تشخيص مسبب مرض تعفن جذور و قواعد سيقان الرقي و تقويم كفاءة البكتريا المرافقة لجذور النباتات السليمة مكافحة المرض تحت ظروف البيت الزجاجي

الملخص EN

This research was aimed to identify the causal agent of crown and root rot disease of watermelon in some provinces in middle and south of Iraq, assess pathogenicity of the causal agent and control it by using bacteria (PGPR) isolated from the rhizosphere of healthy watermelon plants.

Fusarium solani f.

sp.

cucurbitae was present in all the tested samples with frequency between 27-80%.

Pathogenicity test using cabbage seeds showed variation in pathogenicity ability as germination percentage ranged between 0-88% with superior isolate T4FS- 15 and D5FS-2 as completely prevented germination of seeds compared to the control treatment which reached 96%.

The results showed that all isolates was pathogenic to watermelon plants under greenhouse conditions, isolates T4FS-15 and D5FS-2 achieved a reduction of seeds germination to 5% compared to control treatment which achieved 100% , and achieved an increase in the percentage of the disease severity of shoot and root system in its treatments reached 98.12 % , 98.00 % and 98.50 % , 98.00 % respectfully compared to the control treatment which was 0% for shoot and root system.

Seventy one bacterial isolates were isolated from the rhizosphere of the healthy watermelon plants.

Antagonism ability of this isolates against the fungal isolate T4FS- 15 showed superior of 10 bacterial isolates which achieved 100% growth inhibition compared to the control treatment which filled the dish after 7 days.

Identification of the10 bacterial isolates by Vitiq2 compact system technique present the species Achromobacter denitrificans, A.

xylosoxidans, Acinetobacter haemolyticus, Acromonas salmonicida, Enterococcus columbae, Granulicatella elegans, Kocuria rosea, Serratia odorifera, Sphingomonas paucimobilis and Streptococcus thoraltensis were identified for the first time in Iraq.