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.

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.

Safflower diseased plants, showing typical symptoms of damping-off, root and stem rot, wilt and/or rust diseases, were collected from Behera and Giza governorates for isolation the associated microorganisms. Isolated fungi were carefully purified and identified as well as their frequencies were calculated. Fusarium oxysporum, Pythium sp., Rhizoctonia solani, Sclerotinia sclerotiorum were only isolated from Giza. Meanwhile, Fusarium solani and Phytophthora sp. were isolated only from Behera. Macrophomina phaseolina was widespread and isolated from the two governorates with high frequency. Puccinia carthami, the causal of safflower rust was encountered elsewhere. Pathogenicity tests were performed to throw light on the relative importance of the tested fungi to cause the aforementioned diseases. F. oxysporum caused damping-off and vascular wilt symptoms, P. carthami showed also damping-off and the seedling rust phase. The other fungi were able to colonize safflower roots and cause damping-off and root rot symptoms. The results showed that the amount of the disease was affected by the tested fungi and the sowing date(s). In most cases, sowing at November 2nd recorded the intermediate amounts of infection and the best seed germination. One biocide, viz. Biocontrol; one resistance inducer, viz. Biomycin in addition to three fungicides, viz. Moncut, Vitavax-T and Rizolex-T were tested in vivo for their ability to control safflower damping-off and root rot caused by the tested fungi, i.e., M. phaseolina, R. solani and F. solani. The obtained data revealed that none of the evaluated formulations was able to prevent entirely infection with any of the tested fungi. The best control of M. phaseolina was given by seed treatment with Biomycin, Vitavax-T and Rizolex-T. R solani was controlled by Biomycin and Rizolex-T, Meanwhile, Vitavax-T, Biomycin and Rizolex-T were the best treatments against F. solani.