Potassium deficiency-Wine Grape

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Nutrients

Wine Grape - Chlorosis

Symptoms
Intercostal chlorosis starts on the leaf margins and spreads to the internal area of mature leaves. At the margins, necrotic zones develop. The veins remain green for a certain time. Potassium deficiency results in different symptoms, dependent on the date of appearance and the weather conditions.

Reasons
Potassium deficiency

Wine Grape - Necrosis

Symptoms
Interveinal yellowing (white vine varieties) or reddening (red varieties) starts on the leaf margins and spreads over the internal area of older leaves. The veins remain green for a certain time. Later, necrotic areas appear on the leaf margins, which perforate easily. Symptoms of slight deficiency are shown on leaves near grapes firstly. Generally potassium deficiency symptoms are most apparent in mid to late summer.

Reasons
Potassium deficiency

Wine Grape - Chlorosis

Symptoms
Interveinal yellowing (white vine varieties) or reddening (red varieties) starts on the leaf margins and spreads over the internal area of older leaves. The veins remain green for a certain time. Later on the leaf margins necrotic areas appear, which perforate easily. Symptoms of slight deficiency are shown on leaves near grapes firstly. Generally potassium deficiency symptoms are most apparent in mid to late summer.

Reasons
Potassium deficiency

Wine Grape - Necrosis

Symptoms
Interveinal yellowing (white vine varieties) or reddening (red varieties) starts on the leaf margins and spreads over the internal area of older leaves. The veins remain green for a certain time. Later on the leaf margins necrotic areas appear, which perforate easily. Symptoms of slight deficiency are shown on leaves near grapes firstly. Generally older leaves are affected first.

Reasons
Potassium deficiency Very sandy soils and those that have been leveled (removing the topsoil) suffer worst from potassium deficiency. Deficiencies are most apparent in mid to late summer.

Wine Grape - Necrosis

Symptoms
Interveinal yellowing (white vine varieties) or reddening (red varieties) starts on the leaf margins and spreads over the internal area of older leaves. The veins remain green for a certain time. Later on, the leaf margins and intercostal areas become necrotic and perforate easily. Symptoms of slight deficiency are shown on leaves near grapes firstly. Generally older leaves are affected first. K deficiency is one reason among others for a physiological disorder that makes the grape berries wilt and dry.

Reasons
Potassium deficiency Very sandy soils and those that have been leveled (removing the topsoil) suffer worst from potassium deficiency. Deficiencies are most apparent in mid to late summer.

Potassium deficiency made worse by

Acidic soils (low pH)
Sandy or light soils (leaching)
Drought conditions
High rainfall (leaching)
or heavy irrigation
Heavy clay (illite) soils
Soils with low K reserves
Magnesium rich soils

Potassium is important for

Healthy green foliage
Important for fruit size, development and yield
Reduction of fungal diseases
Improved sugar content of berries
Improved maturation of berries
Needed in great quantities

Yara recommended fertilizers for Potassium

YaraVita CROP BOOST

Grapevines: 3 to 5 l/ha at flower buds visible, flower buds separated, fruit set, and early veraison (one month before harvest). Water rate: 200 l/ha.