Biological control of root rot, wilt diseases complex in offshoot date palm and improvement of growth parameters in New Valley Governorate, Egypt

Root Rot wilt disease complex were detected in different date palm offshoots in nurseries and new orchards in New Valley Governorate. Pathogenicity tests showed that Fusarium oxysporum, F. solani and F. moniliforme were pathogenic to date palm offshoots (. Saidy) but they differed in their pathogenic capabilities . The effect of Bacillus subtilis (BSM1), B. megaterium (BMM5), B. cereus (BCM8), Trichoderma viride (TVM2), T. harzianum (THM4) as bioagents against root rot/ wilt disease complex of date palm offshoots under natural infection in nursery cultivated in two location (El-Kharga and El-Dakhla) were studied. The obtained data indicated that all treatments reduced significantly disease severity compared with untreated offshoots (control) in both locations. Bacillus megaterium and T. viride recorded the highest protection against disease severity, while B. cereus and T. harzianum gave the lowest ones in this respect. Under laboratory conditions, all bio-agents inhibited growth of the pathogenic fungi with different percentages. Bacillus megaterium and B. subtilis recorded the highest percentages of growth inhibition, while T. harzianum gave the lowest one. On the other hand, treatments significantly improved growth parameters of date palm offshoots viz . offshoot height, number of leaves, leaflet number leaf -1 , nick leaf thickness in both locations. Bacillus megaterium and T. viride recorded the highest all growth parameters whether in El-Kharga and El-Dakhla, while B. cereus and T. harzianum gave the lowest one.further more Bio-control agents significantly increased chlorophyll a, b and carotenoids in leaf in both locations. Bacillus megaterium and T. viride recoded the highest contents of chlorophyll a, b and carotenoids. Also, all treatments increased nitrogen (N), phosphorus (P), potassium (K), sodium (Na), calcium (Ca), magnesium (Mg) Chlorophyll a, b and carotenoid contents in leaves compared with control in both locations. Bacillus megaterium recorded the highest levels of N, P, Ca contents in offshoot leaves, while B. cereus increased K, Na contents and Mg in both locations. ,and