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: 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 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.
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