Growing Grape
Crop Nutrition Advice

Nutrient requirements

Grape-vines have fewer mineral deficiencies and a lower plant nutrients demand than many other horticultural crops.

Phosphorus, potassium, and lime applications should be based on soil tests and leaf-analysis results.

Nitrogen fertilizer should be applied during periods of active uptake, to minimize loss through soil leaching.

This includes the period from bud-break to veraison, and if leaf fall has not occurred, immediately after fruit harvest.

Multiple applications of nitrogen are preferred over one large spring application. Most nitrogen forms can be used equally in vineyards.

Dynamic of nutrient uptake over a crop season in vineyards

The following dynamics patterns can be seen above:

• N uptake is relatively low at early season, it rises sharply until fruit-set, then decreases sharply until harvest,and increases sharply again after harvest.
• P follows a similar pattern, but it only increases after harvest
• K uptake rate starts highest of all the above, falls steeply until harvest, and slightly recovers after harvest

Role of nutrients

Nitrogen

Promotes high yields and ensures vegetative growth of the crop.

Plays a key role in synthesis of proteins, which are directly involved in growth and yield.

Phosphorus

Promotes development of a good root system. A prerequisite for flowering and hence number and maintenance of fruits.

Essential for appropriate energy management in the plant. Enhances cell division.

Potassium

Enhances transport of sugars to the fruits. A cofactor of tens of enzymes. Regulates water management, mainly through stomata aperture.

Enhances sugar content of the fruit. Reduces susceptibility to many kinds of abiotic, and biotic, stresses. Improves deep green fruit color, firm flesh, shape, and overall yields.

Calcium

Promotes cell-wall stability, hence providing the plant a strong structure, and resistance to diseases.

Adequate calcium prevents blossom-end rot (BER). It also provides improved shelf life.

Magnesium

Is the central part of chlorophyll molecule, playing a key role in photosynthesis. Increases Fe utilization.

Carrier of phosphorus in the plant. It is both an enzyme activator and o constituent of many enzymes. Helps obtaining a deep green fruit color.

Iron

Essential for proteins and chlorophyll synthesis. Important factor in many enzymes, associated with energy transfer and respiratory systems.

Manganese

Translocation of sugars and carbohydrates. Pollination and seed production. Cell division and cell-wall formation, related to Ca uptake and usage.

Zinc

Production of auxin, an essential growth hormone. Promotes proteins and chlorophyll synthesis. Necessary for starch formation and proper root development.

Copper

Involved in metabolism of N and carbohydrates. A catalyst in photosynthesis and respiration. Included in enzymes involved in building and converting amino acids to proteins.

Molybdenum

Important to nitrate reductase activity, converting nitrates to aminoacids. Conversion of inorganic P into organic forms.

Nutrient deficiencies

Nitrogen

• Mature leaves: uniformly small and light-green or yellow, throughout the vine
• Shoot growth: slow and ceases in midsummer
• Internodes: short
• Fruit maturation: precocious
• Fruit quality: poor, including poor color in red varieties

Phosphorous

• P – deficient plants have weak roots, are stunted, and produce small, dark green or brown leaves
• Fruit – set is reduced, thus impairing production
• Phosphorus deficiency is most common when soil pH is too low (<5.5) or too high (>7.0)

Potassium

• The old leaves are the most sensitive ones, they exhibit marginal chlorosis, and in severe cases the leaf margins die
• A dull dark green color appears on the leaves. In mid- to late- summer leaves may have a bronze color, especially on west-facing side of the trellis. Some leaves may develop dark spots or blotches.
• K-deficiency can be aggravated by application of dolomitic limestone, done for raising the pH and enriching the soil with Mg
• Severe K deficiency markedly reduces vine vigor, berry size, and crop yield

Magnesium

• Yellowing of older leaves, beginning between the major veins, which retain a narrow green border. This interveinal chlorosis shows first as scattered blotches. Younger leaves are less affected. Unless the deficiency is severe, it does not become evident until late summer
• Young terminal leaves may never show symptoms unless the entire vine is extremely affected
• Yields are reduced
• Mg deficiency can reduce yield and delay ripening if leaf chlorosis becomes severe enough to inhibit photosynthesis
• Deficiency is revealed mainly in plots with pH<5.5, and plots that have received high N, Ca or K fertilizer rates, on light soils and in very dry years

Iron

• Pale interveinal yellowing appears on younger leaves first. All other leaves remain dark green
• Reduction in shoot growth and yield
• Iron-deficient plants are yellow and stunted
• Most often observed when growing in alkaline (pH > 7.0), or calcareous soils, and can be induced also by over-liming, poor drainage, or high concentrations of metallic ions in the soil or nutrient solution

Manganese

• The symptoms appear in mid-to-late summer, as an interveinal chlorosis, or yellowing of the basal leaves
• Since Mn deficiency only affects the less photosynthetically-active older leaves, yield losses from Mn deficiency are rarely a concern.
• Mn deficiency occurs on pH>7 soils, and on sandy-, calcareous- , or excessively limed soils

Zinc

• Young leaves appear yellowed and they tend to be smaller in size
• Interveinal yellowing similar to the one provoked by Fe deficiency
• New growth is adversely affected with shorter internodes that produce stunted shoots
• Older leaves show initially yellowish-green interveinal chlorosis, developing later to yellow/ whitish. The veins keep their green margins
• Much less flowers, that may be infertile
• Withered clusters with tiny, under-ripe fruit

   

Nitrogen deficiency                         Phosphorus  deficiency 

   

Potassium deficiency                      Magnesium deficiency

   

Manganese  deficiency                    Iron deficiency

   

Zinc  deficiencies

Fertilization methods

Soil application

Apply nitrogen within 30-60 cm of the vine by banding + immediate disking, or by fertigation. If nitrogen fertilization is needed, annual application of 35-60 kg/ha of actual nitrogen, on sandy loam soils, is a good starting point for mature vineyards. Young vineyards (1st and 2nd growing season) in need of nitrogen fertilization, typically require no more than 30 kg/ha of actual nitrogen.

Fertigation by drip irrigation in open fields and protected management

As drip irrigation is so common with this crop, fertilization is generally done by fertigation, using  fully-soluble fertilizers, adapting the N-P-K-Ca-Mg ratios according to the crop’s needs at every growth stage.

Foliar feeding

A properly applied foliar spray program usually focuses on micronutrients and can be beneficial. Before applying any nutrient spray, a laboratory petiole analysis from affected and normal leaves, and a soil analysis, should be performed. This can help make an educated decision, with more evidence than just visual symptoms. Zinc deficiency may be corrected by applying a foliar spray 2-3 weeks before bloom. As Fe is immobile in plants, spray only existing foliage. If chlorosis is severe and persists, repeated applications at 10-20-day intervals may be necessary.