ZINC DEFICIENCY
Zinc is important in early plant growth and in seed formation. It also plays a role in chlorophyll and carbohydrate production.
Leaves
- Symptoms appear on young shoot tips and laterals
- Smaller asymmetrical leaf blades smaller with one half of the leaf being larger than the other and teeth along margin appear elongated
- Interveinal areas turn light green to yellow in a mosaic pattern and can become reddish in black and red cultivars while leaf veins become clear with narrow borders of green
- With severe deficiency, chlorotic areas may die resulting in the leaf blade rolling inward
Berries
- Small, pale yellow berries mixed with large ones in the same bunches resulting in abnormally loose clusters
- Weak rachises may develop stem necrosis
Often Confused With
Manganese deficiency - yellowing pattern between the veins occurs as “islands” of yellow areas rather than a continuous discolouration of the leaf
Boron deficiency – small cupped leaves, poor fruit set and bulges in internodes
Magnesium deficiency-yellowing pattern starts at leaf margin; occurs first on basal leaves
Iron deficiency: yellowing between the small leaf veins, eventually turning almost white
2,4-D injury– herbicide injury has severe margin teeth elongation and distortion of leaf shape
Fanleaf virus – veins remain bright green, interveinal areas turn yellow (white cultivars) or reddish purple (red cultivars)
Scouting Notes
Zinc deficiencies are most often seen on sandy soils with high pH levels, especially in cool, wet springs. Heavily eroded knolls may also have deficiency problems.
Management Notes
Zinc deficiency may be induced by excessive applications of lime. Soils with high phosphorus levels or high applications of phosphorus fertilizers may combine with zinc and make zinc unavailable to the roots. Foliar sprays may be used but deficiency should be confirmed with tissue analyses before use.
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