Invasion and control of water hyacinth (Eichhornia crassipes) in China

Chu et al. /J Zhejiang Univ SCIENCE B 2006 7(8):623-626623Jourmal of Zhejiang University SCIENCE BISSN 1673-1581 (Print); ISSN 1862-1783 (Online)www.zju.edu.cn/jzus; www.springerlink.comJzUsE-mail: jzus@zju.edu.cnInvasion and control of water hyacinth (Eichhornia crassipes) in ChinaCHU Jian-jun*, DING Yi, ZHUANG Qi-jia(School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China)E-mail: shanghaichu@sjtu.edu.cnReeived Feb. 21, 2006; revision accepted Apr. 24, 2006Abstract: By the time of primary 21st century, water hyacinth had become a serious environmental problem in China. Waterhyacinth contributes to the major part of ecological hazards from the invasion of foreign plant species, which is estimated aboutUSD 7 billion a year in values.In the past 10 years, herbicides glyphosate, 2,4-D and paraquat have been used in controlling water hyacinth in China. AI-though the herbicides provided efective control on the weed in some areas, they could not provide the sustainable inhibition on theweed population, while would lead to pollution on water at various levels. At present, the herbicide application on water hyacinthis forbidden in many areas of China such as Shanghai. In this situation, the asexual reproduction inhibitor, KWH02, was inventedfor contolling water hyacinth and it provided about 70% of growth inhibition without any risk of dead plant pollution.It has been about 10 years for bio-control of water hyacinth in China. Works focused on mainly the efficacy and safety of theutilization of foreign insects. Researches on microorganism herbicides to control water hyacinth were started and obtained primaryachievements in recent years.Although there are different opinions on how to face the water hyacinth problem in China, it is accepted widely that thecontrol methods should be high efficient and safe with low cost. Some practical measures for integrated management of waterhyacinth are suggested.Key words: Invasion, Control, W ater hyacinth, Chinadoi: 10.1631/jzus.006.B0623Document code: ACLC number: S451INTRODUCTIONwater foods would be reduced in a large scope. Manywater areas would be difficult to ship and many canalsWater hyacinth (Eichhornia crassipes) was firstwould have problems for irrigation and drainage. Inintroduced from South America into China as a goodaddition, the presence of water hyacinth would befodder plant in 1901, and had become a serious en-negative for sightseeing. In 18 provinces or citiesvironmental problem in China by the early 21st cen-infected by water hyacinth, Shanghai is a typical area.tury (Ding et al., 2001). Of the total loss of USD 7Only in 2002, water hyacinth of 1.68 million tons wasbillion brought about by foreign weed species insalvaged in Huangpujiang River and other water areasChina, water hyacinth occupies the major proportion.in Shanghai and more than USD 10 million was spentThe large coverage of this weed on water would re-in a year. From 2002 to now, and Shanghai govern-duce sunlight penetration and lower oxygen contentment has invested more than USD 1.2 million on the .in water, which has a great impact on waterproject of integrated management on water hyacinth.eco-system, thus the local species would be decreased. Some important results were obtained and in use. ThisFor example, 60% local species living in Dianchipaper focused on our research results and the inte-Lake in Yunnan Province was died out by the inva- grated m;中国煤化工ter hyacinth insion of water hyacinth. The output of fishes and otherChina.Herbic.MHCNMHG,.II .. to control water” Project (No. 03DZ12007) supported by the Committe of Sciencehyacinth (Terry, 1991). In the past 10 years, herbicideand Technology of Shanghai, Chinaglyphosate, 2,4-D and paraquat have been used in624Chu et al. /J Zhejiang Univ SCIENCE B 2006 7(8):623-626controlling water hyacinth in China. Although the treated with KWH02 at 1.5 kg/ha (Fig.2) producesherbicides effectively reduced weed infestation, theyonly an average of 1.3 shoots. Such a treatment pro-do not provide a long-term sustainable control, andvides 72% control of weed after the application.pose problems of polluting water. In addition, weedSimilar results were obtained with further experi-mass killed by the herbicides may also decreasements conducted later in rivers and lakes.oxygen in water and cause a secondary pollutionharmful to fish. It is for this reason that in many areasof China such as Shanghai, we decided to test a6一✧- Untreatedchemical inhibitor of the asexual reproduction of- _o0一TIwater hyacinth, such as KWH02, which has been5- tτ2developed and applied for an patent (Chu, 2004a).430-00-0-0-000-00-0-000KWH02- AN INHIBITOR FORMULATION TOCONTROL ASEXUAL REPRODUCTION OFWATER HYACINTHOct.29Nov.55 Nov. 12Nov.19 Nov. 26Materials and methodsDate1. KWH02 effect on individual branches of wa-Fig.1 Efect of KWH02 on number of shoots of waterter hyacinthhyacinth in the growth poolThe experiments included six treatments andcontrol tested in concrete pools (50 cmx 50 cmx 50 cm3C✧Untreatmentvolume). Each pool contained only one weed indi-2:vidual. The treatments were as follows: treament 1r4(T1)- -KWH02 at the rate of 1.5 kg/ha, treatments 2to 6 (T2~T6) are single chemicals or other formula-5 15十T6tions at the same rate dosage comparatively withKWH02. The data was collected every day in 29 d10after spraying.pooooc0000-00002. KWH02 effect on total branches of waterOct. 29 Nov. 5Nov. 12 Nov. 19 Nov. 26The experiments included six treatments ancontrol also, and the methods were the same as above.But each pool contained a mass of water hyacinthFig.2 Effect of KWH02 on the total number ofwith 250 g fresh weight.branches of water hyacinthResultsToxicity concern of KWH02In the experiments of individual weed, waterThe formulation of KWH02 was tested accordinghyacinth showed to have a strong ability to produceto China GB15670- 1995 (test method on toxicity forbranches. The control, water hyacinth without treat-pesticide registration). The report of the toxicologicalment, produced more than six branches. Treatments 1studies conducted by Jiangsu Provincial Sanitary andto 6 (T1~T6) inhibited the reproduction of waterAnti-Epidemic Station revealed that the oral LDso ofhyacinth at various levels, and K WH02 could providethe male and female rats were higher than 5000 mg/kgthe highest inhibition (70%) on individual branchingbody weight. Such a result makes clear that this .compared to the control (Fig.1).compound中国煤化工of low toxicityIn the experiments of total branches, normally a herbicides.YHC N M H Gritation test andplant of water hyacinth produces an average of four the integral index of the acute eye irritation test onnew shoots branches every 26 d, while the plantrabbit showed no negative effects at all. .Chu et al. /J Zhejiang Univ SCIENCE B 2006 7(8):623-626625Evaluation of KWH02next three years after this release, while no weedThe use of such an inhibitor is a new approach for control was observed and no weevils were found inthe control of water hyacinth population withoutthe other two sites (Ding et al, 2001).killing the plant. The active ingredient of KWH02Research on the use of microorganisms to controlformulation have the advantages of being low toxic,water hyacinth began in 2000 in China. In 2003,decomposed fast, and do not pose any risk of pollu- Shanghai Jiao Tong University received the financialtion to the environment. In addition, it is also of lowsupport from Shanghai government to develop andcast. Its water-soluble powder formulation, in par- test a myco-herbicide formulation for the control ofticular, has a content of natural substances above 90%，water hyacinth. At present, nine fungal species haveand it also includes an adjuvant of plant origin, which been isolated from water hyacinth of Shanghai andhas also been successfully used in a water-solubleZhejiang Province, which showed various effects onpowder formulation of glyphosate during the last 10 the growth of water hyacinth in laboratory test. Inyears. Thus, the use of KWH02 has started recentlyorder to improve the quality of myco-herbicide for-for the integrated management practice of watermulation, particularly when it is sprayed in the field, ahyacinth in Shanghai water bodies, and it gainednon-ionic tenso -active surfactant extracted from wildimmediate success.camellia was included. This adjuvant should improveweed control by keeping the leaves of weed wet foreven more than 5 d, a sufficient period for the fungalBIO-CONTROL OF WATER HYACINTH INmycelium to infect the weed tissue.CHINA .The studies on biological control of water hya-DISCUSSIONcinth started 10 years ago in China. Most of this workhas been focused on the effect and safety of theIn the vast territory of China there are huge dif-utilization of specific exotic insects. It was not untilferences in the environmental conditions amongrecent that research has been initiated on microor-various provinces. Thus, the practical strategy onganisms as potential herbicides for the control o1integrated management of water hyacinth should bewater hyacinth.chosen according to the local condition including theIn 1995, the weevils Neochetina eichhorniae andclimate, level of water pollution, and local afforda-N. bruchi were introduced separately in China frombility.USA and Argentina (Ding et al, 2001). In order toIn South Eastern China, leaves of water hyacinthevaluate the safety of weevils, 46 different plant spe-would perish in winter, while the plant will stop itscies of economical importance were selected, in-growth. However, central buds of the weed are activecluding also ornamentals and some wild aquaticand would produce new shoots in the coming summer.plants in Dianchi Lake, Yunnan Province for studiesIn this case, saving the perished frond in winter wouldof host specificity. As a result none of the 46 speciesbe an efficient method to reduce the weed stand in thewere found to be edible by N. eichhorniae (Liu et al,next year. It would be an excellent preventive meas-1997). Similar results were obtained with the subse-ure to control water hyacinth at low cost. In places ofquent experiments conducted in various provinces,Southern China, such as Fujian, Guangdong andwhich clearly indicate that the weevils are safe to beY unnan provinces, water hyacinth grows throughoutused for the control of water hyacinth in China.the year, and exotic weevils and/or local insects couldThe effects of weevil on water hyacinth controlbe released and used for controlling the weed.varied from one place to another. Four sites in Wen-Chemical herbicides could be used in limitedzhou City of Zhejiang Province were selected for theareas, where water is not used for drinking and theexperiments by CAAS (China Academe of Agricul-weed stan(中国煤化工oduction inhibi-tural Science) in 1996. A release of 1000 intor, KWHiYHC N MH Gagent in areas,sects/(1000 m') in two sites exerted an efficacy where water IS used tor drinking and also in lakes,around 90% of the water hyacinth infestation for thepools, and creeks, where water flow rate is slow. Ir626Chu et al. /J Zhejiang Univ SCIENCE B 2006 7(8):623-626rivers, however, it is necessary to block the abundantReferencesflowing populations of water hyacinth, although it Chu, JJ, 2004a. An Inhibitor to Control Asexual Reproduc-may imply the use of large labour and materials use attion of Water Hyacinth. China Patent, CN1568702.high cost. In the case of plenty water hyacinth savedChu, JJ, 2004b. A Technique to Use Water Hyacinth to Pro-duce Organic Fertilizer. China Patent, ZL 03 11635.X.from water, it is very important to treat the weed inDing, J.Q, Wang, R., Fu, W.D., Zhang, G.L, 2001. Watertime in order to avoid second pollution to the envi-Hyacinth in China: Its Distribution, Problems and Controlronment caused by the dead and decay of the weed.Status. In: Julien, M.H, Hill, M.P, Center, T.D., Ding,We can use water hyacinth to produce organic fertil-J.Q. (Eds.), Biological and Integrated Control of Waterizer (Chu, 2004b).Hyacinth, Eichhornia Crassipes. ACIAR Proceedings102. Canberra, Australian, p.29-32.In long term, water hyacinth management shouldLiu, JQ, Deng, JZ, Wang, H, 1997. Study on controllingbe implemented taking into consideration the wholewater hyacinth wild-growing with natural enemy. Chinaeco-system. There is a need to reduce sewage fromEnviron. Sci, 17:446-448 (in Chinese).industry and man activity, to regulate the pollutionTerry, PJ, 1991. Water Hyacinth in the Lower Shire, Malawi,caused by inputs used in the agricultural, to take ef-nd Recommendations for Its Control. AFRC Inst. offective measures to keep the natural balance of theArable Crops Res., Long Ashton, UK, p.64.eco-system, to solve the present contradiction be-tween economical development and environmentalprotection, and to introduce new successful foreigntechnologies in China that may save resources usedfor research and control. These all are urgent ques-tions, which need to be responded in China.JzuSEditors-in-Chief: Pan Yun-he & Peter H. ByersISSN 1673-1581 (Print); ISSN 1862-1783 (Online), monthlyJournal of Zhejiang UniversitySCIENCE Bwww.zju.edu.cn/jzus; www.springerlink.comjzus@zju.edu.cnJZUS-B focuses on“Biomedicine, Biochemistry & Biotechnology"JZUS-B online in PMC: htp://www.pubmedcentral.nih.govtocrender.fcgi?journal=37 1&action=archiveWelcome Contributions to JZUS-BJournal of Zhejiang University SCIENCE B warmly and sincerely welcome scientists all over theworld to contribute Reviews, Articles and Science Letters focused on Biomedicine, Biochemistryand Biotechnology. Especially, Science Letters (3~4 pages) would he nublished as snon as about 30days (Note: detailed research articles can still be published in中国煤化工the futureafter Science Letters is published by JZUS-B).TYHCNMHG