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Yellow Pond Lily (Nuphar Luteum (L.) Sm.) control in recreative lake of Jarun-Zagreb

Sport and Recreative Centre Lake (SRC) Jarun has an area from 240 ha and about 30% of them are the Lakes nearly 75 ha. Median deep of the Lakes is about 4 meters ; the water is clean because flows from alluvial patches connected with River Sava. Average years water temperature is 14, 3oC, and during summer 24, 1 oC. In this conditions Yellow Pond Lily (Nuphar Luteum (L.) Sm.) has develop. It grows in shallow water and during hot summers when water level sinks, the Yellow Pond Lily expands on the areas where the depth is until 2-3 meters. This is situation on Kayak track where Yellow Pond Lily covers 70-90% of water area, and also on shallow runways between Lakes, near the coastlines, on beaches and so on. The control was conducted some years mechanically: divers rummage manually, cutting with different boat mowing machine. The results were not satisfactory and from year to year Yellow Pond Lily expands. Specific problem is the sludge washing out from the lake banks. The sludge is excellent ground for different water plants especially for Yellow Pond Lily. Big problem of constant expanding of Yellow Pond Lily we tried to solve with chemical methods using permitted herbicides based on glyphosate with addition of organic oil as surfactant and sticker. For this purpose we conducted investigations during the season 2007. As the problem was really big on the other side SRC Jarun buy the specialized boat dredger with rotary cultivator mounted on hydraulic lifter, soaking in sludge and pumping rhizomes. They have cultivated the full area infected with Yellow Pond Lily during the Autumn 2007. and Spring 2008. This was really big and spacious intervention. The sludge was deep mostly to 65 cm, the soaking-in suspension was about 310.000 m3 and after precipitations the sludge was about 60.000 m3. The amount of Yellow Pond Lily rhizomes was 200 m3. In full vegetation we will try with chemical methods to correct the faults from mechanical interventions.

Yellow Pond Lily; Jarun lake; control

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