| Aquatic weeds 
               
                |  Before |   
                |  After |  Aquatic weeds 
              can bring rivers and lakes to a standstill, destroying their ecology 
              and also the livelihoods of communities who depend on them. Two 
              of the most notorious are salvinia, 
              Salvinia molesta, and water 
              hyacinth, Eichhornia crassipes. They have an 
              incredible ability to spread. Salvinia can double its size every 
              2-3 days and mechanical harvesting and herbicidal control can be 
              too slow to keep up. Neither is practical nor affordable in many 
              wetland situations. Environmental sensitivities often prevent the 
              use of herbicides. The success 
              of biological control has been spectacular. In many countries, water 
              ways that were once unusable are now returned to full use and the 
              agents have reduced the weeds to relatively insignificant populations. The expertise 
              developed has been passed on through collaborative research and 
              technology transfer projects with organisations in Australia, Asia, 
              the Pacific, Africa and the Americas. The spectacular 
              results are long-term, sustainable (require little or no additional 
              inputs), environmentally friendly (non-polluting) and affordable 
              (repeat application is not required).
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