**5. Existing control mechanisms and challenges**

Biological, chemical, and physical (manual and mechanical removal) control, and/ or an integrated approach (the use of two or three control mechanisms together) are used to eradicate WH. However, no single method seems ideal for all infested areas as suitable, and each method has its limitations and challenges [5, 53]. One of the significant components in deciding on a control approach is the uniqueness of the infested area (infestation chronology, water body uses, size, spatial arrangement, and weather) [16].

#### **5.1 Biological control**

Biological control is also one of the processes employed to remove or stop the growth of WH plants. In this mechanism, several insects, moths, fungi, pathogenic bacteria, and weevils among others have been distinguished as control agents for WH proliferation [53]. It should be noted that because of the fast proliferation rate, the major obstacle can be a long time to start such projects because it can take many years to reach a sufficiently large population to cope with pests [1].

*Invasive Water Hyacinth Challenges, Opportunities, Mitigation, and Policy Implications… DOI: http://dx.doi.org/10.5772/intechopen.106779*

#### **5.2 Chemical control**

Chemical control is an immediate and short time solution to remove WH using chemical herbicides. However, it greatly affects the sustainability of the water systems since it utilizes herbicides and other poisonous synthetic compounds that impact and affect sea-going life [54]. Furthermore, chemical processes for WH control are wasteful when there is generous rain [55].

### **5.3 Physical control**

Physical methods consist of two kinds of control(both manual and mechanical removal), the most widely utilized technique for WH management. Manual removal is done by human effort, to remove the WH plants from the water bodies [5], while the mechanical removal method is carried out by machines. Mechanical removal of WH consists of using weed cutters, harvesters, chaining, shredder boats, and a dredging process. Mowing, netting, and barriers are also used as ways of mechanical removal. Physical control remains the only method through which WH can be transformed into value-added products [16]. However, the significant disadvantage of this mechanism is that it expends a great deal of energy and needs a high investment cost [56].
