The Importance of Good Vine Nutrition
As flowering occurs, it is important to give consideration to the nutritional status of the grapevines. Zinc, Boron, and Phosphorus are the priority nutrients during flowering and fruit set. Where levels are low it is important that these nutrients are applied pre-flowering and at fruit set, to ensure adequate levels. As both zinc and boron are relatively immobile in the plant a foliar application of Zintrac and Bortrac, directly targeting the foliage, is an effective way of elevating these elements.
Nitrogen, Magnesium, Iron and Manganese are the most critical nutrients to ensure good photosynthetic activity, as they are all essential in the production of chlorophyll. The major effects of poor photosynthesis on the vine are low glucidic reserves within the plant leading to problems at flowering and fruit set, reduced shoot growth and poor vigour, death of the grape stalk and loss of grapes. There can also be a general weakening of the plant leading to premature senescence and early leaf fall.
Iron and Manganese levels tend to be sufficient in most Hawkes Bay vineyards, and excess Nitrogen is more commonly a problem than low Nitrogen. Magnesium uptake from the soil can be affected by many factors including, rootstock, weather conditions, and the level of other nutrients in the root zone e.g. high levels of potassium will restrict the uptake of magnesium. Prevention of magnesium deficiency is far more effective than cure, so a foliar programme of Hydromag Liquid would be strongly recommended. Last season's petiole analysis results at flowering showed that 26% of samples in NZ grapevines were low in Magnesium and 18% of samples were low in Boron at the critical flowering stage.
New Composite Product
If Magnesium, Boron and Zinc are all low consider Bud Builder, a new composite product containing the essential balance of Magnesium, Boron, Zinc, and Phosphorus. It has been developed by Phosyn to supply a "Ready Made" solution for pre-flowering requirements to grapevines. Benefits:
• Supplies critical nutrients at the right time
• Less containers taking space in the spray shed
• Easily disposable 10 kg cardboard container
• Easy to mix powder
• Wide tank mix compatibilities
• Crop safe
• Rainfast
• Cost effective
Megalab is a computerised database developed by Phosyn, international specialists in crop nutrition, to give an interpretation and recommendation from analysis results. Nutrient guidelines were developed over many years to look at optimum nutrient levels so that the crop can be monitored right through the season. Megalab interpretation is a free Internet based service available exclusively from Phosyn to give customers precise interpretation and recommendations from analysis. An important time to take samples for analysis in vines is at the flowering stage. Interpretations can be made from analysis of petioles or leaves. Last season saw more than 3000 analysis results go through the NZ Megalab service.
Author: David Spencer, New Zealand
Published: November 2000