Ophiognomonia leptostyla

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Ophiognomonia leptostyla
Ophiognomonia leptostyla on walnut leaf

Ophiognomonia leptostyla on walnut leaf

Systematics
Class : Sordariomycetes
Subclass : Sordariomycetidae
Order : Diaporthales
Family : Gnomoniaceae
Genre : Ophiognomonia
Type : Ophiognomonia leptostyla
Scientific name
Ophiognomonia leptostyla
( Fr. ) Sogonov

Gnomonia leptostyla ( Syn. Gnomonia leptostyla ) is a fungal art from the family of gnomoniaceae . It causes the so-called Marssonina leaf spot disease on walnuts and black walnuts , named after their minor crop form Marssoniella juglandis .

features

Macroscopic features

typical spots on the fruit

Ophiagnomonia leptostyla can be identified macroscopically mainly on the basis of its symptoms of infestation. The leaves initially get small dark brown spots with a lighter center. As a result, entire leaflets turn yellow, larger leaf areas turn brown and leaflets and leaves fall off prematurely in different stages of infestation. Fruits and occasionally sprouts are also attacked. Infested nuts have dark sunken spots and a dark, wrinkled flesh.

Microscopic features

The perithecia are sunk into the leaves. Their necks are shorter than 250 microns. The ascospores are 19-23 micrometers long and 3.5 μm wide. In the secondary fruit form, two-celled, curved conidia are formed on the underside of the leaf in acervuli .

Ecology and phenology

Ophiognomonia leptostyla affects different types of walnuts . The species overwinters on the fallen leaves and infects leaves and fruits again in early summer.

distribution

Ophiognomonia leptostyla is common throughout Europe and North America.

meaning

Especially in wet years, the disease causes considerable losses in the walnut harvest and can lead to severe defoliation. Important measures against the disease are removing and destroying the leaves in autumn. Control with fungicides should only be considered in exceptional cases. High fertilization with nitrogen also reduces the extent of the disease.

Systematics

Ophiognomonia leptostyla was first described by Elias Magnus Fries as Sphaeria leptostyla in 1823 , Vincenzo de Cesati and Giuseppe De Notaris placed the species in the genus Gnomonia . In 2008 it was placed in the genus Ophiognomonia due to molecular biological studies.

swell

Individual evidence

  1. ^ A b c d e MV Sogonov, LA Castlebury, AY Rossman, LC Mejía, JF White: Leaf-inhabiting genera of the Gnomoniaceae, Diaporthales . In: Studies in Mycology . tape 62 , 2008, p. 1–79 , doi : 10.3114 / sim.2008.62.01 ( online [PDF]).
  2. ↑ a b c d e Forst TU Munich, accessible via webarchive, accessed on April 25, 2016. Archived from the original on June 10, 2007 ; Retrieved December 24, 2012 .
  3. ↑ a b Forest Insect & Disease, USDA Leaflet 85. Accessed on 24 December 2012 .

Web links

Commons : Ophiognomonia leptostyla  - collection of images, videos and audio files