Pruning & skiffing

Pruning is one of the most important operations, next to plucking, which directly determines the productivity of tea bushes. It is a necessary evil in the sense that it has to be carried out periodically in spite of huge crop loss it results. If pruning is delayed, in other words as the age of wood from pruning increases, the size and weight of growing shoots on plucking surface decreases. There is preponderance of banji shoots on plucking table as more and more buds fail to grow with loss of vigour of growing apices. Therefore, to maintain the vegetative growth, pruning is necessary. The objectives are:

  • To renew the wood.
  • To provide stimulus for vegetative growth.
  • To divert stored energy to production of growing shoots.
  • To correct past defects in bush architecture.
  • To maintain ideal frame height for economic plucking.
  • To improve bush hygiene.
  • To reduce the incidence of pests and diseases.
  • To regulate the crop.
  • To facilitate consolidation by infilling of vacancies.

Types of pruning:

Light Prune

Tea bushes are usually pruned every 3 or 4 years at 4 -5 cm above the last pruning cut. This type of pruning is called light prune (LP). The time period from one light prune year to another is called one pruning cycle and LP is a thus, natural sequence given at the end of a pruning cycle. It helps to renew the wood, regulate crop distribution, reduce pests and diseases and maintain ideal frame height of the bushes.

Height Reduction Prune and Medium Prune

However, when the tea bushes grows tall and plucking becomes difficult, they are brought down to an optimum height by height reduction prune (HRP) at 60-70 cm, or medium prune (MP) at 45-60 cm above ground. Both HRP and MP help in rejuvenating the tea bushes that have become old and their yields have started declining. MP removes the knots and unproductive excess woods and facilitate consolidation by infilling of vacancies. Medium pruning thus provides opportunity for taking many corrective measures for improving the health and production capacity of old tea sections. Such sections are brought back to the normal 3-4 year pruning cycles in about 4-5 years.

Heavy prune

Heavy prune (HP) is given at 15-45 cm for complete renewal of frame. In collar prune, all above ground parts of the tea bushes are cut down and this operation is carried out only when the root system is considered strong enough to withstand the shock and initiate new growth. In practice however, very low pruning is generally avoided now a days as it results in heavy mortality, particularly in Assam jats growing in poorly shaded sandy soil. In between two successive prune (LP) years, tea bushes are given lighter forms of cuts which are termed as deep skiff (DS), medium skiff (MS), light skiff (LS), level of skiff (LOS) or untouched which is called unpruned (UP).

Deep Skiff

Deep skiffing (DS) of tea bushes is done normally between 12-15 cm above the last LP mark. The DS helps to regulate crop distribution and to reduce the ill effects of drought, excessive creep and the height of plucking table.

Medium Skiff

Medium skiff (MS) is normally given at 5 cm over last Deep skiff mark. The objective of MS is to regulate crop distribution, reduce the ill effects of drought, reduce the incidence of excessive banji formation and reduce the height of plucking table.

Level of Skiff and Light Skiff

Level of Skiff (LOS) is given 4-6 cm above the tipping mark mainly to level the plucking surface. Light Skiff (LS) is usually given up to 1 cm above the previous tipping height.

Time of pruning and skiffing

In general, pruning is carried out when the tea bush is dormant and there is a good reserve of root starch. In draughty areas of Northeast India, pruning is done in mid-December to mid-January avoiding shoot initiation during drought. Medium pruning can be carried out in mid-December to end of January. Skiffing is performed at anytime between mid-December and end January; deeper the cut earlier is the skiffing time. In Darjeeling, pruning can be started as early as November. The best time for pruning may differ with cultivars, which can be ascertained by root starch reserve test.

Resting before pruning

For LP generally resting is not required. However, if there is inadequate foliage, the tea bushes are given rest by stopping plucking from 3 weeks before pruning. Very weak tea plants and those due for MP should be rested 5-8 weeks prior to pruning. Vigorously growing well-shaded tea bushes are pruned first. For MP/HP in the year of prune additional doses of potash and phosphate are also applied and in inadequate shaded areas, temporary shade of Indigofera teysmanii at 3-4 m apart should be planted a year before pruning.

Pruning and bush sanitation

After pruning at predetermined height, bushes are sprayed with an aqueous solution of copper fungicide on the same day. This reduces chances of damage by Poria, Aglaospora etc. Knife cleaning out (KCO) can be started any time after prune, and should be completed before bud-break starts. KCO involves removal of knots and of dead, diseased and unproductive wood. All large cuts should be indopasted within 24 hours. In MP some of the branches may have to be cut below the general pruning height to get clean wood. To prevent the chances of sun scorch, the bushes may be covered with the pruning litter immediately after the prune. At times they may also require demossing and lime-caustic-wash. Bushes, which are dead, badly damaged and affected by primary root rots should be uprooted and removed out of the section. In bushes attacked by termites the earth runs should be removed, and the bush and the surrounding area treated with recommended insecticide.

The caustic wash is prepared using 6 kg washing soda and 2kg quick lime in 100 lit of water and is used after keeping the preparation overnight.

Crop loss associated with prune/skiff compared to unprune

Type of skiff/skiff % loss of crop
MP 60-70
LP 30-35
DS 10-15
MS 5-10
   

When to go for medium or rejuvenation prune

Only those sections, which show potential for improving after the prune, should be considered for heavy prune. Some of the important criteria for judging the suitability to go for heavy, prune are as follows:

  • The section should not be affected by primary root diseases.
  • There should be scope for immediate improvement of drainage in the area.
  • Vacancy should not be normally more than 30 per cent.
  • Not more than 25 per cent of the remaining bushes should be affected by Poria and termites down to the collar region.
  • Bushes show a steady decline in yield over the last 5 years or so.
  • Recovery potential should be good. It is essential to build up enough starch
    reserves by giving adequate rest prior to pruning.

Pruning Cycle

In a pruning cycle, all forms of pruning/skiffings are introduced sequentially for distribution of crop and renewal of wood producing crop/quality. In comparison to annual prune, which causes a heavy rush only during the main season, well-balanced extended pruning cycles will provide an even distribution of crop resulting in an even flow to the factory throughout the season. The choice of pruning cycles depends on a number of factors, viz., crop, labour, quality and market requirements, pests and diseases, climate and soil, bush height, age, vigour and kind of tea, etc. In the plains of Northeast India under normal growing conditions 3-4 year pruning cycle and for Darjeeling depending upon elevation a 4-5 year pruning cycle is suitable.

Some of the normally followed pruning cycles are

   
1. Well shaded, young and vigorously growing tea areas : LP-UP-UP
2. Normal tea growing areas : LP-UP-DS-UP
3. Droughty areas : LP-UP-DS/LP-DS-UP
4. Darjeeling (low elevation) : LP-UP-DS-UP
5. Darjeeling (mid & high elevation) : LP-UP-UP-DS-UP
   

Primary objective of leaving the bushes unprune or giving LS/LOS is to have more early and total crop. Therefore, conditions favourable to achieve that objective must be ensured before hand. The first two cycles shown above are crop oriented and the 3-year cycle of LP-UP-DS or LP-DS-UP is considered to be quality oriented.

The above is general guideline only. Depending upon specific situations, modifications may be required without overlooking the basic objectives.

Approximate Gain in Crop Over Annual Prune

   
DS 10 – I5%
MS 15 – 20%
LS 20 – 25%
LOS 25 – 30%
UP 30 – 35%
   

(Above figures may vary if bushes are weak and growing conditions not favourable)