WEATHER BASED GRAPE ADVISORY

II. Water Management

a. Number of days after fruit pruning: 166

b. Expected Pan evaporation: 6-7.5 mm

Amount of irrigation advised:

1.      In case the soil is under wapsa (field capacity) condition, donot irrigate the vineyard.

2.      Practice mulching to keep the bunds moistened. This will reduce the salinity build up in the root zone due to evaporation of the moisture from the surface of the bund.

3.      From Veraison stage onwards till maturity, apply irrigation through drip @ 10,200 to 11,900 L/ acre/ day.  In the area where max. temperature exceeds 36°C, apply irrigation ranging from 11,900 to 12,750.

4.      Whereever temperature is crossing 35°C, donot withhold irrigation during ripening to harvest stage for faster sugar accumulation, as this will lead to loose bunch, thereby affecting the quality of produce.  This is especially true in case of light soils and saline soils.

Soil and Nutrient management

Berry Development stage:

1.      After 8-10 mm berry size, start application of nitrogen in the form of ammonium sulphate @ 25kg /acre in 4 splits in calcareous soil and as urea @ 15 kg/acre in other soils in 3 splits.  Follow this up with Sulphate of potash or 0-0-50 @ 25 kg/ acre in 3-4 splits for next two weeks.

2.      If soils are calcareous, then apply zinc sulphate and ferrous sulphate @ 5-10 kg/acre at 65-70 days after pruning.

3.      Possibility of powdery mildew infection.  Build up potassium levels in grapevine either through foliar spray @4-5 gm SOP/L and drip @ 15 kg SOP/L if not applied since last 20 days.

Ripening to Harvest stage:

1.      Apply Sulphate of potash or 0-0-50 @ 25 kg/ acre in 3-4 splits for next two weeks.  Total potassium application (SOP) should be approx. 60 kg/acre during this stage.  Follow this up with Magnesium sulphate @ 10 kg/acre in two splits. 

2.      Spray Magnesium sulphate  and potassium sulphate @ 4g/L in calcareous soil.

3.      Possibility of powdery mildew infection.  Build up potassium levels in grapevine either through foliar spray @4-5 gm SOP/L and drip @ 15 kg SOP/L if not applied since last 20 days.

4.      In case leaf curling/marginal leaf yellowing (potassium deficiency) and mites infection is observed, first control mites and then spray SOP@5g/L to take care of potassium deficiency and drip @ 15 kg SOP/L if not applied since last 20 days.

5.      Manage canopy for adequate sunlight and air movement within the canopy for avoiding/ minimizing problems of berry cracking.

Rest Period

            After the harvest of grapes during February – March, vine reserves are exhausted.  After foundation pruning, till photosynthetically active leaves are formed, it is the vine reserves that contribute to the growth and development of the vines. Hence, following is advised:

1.      Provide only need based irrigation to protect the existing leaves from drying and also contribute towards increasing the reserves of the vines through photosynthetic activity.  The quantum of irrigation water applied should be approx. 5000 – 6000 L/ acre, once in a week.  Care should be taken to reduce/stop the water in case new growth is observed on the shoot. 

2.      Apply 10-15 kg urea, 25-30 kg SSP and 10-15 kg Sulphate of Potash per acre every 15-20 days till foundation pruning is not done. 

3.      Flooding the vineyard is not advised as it will lead to wastage of water.  Concentrate irrigation water application in the root zone only.

Foundation pruning:

1.      If planning for foundation pruning in next 10- 15 days, it is advised to get soil and water analysed for planning nutrient and water application schedule for foundation pruning season.

III. Canopy Management

Based on the weather data and growth stages, following suggestions are offered for vineyard management.

1.      The temperature in the vineyard has started increasing. This will demand more irrigation water for berry development. Under the situation of shortage of irrigation water in the vineyard, use of mulching, irrigation during either evening time or early morning need to be followed.

2.      As the development of grape bunches are in progress, the irrigation is also being increased in the vineyard. This is also helping to increase the relative humidity in the vineyard. Due to this the chances of incidence of powdery mildew may increase. Hence, under this condition, spray of biologicals need to be used in the vineyard.

3.      Open canopy in the vineyard will help to reduce the disease incidence and effective coverage of fungicide. Arrangement of shoots on foliage wire and removal of 2-3 basal leaf on a shoot will help to reduce the microclimate.

4.      Bunch load management in case of colour varieties is important. To avoid delay in colour development, minimum bunch load to be maintained. 

5.      The grape bunches at the stage of veraison, should be placed under the canopy to maintain uniformity in bunch colour.

6.      Elongated varieties in the market are preferred when the TSS is higher. To achieve, the leaf around the grape bunch needs to be removed. This will help in obtaining yellow colour of grape berries having higher TSS.

7.      The preparation for re-cut in newly grafted vines to be initiated. Opening of trench (size: 2 feet wide and 3–4-inch depth) and application of FYM along with recommended dose of fertilizer will help for vegetative growth after the re-cut is taken.

8.      The re-cut of grafted vines should be taken only after the minimum temperature in the vineyard starts rising above 15⁰C.

9.      Application of hydrogen cyanamide @ 40 ml/L water along with Mancozeb @ 3g/L water can be used for bud sprouting.

10.  The cutting of shoot above graft joint with uniform diameter and height should be maintained for framework development.

11.   After the bud sprouting, only straight and fast-growing shoot to be selected for trunk development.

12.  The selected shoot to be tied to bamboo with sutali.

13.  While developing the trunk, stop and go method to be followed. The growing shoot to be pinched at 7-8 leaf stage when it is at 10-11 leaf.

14.  The side shoots on the new growth is then pinched at 3-4 leaf and the upper shoot to be tied for next instalment of cordon.

IV. Disease management

Application of Trichoderma@2-3ml/L and Ampelomyces quisqualis @ 5ml/L should be done at an interval of 7-10 days to all vines for powdery mildew control. Before harvest two sprays of Bacillus subtilis may be given which will not only control powdery mildew but will also help in reduction of pesticide residues.

V. Insect and Mite management

Growth Stage: Berry development and veraison stage after October pruning

1.    Buprofezin 25 SC @ 1.25 ml/L (PHI 65 days) water or spirotetramat 15.31 OD @ 700ml/hectare (PHI 60 days) may be used for the management of mealybugs. In case PHI cannot be maintained for application of insecticides, tag mealybug infested vines and wash with any trisiloxane polyether-based surfactant @ 0.3 ml per litre water with water volume10-12 litres per vine with single gun with mild pressure to wash off the mealybugs. It should be followed by washing with plain water.

2.    Mite infestation may increase in most of the grape areas. Sulphur 80 WDG @ 1.5-2.0 g/L or Abamectin 1.9 EC @ 0.75 ml/L (PHI 30 days) or Bifenazate 22.6 SC @ 0.5 ml/L (PHI 30 days) water may be applied if mite infestation is observed.

3.    All the cracked/damaged berries should be removed from the grape bunches. These berries should be destroyed by burying them minimum two feet deep in the ground away from the vineyards. It will reduce the scavenging fly population in the vineyard. The berry cracking of grapes should be managed by following suitable viticultural practices.