STiR coffee and tea magazine

Volume 3, Number 2

Issue link: https://read.dmtmag.com/i/491356

Contents of this Issue

Navigation

Page 58 of 83

STiR tea & coffee industry international 59 more than 60% to 80% of pesticide MRLs are lower than 1ppm (parts per million) and 5% are at an even smaller ppb (parts per billion) level," said Chen, who formerly served as chairperson of CCPR (Codex Committee on Pesticide Residues). Chen elaborated on the evolving global MRL standards. He advocates a program launched in China to replace the use of water-soluble pesticide in tea gardens. "We've tested hundreds and thousands of pes- ticide samples annually," he explained. "In water solubility tests, oil-soluble pesticides and water- soluble ones showed a maximum difference of 300 times in solubility," he said. "We are drinking tea liquid rather than con- suming the leaves: water-soluble pesticide residues can easily dissolve into water, while oil-soluble ones have a much narrower chance to dissolve and the actual intake from drinking tea is significantly reduced," he said. Since 2012, a total of 250,000 Chinese mu (41,000 acres) of tea gardens have successfully switched to four well-tested oil-soluble alterna- tives replacing a broad range of water-soluble pes- ticides. This figure is less than 1% of China's total tea gardens but demonstrates the value of the pro- gram which will now continue at a national level. Endosulfan is difficult to dissolve in water. Even at the U.S. 24 ppm standards, the actual in- take from drinking tea is minimal. However, as a POP chemical, it has a longer half-life and is ca- pable of bioaccumulation in fatty tissues. "This volatile chemical will adhere to soil par- ticles and evaporate into the air under the sun. Va- porized Endosulfan is carried along by the wind to nearby or distant places, and will be disposed back to the earth," Chen said. "If a cotton field is sprayed with Endosulfan, a nearby tea garden that never uses this chemical will be contaminated through air transport," he said. "I recommend three alternative pesticides to replace Endosulfan: Indoxacarb by DuPont, Palit by BASF and Arica by Syngenta," said Chen, "In- doxacarb is pending a MRL standard, and we are testing that." Green pest management Green Pest Control is another of Chen's key pur- suits. Growers use chemicals with an understand- ing of the local ecology to reduce the use of syn- thetic pesticides. Beneficial insects like ladybugs, for example, offer natural aphid control eating 50 aphids a day and then attack leaf scale for dessert. A ladybug will consume 5,000 aphids during its lifespan. "We also experimented with color on glue boards designed to trap tea green leaf hoppers, a common pest found in tea gardens, and discov- ered the most attractive color code to lure the Prof. Chen Zongmao, expert in protecting tea. hoppers," Chen said, adding that authorized man- ufacturers have produced coverings for thousands of these boards. "Insects and mites are attracted to a tea garden by semiochemicals emitted by healthy tea plants," he continued. "When the plants were bitten by in- sects or mites, they will emit defensive, repelling and/or predator attracting semiochemicals. We've spent 10 years to identity these chemicals with the potential to repel pests or to attract their preda- tors," said Chen. Semiochemicals are substances that communi- cate a message by chemical means, examples in- clude pheromones and kairomones. "We are now able to produce semiochemi- cals for plant protection purposes: however, the capsules only last one week in the field, which is not cost-effective. We are looking for potent time technology to obtain sustained release lasting half a month or longer," he said. Planting selective aromatic trees in the tea garden also can help to repel pests. Furthermore, these trees shade surrounding tea plants which will acquire a sweeter taste due to the less intense sun- light, explains Chen. Other research targets the use of sex phero- mones. Female pests emit sex pheromones to at- tract male partners for mating. Chemical imitation of strong sex pheromones can lure male insects away and disturb their reproduction combined with proper setting of glue boards or water buck- ets to kill the allured male pests. Chinese tea planters are mainly small holders. There are more than 300,000 tea producers and four million farmers growing tea. It is difficult to educate and monitor such large numbers. The Tea Research Institute has been appointed by the Ministry of Agriculture to take charge of building a national-level tea plant protection system. The program is funded by the Ministry of Ag- riculture and focuses on planters' training, predic- tion and forecast of pest and disease outburst, replacement of water-soluble pesticides and green pest control.

Articles in this issue

Archives of this issue

view archives of STiR coffee and tea magazine - Volume 3, Number 2