cause severe losses on cereals and other crops as well as ornamental plants such as turfgrass. To study the role of Pythium species in causing seed and root rot and damping-off, plant and soil samples were collected from different regions of Tehran province. Isolates were identified on the basis of morphological characters and cardinal temperature. Pathogenicity of the recovered species was determined on common cool season turfgrasses (Loliumperenne, Poaparatensis and Festucaarundinaceae). Of the 48 recovered Pythium isolates, three species were identified include 66.7% P. aphanidermatum, 18.7% P. catenulatum and 14.6% P. okanoganense. Comparative pathogenicity of Pythium species (total diseases) on turfgrasses showed that P.aphanidermatum was the most aggressive species and P. catenulatum and P. okanoganens were in second and third levels respectively. more

Topics: Pythium (56%)

2 Citations

Journal ArticleDOI: 10.1080/07060661.2021.1988712
Alastair J. Roberts1, Zamir K. Punja1Institutions (1)
Abstract: Cannabis (Cannabis sativa L., marijuana) plants grown at indoor and outdoor production sites in British Columbia (BC) and Ontario with stem canker symptoms were sampled and affected tissues were su... more

Topics: Neofusicoccum (57%), Canker (54%), Alternaria (51%)

Open accessJournal ArticleDOI: 10.7202/1076365AR
01 Jan 2021-Phytoprotection
Abstract: Cannabis (Cannabis sativa L.; Rosales: Cannabaceae) is a newly legalized crop and requires deeper insights on its pest communities. In this preliminary study, we identified a thrips species affecting indoor-grown cannabis in Canada and tested its impact on plant yield. We used three levels of initial infestation (zero, one, and five thrips) on individual plants grown in two growing mediums: conventional substrate or substrate containing the biostimulant Bacillus pumilus Meyer and Gottheil (Bacillales: Bacillaceae). We found that the onion thrips, Thrips tabaci (Lindeman) (Thysanoptera: Thripidae), is proliferating in indoor-grown cannabis. Furthermore, our results showed that fresh yields were higher for the plants that initially received zero thrips compared to those that initially received five thrips. Moreover, the biostimulant only marginally helped reduce the impact of thrips. We highlight the importance for growers to carefully monitor thrips infestations in indoor-grown cannabis. Finally, we emphasize the need for more research related to the impact of pests on cannabis yields and safe means of pest control for this strictly regulated crop. more

Topics: Thrips (72%), Thripidae (65%)

Open access
01 Jan 2013-
Abstract: We announce the release of an advanced version of the Molecular Evolutionary Genetics Analysis (MEGA) software, which currently contains facilities for building sequence alignments, inferring phylogenetic histories, and conducting molecular evolutionary analysis. In version 6.0, MEGA now enables the inference of timetrees, as it implements the RelTime method for estimating divergence times for all branching points in a phylogeny. A new Timetree Wizard in MEGA6 facilitates this timetree inference by providing a graphical user interface (GUI) to specify the phylogeny and calibration constraints step-by-step. This version also contains enhanced algorithms to search for the optimal trees under evolutionary criteria and implements a more advanced memory management that can double the size of sequence data sets to which MEGA can be applied. Both GUI and command-line versions of MEGA6 can be downloaded from www. free of charge. more

Topics: Mega- (50%)

30,478 Citations

Open accessJournal ArticleDOI: 10.1093/MOLBEV/MSW054
Sudhir Kumar1, Glen Stecher2, Koichiro Tamura3Institutions (3)
Abstract: We present the latest version of the Molecular Evolutionary Genetics Analysis (Mega) software, which contains many sophisticated methods and tools for phylogenomics and phylomedicine. In this major upgrade, Mega has been optimized for use on 64-bit computing systems for analyzing larger datasets. Researchers can now explore and analyze tens of thousands of sequences in Mega The new version also provides an advanced wizard for building timetrees and includes a new functionality to automatically predict gene duplication events in gene family trees. The 64-bit Mega is made available in two interfaces: graphical and command line. The graphical user interface (GUI) is a native Microsoft Windows application that can also be used on Mac OS X. The command line Mega is available as native applications for Windows, Linux, and Mac OS X. They are intended for use in high-throughput and scripted analysis. Both versions are available from free of charge. more

Topics: Mac OS (56%), Mega- (55%), Microsoft Windows (55%) more

25,894 Citations

Open accessJournal ArticleDOI: 10.1111/J.1755-0998.2011.03041.X
Abstract: Oomycete species occupy many different environments and many ecological niches. The genera Phytophthora and Pythium for example, contain many plant pathogens which cause enormous damage to a wide range of plant species. Proper identification to the species level is a critical first step in any investigation of oomycetes, whether it is research driven or compelled by the need for rapid and accurate diagnostics during a pathogen outbreak. The use of DNA for oomycete species identification is well established, but DNA barcoding with cytochrome c oxidase subunit I (COI) is a relatively new approach that has yet to be assessed over a significant sample of oomycete genera. In this study we have sequenced COI, from 1205 isolates representing 23 genera. A comparison to internal transcribed spacer (ITS) sequences from the same isolates showed that COI identification is a practical option; complementary because it uses the mitochondrial genome instead of nuclear DNA. In some cases COI was more discriminative than ITS at the species level. This is in contrast to the large ribosomal subunit, which showed poor species resolution when sequenced from a subset of the isolates used in this study. The results described in this paper indicate that COI sequencing and the dataset generated are a valuable addition to the currently available oomycete taxonomy resources, and that both COI, the default DNA barcode supported by GenBank, and ITS, the de facto barcode accepted by the oomycete and mycology community, are acceptable and complementary DNA barcodes to be used for identification of oomycetes. more

Topics: Cytochrome c oxidase subunit I (59%), DNA barcoding (58%), Oomycete (58%) more

374 Citations

Journal ArticleDOI: 10.1146/ANNUREV.PY.11.090173.000453
Abstract: The genus Pythium includes a number of readily recognized species with wide distributions and host ranges. The taxonomic position of the genus and its relationship to other Phycomycetes were well established during the latter part of the 19th century. In the early 1900s pathologists found Pythium spp. consistently associated with root diseases and it soon became apparent that these fungi were important plant pathogens. Certainly, while 1),ot all isolates of Pythium species are capable of causing diseases of plants, many are soil­ borne pathogens that cause serious economic loss on a wide variety of hosts, while others are more limited in host and geographic range or affect plants only under special environmental conditions. New species are being discov­ ered as pathologists investigate soil organisms associated with plant growth problems. Rands & Dopp (123) in their classic investigation of sugarcane root dis­ eases established the symptoms and determined the conditions needed for these fungi to become destructive. This work, and others of a similar nature, are part of the extensive literature on diseases caused by species of Pythium. This review will concentrate on examples of the readily available literature of the past 50 years and will emphasize the pathology of the genus, with only brief treatment of other aspects such as taxonomy and control. It will be con­ fined to Pythium spp. as they affect economic plants and will not deal with those affecting algae, other marine plants, fungi, and unusual hosts. more

Topics: Pythium (59%), Plant pathology (56%), Pythium irregulare (53%)

346 Citations

Journal ArticleDOI: 10.1016/S0735-2689(99)00389-5
Frank N. Martin1, Joyce E. Loper1Institutions (1)
Abstract: Soilborne root diseases caused by plant pathogenic Pythium species cause serious losses in a number of agricultural production systems, which has led to a considerable effort devoted to the development of biological agents for disease control. In this article we review information on the ecology and biological control of these pathogens with the premise that a clear understanding of the ecology of the pathogen will assist in the development of efficacious biocontrol agents. The lifecycles of the pathogens and etiology of host infection also are reviewed, as are epidemiological concepts of inoculum-disease relationships and the influence of environmental factors on pathogen aggressiveness and host susceptibility. A number of fungal and bacterial biocontrol agents are discussed and parallels between their ecology and that of the target pathogens highlighted. The mechanisms by which these microbial agents suppress diseases caused by Pythium spp., such as interference with pathogen survival, disruption of the... more

Topics: Pythium (57%), Ecology (disciplines) (52%)

332 Citations