Screening rhizobacteria for biological control of Fusarium root and crown rot of sorghum in Ethiopia

Abstract

Fusarium oxysporum Schlectend causes root and crown rot in several crops including sorghum that results in low grain yield in Ethiopia and other East African countries.Seventy-eight bacterial isolates were obtained and subsequently tested both in vitro and in the greenhouse. Of the 78 isolates tested, 23 displayed between 30 and 66.3% inhibition of in vitro mycelial growth of F. oxysporum and also showed significant root colonization ability on sorghum seedlings. These isolates were further tested for their biocontrol ability against F. oxysporum in the greenhouse. Four isolates viz. KBE5-7, KBE5-1, KBE2-5 and NAE5-5 resulted in 100% disease suppression and no symptoms of root and crown rot were observed compared to the control. The complete suppression of F. oxysporum by these isolates was also confirmed by root plating on Fusarium-

Antagonistic Potential of Fluorescent Pseudomonads and Control of Crown and Root Rot of Cucumber Caused by Phythophtora drechsleri

“…An inhibition zone assay on PDA was then employed to screen for strains with high antagonistic potential. This assay had been used as a basic procedure in numerous screens for antagonistic agents (Ahmed Idris et al, 2007;Tjamos, 2004;Weller, 1985;Hagedorn et al, 1989;Ahmadzadeh and Sharifi-Tehrani, 2009). However, in some works there was no clear correlation between the results of this assay and in situ biological control results (Expert and Digat, 1995;Lindow, 1988;Reddy et al, 1993).…”

“…In vitro inhibition of mycelial growth of P. drechsleri by non-volatile compounds of the bacterial isolates was tested by using the dual culture technique as described by Ahmed Idris et al (2007). Three 10 µl drops from a 10 8 cfu/ml suspension of the bacterial isolate were equidistantly placed on the margins of potato dextrose agar (PDA) plates and incubated at 28 o C for 24 h. A 6 mm agar disc from a fresh culture of P. drechsleri was placed at the centre of the PDA plate for each bacterial isolate and incubated at 27 ± 1 o C for seven days.…”

“…Isolates displaying high antagonistic activity in the dual culture assays and that carried antibiotic-encoding genes were tested for their ability to colonize cucumber roots in vitro using the method described by Ahmed Idris et al (2007). Cucumber seeds (Soltan cultivar) were surface-sterilized with 5% sodium hypochlorite for 3 min, then with 70% ethanol for 1 min before rinsing three times in sterile distilled water.…”

Induction of defense-related proteins and growth promotion in tomato by mixture of Trichoderma harzianum OTPB3 and Bacillus subtilis OTPB1 and Pseudomonas putida OPf1 against Phytophthora infestans

“…Many studies demonstrated that certain bacteria and fungi promote plant growth directly through increased nutrition uptake excited by growth regulators (Idris et al, 2007;Gravel et al, 2007;Harman, 2011;Shoresh et al, 2010;Kloepper et al, 2004;Chen et al, 2007;Chowdappa et al, 2013b). They also colonize plant roots, suppress many soil borne fungal pathogens and also stimulate growth and crop yield (Idris et al, 2007).…”

Antagonism of Bacillus thuringiensis NCIM2130 against Sclerotium rolfsii Sacc., A Stem Rot Pathogen of Groundnut

“…Enhancement of plant growth by root colonizing Bacillus sp. is well documented (Kloepper et al, 2004;Idris et al, 2007a;Idris et al, 2007b).…”