The climatic factors such as temperature, occurrence of frost, rainfall and relative humidity play a vital role for commercial cultivation of grape. Generally grape requires a hot and dry climate. Regions with high rainfall and humidity is not conducive for grape cultivation. Hence the coastal districts of the state are not suitable for grape production. Grape is successfully grown in regions of Maharashtra with a temperature range of 150C to 400C and rainfall of 50 to 60 cm. The weather should be clear for about 3-4 months during the cropping period. Cloudy weather, high humidity low temperature and rain during flowering and berry development are detrimental as they promote spread of diseases.
Although grape can adapt to a variety of soils, it grows and performs best in deep medium-textured soils (loams and sandy loams) with good drainage and low salt content. Salinity is the major hindrance in the development of grapes. It grows well in soils with a pH range of 6.5 to 7.5.
Development of salt resistant rootstocks like Dogridge and Salt Creek has given an impetus for area expansion under grape in saline areas. Most of the new vineyards are established on Dogridge rootstocks in the state of Maharashtra. The rootstocks are supplied by NRC Grapes, Maharashtra Grape Growers’ Association etc. Some of the progressive farmers produce rootstocks for their own use and sale. The mother plants are available with NRC Grapes and farmers’ field. The rootstocks are raised by planting hard wood cuttings on flat beds at desired spacing, depending upon the variety and method of training.
The main varieties grown under organic cultivation in the state are Thompson Seedless, Sharad Seedless and Tas-A-Ganesh.
Spacing varies with variety and soil fertility. Generally under organic cultivation, spacing of 2.5 m x 1.5 m, 2.75 m x 1.50 m and 3.0 m x 1.5 m are followed. For this model scheme, a spacing of 2.75 m x 1.50 m with a plant population of 2425 plants/ha is considered.
The land is prepared by ploughing it twice and harrowing it thrice.
Pits of 90 cm x 90 cm x 90 cm are dug and filled with soil and well decomposed FYM/Compost @ 55 t/ha. The pits are then irrigated in order to allow the soil to settle. Rectangular system of planting is adopted for growing grape.
Training is an important operation in grapes. It helps to maintain the stature and spread of the vine and facilitates operations like pruning, intercultivation, spraying and harvesting. There are many systems of training. The common systems in India are Bower, Kniffin, Telephone, Trellis and Head system. Under the climatic conditions of Maharashtra, Bower and Trellis system has been found to be the best for commercial varieties like Thompson seedless, Sharad Seedless and Tas-A-Ganesh. In Bower system, a bower of 2.1 m height is erected using stone pillars as support and galvanized iron wire of 8 and 10 guage thickness for mesh. One vigorous growing shoot is selected by nipping off other shoots and this single shoot is allowed to grow up straight with the support of bamboo or plastic wire stake.
All the axillary shoots are pruned and the main growing shoot pinched off at 15 cm, below the pandal level. Two shoots arising below the cut area are allowed to grow in opposite direction on the wires overhead. These two shoots develop into main arms. On the main arms, side shoots are allowed to grow at regular intervals of 40 to 45 cm. These side shoots are called secondaries and tertiaries or canes from which fruiting spurs develop. The arms and secondaries form the permanent frame work of the vine.
The main arm should be trained towards East and West direction so as to reduce damage due to sunburn during summer months especially after February-March pruning. The entire space allocated for each vine is covered in a gradual manner by intermittent pinching of the primary arms and secondaries, not allowing them to grow more than 60 cm at a time. As they grow, the shoots are tied with jute twine and all tendrils are removed.
Removal of any vegetative part in a vine is called pruning. It is a critical operation in grape cultivation. Therefore much care and precision needs to be exercised in pruning a vine. The main objective of pruning grapevine is to increase productivity, facilitate interculture operations and maintain desired vine framework and vitality of the vine for consistent productivity. In organic grape cultivation, the vines are forced to undergo rest for about a month immediately after harvest.
This helps in storing the food material in the mature parts of the vine. The canes are cut back in April by keeping 1-2 buds which develop into canes in 4-5 months. The removal of dried canes is called ‘back pruning’ or ‘growth pruning’. In the month of September-October these canes are pruned for fruiting. This pruning is called ‘forward pruning’ or ‘winter pruning’. Vines, which have attained the age of one year can be subjected to this pruning.
Manuring is done by applying FYM at the rate of 55 t/ha. Biofertilizers like Azatobacter, Phosphate Solubilizing Bacteria(PSB), Effective Microorganism (EM), Neem cake and vermiwash are being used to supplement the nutrient requirement of crop. Trichoderma, Azatobacter and PSB are applied at the rate of 25 g/plant. Neem cake is applied at the rate of 1.25 t/ha. Jeevamrut is prepared by adding 10 kg cow dung, 5 l cow urine, 2 kg black jaggery, 2 kg ground pulses powder, handful of bund soil in 200 l of water. The solution is kept for 2 to 7 days in shade for fermentation. During the fermentation, the solution is stirred daily. To improve the quality of grapes, a solution of sugar, humic acid and coconut water is sprayed at bud development stage.
A fully grown vine requires about 1000 l of water in winter and 2000 l in summer season immediately after pruning and application of fertilizer. Vines are given 2 to 3 summer irrigation at 3-4 days interval. During winter, an interval of 8-10 days is maintained between two irrigation. The vines are to be irrigated when the top 5 cm soil is dry in winter and 3.5 cm top soil is dry in summer. During berry development stage irrigations are given at weekly intervals and the same is withheld 10 days before harvesting to improve quality.
In the vineyards, weeding is generally done mechanically. Frequent weeding is required to allow feeder roots to absorb the nutrients and moisture without any competition. Bullock drawn or tractor drawn implements can be used for inter-cultivation and weed control. Weeding is done 3-4 times in a year.
Shoot pinching is a part of pruning mainly done to promote fruit bearing and regulate the current season’s growth. This is done when the main shoot attains 7-8 leaf stage. During pinching, the tip of the mature shoot is pinched by retaining only five nodes. As a result, the terminal bud along with 1-2 laterals resumes growth. These laterals are called sub-canes. Buds up to the third node from the base on the sub-cane are observed to be bearing fruits.
Pests and Diseases
The major pests affecting the grape crop are flea beetles, thrips, mealy bugs and leaf hoppers. The major diseases are downy mildew, powdery mildew and anthracnose. The schedule of plant protection measures are given below:
|Pest/disease||Plant protection measures - Spraying of|
|Downy mildew/ Powdery mildew||Trichoderma, 1% Bordeaux mixture + Dasparni arka + Gomutra<|
|Mealy bug||Cowdung urine|
|Anthracnose||Solution of acacia leaves|
The dasparni arka is prepared by adding 25 kg leaves of Neem and 2 kg leaves each of custard apple, Nirgudi, Kaner, Cotton, Papaya, Castor, Karanj, Gudwel, Drumstick in 200 l of water. In the solution, 5 to 10 l of gomutra and 2 kg of green chillies are added. The solution is kept for 15-20 days for fermentation. The stock solution is prepared by filteration through muslin cloth. The spraying is done by adding 5 l of stock solution in 200 l of water.
Grape is harvested almost all the year round. If not all the varieties, one or the other variety is always available at any given time of the year. However, in Thompson Seedless and its clones, major part of the produce is harvested during March-April from the hot tropical region contributing to more than 70% of the total harvest.
An average yield of 15 -20 t/ha is obtained during the second and the third year onwards which increases upto 25 t/ha from the fourth year onwards. The economic life of grape is fifteen years and harvesting of fruits can be done upto an age of 15 years.