Full TGIF Record # 11326
Item 1 of 1
Publication Type:
i
Report
Author(s):Böttner, Frank
Author Affiliation:Dipl.-Ing. agr., Sudgolf Management GmbH, Badenstedter Str.78, 3000 Hannover 91
Title:Die wichtigsten Krankheiten der Rasengräser Mitteleuropas--Systematik, Biologie, Auftreten und Symptome [Teil I]
Translated Title:The most important diseases of the turf grasses in Central Europe--systematics, biology, occurrence and symptoms [part 1]
Les principales maladies des graminees a gazon en Europe centrale--Leur systematique, biologie, apparition et symptomes
Article Series:Die wichtigsten Krankheiten der Rasengräser Mitteleuropas--Systematik, Biologie, Auftreten und Symptome
Translated Series Title:The most important diseases of the turf grasses in Central Europe--systematics, biology, occurrence and symptoms
Source:Rasen-Turf-Gazon. Vol. 23, No. 1, March 1992, p. 9-17.
Publishing Information:Bonn-Bad Godesberg, Germany: Hortus Verlag
# of Pages:9
Keywords:TIC Keywords: Disease specificity; Fungal diseases; Fungus infection; Diseases; Pythium; Gaeumannomyces; Typhula incarnata; Fungi; Microdochium nivale; Saprophyte
Abstract/Contents:Includes: Anatomy, life processes, macro and micro symptoms as well as lists of favorable and unfavorable conditions for the specific fungal diseases Pythium spp., Gaeumannomyces graminis, Typhula incarnata, and Microdochium nivale. Summary of pertinent information as follows: 1) Possessing a good saprophytical growing capability, Pythium spp. (class Oomycetes, order Perenosporales) can infest all species of grasses, building soft, fast growing mycel, protected by Chlamydospores and thick walled Oospores that can survive extended unfavorable environmental conditions as saprobiontic ground dwellers. The transition into the active phase is initiated by chemotactic stimulation from injured or weakened grass roots, which emit high levels of exudaten in the rhizosphere. This chemical acts like a light beacon for the myzel and zoo spores. Penetration shafts are built and bore into host plant walls, after 40-60minutes the cytoplasm coagulates and the cell dies, to be dissolved by fungal enzymes. Pythium is most deadly to young turf, older grasses prove more resistant. The early stages of the disease manifest a browning in the main roots, with moist blights soon forming on the leaves of the grass. Conditions most favorable to Pythium are: periods of warm weather followed by dry periods, high levels of air moisture, lasting surface moisture on the grass, strong dew buildup, ground compression, low light levels, too few nutrients in the soil, low pH levels, and too much nitrate. A minimum microscopic magnification of 100x will show Oospores in the roots even at the earliest macroscopic visible signs. 2) Gaeumannomyces graminis is an ascomycet of the class pyrenomycetes and order spheariales(=diaporthales). Surviving as a saphrophyte or a mycel, its small grey mycel is morphologically differentiated. It builds infection hyphens [Infektionshyphen] that attack the host plant by growing electrotropically over its surface, moving from plant to plant using running hyphens [Laufhyphen] that allow it to use the rhyzones, roots and stolons. High pH levels, particularly in the top 2 cm promote outbreaks; levels of 6.7 and above are regarded as critical, yet direct correlation between pH levels and outbreaks does not exist. Shallow surfaces, compacted surfaces, water defecit, and high air moisture levels all contribute to outbreaks. Visible symptoms include small yellow specks from 10-15 cm which grow and spread as much as 100 cm in one growing period. Roots turn black/brown, and are easy to pull out. Microscopically, the running hyphens are visible on the plant's surface. 3) Typhula incarnata belongs in the sub category basidiomycotina, class hymenocytes. Typhula is a surface dwelling saphrophyt, suited to temperatures until freezing. It survives warm periods as sclerotium, which are built at the end of winter, designed for resistance against heat and dryness. Sinking temperatures initiate the transition into its active phase (18 C). The stress factor of winter makes the grasses most succeptable, but in addition to low temperature, moisture, and snow cover, a reduced winter hardness of the grass renders it vulnerable. Spots and sclerotium are visible to the naked eye, microscopically the sclerotium are first smooth, then develop a gummy consistency. 4) Microdochium nivale, a deuteromycet, taxonomically in the class hyphomycetes, order tuberculariales, thrives in an optimum temperature of 0-21 C, yet temperatures as low as -20C do not suffice to kill it, nor does extreme heat or dryness in the summer much affect it, so strong are its mycel. Possessing a pronounced saphrophytical growing potential, its mycel grow ectotropically, building a surface mycel that spreads across adajacent plants, killing its leaves, only rarely spreading to the root systems. Only a few seconds of light are needed to create its sporodochs and konids [Sporodochien, Konidien]. Fluctuating temperatrures close to the freezing point, damp weather, snow cover, remaining mulch and grass clippings, as well as lessened winter hardness, soil compression or moisture, too short a fall cutting, too intensive care performed late in the fall and damage done to the hardened blades all contribute to the onset . Watery grey specks on the tips or edges of the grass form and quickly spread, turning the leaves a slimy red. Microscopically, the mycels are visible, the macroconids are not always present in the early stages, but the sporodochs and the micro conids, the latter of which possessing a half moon appearance, are.
Language:German
References:unknown
See Also:See also part 2: "Die wichtigsten Krankheiten der Rasengräser Mitteleuropas--Systematik, Biologie, Auftreten und Symptome (Teil II)" Rasen-Turf-Gazon, 23(2) June 1992, p. 59-63 R = 34360 R=34360

See also part 3: "Die wichtigsten Krankheiten der Rasengräser Mitteleuropas--Systematik, Biologie, Auftreten und Symptome (Teil III)" Rasen-Turf-Gazon, 23(4) December 1992, p. 106-110 R = 31959 R=31959

See also part 4: "Die wichtigsten Krankheiten der Rasengräser Mitteleuropas--Systematik, Biologie, Auftreten und Symptome (Teil IV)" Rasen-Turf-Gazon, 24(2) June 1993, p. 40-44 R = 29088 R=29088

See also part 5: "Die wichtigsten Krankheiten der Rasengräser Mitteleuropas--Systematik, Biologie, Auftreten und Symptome (Letzter Teil)" Rasen-Turf-Gazon, 24(3) September 1993, p. 64-68 R = 34508 R=34508
Note:Pictures, b/w
Abstract appears in German, English, and French
References for this article can be obtained from: Hortus Verlag GmbH, Redaktion Rasen/Turf/Gazon, Rheinallee 4 b, Postfach 20 06 55, 5300 Bonn 2
ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Böttner, F. 1992. Die wichtigsten Krankheiten der Rasengräser Mitteleuropas--Systematik, Biologie, Auftreten und Symptome [Teil I]. (In German) Rasen Turf Gazon. 23(1):p. 9-17.
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