Six common fungicides, Dithane M45, Kocide 2000, Ridomil Gold Plus, Score, Equation Pro and Kemazed were tested for controlling the draceana leaf spot fungi. All the tested fungicides significantly decreased the in vitro growth of the tested dracaena leaf spot fungi. Percentage of inhibition on colony diameter ranged between 49.64% with Dithane M45 to 82.18% with Score which was followed by Kemazed (69.15%). However, inhibition of spore germination was the highest (72.8%) by Dithane M45, while inhibition of germ tube reached 89.91% with Kemazed. Meanwhile, in the in vivo tests, treatment with Kemazed decreased disease incidence of leaf spots on potted plants to 16.67% compared to 100% for the untreated inoculated control. On the other hand, the bacterial and fungal biocontrol agents tested proved to be effective against the dracaena leaf spot fungi. The in vitro assays conducted showed that the bacterial biocontrol agents namely, Stenotrophomonas maltophilia, Pseudomonas ultimum, P. fluorescens, P. putida, P. aeruginosa, Bacillus subtilis, B. megaterium, significantly decreased colony growth diameter (76.84-45.69%) of dracaena leaf spot fungi as well as spore germination (48.80-23.20%) and length of germ tube (88.77-65.65%) of the germinated spores compared to untreated control. Treatment with S. maltophilia showed the most consistent highest inhibition effect, followed by P. ultimum, B. subtilis, and B. megaterium, respectively. The in vivo tests of the most effective bacterial bioagents supported the in vitro results. Treatment with S. maltophilia showed the highest effect as it decreased disease incidence and disease index to 29.33% and 7.6%, respectively in comparison with 100% and 83.6% for the untreated inoculated control in the potted dracaena plants (cv. Bicolor). Meanwhile, the in vitro tests of the three Trichoderma spp., i.e. T. harzianum, T. hamatum and T. album showed significant inhibition effect on colony growth diameter of the tested dracaena leaf spot fungi in which T. harzianum showed the highest inhibition effect (75.02%), while T. album was most effective to inhibit spore germination (48%) and germ tube (90.21%) of the germinated spores. The in vivo tests of the fungal biocontrol agents supported the in vitro results. T. album (Bio-Zeid) showed the highest effect and decreased disease incidence and disease index on potted plants to 19.99% and 4.39%, respectively compared with 100% and 92.8% for the untreated inoculated control.

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Isolation trials from infected sage seedlings and plants, growing in Ismailia, North Sinai and Qalubyia governorates, showing symptoms of damping-off and root rot diseases yielded Fusarium oxysporum, F. solani, Macrophomina phaseolina, Pythium ultimum and Rhizoctonia solani. However, R. solani recorded the highest frequency in isolation (52.6%), followed by Fusarium solani (24.6%), while M. phaseolina was the least (3.5%). These fungi were found to be pathogenic to sage seedlings. Rhizoctonia solani followed by F. solani were the most virulent fungi, causing the highest damping-off incidence. Three silicon (si) sources, i.e. calcium silicate, potassium silicate and sodium silicate with four concentrations (25, 50, 100 and 200 ppm) significantly inhibited the in vitro growths of R. solani in different degrees. Potassium silicate was more effective than the other silicon sources tested, and completely inhibited mycelial growth at 200 ppm. Soaking seeds (30 min.) and /or dipping treatment for seedlings (30 min.) in each of these silicon sources (400 ppm) or the fungicide Vitavax /Thiram (3 g/l water) gave sufficient control to R. solani diseases, i.e. damping-off in greenhouse and nursery as well as root rot in the field .Also, they recorded significant increases in growth parameters of seedlings (height & root length) and mature plants (height & no. of branches /plant). Potassium silicate, however, was significantly the most effective treatment among other silicon sources. Using calcium silicate and potassium silicate as dipping treatment for seedlings, gave significant increases in yields of fresh herb and essential oil content. Vitavax /Thiram treatment in the nursery and field experiments was more effective than silicon treatments, except with potassium silicate in the field, which increased fresh herb weight per plant and essential oil content than the fungicide.

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