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The efficacy of eight plant extracts (garlic, clove, garden quinine, Brazilian pepper, anthi mandhaari, black cumin, white cedar and neem) in controlling leaf rust disease of wheat was investigated in vitro and in vivo. In vitro, all treatments inhibited spore germination by more than 93%. Neem extract recorded 98.99% inhibition of spore germination with no significant difference from the fungicide Sumi-8 (100%). Under greenhouse conditions, seed soaking application in neem extract (at concentration of 2 ml/L) resulted in 36.82% reduction in the number of pustules/leaf compared with the untreated control. Foliar spraying of plant extracts on wheat seedlings decreased the number of pustules/leaf. Foliar spraying of plant extracts four days after inoculation led to the highest resistance response of wheat plants against leaf rust pathogen. Spray application of wheat seedlings with neem, clove and garden quinine extracts, four days after inoculation with leaf rust pathogen completely prevented rust development (100% disease control) and was comparable with the fungicide Sumi-8. Foliar spray application of wheat plants at mature stage with all plant extracts has significantly reduced the leaf rust infection (average coefficient of infection, ACI) compared with the untreated control and neem was the most effective treatment. This was reflected on grain yield components, whereas the 1000-kernel weight and the test weight were improved whether under one-or two-spray applications, with two-spray application being more effective in this regard. Thus, it could be concluded that plant extracts may be useful to control leaf rust disease in Egypt as a safe alternative option to chemical fungicides.

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Five plant extracts, i.e., henna, Lawsonia inermis; acalypha, Acalypha wilkesiana; chinaberry, Melia azedarach; pomegranate, Punica granatum; and lantana, Lantana camara, were tested as inducers to protect wheat against leaf rust infection caused by Puccinia triticina Eriks. The plant extracts were applied pre-infection on susceptible wheat cultivar "Gemmiza-7" under field conditions during two growing seasons (2016/2017 and 2017/2018). All the tested plant extracts were found to be effective against the leaf rust infection. They significantly reduced the coefficient of infection (ACI) to be ranging 7.50 to 20.00, compared to the non-treated control (ACI = 75.00). Lantana extract was the most effective one (efficiency = 88.88%), which was very close to the fungicide "diniconazole" (efficiency = 89.92%). Henna extract ranked second (80.00%), followed by chinaberry (76.00%), acalypha (72.00%), and pomegranate (68.00%). However, wheat yield components were significantly increased by all the tested treatments, especially lantana extract and the fungicide. Similarly, biochemical analyses revealed a significant increase in the plant contents of chlorophyll a and b, total phenolics, and oxidative enzymes activities (POX and PPO) at all the tested treatments. Results indicated that the tested plant extracts could induce wheat resistance to leaf rust.

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