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Potassium
deficiency
Tom
Zabadal , MSU Horticulture |
| Home > Scouting guide> potassium deficiency |
| Potassium is
important for grapevines to function and is one of the most frequent
nutritional deficiencies of vines. A grapevine with inadequate potassium
produces poor, unevenly ripened fruit and reduced yields. Severe
deficiency results in defoliation. Leaves in the mid- to basal portions
of shoots are affected. Clusters of deficient vines tend to be small
with a few unevenly ripened berries. Shatter of berries occurs in
extreme cases. The relationship between another reported symptom,
“black leaf,” and potassium deficiency is in doubt. Leaf
petiole testing can reliably confirm potassium deficiency. |
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| Leaf
symptoms may begin in mid-June. Leaf margins turn yellow (left)
and progress so that leaf margins become brown (right) and the
tissue around the veins blackens. Photos: T.
Zabadal |
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