Best Practices for Weed Management in Tea Plantations

Tea plantations look lush and well-ordered from a distance, but at ground level, a constant battle is underway. Weeds are considered the primary pests in tea cultivation, competing directly with tea bushes for nutrients, water, and space. Left unchecked, they can reduce yield by anywhere from 15% to 50%, and even affect the color, taste, and aroma of the final product. Weed control is, in fact, the second most costly operation in tea farming – right after plucking. Managing weeds effectively is therefore not optional; it is central to sustainable tea production.

Why weeds are a serious threat in tea plantations 🔗

Tea (Camellia sinensis) is a perennial crop grown under specific agro-climatic conditions, and its long cultivation cycle makes it highly susceptible to persistent weed infestation. Grassy weeds alone can cause up to a 21% decline in tea productivity, while broad-leaved weeds account for a further 9-12% reduction. Weed pressure is most intense during the period from April to September, and it peaks in young plantations and in fields that have recently undergone pruning operations.

Pruning – whether light, medium, or deep skiffing – exposes the soil surface, creating ideal conditions for weed germination. This exposure encourages heavy weed growth, so while pruning is essential for bush maintenance, it inadvertently creates a more favorable environment for weeds. New clearings and replanted areas face particularly intense weed competition because the tea plants are young and have not yet developed the canopy that naturally shades out some weeds.

Beyond yield loss, weeds serve as alternate hosts for pests and pathogens, interfere with field operations like fertilizer application and plucking, and – as a recent review in ScienceDirect highlights – can even bioaccumulate phytotoxic compounds that threaten the broader health of the plantation ecosystem.

Common weeds found in tea plantations 🔗

Over 200 weed species – predominantly from the Poaceae and Asteraceae families – have been recorded in tea plantations worldwide. In practice, a handful of species cause the most damage.

Bidens biternata (hairy beggarticks) 🔗

Bidens biternata is a broadleaf annual weed from the Asteraceae family that thrives in the warm, humid conditions typical of tea-growing regions. It germinates readily in disturbed soil, especially after pruning or cultivation, and spreads quickly through hook-like seeds that attach to clothing and animal fur. Research comparing B. biternata with its more invasive relative Bidens pilosa shows that B. biternata performs comparably under low-light and low-moisture conditions, making it well-adapted to shaded inter-row spaces in established tea fields. Its fast growth and competitive nutrient uptake make early control essential.

Cynodon dactylon (Bermuda grass) 🔗

Cynodon dactylon, commonly known as Bermuda grass, is one of the most problematic grass weeds in tea plantations. It spreads aggressively through both seeds and underground stolons (creeping stems), making it difficult to eradicate once established. Studies on tea fields in Palampur, India, have confirmed Cynodon dactylon as a consistent and significant component of the weed flora in established gardens. Its deep and extensive root system allows it to survive dry periods and bounce back quickly after surface removal, which is why chemical control is often needed alongside physical methods.

Other frequently recorded weeds in tea gardens include Ageratum conyzoides, Imperata cylindrica (thatch grass), Chromolaena adenophorum, and Polygonum species, with the exact weed flora varying by elevation, season, and geography.

Cultural methods of weed management 🔗

Cultural weed management involves modifying field practices to reduce weed establishment and give tea plants a competitive advantage. These methods are environmentally friendly and cost-effective, and include land preparation, proper bush management, mulching, establishment of cover crops, and green manure crops.

Mulching 🔗

Mulching is one of the most reliable cultural practices for weed suppression in tea. A layer of organic material – such as grass cuttings, leaf litter, or crop residues – placed around tea bushes blocks sunlight from reaching the soil surface and prevents weed seed germination. Research from organic tea plantations in Yunnan Province, China, confirms that mulching effectively controls weeds while delivering additional agro-ecological benefits, including increased tea yield, enhanced soil biodiversity, and improved soil quality. Rice straw mulch and living mulch systems have also shown the ability to increase soil organic matter and available nutrients simultaneously.

Cover crops and green manures 🔗

Planting cover crops between tea rows can suppress weeds through shading and competition. Leguminous cover crops are especially useful because they fix atmospheric nitrogen, improving soil fertility while reducing the space available for weed colonization. Green manure crops, when lopped and incorporated into the soil, also add organic matter and further suppress weed regrowth. These approaches are particularly relevant in new clearings where full tea canopy cover has not yet developed.

Land preparation and proper spacing 🔗

Thorough land preparation before planting reduces the initial weed seed bank in the soil. Correct spacing between tea bushes encourages early canopy closure, which naturally shades out weeds once the plantation matures. Infilling – replacing dead or missing tea plants promptly – also prevents open gaps from being colonized by aggressive weed species.

Manual and mechanical weed control 🔗

Manual weeding – using tools like hoes, sickles, and forks, or simply pulling weeds by hand – remains widely practiced in tea plantations. It is precise, leaves no chemical residues, and delivers immediate results. It is particularly important around young tea seedlings where herbicides could cause injury, and in sensitive areas near water sources where chemical use is restricted.

However, manual weeding comes with serious drawbacks. Young tea plantations may require around 75 man-days per hectare annually for manual weed control, compared to just 15 man-days when herbicides are used. On sloped terrain – which is typical of many tea-growing regions – repeated digging and hoeing can loosen the topsoil and lead to serious erosion. Mechanical weeding tools like cheeling can also expose buried weed seeds in the top soil layer, sometimes causing a subsequent flush of new weed growth. If performed carelessly, manual weeding can also damage the shallow feeder roots of tea plants.

Despite these limitations, manual weeding retains an important role as a precision tool, particularly for spot-treating isolated or herbicide-resistant weeds that other methods fail to control.

Chemical weed control: herbicides in tea 🔗

Herbicide application is currently the most widely used weed management method in commercial tea plantations, largely because of its efficiency and relatively low labor demand. Herbicide use has proven to be the most convenient and effective method, and it can also minimize soil erosion and reduce loss of plant nutrients compared to mechanical tillage.

Glyphosate: the most common post-emergence herbicide 🔗

Glyphosate is a non-selective, systemic post-emergence herbicide that translocates throughout the plant and kills it down to the roots. It is the most widely applied herbicide in tea gardens for controlling both grass and broadleaf weeds. Research from the CSK Himachal Pradesh Krishi Vishvavidyalaya confirms that glyphosate is effective against a broad spectrum of weeds in tea, including Cynodon dactylon, Bidens pilosa, Ageratum conyzoides, Imperata cylindrica, and several others. In one study, uncontrolled weed growth for just one season reduced tea leaf yield by 48.5%, underscoring how critical timely herbicide application can be.

Glyphosate is typically applied as a directed spray to weed foliage, taking care to avoid contact with tea leaves or stems. Dose and timing must be calibrated correctly – newer formulations such as glyphosate 71% SG have been shown to perform comparably to the older 41% SL formulation when applied at the right rate.

Other herbicides used in tea 🔗

2,4-D (sodium salt) is another herbicide commonly used, particularly effective against broadleaf weeds. It is typically applied at a concentration of 0.25% (0.50 kg per 200 liters of water) and is sometimes combined with glyphosate for broader-spectrum control. Trials at Assam Agricultural University found that a glyphosate and 2,4-D combination achieved over 90% control of grasses and 61% control of broadleaf weeds up to 60 days after treatment. Pre-emergence herbicides such as diuron are also applied to clean soil before weed germination to prevent establishment.

The challenge of herbicide resistance 🔗

A growing concern in tea weed management is herbicide resistance. A two-year study at Hapugastenne Tea Garden in Maskeliya, Sri Lanka, found that over 20 out of 23 acutely problematic weed species were entirely tolerant to diuron, paraquat, and glyphosate. Herbicide-resistant weeds are capable of suppressing tea bush growth and turning a plantation economically non-viable within one to two years if not manually removed. This makes rotating herbicide modes of action and combining chemical control with other methods critically important.

Biological weed control 🔗

Biological control uses living organisms – insects, fungi, bacteria, or competitive plants – to suppress weed populations. In tea, this approach is still developing but offers promising sustainable options. A recent scientific review highlights microbial herbicides – derived from naturally occurring fungi and bacteria – as environmentally beneficial alternatives to chemical herbicides, though their field performance can be variable. Research is ongoing into precision biological solutions, including microbiome engineering and naturally occurring phytotoxic compounds that selectively target weed species without harming the tea crop or surrounding ecosystem.

On a practical level, competitive cover crops and green manures function as a form of biological suppression by outcompeting weeds for light and space. Some tea estates also manage low-growing, non-competitive “desirable weeds” on the ground between rows as a living mulch, which prevents more aggressive weed species from establishing while minimizing bare soil exposure.

Integrated weed management: the most effective approach 🔗

No single method is sufficient for sustainable weed management in tea. Each approach – cultural, manual, chemical, and biological – has strengths and weaknesses, and the most effective programs layer these methods strategically. Research consistently shows that a rational, integrated weed management strategy is the most cost-effective solution for healthy and productive tea cultivation.

In practice, an integrated approach works like this: sound land preparation and mulching reduce initial weed pressure; cover crops suppress inter-row weeds and improve soil; targeted herbicide applications (pre- and post-emergence) handle broad-area weed control during peak pressure periods; and manual weeding provides precision control around young plants, near water sources, and for resistant weed species. The key is timing – aligning each intervention with the plantation’s seasonal cycle and the biology of the dominant weed species present.

Integrated weed management (IWM) requires understanding the weed species present in a given field – their lifecycle, emergence timing, growth rate, and reproductive strategy – and building a management program that targets weeds in multiple ways across more than one season. This approach reduces dependence on any single herbicide, slows the development of resistance, and is better for soil health and long-term plantation sustainability.

Key takeaways for tea growers 🔗

Effective weed management in tea is not a one-time event – it is an ongoing program that adapts to changing conditions. Start with strong cultural practices to reduce weed pressure from the outset. Use herbicides like glyphosate strategically and at the correct dose, rotating modes of action to prevent resistance. Reserve manual weeding for precision tasks and sensitive areas. Incorporate biological tools and cover crops where feasible. And monitor weed populations regularly so the program can be adjusted before infestations become costly to address.

The cost of poor weed management – in lost yield, degraded tea quality, and escalating control expenses – far exceeds the investment in a well-planned, integrated program.

What do you think? Given that herbicide resistance is an increasing problem in tea plantations, should growers prioritize cultural and biological methods as the first line of defense rather than defaulting to chemicals? And how feasible is a shift toward lower-chemical integrated weed management for smallholder tea farmers who face real constraints in labor and budget?

References

1. https://www.agrifarming.in/weed-management-in-tea-crop-common-weeds-of-tea-plants-and-herbicides-safe-for-use-on-tea-plants
2. https://www.sciencedirect.com/science/article/pii/S2090123225008495
3. https://www.mdpi.com/2223-7747/13/3/356
4. https://jase.samipubco.com/article_179998_5f726995adb5395ab92adf513a73e8aa.pdf
5. https://tare.sljol.info/articles/10.4038/tare.v6i0.5447
6. https://www.sciencedirect.com/science/article/abs/pii/S1161030125003843
7. https://www.sciencedirect.com/science/article/pii/S2211601X1600064X
8. https://growiwm.org/cultural-practices/