SUBMERGED MACROPHYTE CONTROL USING PLASTIC BLANKETS

Penrith Lakes Scheme is concerned with the rehabilitation of gravel pi ts to create a system of large recreational lakes. A potential submerg ed macrophyte problem has been identified in an existing man-made lake . The need to control the macrophytes is dependent on the proposed end use of the lakes and the potential area of invasion. A variety of con trol options were assessed. Plastic blankets were tested to determine their effectiveness in controlling macrophyte growth specifically in s wimming and boat access areas. Comparisons of clear, black and black w oven blankets were conducted. Experiments revealed that 90% of the pla nts under the black and black woven blankets died within six weeks. Un der clear blankets plants were reduced by between 20%-90%. Analysis sh owed that significant interactions occurred between sites and treatmen ts and times, from which it can be inferred that none are independent of each other. Success in the reduction of macrophytes appears depende nt on such factors as plant species, sediment accumulation and light r eduction.