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KEYWORDS Fusarium oxysporum f. sp. cucumerinum Chaetomium cupreum Trichoderma viride Bacillus pumilus Salicylic acid Cucumber PCR ABSTRACTThis study was aimed to isolate and identify the phytopathogenic fungus Fusarium oxysporum f. sp. cucumerinum (Foc) the causal agent of the Fusarium vascular wilt disease of cucumber in the middle and south of Iraq. The results of study indicated the presence of the pathogen with percentage of appearance 71.43% with frequency 46.43%. Molecular identification carried out using polymerase chain reaction technique indicated the presence 18 isolates of Foc pathogenic group I and 6 isolate of Foc pathogenic group II. Among these, the isolate Foc-b3 was most virulent under in vitro pathogenicity test on the cucumber seed and it exhibited 0% seed germination compared with control. An attempt of integrated management of F. oxysporum f. sp. cucumerinum under in vitro conditions was also carried out in present study and a significant inhibition were reported on the application of various bioagents such as Chaetomium cupreum (Cc), Trichoderma viride (Tv) and Bacillus pumilus (Bp) on the potato dextrose agar (PDA). Further, under greenhouse conditions, combined application (tetrainoculums) of Cc+Tv+Bp+ Salicylic acid (Sa) was significantly reduced the percentage of the disease incidence and severity up to 0% as compared with the control where it was reported 97.50%, 75.72% respectively. Effect of this combination was also reported on the dry weight of the plants and significant improvement (0.975 gm/plant) was reported as compared to control (0.098 gm/plant).

Fusarium vascular wilt disease is one of the most harmful disease that affected broad range of plant species including zucchini (Cucurbita pepo). The objective of the research was to investigate the presence of the phytopathogenic gungus Fusarium oxysporum the causal agent of the disease in zucchini fields. Forty five isolates of F. oxysporum were isolated from four locations in province of Dyala during 2014-2015. Isolate Foq9 was most virulent in the pathogenicity test in vitro. Twenty nine isolates of them amplified their DNA positively with the universal primer of F. oxysporum in the polymerase chain reaction technique (PCR). In vitro significant suppression efficiency were observed of the fungicides Topsin M 70 WP (Tm) and Tecto 500 SC (Tc) and two botanical extract solution extracted from Garlic (Gr) and Ginger (Gn) against the pathogen on the potato sucrose agar (PSA). In greenhouse experiments all of the agents decreased the percentage of disease incidence and severity significantly, while the tetra-inoculum (Tm+Tc+Gr+Gn) was superior which exhibited 0% disease incidence and severity compared to the negative control which was 95%, 79% respectively, also the combined application of the botanical extracts (Gr+Gn) reduced the disease incidence and severity significantly. All of the treatment increased plant growth criteria represented by dry weight of the plant compared to the control.

Isolation from infected Tomato’s plants has demonstrated the presence of the phytopathogenic fungus Drechslera halodes (Dh) the causal agent of leaf spot, crown and root rot disease, samples were collected from three provinces in the middle and south of Iraq, Dh was predominant while appeared in 83.33% of the samples with frequency of 50.25%. Results of pathogenicity test under greenhouse conditions indicated that all the isolates of Dh were pathogenic to tomato plants, the isolate Kkd-6 showed highly pathogenicity effect. Four isolates of beneficial free-living soil bacteria isolated from healthy tomato’s rhizosphere of Bacillus subtilis (Wb-12), B. subtilis (Kb-9), Enterococcus columbae (Bb-8) and Pseudomonas putida (Kb-18), were exhibited 100% antagonism efficiency against the pathogen on the potato dextrose agar medium (PDA) in vitro. Under greenhouse conditions all the biocontrol agents were reduced significantly the percentage of disease incidence to 5-10% and severity of shoot and root system to 5.00-8.33%, 2.14-7.14% respectively compared to fungal treatments control which exhibited 100% disease incidence and severity of shoot and root system of 90.00%, 93.57% respectively. All the biocontrol agents promoted plant growth. This is first report of Drechslera leaf spot, crown and root rot disease of tomato in Iraq.

This study was conducted to evaluate the efficacy of the biocontrol fungi Chaetomium cupreum, Trichoderma viride, and Saccharomyces cerevisiae and some chemical nutrients that stimulate plant growth, such as calcium nitrate, ammonium phosphate, aqueous magnesium sulfate, copper and boron in controlling some common soil-borne pathogenic fungi and evaluating their role in stimulating plant growth. All the bioagents showed significant antagonistic efficiency In vitro against the pathogenic fungi Drechslera Halodes, Fusarium oxysporum, Fusarium solani, Macrophomina phaseolina, Pythium aphanidermatum and Rhizoctonia solani. Under greenhouse conditions, BC treatment composed of biological and chemical elements, achieved the highest germination rate for tomato, cucumber and cowpea seeds inoculated with the pathogenic fungi, and reached 95.83-100.00% compared to 36.67- 47.50% for the control treatment. BC treatment also excelled in reducing disease incidence and severity, as the disease rate reached 0% compared to 95.83-99.17 % for the inoculated control treatment, and without significant difference with the non-inoculated (healthy) control. In addition, the BC treatment produced 0 % disease severity rate as compared to 82.58-85.83% for the inoculated control, and without significant difference with non-inoculated control. Furthermore, the BC treatment was superior to the rest of the treatments in increasing dry weight of all the plant species tested. Keywords: Chaetomium cupreum, Trichoderma viride, Saccharomyces cerevisia, Soil-borne fungi, biological control.