A nonpathogenic species of binucleateRhizoctoniainhibits the formation of infection structures caused byRhizoctonia solanion cucumber

Abstract

Binucleate Rhizoctonia (BNR) W7 was evaluated for the efficacy to control damping-off disease in cucumber seedlings. Results revealed that Lobate appresoria and dome-shaped infection cushion were produced by virulent Rhizoctonia solani C9 AG4 on the surface of the cucumber seedling hypocotyls, causing damping-off, 12 h after inoculation. A significant positive correlation was observed between disease severity rating and number of infection cushions (r = 0.94) and appresoria (r = 0.97) on the hypocotyls of seedlings inoculated with virulent R. solani C9 alone. Inoculation of a nonpathogenic species of BNR prior to virulent R. solani significantly reduced the number of appresoria on hypocotyls surface and inhibited the formation of infection cushions that accompanied by highly significant (P ≤ 0.01) reduction in disease severity in comparison with seedling inoculated with R. solani C9 alone. Formation of mucilaginous material upon recognition of the nonpathogenic isolate of BNR followed by hyphal lysis of BNR W7 6 h after inoculation was responsible for reduction in appresorium formation and complete inhibition of infection cushion formation. However, the number of infection structures produced on cucumber was not significantly different for hypocotyls of seedlings inoculated with R. solani C9 with and without the nonpathogenic BNR W7.

Biological Activity of Four Trichoderma Species Confers Protection against Rhizoctonia solani, the Causal Agent of Cucumber Damping-Off and Root Rot Diseases

“…Most (80%) isolates belonged to the multinucleate AG-4 group. According to the literature, AG-4 R. solani frequently causes root rot on cucumber [44,[61][62][63]. Other investigators have reported similar results on cucumber.…”

“…Afterwards, the mixture was placed in the flasks and autoclaved at 121 • C for 30 min. A 5 mm mycelial plug of 5 day-old R. solani culture was inoculated in each flask and incubated for 15 days at 25 ± 2 • C [44].…”

“…This was followed by incubating the inoculated plates for 5 days at 25 ± 2 • C. This experiment was performed with three replicates (five plates per each) for each treatment, as well as for the control. When the R. solani mycelial growing reached the petri dish edge, the diameters of the developed R. solani colonies were measured and assessed using the suggested formula according to Hassan et al [44]: I = [(C − T)/C] × 100; I = inhibition of radial mycelia growth; C = the pathogen radial growth measurement in control; T = the pathogen radial growth in the existence of Trichoderma isolates.…”

Soil properties related to suppression of Rhizoctonia solani on tobacco fields from northwest Argentina

“…Also, in addition to the presence of pathogenic inoculum, root diseases caused by Rhizoctonia require a susceptible host and favourable environmental conditions. Moreover, it has been documented that nonpathogenic Rhizoctonia inhibited the formation of infection structures of R. solani in cucumber (Hassan et al , ). Thus, the presence of nonpathogenic Rhizoctonia inoculum in tobacco soils might limit infection by R. solani.…”

Suppressive effects of a polymer sodium silicate solution on powdery mildew and root rot diseases of miniature rose

“…The smallest varieties ("micro-minis") grow to 6 inches or less. Recently, environment-friendly agriculture attempts to minimize the use of fungicides (Elsharkawy et al, 2012a(Elsharkawy et al, , 2012b(Elsharkawy et al, , 2013Hassan et al, 2014bHassan et al, , 2014cTaguchi et al, 2014;. Disease control by materials with low environmental effects is desired ((El-kazzaz et al, 2015).…”