fficacy of Trichoderma harzianum, T. hamatum, T. viride, and Chaetomium sp. as foliar spray against purple blotch of onion (Allium cepa) was evaluated. The fungicides Blight stop (bio) and Luna Experience SC (chemical) at certain doses were used as a check. All treatments recorded the highest efficacy percentage for reducing severity of purple blotch compared to control, where it gave 88.85 and 69.76% after four and seven sprays respectively. Trichoderma harzianum was the superior treatment more than Blight stop as a check. On the other hand, Chaetomium sp. showed the lowest effect. Also, all treatments increased onion yield, plant height, number of leaves and fresh weight/plant, total carbohydrates, total nitrogen and total soluble solids as compared to non-treated plants.

Trichoderma bioagents, i.e., Trichoderma hamatum, T. harzianum and T. viride were isolated from the rhizospheric soil of the healthy pea plants. They were used in combination with the resistance inducing chemicals, Bion and compost for studying their impact on managing pea damping-off and root-rot diseases caused by Macrophomina phaseolina (Tassi) Goid (the pycnidial stage of S. bataticola Taub.) and Rhizoctonia solani Kuhn (the anamorph stage of Thanatephorus cucumeris (Frank) Donk.). The inhibitory effect of the three bioagents as well as compost and resistance inducing chemicals (RICs), Bion, chitosan and salicylic acid was investigated to determine their inhibitory effect against each of M. phaseolina and R. solani in vitro and in vivo. Data demonstrated significant inhibition to the linear growth of both M. phaseolina and R. solani due to using the tested bioagents, compost and the RICs compared to control treatment. This reduction was gradually increased by increasing the incorporated concentration to PDA medium. In addition, RICs were less efficient in this regard than Trichoderma spp. and compost. The obtained data showed that soaking pea seeds in 50 mM Bion for six hours then pelleting with the inoculum of Trichoderma spp. and sown in soil amended with compost resulted in significant reduction to the incidence of damping-off and root-rot severity caused by each of the tested fungi with significant increase to the produced green pods yield, phenolic compounds, % nitrogen and % protein content compared with control treatment. This research provides alternative and safe compounds to management damping-off and root-rot diseases and consequently reduces environmental pollution as well as improving plant growth and seed yield of pea plants.

Potato tubers (Solanum tuberosum L.) is considered as one of the most essential vegetable crops worldwide, The most communal viruses attacking potato all over the world are potato leaf roll virus (PLRV), potato virus Y (PVY) and potato virus X (PVX). Our current study aimed to eradicate potato viruses PVY, PVX and PLRV through shoot tip meristem via tissue culture combined with thermotherapy and chemotherapy. Sprouts of potato cultivars ex. Spunta, Selana, Diamond and Cara were used as biological material for investigating their performance using shoot tip meristem. During multiplication stage, the resulted plantlets were subjected to ribavirin (50 mg/L), while the untreated plantlets served as control. In general, the control treatment (0.0 mg/L) provided the best results, while ribavirin (50 mg/L) gave reverse effect on the estimated vegetative parameters (shoot length (cm), number of leaves and number of shoots). Detection of the presence and absence of PVY, PVX and PLRV using DAS-ELISA technique indicated that, thermotherapy and chemotherapy treatments for shoot tip meristem culturing minimized the occurrence percentage of PVX, PVY and PLRV in all tested potato cultivars compared to positive control. The results of RT-PCR revealed that, the amplicons of amplified fragments and primed by PVX-, PVY-and PLRV-specific sense and antisense primers were appeared only in the positive control (lane 1 at ~750, 801 and 548 bp), respectively, while, no amplicons appeared in the rested treatments. In conclusion, shoot tip meristem followed by thermotherapy and chemotherapy treatments enhanced the growth of potato plantlets and suppressed potato viruses.

The rapid spread of late wilt disease among maize cultivations has resulted in serious economic losses in many countries. Harpophora maydis is the main cause of this destructive vascular disease. Here we evaluate the fungicidal activity of chitosan and nano-chitosan against six aggressive isolates of H. maydis collected from different Egyptian governorates. Pathogenicity tests for these isolates show that the highest disease severity was found for the Giza isolate. The isolates were tested for their response to the fungicide Permis, chitosan, and nano-chitosan treatments in vitro and in vivo. Nano-chitosan treatments fully inhibited the radial growth of H. maydis isolates at concentrations of 5 and 10 mM, compared to the full control growth (9 cm in diameter). On the other hand, in vitro, in vivo, and molecular diagnosis results showed high antifungal activity of chitosan and nano-chitosan compared to the Permis fungicide. Chitosan at the nano and normal scales proved a potent ability to enhance plant resistance in response to H. maydis. Disease severity (DS%) was extremely decreased among the tested cultivars by using nano-chitosan; the highest percentage was obtained on Giza 178 cv, where the DS% was 21.7% compared to 42.3% for the control. Meanwhile, the lowest percentage was obtained on Giza 180 cv with DS% 31.2 and the control with 41.3%. The plants treated with nano-chitosan showed the highest growth parameters for all cultivars. Such natural treatments could reduce the impact on the environment as they are non-pollutant natural compounds, protect the plants by reducing fungal activity, and induce plant resistance.

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The antifungal activity of 5 fungicides, 3 commercial plant oils and 2 bio-agents were tested in vitro and in vivo against Drechslera graminea (Rabenh. ex. Schlech) Shoemaker (telemorph: Pyrenophora graminea Ito and Kuribayashi, the causal organism of leaf stripe disease on barley (Hordeum vulgare L.). Among fungicides tested, Opus at 1µl/L and Switch at 1mg/L concentration and Bellis at 2mg/L showed 100% mycelia growth inhibition of D. graminea. The results of commercial plant oils tested in vitro revealed that the coriander showed highest inhibition of mycelial growth at 15%. The dual culture technique revealed that fungal bio-agent (Trichoderma harzianum) was better than bacterial bio-agent (Bacillus subtilis) in inhibiting the growth of D. graminea. Greenhouse and field experiments were carried out to evaluate the efficacy of all tested treatments on disease incidence, yield components, enzymes activity and phenolic compounds. The tested fungicides, plant oils and bioagents applied as seed dressing showed an effectiveness to large extent for controlling leaf stripe disease expressed as a reduction in disease incidence and increased yield components in comparing with the untreated plants. As well as, the all treatments caused an increment in activities of peroxidaxe, polyphenol oxidase and chitinase enzymes and increasing in phenolic compounds compared to control treatment. Although the five tested fungicides were more effective in reducing the linear growth of the pathogen (D. graminea) in vitro and suppressing the disease in vivo than the plant oils and bio-agents, they are considered environmentally safe and can be used as alternative substances in disease management.

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