Controls on Chemicals and Residues - Delavitas Fine Teas

Controls on Chemicals and Residues

The Tea Research Institute (T.R.I.)

Ceylon as it was in the 1800's ventured into coffee as the first British plantation crop, established to create the funds needed by the Governor of the island to fund the costs of undertaking the infrastructure needed. Unfortunately, not long after its establishment, disease in the form of Hemileia Vastatrix struck the crop.

Because of a lack of a proper established research station, no effective treatment to combat the disease was available and between 1848 and 1870 coffee declined and by the 1880's tea had emerged as the new plantation crop and coffee had been wiped out as an effective crop.

As planters recovered with tea, they made sure that this could not happen again and in 1925 the Tea Research Institute was born and funded. Today it is a huge organization with seven sub stations and today recognized as one of the most important tea research stations in the world.

Shot-Hole Borer Beetle

In the 1950's spraying with chemicals was the standard response to disease control not just in Ceylon but also around the world. The Shot-Hole problem revealed itself when the branches of the tea bush started breaking and falling off as the tea pluckers walked between the bushes and were found to have little holes bored into the wood.

Spraying Dieldrin on the bushes when pruning took place was promoted to the planters as the control. However it created as many problems as it solved, by killing the Braconid Wasp (Macrocentrus Hormonae) which parasitized the Tortrix moth.

Bio-Control Revolution: In the late 1960's the TRI decided that there was a need to create a different approach to disease control and one of 'Bio' control was created. This was partly due to consumer demands for foods that were not contaminated by harmful residues.

The TRI set-up a strict licensing programme, which required the chemical importing companies like Baurs to submit any chemical they wished to import to the TRI testing programme for three years of assessment. If the chemical passed their testing and was considered acceptable, the TRI would issue a licence for its import.

Blister Blight

This largely appears in wet, misty conditions and in the hills we can experience periods of mist rolling in and over the fields. Within the mist are large numbers of spores that settle on the tea leaves, mainly affecting the younger shoots with blistering that curls up the young shoots and then turn them black.

The accepted treatment is to spray the fields with a copper sulphate solution immediately after a plucking round has taken place. At one time a systemic spray was allowed but as this is a very expensive treatment, it is rarely if ever used.

Poria (Red Root Disease)

This is the attacking of the roots of the tea bushes by a mass of strands of fungal mycelium, it is called 'Red Root Disease'. Having rotted large number of the roots, the tea bush dies within a field of tea. This problem is a left over from the days when the Crown lands that were purchased for the planting of coffee.

During my time the traditional treatment was to have a gang of Poria workers who understood the seriousness of the work. On Le Vallon we had an agreement with the Unions that any persons found carrying or removing Poria infected material from a field could face instant dismissal. The problem was costing the estate hundreds of thousands of Rupees.

TEA RESEARCH INSTITUTE (TRI) PORIA FUMIGATION TRIAL AT LE VALLON GROUP - 1961-1962

In 1961 Redlich of the TRI visited Le Vallon (L.V.) Group to set-up two trial plots with me. We selected areas in L.V. Division No: 9 field where PH was 6.0 and also L.V. No: 10 field where the PH was 5.2. This was to trial a new system of fumigating the soil using a heavy duty gun with a pump handle delivering Dichloropropane-Dichloropropene mix (D.D.).

June 1961: The designated areas had their bushes winched out and recorded. The infected bushes plus two surrounding healthy tea bushes and all surface roots were burnt at site.
Preparation: Prior to fumigating it was necessary to dampen the soil and to have nearby old wet manure sacks or Guatemala grass on standby to cover the soil as fumigation took place.
June 28-29: The sites were lined to mark out 1 foot squares and fumigation was carried out. The lining left a 2 foot barrier space from the surrounding healthy tea bushes.
Application: The gun delivered the fumigant to varying depths between 8 inches, 1 foot and 2 feet in depth, at the points where the lines crossed.
November 1961: Tephrosia plants were planted across the sites.
Five months later: Planting of V.P. tea plants took place five months after treatment.

Results: We came to the opinion that the fumigation should be carried out at the 20 ML level. At that level 2,000 Lbs of fumigant was used, at a cost of Rs.4,000/= per acre, compared to Rs.5,700/= per acre for the traditional system.

Scale: 50 estates were known to have a Poria problem at that time, which was a total of 57,680 acres, 10% of the total tea area.

Download Poria TRI Fumigation Trial Results (PDF)

History of Residue Levels in Ceylon Teas

In 1997 the Chairman at the International Standards Organization (I.S.O.) meeting in Colombo, stated that Ceylon teas were the cleanest in the world as far as pesticides and residues were concerned.

1997
First ISO recognition - Colombo
1999
Confirmed - Calcutta
2001
Reconfirmed - Mombassa
2003
Maintained - Hangzhou
2005
Sustained - Hamburg

EU Standards Compliance

In 2003 the European Union (EU) declared a maximum residue level (MRL) of 0.01 Mg/Kg. This set the standards that all producing areas had to work to.

Ceylon teas continue to maintain their reputation as the cleanest teas in the world, setting the global standard for quality and safety.