Control of the Citrus Disease Complex in Iraq

Abstract

This study was conducted in a citrus orchard in Baghdad province, Iraq. Roots were severely infected with citrus-root nematode Tylenchulus semipenetrans and the fungus Phytophthora citrophthora, die back symptoms were highly observed on the vegetative growth, and the yield of these trees were very poor. The experiment included 16 treatments using three nematicides Rugby (Cadusafos), Mocap and Garland, and three fungicides Previcure, Agrifos and Nando, and the control (untreated) with three replicates/treatments. Each treatment was about 50 m2 and consists of ten citrus trees using complete randomized block design (CRBD). Soil and root samples were taken a week before treatment and six months after treatment for nematode extraction (250 g soil and 1 g roots) and for fungus using potato dextrose agar media (PDA) for germination. Results indicated that all the fungicides applied had no effect on citrus root nematode, but when they were applied with nematicides simultaneously there was a sharp decline in nematode population. All the nematicides applied in this experiment were highly effective against the nematode and significantly reduced their number compared to the untreated (control) plot. Rugby (Cadusafos) was significantly effective than the other nematicides, where the number of nematodes in 250 g soil and 1 g root reduced from 3833.3 and 1876 juvenile before treatment to 333.3 and 124 juveniles after treatment respectively. Similar effect was found when these nematicides were applied with the fungicides for controlling the disease complex and it was found that Rugby again was highly effective than the other applied nematicides.