A Study on Population Diversity of Citrus Nematodes in District Sargodha.

Citrus slow decline caused by Tylenchulus semipenetrans deteriorates the quality and quantity of citrus fruit and make it prone for the invasion of other microbes. A survey was carried out for the assessment of nematode population distribution in all 7 Tehsils of district Sargodha (Pakistan) viz: Sargodha, Silanwali, Sahiwal, Shahpur, Bhalwal, Kot Momin and Bhera. Population densities of nematode were assessed in different genera of citrus crop i.e. kinnow, sweet orange, feutral's early, grape fruit and sweet lime, both in healthy and declining orchards. Whitehead and Hemming tray method was used for the isolation of T. semipenetrans which showed that the population was low in declining orchards as compared to the population densities found in healthy orchards. Kinnow was the most infested by nematode with mean population 1161 while sweet orange was the least infested with 595 nematodes, in all localities. Maximum nematode population density in healthy and declining orchards was recorded in Kot Momin that was 2600 and 946 nematodes per 50 ml of soil, respectively. The lowest mean population was recorded in Silanwali with 1200 in healthy and 300 in declining orchards. The assessment of spatial distribution of nematode population would pave foe effective disease management strategies. [ABSTRACT FROM AUTHOR]