EFFECTS OF LEVELS OF CHEMICAL FERTELIZERS ON INFESTATION OF CITRUS NURSERIES WITH CITRUS LEAFMINER PHYLLOCNISTIS CITRELLA STAINTON

Abstract

The study was conducted in one of citrus nurseries in Baghdad during fall and spring seasons of 2005-2006. The study of host preference of citrus leafminer Phyllocnistis citrella stainton showed that the sour orange Citrus aurantium was the most preferred to the insect with infestation percentages reached to 49.97% and with an average of a living larvae number reached to 4.68 larva/new branch, while the mandrine citrus reticulate was much less preferred with infestation percentage reached to 28.8% and less number of living larvae which reached to the average of 2.31 larva / new branch. The results also illustrated that the treatment of citrus nurseries with different levels of chemical fertilizers of (NPK+K), (NPK+N) and (NPK) had a great effect on both the infestation percentage and the number of living larvae. It was found that the treatment, in which the nitrogen was increased, had a greater effect and caused a highest percentage of infestation in comparison with the treatment of potassium increase. The infertation percentages were 6.20%, 13.21% and 9.7% and the number of living larvae were 0.33, 2.11 and 0.55 larvae/new branch when the citrus nurseries were treated with (NPK+K), (NPK+N) and (NPK) fertilizers in full season of 2005 respectively, while in spring season of 2006, the infestation percentages of new branches reached to 3.53%, 9.93% and 8.30%, respectively. These results could indicate an integration between host and leaf of fertilizers to control the population of this pest.