Soğan Sak Nematodu (Ditylenchus dıpsaci) (Kühn, 1857) (Tylenchida: Anguinidae)’nun Karaman İlinde Soğan (Allium cepa l.) Bitkisinde Populasyon Değişiminin Araştırılması

Abstract

Stem and bulb nematode (Ditylenchus dipsaci) was found widely distributed in 61% in Karaman onion growing areas. In some fields,
the population density was 165 nematodes per 100 g of dry soil. Accordingly D. dipsaci causes yield loses on onion cultivation in Karaman
province. Infected bulbs affect the quality of onion and reduce the market value. To control the stem and bulb nematode, it is important to
determine population development during the growing season. For this purpose, population development of the nematode was followed
during one onion growing season. Onion was cultivated in March and harvested in September in 2013. During this time, in March and April
the population density of soil nematodes were 106 nematodes/ 100 g dry soil at temperature between 8-12 oC. Population density decreased
to 52 nematodes/ 100 g dry soil with the temperature increase to 15 oC in May and then remained constant at 27 nematodes/ 100 g dry soil at
average 21 oC. Nematode numbers were found significantly negative correlated with soil temperature (R2= 0.751). Soil moisture level was
averagely 0.5 volt during the growing season which is sufficient for nematode development.