Top Working: Rejuvenating Old Aonla Trees for Improved Yield

Imagine walking through an old aonla orchard where the trees have stood for decades. Once productive, these trees now yield fruit that’s smaller, less abundant, and increasingly unpredictable. For many growers, the traditional solution would be to uproot these ageing trees and start fresh-a process that takes years before new trees become productive. But what if there was a way to breathe new life into these established trees, harnessing their robust root systems while transforming them into high-yielding, premium-quality producers? This is exactly what top working offers: a remarkable horticultural technique that can rejuvenate old aonla orchards and extend their productive lifespan by decades.

What is top working and why does it matter for aonla cultivation? 🔗

Top working is a specialised grafting technique where the existing scaffold branches of a mature tree are cut back and then grafted with scions from superior varieties. Unlike standard grafting performed near ground level, top working occurs several feet up from the ground, utilising the established trunk and root system of the older tree. The result is essentially a new tree growing on an old foundation-combining the vigour of a mature root system with the desirable fruiting characteristics of improved cultivars.

For aonla (Emblica officinalis), this technique holds particular significance. India, being the world’s largest producer of aonla, has vast areas under cultivation, many of which contain old seedling trees or inferior varieties. Research conducted by horticultural institutes has shown that approximately 30-35% of fruit crop areas in India are occupied by old, dense, and declining orchards. Top working presents an economically viable alternative to the expensive and time-consuming process of complete orchard replacement.

Understanding the science behind top working 🔗

The success of top working relies on a fundamental principle of plant biology: the cambium connection. The cambium is a thin layer of actively dividing cells located just beneath the bark, responsible for producing new wood and bark tissue. When the cambium layers of the scion (the new variety being introduced) and the stock (the existing tree) are brought into close contact and held firmly together, they can fuse and create vascular connections that allow water and nutrients to flow between the two.

Why established trees make excellent rootstocks 🔗

Old aonla trees, despite their declining productivity, possess remarkably well-developed root systems that have spent years establishing themselves in the soil. These extensive roots can efficiently absorb water and nutrients, providing the energy needed for rapid scion growth after grafting. Additionally, the existing trunk provides structural support that would take a new tree many years to develop. This is why top-worked trees often begin bearing fruit within two to three years of the operation-significantly faster than establishing an entirely new orchard.

Research from the Central Institute for Subtropical Horticulture (CISH) in Lucknow has demonstrated that rejuvenated aonla trees can remain productive for another 25-30 years following successful top working. This extended productive life, combined with the relatively quick return to bearing, makes top working an economically attractive proposition for orchardists.

Selecting the right cultivars for top working 🔗

The choice of scion variety significantly influences the success of top working operations. Commercially cultivated varieties such as NA-7, NA-6, NA-10, Kanchan (NA-4), and Krishna (NA-5) are commonly used for top working operations. Studies conducted on rejuvenating sixty-year-old unproductive seedling aonla trees found that the variety Krishna showed the best performance during top working, achieving approximately 77.77% bud take success, followed closely by NA-10 and NA-7.

When selecting varieties, growers should consider local climate conditions, market demand, and disease resistance. NA-7, in particular, has demonstrated excellent overall performance in grafting trials, with research showing the shortest bud sprouting time and highest graft success rates when properly executed. The top-worked trees started bearing fruit within two years of the budding operation, with NA-7 consistently outperforming other cultivars in subsequent yield evaluations.

Step-by-step process of top working aonla trees 🔗

Successful top working requires careful planning, proper timing, and precise execution. Here’s how experienced horticulturists approach this transformative technique:

Preparing the mother tree 🔗

The process begins during December-January when trees are in their dormant phase. The plants are headed back to approximately 2.5 to 3.0 metres above ground level. Before making cuts, experienced growers mark the selected branches with white chalk, creating ring markers to ensure consistent cutting heights. The selected branches should initially be cut from the underside, making at least a 10-centimetre deep cut before completing the cut from above. This technique prevents bark tearing and produces cleaner wounds that heal more readily.

Timing the grafting operation 🔗

The optimal period for top working aonla is during the active growing season when the bark separates easily from the wood. According to extension guidelines, this typically occurs from June to September in most regions. The key indicator of readiness is when the bark can be easily peeled from both the rootstock and scion wood-a condition called “bark slipping.” During this period, the cambium layer is most active, promoting faster healing and union formation between the bud and rootstock.

Grafting techniques suitable for aonla 🔗

Several grafting methods can be employed for top working aonla trees, with patch budding and cleft grafting being the most common:

Patch budding involves removing a rectangular patch of bark containing a bud from the desired variety and fitting it onto a similarly prepared area on the stock branch. This method gives 60 to 90 percent success when performed during mid-May to September and is particularly effective for aonla due to its relatively thick bark.

Cleft grafting is performed by splitting the stock branch and inserting wedge-shaped scions into the split. This technique is especially useful for larger diameter branches and can accommodate two scions per stock, increasing the chances of successful union. The branches selected for cleft grafting should ideally not exceed 2.5 inches in diameter, and those fully exposed to sunlight with good sap flow typically show better success rates.

Post-grafting care and management 🔗

After grafting, careful attention ensures the success of the operation. The grafted area must be thoroughly sealed with grafting wax or wound dressing to prevent moisture loss and pathogen entry. Once the buds show signs of growth-usually four to six weeks after the operation-growers should gradually reduce the top growth of the remaining stock. This redirects the tree’s energy toward the newly grafted scions.

It’s crucial to remove any suckers or water sprouts that emerge from the rootstock, as these compete with the desired scion growth. Only the grafted shoots should be allowed to develop into the new canopy. During the first year, minimal pruning is recommended to allow the grafts to establish; vigorous shoots may need tip pinching to encourage branching.

Factors affecting top working success 🔗

Several factors influence the outcome of top working operations, and understanding these can significantly improve success rates:

Height of grafting 🔗

Research has shown that budding height significantly influences the success rate. Studies indicate that grafting at heights exceeding 2.5 metres from ground level reduces bud take considerably. The optimal height appears to be between 0.75 and 2.5 metres, where bark activity and sap flow are most favourable for union formation.

Scion wood quality 🔗

The quality of scion material directly impacts grafting success. Scions should be collected from healthy, disease-free mother trees that are known for their prolific bearing characteristics. Wood that has recently shed its leaves and is in active growth phase gives the best results. The scion shoots should be about pencil thickness (approximately 8mm) and contain well-developed, plump buds. Collecting scion wood early in the morning when moisture content is highest improves survival rates.

Environmental conditions 🔗

Temperature and humidity play crucial roles in graft union formation. High humidity promotes callus development, while extreme temperatures can cause desiccation of the delicate cambial tissues. Providing temporary shade to newly grafted areas during hot weather can improve success rates significantly.

Economic benefits of rejuvenating old orchards 🔗

The economic case for top working rather than complete orchard replacement is compelling. Establishing a new aonla orchard requires significant investment in land preparation, planting material, irrigation infrastructure, and years of maintenance before trees reach full bearing capacity. Vegetatively propagated aonla plants typically attain full bearing within 10-12 years and can continue producing for 60-75 years under good management.

In contrast, top-worked trees can begin producing marketable fruit within two to three years of the operation, using existing infrastructure and requiring far less capital investment. Research has documented that rejuvenated ber trees achieved 3.55 times higher yield compared to pre-rejuvenation levels, and similar improvements have been observed in aonla. The technique essentially provides a shortcut to productive orchards, allowing growers to respond more quickly to changing market preferences for specific varieties.

Intercropping opportunities during establishment 🔗

The initial two to three years after top working present excellent opportunities for intercropping. As the rejuvenated trees develop their new canopies, the inter-spaces can be utilised for growing vegetables like bottle gourd, okra, and cauliflower, or flowers such as gladiolus and marigold. This provides additional income during the establishment phase and optimises land use efficiency. In salt-affected soils, intercropping with green manure crops like Sesbania (dhaincha) can improve soil physicochemical and biological properties.

Common challenges and how to overcome them 🔗

Despite its advantages, top working can present challenges that growers should anticipate:

Graft incompatibility occasionally occurs even within the same species. If a graft union fails to develop properly, the symptoms include stunted scion growth, early leaf drop, or complete failure. While aonla varieties generally show good mutual compatibility, some combinations perform better than others. Keeping records of successful variety combinations helps guide future operations.

Sunburn and desiccation of newly exposed trunk areas following severe heading back can damage the tree. Applying whitewash or wound dressing to exposed bark surfaces protects against sun damage while the new canopy develops.

Vigorous water sprout growth from the rootstock can overwhelm grafted scions if not managed promptly. Regular monitoring and removal of unwanted sprouts ensures that the tree’s resources are directed toward scion development.

Looking ahead: the future of orchard rejuvenation 🔗

As consumer demand for high-quality aonla products continues to grow-driven by increasing health consciousness and the popularity of Ayurvedic medicines-the pressure on growers to maintain productive orchards will intensify. Top working offers a sustainable path forward, allowing the transformation of underperforming orchards into profitable enterprises without the environmental and economic costs of complete replacement.

Modern research continues to refine techniques and identify optimal variety combinations for different growing regions. The integration of drip irrigation and fertigation systems with rejuvenated orchards has shown promising results, with some growers achieving yields of 30 kg per tree by the third year-significantly higher than the 20 kg typically seen in rainfed conditions over four to five years.

What do you think? Have you considered how rejuvenating older fruit trees might benefit your orchard’s productivity and profitability? What factors would influence your decision between top working existing trees versus establishing new plantings?

References

1. https://extension.missouri.edu/publications/g6971
2. https://nhb.gov.in/model-project-reports/Horticulture%20Crops/Aonla/Aonla1.htm
3. https://courses.cit.cornell.edu/hort494/mg/methods.alpha/ClefMeth.html