Chapter 16

Vineyard Nutrient Management

Macronutrients and Micronutrients

Manganese

Role and Deficiency Symptoms

Manganese is involved in the synthesis of chlorophyll, fatty acid synthesis, and in photosynthesis.

Manganese symptoms can appear on severely deficient vines 2 or 3 weeks after bloom commencing with the basal leaves. A mild to moderate deficiency will not become apparent until mid- to late summer.

Assesing the Need for a Manganese Fertilizer

As with most micronutrients, tissue sampling can be used to determine the vines’ manganese status. Tissue analysis results (Table 16.3) coupled with visual observations should indicate whether to apply manganese.

Time of Application

Two applications usually will provide season-long control of manganese symptoms.

Application Methods

Direct Soil Surface Application: Broadcast and band applications of manganese fertilizer or attempts to build soil manganese levels are not recommended, particularly on high pH, high organic matter soils because of their capacity to rapidly fix manganese.

Fertigation: Manganese applied to vineyards with the drip system is effective and feasible. Drip irrigation is effective since nutrients are placed where roots are highly concentrated, and uptake is supported by continuous high soil moisture beneath emitters.

Foliar Application: A foliar application of manganese can be sprayed for immediate effect. Manganese sulfate is most widely used as well as chelated forms (EDTA) of manganese.

Soil Factors Affecting Availability

Manganese deficiencies mainly occur in organic soils, high-pH soils, sandy soils, calcareous (alkaline) soils, or in soils with high levels of available iron.

Manganese Toxicity

Symptoms of toxicity are rarely seen in grapevines. Manganese toxicity is seen as black spots on leaf blades, shoots and bunch stems.

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