Tea and Pesticides part 2: What pests and disease? Which pesticides are used?

1. The relationship between wild grown tea plants and pests
2. How modern tea farming amplify the pest and disease problems,
3. What pesticides they use to treat the problems,
4. As a consumer how to avoid heavily sprayed tea
5. Organic and wild harvest tea

3. What pests and pesticides?

The following is a list of typical pests and recommended pesticides in major tea producing area in Japan.  This is just to show tea has lots of pest problems.  Some minor pests are not even mentioned here to keep it simple.  The pesticides are used to prevent pest damage from happening.

The types of pesticides used may be replaced with pheromone traps, BT, bordeaux mixture, and organic pesticides that are derived from natural source and has less environmental impact, but typically result in higher cost.  Some lab testing claim that the pesticides recommended below have less human and environmental health impact from pesticide residue.  Some developing countries may not have regulations restricting use of more toxic chemicals.

To identify pests and disease, please see UH CTAHR disease ID page
Insect pests (http://www.ctahr.hawaii.edu/oc/freepubs/pdf/IP-28.pdf)
Disease (http://www.ctahr.hawaii.edu/oc/freepubs/pdf/PD-33.pdf)

Most pests and disease require specific pesticides.  More than one pesticide is used to avoid pests acquiring pesticide resistance.

Month	Pests / Disease	Preventative Pesticide uses
Feburary	Blight (disease)	Copper dihydroxide x1
March	Spider mite, Leaf roller* (insect pests) Beetle (insect pests)	Etoxazole x1 x1
1st Flush	Aphid (insect pests)	Pirimiphosmethyl x1
April (after 1st flush harvest)	Spider mite (insect pests) Leaf roller (insect pests) Scale* (insect pests)	Milbemectin x2 Tebufenozide x2 DMTP x1
May (before 2nd flush harvest)	Leaf hopper, Leaf roller, Thrips,  (insect pests) beetle*  (insect pests) Anthracnose (disease)	Neonicotinoid x1 Tefluthrin  x1 Tebuconazole x1
May (after 2nd flush harvest)	Leaf hopper, Leaf roller, Thrips (insect pests)	Bifenthrin x2
June (before 3rd flush harvest)	Leaf hopper, Thrips (insect pests) Anthracnose (disease)	Acephate x2 Fluazinam x1
July (before 3rd flush harvest)	Leaf hopper, Thrips, leaf roller (insect pests) Anthracnose (disease)	Acetamiprid x1 Fenbuconazole x2
August (before 3rd flush harvest)	Leaf roller, Looper,  (insect pests) Leaf hopper, Thrips (insect pests)	Methoxyfenozide x2 Chlorfenapyr x2
September	Leaf hopper, Thrips, Broad mite, Rust mite,  (insect pests) Leaf roller, Moth larvae, Looper,  (insect pests) Scale (insect pests)	Tolfenpyrad x1 Emamectin benzoate x1
October (after fall harvest)	Leaf Roller, Spider mite, (insect pests) Blight (disease)	Profenofos x1 Copper dihydroxide
November-December	Beetle (insect pests) Gray mold (disease)	Fenitrothion x1 Fluazinam x1

*sprayed as necessary.

Tea and Pesticides: how to avoid pesticide exposure from drinking tea

 Pests and disease are inseparable parts of tea farming, thus pesticides to prevent and treat the pest and disease problems.  In this series we will look at:

1. The relationship between wild grown tea plants and pests
2. How modern tea farming amplify the pest and disease problems,
3. How and what pesticides they use to treat the problems,
4. As a consumer how to avoid heavily sprayed tea
5. Organic and wild harvest tea

Part one focuses on the first two topics.

1. The Relationship Between Tea and Pests

Wandering into old mountain forest of Japan, I have encountered wild tea plants growing sporadically in their own natural habitat.  There are not abundant tender supple tips to harvest, but in general plants are healthy.  The wild tea shows small signs of pests and disease, but it is minimal.  The plants vary widely in their leaf shape, size, color, and even growth form.  Some even appear as bonsai trees found in Japanese garden.  The plants seem 20-50 years of age, could be more than 100 years.  They mostly live humble and thrifty existence, yet appear rather healthy.

In the wild, tea is often found in subtropical moist environments under forest canopy.  The soil is highly acidic (pH 4-5) and very low in nutrients.   Tea plants typically contain high levels of theanine, polyphenols, and caffeine.  These chemicals are its natural defense and especially high in new growth.  Low levels of available nitrogen and deep taproot demand tea plants to be hardy.  Flush is seasonal, tough and often in very small quantity, yet highly aromatic much like wild herbs.  Wide genetic diversity of tea plants and wild ecosystem make tea plants to blend into the natural surrounding and makes it difficult for pests and disease to spread like a epidemic.

2. Modern Tea Farming and Pest Control

Many tea farmers I have come across often say that pests and disease are inseparable parts of tea farming, thus pesticides to protect the crops.  Although it may diminish certain pest problems, large scale monoculture, heavy fertilizer use, open canopy and low lying cultivation area all deviate from natural growing conditions and further pose potential pest problems.

Heavy use of nitrogen fertilizer, for example, generally enhance vegetative growth and helps increase yield and tender tips, but excessive level of nitrogen makes plants weaker and more susceptible to pests and disease.

Tachibana (1997) found that amount of nitrogen fertilizer applied has effect on healthy root system on top soil and subsoil.  Heavy application of nitrogen fertilizer acidify the soil and burn the roots.

Modern farming practices focus on maximizing the yield.  This yield increase generally involves excessive amount of fertilizer use in highly altered growing environment.  It is easy for pests to find the host and spread.

3. How and what pesticides?

Next time we will look at what pesticides are applied and how they are applied.  There are many types of pests and disease.  Young tips, mature leaves, stems, and roots all have different pests and are affected in different seasons.

However busy we get, it's important to live with the value that we believe in.  We have to ask ourselves sometimes why we farm and live in the country.

During busy harvest season we still need to maintain our business and our lives, but often we get so overwhelmed by busy-ness of everyday life.  Yes, we are doing farm work, but what is it that made us want to farm at the first place?

We want to grow our own foods that meet our expectation and life that revolves around seasonal changes.  It's easy to say, but when we try to do all these, it's a lot more work than we imagine.

Winter-spring crops are ready to harvest now.  We make pickles and kimchi with cabbage and fruit wine with noni, jaboticaba and seasonal ingredients.

Each bite, each sip, they bring us back to our value of living on the farm and life in the country.