Английская Википедия:Golovinomyces orontii

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Golovinomyces orontii on clover

Golovinomyces orontii is a species of fungus that causes powdery mildew disease and it is in the family Erysiphaceae. It is an obligate biotroph that infects plants in several families including Acanthaceae, Asteraceae, Brassicaceae, Cucurbitaceae, and Lamiaceae.

Taxonomy

Previously known as Erysiphe orontii, by Castagne (1851). It is now known by Golovinomyces orontii by Heluta (1988).

Description

Causes powdery mildew disease in multiple families including Acanthaceae, Asteraceae, Brassicaceae, Cucurbitaceae, etc. Conidia is produced on the surface of the infected plant and that as well as hyphal growth gives it its white powdery appearance. Conidia are dispersed through the wind, water droplets, and similar methods to nearby plants to start new infections. The mycelium is able to absorb nutrients through haustoria.

Disease symptoms

When Golovinomyces orontii infects its host plants, it causes a disease commonly known as powdery mildew. This gives the appearance of white, powdery sections on the surface of the plant. These powdery sections are caused by an abundance of conidia and mycelium. This can lead to deformation, discoloration, reduced growth, and death in the host plant

Lifecycle

The lifecycle begins when a conidia lands on the surface of a host plant. The conidia then develop germ tubes, forming an appressorium, that later forms into haustoria. These haustoria are used to siphon nutrients needed for growth.  

Golovinomyces orontii completes a full life cycle within a few days. The fungus produces new conidia asexually, which are easily dispersed to nearby susceptible plants. These conidia can initiate new infections, leading to the spread of the disease.

Ascomata (chasmothecia) are rarely formed on most hosts. Chasmothecia may form under unfavorable conditions. Chasmothecia are resistant structures that protect the sexual spores (ascospores) of the fungus. They can remain viable for extended periods and serve as a means of survival until conditions become favorable again.

Management and control

The control of Golovinomyces orontii and powdery mildew diseases generally involves a combination of chemical and nonchemical strategies. Nonchemical strategies include; proper plant spacing, pruning and removing infected plant parts, avoiding overhead irrigation, improving ventilation, and crop rotation. Natural Fungicides by be used as well. In severe cases, fungicides can be applied, but it is important to minimize the environmental risk of these fungicides and the prevention of resistance. For many vegetable crops, sulfur, copper-based products, chlorothalonil, horticultural oil, potassium bicarbonate, and Bacillus subtilis can be used for powdery mildew control.