Black leaf
Encyclopedia
Black Leaf is a physiological plant disorder
that affects some grape varieties such as Concord
. 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.
Physiological plant disorders
Physiological plant disorders are caused by non-pathological disorders such as poor light, weather damage, water-logging or a lack of nutrients, and affect the functioning of the plant system. Physiological disorder are distinguished from plant diseases caused by pathogens, such as a virus or fungus...
that affects some grape varieties such as Concord
Concord grape
Concord grapes are a cultivar derived from the grape species Vitis labrusca which are used as table grapes, wine grapes and juice grapes....
. It is essentially a potassium deficiency
Potassium deficiency (plants)
-Soil type and potassium deficiency:Potassium deficiency, also known as potash deficiency, is a plant disorder that is most common on light, sandy soils, because potassium ions are highly soluble and will easily leach from soils without colloids. Potassium deficiency is also common in chalky or...
that causes the leaves on a vine to turn purple and eventually black as chlorophyll
Chlorophyll
Chlorophyll is a green pigment found in almost all plants, algae, and cyanobacteria. Its name is derived from the Greek words χλωρος, chloros and φύλλον, phyllon . Chlorophyll is an extremely important biomolecule, critical in photosynthesis, which allows plants to obtain energy from light...
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
Brix
Degrees Brix is the sugar content of an aqueous solution.One degree Brix is 1 gram of sucrose in 100 grams of solution and represents the strength of the solution as percentage by weight . If the solution contains dissolved solids other than pure sucrose, then the °Bx is only approximate the...
count that may be less than ideal for wine making.
External links
- Photosynthesis and Chlorophyll Fluorescence in Blackleaf-Affected Concord Leaves - American Society for Enology and Viticulture
- Blackleaf in Grapes on www.extension.org