Black spot leaf disease is a

physiological plant disorder Physiological plant disorders are caused by non-pathological conditions such as poor light, adverse weather, water-logging, phytotoxic compounds or a lack of nutrients, and affect the functioning of the plant system. Physiological disorders are d ...

that affects some grape varieties such as

Concord Concord may refer to: Meaning "agreement" * Pact or treaty, frequently between nations (indicating a condition of harmony) * Harmony, in music * Agreement (linguistics), a change in the form of a word depending on grammatical features of other ...

. It is essentially a potassium deficiency that causes the leaves on a vine to turn purple and eventually black as chlorophyll is lost. For wine growers this lack of chlorophyll inhibits the vine's ability to transmit sugar to the grape, leaving the resulting grapes with a low brix count that may be less than ideal for

wine making Winemaking or vinification is the production of wine, starting with the selection of the fruit, its fermentation into alcohol, and the bottling of the finished liquid. The history of wine-making stretches over millennia. The science of wine and w ...

Causes

Black leaf, also known as black spot disease can be caused by different types of

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

and

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

. Most common being ''Asterina, Asterinella, Diplotheca, Glomerella, Gnomonia, Schizothyrium, Placosphaeria, and Stigmea.'' Black leaf can affect many different plant species during wet, damp climate. It may appear as black spots on leaves, stems, and flowers.

Prevention and Treatment

Treating black leaf disease can be achieved in many ways. Some include removing each affected leaf of any yellow or black color. If the infection has spread throughout a larger area, it may be best to remove the affected limb of the plant to reduce further spread.

Fungicides Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality ...

may be used as treatment. There are a number of remedies used to prevent the spread of black leaf disease, including mixtures of baking soda, soap, vegetable oil, and water.https://www.wikihow.com/Deal-with-Black-Spot-Leaf-Disease Deal with Black Spot Leaf Disease

References

External links

Photosynthesis and Chlorophyll Fluorescence in Blackleaf-Affected Concord Leaves
- American Society for Enology and Viticulture
Blackleaf in Grapes
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www.extension.org

Black Spot Plant Disease

Deal with Black Spot Leaf Disease
Grape diseases Leaf diseases {{plant-disease-stub