Pythium dissotocum

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Pythium dissotocum
Systematics
Department : Egg mushrooms (Oomycota)
Class : Oomycetes
Order : Peronosporales
Family : Pythiaceae
Genre : Pythium
Type : Pythium dissotocum
Scientific name
Pythium dissotocum
Wood turner, (1930)

Pythium dissotocum is a phyto-pathogen belonging to the Pythiaceae familywithin the group of egg fungi . It infects a wide range of hosts, including many agricultural and horticultural crops.

Development cycle

Pythium dissotocum is a polycyclic, root rot- causing egg fungus that can go through both sexual and asexual reproductive cycles. About halfway through its asexual phase, P. dissotocum spreads through the formation of filamentous sporangia , which produce conidiophores that house 10… 75 mobile zoospores . When the conidiophores open, the zoospores are released. Upon contact with the hosts' roots, they encyst and form a germ tube which infects the root and begins to form a mycelium .

In sexual reproduction, when several mating types are present, an antheridium derived from the hyphae can come into contact with each other and fuse by plasmogamy by uniting cell membranes at the end of the growing season. After several steps of differentiation and meiosis , an oospore is formed, the primary survival stage. These thick-walled oospores can last for several months and finally germinate in two ways. Either a sporangium is formed that forms a cyst and releases zoospores, or the oospore forms a germ tube that penetrates the host cells directly and infects the host. This development cycle is extremely dependent on water for its spread, which means that greenhouses, irrigation systems and hydroponics are predestined for the spread of P. dissotocum .

meaning

Pythium dissotocum is primarily a waterborne pathogen, so plants in hydroponics and in irrigated growing regimes are seriously endangered. With fast moving mobile spores, the infection spreads rapidly in such cultivation systems. P. dissotocum can infect a wide range of hosts, including many agricultural crops such as lettuce, spinach, bell peppers, parsnips, parsley, tomatoes, sugar cane and carrots. Other commercial products are also at risk from the presence of P. dissotocum , including trees from nurseries. Infection with P. dissotocum can significant yield loss due to the root necrosis , root lesions , chlorosis and wilting lead. This ends up with heavy losses for farmers who grow crops for food production as well as other commercial products. The pathogen is common in many regions of the Americas , Europe and Asia , meaning that increasing globalization is promoting its spread to all potentially sensitive cultures and ecosystems.

Combat

As the causative agent of root rot, Pythium dissotocum tends to have more severe effects on young plants and seedlings, in which the newly formed roots, which are important for growth and nutrient supply, are affected. In the end, one of many control methods is to limit the number of possible infections at the beginning of the growing season. An effective measure includes applying fungicides such as metalaxyl (e.g. mefenoxam ) and phosphonates , often in combination. In addition, inoculation with Pseudomonas chlororaphis , a bacterium often used in biological pest control , can be used in horticulture , which potentially suppresses the symptoms of P. dissotocum infection . However, this is not always the case in current experiments, and colonization by the pathogen is not prevented. Like most root rot pathogens, P. dissotocum thrives in moist environments. Preventing overhydration lowers the risk of infection. The implementation of hygiene measures and the use of fungicides can reduce the transmission and infection with P. dissotocum, especially in irrigated and hydroponic crops . If an infection has occurred, removing the damaged roots and sterilizing the still white and healthy roots can sometimes help.

Individual evidence

  1. ^ Charles Drechsler: Some new species of Pythium . In: Journal of the Washington Academy of Sciences . 20, No. 16, 1930, pp. 402-403.
  2. ^ Charles Dreschler: Some New Species of Pythium . In: Journal of the Washington Academy of Sciences . 20, No. 16, 1930, pp. 398-418.
  3. ↑ a b c J. Van Der Plaats-Niterink: Monograph of the genus Pythium . In: Studies in Mycology . 21, December 22, 1981.
  4. ↑ a b c T. Naleesh: Pythium: Introduction, Structure and Reproduction . August 24, 2016. Retrieved July 18, 2019.
  5. ^ A b Kurtis L. Schroeder, Frank N. Martin, Arthur WAM de Cock, C. André Lévesque, Christoffel FJ Spies, Patricia A. Okubara, Timothy C. Paulitz: Molecular Detection and Quantification of Pythium Species: Evolving Taxonomy, New Tools , and Challenges . In: Plant Disease . 97, No. 1, January 2013, pp. 4-20. doi : 10.1094 / PDIS-03-12-0243-FE .
  6. ^ A b Rosa E. Raudales, Jennifer L. Parke, Charles L. Guy, Paul R. Fisher: Control of waterborne microbes in irrigation: A review . In: Agricultural Water Management . 143, 2014, pp. 9-28. doi : 10.1016 / j.agwat.2014.06.007 .
  7. ^ A b Roger Cuan Bagnall: Control of Pythium Wilt and Root Rot of Hydroponically Grown Lettuce by Means of Chemical Treatment of the Nutrient Solution. Dissertation . University of Pretoria. 2007. Retrieved July 18, 2019.
  8. ^ A b Gary Moorman: Pythium . Retrieved July 18, 2019.
  9. ↑ AS Corrêa, AB Rocha, SA Willani, JM Dariva, MV Souza, MG Moraes: Yellow Stunt, a Tobacco Disease Caused by Pythium Dissotocum, in Southern Parts of Brazil . In: Plant Disease . 95, No. 3, 2010, pp. 354-354. doi : 10.1094 / PDIS-10-10-0759 .
  10. Jump up ↑ C. McGehee, RE Raudales, WH Elmer: First Report of Pythium Dissotocum Causing Pythium Root Rot on Hydroponically Grown Lettuce in Connecticut . In: Plant Disease . 102, No. 10, 2018, p. 2043. doi : 10.1094 / PDIS-02-18-0365-PDN .
  11. ↑ JE Petkowski, RF de Boer, S. Norng, F. Thomson, EJ Minchinton: Pythium species associated with root rot complex in winter-grown parsnip and parsley crops in southeastern Australia . In: Australasian Plant Pathology . 42, No. 4, July 1, 2013, pp. 403-411. doi : 10.1007 / s13313-013-0211-5 .
  12. ^ WJ Botha, RLJ Coetzer: Species of Pythium associated with root-rot of vegetables in South Africa . In: South African Journal of Botany . 62, No. 4, 1996, pp. 196-203. doi : 10.1016 / S0254-6299 (15) 30634-7 .
  13. ↑ AP Trivilin, S. Hartke, MG Moraes: Components of different signaling pathways regulated by a new orthologue of AtPROPEP1 in tomato Following infection by pathogens . In: Plant Pathology . 63, No. 5, 2014, pp. 1110–1118. doi : 10.1111 / ppa.12190 .
  14. ↑ a b Jerry E. Weiland, Luisa Santamaria, Niklaus J. Grünwald: Sensitivity of Pythium Irregulare, P. Sylvaticum, and P. Ultimum from Forest Nurseries to Mefenoxam and Fosetyl-Al, and Control of Pythium Damping-Off . In: Plant Disease . 98, No. 7, 2014, pp. 937-942. doi : 10.1094 / PDIS-09-13-0998-RE .
  15. ↑ Jerry E. Weiland, Bryan R. Beck, Anne Davis: Pathogenicity and Virulence of Pythium Species Obtained from Forest Nursery Soils on Douglas-Fir Seedlings . In: Plant Disease . 97, No. 6, 2013, pp. 744-48. doi : 10.1094 / PDIS-09-12-0895-RE .
  16. ↑ a b Root Rot - Causes, Symptoms, Prevention, and Control . Retrieved July 18, 2019.
  17. ↑ S. Koike, C. Wilen: UC Management Guidelines for Pythium Root Rot on Floriculture and Ornamental Nurseries . In: UC IPM . University of California. Retrieved July 18, 2019.
  18. ↑ Dominique Blancard: 3 - Principal Characteristics of Pathogenic Agents and Methods of Control . In: Tomato Disease (Second Edition) 2012, ISBN 978-0-12-387737-6 .
  19. ↑ S. Chatterton, JC Sutton, GJ Boland: Timing Pseudomonas chlororaphis applications to control Pythium aphanidermatum, Pythium dissotocum, and root rot in hydroponic peppers . In: Biological Control . 30, June 1, 2004.
  20. ^ Brian Hudelson, Laura Jull: Root Rots in the Garden . In: Wisconsin Horticulture . Retrieved July 18, 2019.
  21. ↑ Recovering from Root Rot . Retrieved July 18, 2019.

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