Abstract
In the current work an attempt was made to find out the most suitable bioagents that have the ability toprotect Date palm cv. Zaghloul (Phoenix dactylfera L.) from some soilborne fungal diseases. Several soilbornefungi were isolated from root rots of date palm trees located in the farms of El-Beheira Governorate, Egypt,including; Fusarium solani, F. oxysporum, Rhizoctonia solani and Macrophomina phaseolina, and theirpathogenicity were confirmed on date palm seedlings in the greenhouse. These fungi cause economic losses indate palm yield and a wide range of other cultivated plants. Many different antagonistic isolates (bioagents) i.e.Trichoderma album, T. harzianum, T. viride and T. hamatum were isolated from the rhizosphere soil of healthydate palm trees. For comparison of results, bio-commercial preparations mainly “Bio-zeid (T. album 10×106 cfu/ml)” and “Plant guard (T. harzianum 30×106 cfu/ ml)” were also used to detect their antagonistic potential againstthe mycopathogens of date palm. In vitro antifungal efficacy of the bioagents was evaluated against all thepathogens, where T. harzianum was the most effective as it caused 87.10, 81.55, 77.60 and 68.55% reduction inthe radial growth of F. solani, F. oxysporum, R. solani and M. phaseolina, respectively. In vivo assays under fieldconditions, all tested biotic treatments significantly reduced severity of root rot diseases caused by the concernedpathogens. Moreover, they increased the percentages of survived date palm plants in infested soils during bothsuccessive growing seasons of 2016 and 2017, where T. harzianum was the most effective bioagent as it showedan increase in date palm survival of about 82.35 and 86.67% at both seasons, respectively. In addition, allbioagents enhanced the growth parameters of date palm, i.e. plant height (cm), number of leaves/ plant andnumber of leaflets/ leaf, compared with the control treatment. Thus, these effective bioagents could be used asbiofungicides to control the root rot diseases of date palm in the field; accordingly, we could displace the use ofnon-ecofriendly and health hazards synthetic fungicides.
Highlights
Date palm is one of the most valuable domesticated fruit trees because of its significance in human societies, health benefits, and the range of subsistence products from its fruits and other parts of the large palm (Johnson et al, 2015)
According to Maitlo et al, (2013); Ziedan et al, (2013), M. phaseolina, Phoma sp., F. oxysporum, F. solani, F. moniliforme, F. equiseti, F. semitectum, R. solani and Thielaviopsis paradoxa have been reported in different countries to cause root rot diseases in young and adult date palm trees
The highest % of decrease in radial growth of F. solani, F. oxysporum, M. phaseolina and R. solani on Potato dextrose agar medium (PDA) was recorded by T. harzianum; 87.10, 81.55, 68.55, and 77.6 %, respectively
Summary
Date palm is one of the most valuable domesticated fruit trees because of its significance in human societies, health benefits, and the range of subsistence products from its fruits and other parts of the large palm (Johnson et al, 2015). Date palm trees and offshoots are attacked by several soilborne pathogenic fungi causing severe losses and worldwide deterioration of these trees (Baraka et al, 2011; Arafat et al, 2012). According to Maitlo et al, (2013); Ziedan et al, (2013), M. phaseolina, Phoma sp., F. oxysporum, F. solani, F. moniliforme, F. equiseti, F. semitectum, R. solani and Thielaviopsis paradoxa have been reported in different countries to cause root rot diseases in young and adult date palm trees. Use of synthetic chemicals to control soilborne pathogens caused several negative effects on the plants such as: i) development of pathogen resistance, ii) harmful effects on humans, iii) bad impact on beneficial organisms, and iv) environmental pollution. Soilborne pathogens still need to be controlled in order to ensure healthy plant growth and productivity in sustainable agriculture. Soilborne pathogens still need to be controlled in order to ensure healthy plant growth and productivity in sustainable agriculture. Kaewchai and Soytong, (2010) stated that biological control of plant pathogens by using microorganisms has been considered more natural and environmentally acceptable alternative to the use of chemicals
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