Determination of aquatic weed species, their densities and possible biological control agents in lower Seyhan plain

This study was conducted to determine aquatic weed species, their observation frequencies and percentage coverages in irrigation and drainage channels in Lower Seyhan Plain, Turkey.The most important step in weed management is to know present weed species. In Lower Seyhan Plain, agricultural irrigation is mostly based on irrigation channals, and aquatic weeds are among the most important problems associated with irrigation channals. Three surveys were conducted to determine aquatic weed species, one in July-August (2007), and in September-October (2007) the other was in April-May (2008). To do this, went on the way of channels and sampling points were chosen randomly by stopping at every 6 km. Totally 50 sampling points were determined for each three surveys. On each point, 100 m distance were determined on channel and devided into four parts. Thus aquatic weeds were taken from channel with a hook, 5 times on every part. Then, samples were collected from all weed species to bring laboratory to identify. Percentage coverage areas of weeds were also determined during surveys. Additionally, weed species found on the edges of channels and their percentage coverage areas were determined.The surveys resulted with 21 aquatic weed species belonging to 15 families. Potamogetonaceae was found as the largest family with five species. Chara globularis (% 38), was found as the largest species in July-August (2007), Potemogeton nodosus (% 40) in September-October (2007), and Phragmites austrialis (% 30) April-May (2008). According to average observation frequencies of three surveys, top 5 species were determined as Potemogeton nodosus (33%), Stigeoclonum sp. (31%), Chara globularis (28%), Phragmites australis (25%) and Potamogeton lucens (% 15).In the same time, in this study the biological agent of aquatic weeds were studied and acording to our research the biological control agents have the potential impact on weeds are Alternaria sp. can be used on Polygonum lapathifolium L., Hydrellia sp. on Potamogeton nodosus, Lymnaea sp. on Potamogeton nodosus, Melanopsis sp. on Chara globularis and Potamogeton nodosus.