Background: Damping-off and root rot/wilt diseases caused by the soil-borne fungi Fusarium solani and F. oxysporum are a serious problem of dry bean productions in Egypt. This study examines the potential of controlling these diseases biologically by using three Trichoderma isolates, compatible with the fungicide thiophanatemethyl, i.e., T. harzianum, T. viride, and T. virens. Soil application with inoculants containing these isolates employed either alone or in combination with seed coating with thiophanate-methyl was applied. Results: Under greenhouse and field conditions, all treatments significantly reduced the incidence of damping-off and root rot/wilt diseases and increased the percentage of survival plants. These treatments increased vegetative growth parameters and yield components of the survival dry bean plants compared with untreated control. Soil application with Trichoderma isolates combined with thiophanate-methyl seed treatments was more effective than using both of them individually. Meanwhile, T. virens + thiophanate-methyl was the most effective treatment. The tested treatments stimulated systemic defense responses in dry bean plants by activating defense enzymes including peroxidase, polyphenoloxidase, and chitinase. Conclusions: Based on the obtained results, compatible isolates of Trichoderma spp. as soil treatment combined with thiophanate-methyl as seed treatment may have potential to develop a new biofungicide for integrated management of damping-off and root rot/wilt diseases in dry bean.
Background: Due to the fact that chemical nematicides frequently cause environmental pollution and toxic hazards to human, plants, and domestic animals, certain biocontrol agents of environmentally and toxicologically safe properties and secure to human and animals were tested against root-knot nematode Meloidogyne incognita on cowpea. Objective: The protective effect of two isolates of Bacillus subtilis, B. pumilus, or Pseudomonas fluorescens on M. incognita reproductive parameters infecting cowpea was examined, and consequently, plant growth and yield parameters were investigated. The nematicide, Furadan (10% G) was, also, included in this study for comparison. Results: Bacillus subtilis (Bs 2) recorded the highest average total percentage reduction (82%) of M. incognita reproductive parameters followed by B. pumilus Bp 2 (81.8%). Also, Carbofuran 10% recorded the highest average total percentage reduction (76.5%) in terms of numbers of second-stage juveniles (J 2) in plant roots and soil as well as nematode galls and eggmasses compared to the untreated check. The highest total average percentage plant growth increase (99%) was obtained by B. pumilus (Bp1), but B. subtilis (Bs2) and medium recorded 26.3 and 12.8% only, respectively. P. fluorescens (Pf 1) scored the highest yield increase (97%) followed by Pf2 (63.8%). Number of bacterial nodules showed the highest percentage increase (78%) by P. fluorescens (Pf 2). B. pumilus (Bp 1) caused the highest increase of phenolic compound contents followed by P. fluorescens (Pf 1). The nematicide Carbofuran 10% G was the first in increasing soluble protein contents followed by P. fluorescens (Pf 1). Bacillus pumilus (Bp 1) caused the highest total contents of photosynthetic pigments followed by P. fluorescens (Pf 1) and (Pf 2). Conclusions: The tested biocontrol agents could achieve various degrees of M. incognita control on cowpea under screen house conditions with consequent increase in cowpea growth and yield parameters. These bacterial isolates need to be studied under different field conditions for confirmation.
Background Several chemical bactericides were applied for controlling soft rot bacteria, Pectobacterium carotovorum subsp. carotovorum, which causes the destructive soft rot disease to many economically important vegetables, but because of their toxic hazards on human and environment became limit. The biocontrol was applied to control many plant pathogens. Therefore, this work is aimed to study the antagonistic activity of bacterial agents, i.e. Bacillus subtilis, Bacillus pumilus, Bacillus megaterium and Pseudomonas fluorescens, and fugal agents, i.e. Trichoderma harzianum, Trichoderma viride and Trichoderma virens, to control bacterial soft rot disease under in vitro and in vivo tests. Results The tested treatments could protect the potato tubers against the development of soft rot. T. viride and T. virens were highly effective in reducing soft rot symptoms on inoculated potato tuber slices, when applied at the same time or 2 h before pathogen inoculation, while B. megaterium and T. harzianum were highly effective when applied at the same time or 2 h after pathogen inoculation. In whole potato tubers technique, B.pumilus highly protected the stored potato tuber under artificially infection conditions, than P. fluorescens, T. harzianum, B. subtilis, T. viride, T. virens and B. megaterium, respectively. Conclusion Application of fungal agents or specify the bacterial species can play an important role in controlling bacterial soft rot disease in vegetables and increase the stored periods of potato tubers under storage conditions without any toxic effects.
The importance of benign approaches to manage the root-knot nematodes (RKNs, Meloidogyne spp.) in strawberry farms has become more evident with increasing strawberry production and export in Egypt. Therefore, data accumulated on biosolarization and soil amendments to favor beneficial microorganisms and maximize their impact on RKN management are built on a robust historical research foundation and should be exploited. We examined RKN population levels/parameters in three strawberry export governorates, six farms per governorate, to characterize the exact production practices that are responsible for RKN-suppressive soils. All selected farms enjoyed soil biodisinfestation resulting from incorporating organic amendments followed by a plastic cover to suppress soil pathogens. Various safe and inexpensive agricultural practices in the El-Ismailia and El-Beheira governorates were compared to the toxic and expensive fumigants that could eliminate RKNs in the Al-Qalyubia governorate. Two farms at El-Ismailia were of special interest as they ultimately showed almost zero counts of RKNs. The two farms were characterized by incorporating cow manure [containing 0.65% total nitrogen, 21.2 carbon to nitrogen (C/N) ratio] and poultry manure (0.72% total nitrogen, 20.1 C/N ratio) followed by soil solarization via transparent, 80-µm thick plastic covers for 60–65 summer days as pre-strawberry cultivation practices, and similar covers were used after transplanting. Typically, the longer the pre-plant soil solarization period with thicker transparent plastic covers, the better it could suppress the RKN population densities in the tested farms. Their soils were characterized by relatively high pH and low electrical conductivity. The significant development in biocontrol genera/species abundance and frequency could explain the lower (p < 0.0001) RKN population levels inhabiting the farms of El-Ismailia than the El-Beheira governorate. These factors could provide the first approximation of key practices and factors that could collectively contribute to distinguishing and exploiting soil suppressiveness against RKNs. We discussed edaphic properties and production practices that could modulate populations of natural RKN antagonists for sustainable strawberry cultivation.
Background: Eggplant (Solanum melongena L.) is one of the important vegetable crops infected by Meloidogyne incognita all over the world, including Egypt. Chemical nematicides frequently cause environmental pollution and toxic hazards to human, plants, and animals; certain biocontrol agents that are environmentally friendly and safe to humans and animals were tested against the root-knot nematode Meloidogyne incognita in eggplant. Objective: This work is aimed to determine the nematicidal activity of Bacillus spp., viz., B. subtilis and B. pumilus, against M. incognita in three separated experiments to study their ability in controlling M. incognita and in improving the growth parameters of eggplants. Bacillus spp. were applied as single or in combination (experiment I), single treatment at different doses (experiment II), and different times (three times) of application (experiment III). Results: The results of experiment I revealed that Bacillus sp. + B. subtilis significantly reduced the second-stage juvenile (J 2) in soil and galls and egg masses in roots, while Bacillus sp. + B. pumilus significantly reduced J 2 in roots. Bacillus spp. in pairs were more effective against M. incognita. In experiment II, Bacillus sp. (40 ml) significantly reduced the J 2 in soil and galls and egg masses in roots, while B. pumilus (40 ml) significantly reduced the J 2 in roots. The nematicidal activity of Bacillus spp. was increased by increasing the applied dose. In experiment III, B. subtilis, when applied three times, significantly reduced the J 2 in soil and the J 2 and galls in roots, while B. pumilus (applied three times) significantly reduced the egg masses in roots. All Bacillus spp. treatments highly increased the tested growth parameters compared to the controls. Conclusions: The tested biocontrol agents used more than once or in combination are more effective than those used only once in controlling nematode parameters in eggplant under greenhouse conditions with a consequent increase in eggplant growth. These bacterial isolates need to be studied under different field conditions for confirmation.
The effect of commercial biocontrol products viz. Nemakill, Nemaless, Micronema as well as an Egyptian entomopathogenic nematode (EPN) strain of Heterorhabditis bacteriophora-infective juveniles (IJs) within either cadavers of Galleria mellonella last instar larvae or EPN-IJs in water suspension, compared to chemical nematicides of Nema Plus Zero and Oxamyl on Meloidogyne incognita developmental parameters, strawberry growth and yield and rhizosphere microbial community were determined in two separated field experiments. Six months after strawberry transplanting, 30-88% reduction in nematode juveniles (J 2) in soil was achieved by Nemakill, Nemaless and Micronema, while reduction range was 37-64% by EPNs compared to 64-73%, by chemicals. The commercial products followed by EPNs significantly reduced the numbers of M. incognita-J 2 , galls, and egg masses in strawberry roots. All treatments enhanced strawberry growth and yield parameters. Nemakill followed by EPNs in water and within insect gave best fruit yield of strawberry cv. Festival. Nemaless followed by Nemakill and Micronema gave best fruit yield of strawberry cv. Fertona. Effect of tested treatments on rhizosphere microbial community and mycoflora frequency in treated strawberry plants was presented and discussed.
Background: Orobanche crenata is an obligate root parasite belonging to Orbanchaceae. Broomrape causes great damage to the faba bean. Several attempts were applied for controlling parasitic weeds. So, the aim of this work is to study the application of Trichoderma spp. as well as three rhizobacteria species in comparison to herbicidal effect of Glyphosate (Glialka 48% WSC) for controlling broomrape infesting faba bean (Vicia faba). Materials and methods: Three pot experiments were carried out in the greenhouse of the National Research Centre, Dokki, Giza, Egypt during two successive winter seasons. Trichoderma inocula were adjusted to 3.6 × 10 8 propagules/ml and the bacterium inocula were adjusted at 10 7-10 9 colony-forming unit (CFU)/ml. All treatments were applied, before 1 week of sowing, at rate of 50 ml per pot in experiments I and II, while 100 ml per pot in experiment III. Results: Trichoderma spp. (T. harzianum, T. viride and T. vierns) as well as three rhizobacteria species (Pseudomonas fluorescens, Bacillus subtilis and Bacillus pumilus) enhanced the growth parameters in faba bean plants, i.e. shoot length, shoot fresh weight, shoot dry weight and leaf number in the first experiment when applied without O. crenata infection. In the second experiment, all bio-control could protect plants against O. crenata infection, where it had better juvenile number reduction, than glyphosate after 2 months of application. Both B. subtilis and B. pumilus had the highest reduction to juvenile fresh weight, while their effect was equal to herbicide for juvenile dry weight, respectively. The bio-control agents had high effects until the 4th month, but it was less than that of the herbicide. In experiment III, the bio-control agents could highly reduce the juvenile parameters after 2 months, as well as juvenile fresh weight and juvenile dry weight after 4 months, than the herbicide, respectively. The biocontrol agents were effective until 6 months, but less than the herbicide effect. All bio-control treatments highly increased the plant growth parameters, than the herbicide. Conclusion: The application of Trichoderma spp. as well as rhizobacteria species could play an important role in controlling broomrape in faba bean as a natural bioherbicide.
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