Horticulture is the back-bone of the economy generating about 10,000 crores annual income and contributes 8 per cent to Gross Domestic Price (GDP) of the Union territory of J&K. As per the official data, the total area under fruits in J&K during 2019-20 was estimated at 3.31 lakh hectares with a production of about 25.41 lakh MTs. Among fruits, apple in J&K occupies a distinct feature both in terms of acreage and production. The area under apple during the aforesaid period was recorded at 1.66 lakh hectares while the production was estimated at 20.27 lakh Mts accounting for about 49.85 per cent and 79.78 per cent respectively in terms of the total area and production of the fruits in J&K. Apple is the main source for employment generation because of the backward and forward linkages and provides the maximum marketable surplus of about 30 per cent, 40 per cent and 30 per cent of A, B and C grades respectively.
Despite the fact that Jammu and Kashmir is leading both in terms of acreage and production of Apple in the country, however, productivity in J&K has remained a matter of concern since decades with an average productivity of 10 to 12 MT/ha in comparison to the developed countries wherein it is estimated at an average yield of 65-75 MT/ha. There are various fundamental reasons for the low productivity per unit area and one of the major reason appears to be the faulty pruning practices during dormant season (Dec to Feb) and non-adoption of the same during summer (Last fortnight of July).
Pruning is a dwarfing process used to maintain any desired tree size. Pruning removes not only stored carbohydrates but also reduces the potential leaf surface as well as loss in root growth as well. Pruning increases fruit size, nitrogen per growing point and stimulates growth near the cut. Large cuts result in excessive stimulation of sprouts near the cut. In areas where winter chilling of trees may be experienced, dormant pruning should be done as late as possible in the winter. Basically pruning is of two types. Winter pruning/ Dormant pruning and Summer pruning. The difference between dormant pruning and summer pruning is that, in dormancy dead and redundant branches are removed and a cut is made on the terminal end of the shoots.
While in summer pruning some water shoots are removed from the base (thinning out and in some shoots) with heading back left so that some fruit buds will appear and simply vegetative growth is converted into reproductive growth. Apple fruit trees being deciduous in nature must be pruned every year, usually during the dormant period to give a proper framework to the plant remove the dead and diseased branches, regulate fruiting buds, maintain root-shoot ratio and save the trees from snow damage during winter months. Nevertheless, need of pruning of apple trees in the summer is being felt in order to open up the tree canopy to sunlight for improving air circulation for fruit production and to promote plant hygiene.
Summer pruning, a cultural practice has generated the interest among apple growers in Kashmir valley since the implementation of High Density Plantation (HDP) and is being done to control the height of the tree so that most of the fruit doesn’t grow out of the desired reach. Only current season growth should be removed which exposes the fruit for better quality and colour, leaving removal of large branches and/or tree restructuring for the dormant season. It also helps in developing good limb structure for strength, fruit size besides quality improvement. And if, rightly executed, summer pruning encourages a plentiful supply of necessary nutrients to the new limbs, which will begin to bear fruit in their second year.
During the process of summer pruning, removal of apical portion of the plants results in the formation of lateral shoots and induction of branching besides this minimal extension growth is produced which increased fruit yield by way of increasing flower bud formation and return bloom as well. If done correctly, fruit colour development could be significantly improved without any other loss of yield or quality. The fruits retain better quality characteristics in terms of size, weight, volume, colour, firmness, organoleptic rating, physiological loss in weight, spoilage, acid content, total soluble solids, sugars (total, reducing and non-reducing sugars) and calcium content due to summer pruning.
When to Prune in Summer
Summer pruning need to be carried out in late summer mainly last fortnight of July at fruit development phase-III. At this stage Growth is almost exclusively by cell enlargement. During this phase, food reserves are accumulated and most fruits attain their final shape and size before the onset of ripening. Pruning plants in summer is just as important as pruning in winter. Basically summer pruning promotes reproductive growth and winter/dormant pruning promotes vegetative growth.
Practical implications for summer pruning in apple trees
Cut back new shoots (laterals) more than 25cm long (9 inch) growing from the main stem to three leaves above the basal cluster of leaves. Any shoot under 9 inches (23 cm) can be ignored because this shorter growth is likely to carry fruit buds naturally. In shoots where a cut is made, always made a cut on the upper side of ring, remove any upright, vigorous growth completely. Water sprouts could be removed during the same process also otherwise they can be removed during any season of the growing period. If secondary growth occurs after summer pruning, remove this in September. If this is a persistent problem, leave some longer shoots unpruned as these will draw up the sap and grow at the expense of secondary growth elsewhere. Cut these back to one bud in spring, as well as any vigorous growth projecting above the level of the supporting wire. It should be accomplished at proper time otherwise it results in more vigorous growth which is otherwise a laborious and time consuming process. Cut the remaining side shoots along each branch back more severely to two or three buds from the base of the current season leafy growth, cutting just above the bud. This encourages the formation of short fruiting spurs.
Advantages of summer pruning
Summer pruning is a practice used primarily to enhance fruit quality through the manipulation of tree physiology, alteration of canopy environment particularly light. The following are some of the important benefits of the summer pruning
- To activate the sleeping buds in apple plant.
- To minimised possibility of secondary growth.
- To provides good aeration and proper sunlight to the apple plant, and thus reduces the possibility of fungal disease.
- To help the orchardists to minimize the use of pesticides.
- To increase the number of fruit buds and hence increase the production of apples in coming next year.
- Reduction of excessive growth in plants while active season.
- Convert vegetative growth into spur formation because in apple tree our motive is to produce more apple fruits not wood.
Summer pruning reduces canopy transpiration rate which indicates that less water is lost through the leaves after summer pruning. However, with respect to severity we have to be very cautious and cuts be given away from fruits. Therefore, practicing, medium pruning (not heading back every shoot) is quite good. Summer pruning must be used with care to avoid reduced fruit size and soluble solids, which may reduce crop value. Further, reduced cold hardiness of flower buds, delayed defoliation, carbohydrate levels in the tree and trunk enlargement needs to be taken care as well.
Prominent impacts of Summer Pruning
- Impact on growth, yield and fruit quality.
- Excess regrowth.
- Impact on disease.
- Impact on nutritional disorders.
Summer pruning: The way forward
Severe summer pruning could result in suppression of vegetative growth due to the lowered photosynthetic capacity, reducing the carbohydrate reserves in apple tree. Summer pruning in apple is thus the key for good quality fruits, also to aerate all the branches of a plant to lower the fungal infection and alterneria in apple. Growers should employ summer pruning methods while carefully monitoring for potentially negative effects on tree growth and fruit quality. It is a labour intensive process and should be practiced during the last fortnight of July to remove the current season growth.
(The authors are associated with SKUAST Kashmir and can be reached at email@example.com, firstname.lastname@example.org, email@example.com)