SURVEILLANCE AND MANAGEMENT OF WHITE RUST (Albugo candida) DISEASE OF RED AMARANTH FOR SEED PRODUCTION

Abstract

Experiments were conducted in Sher-e-Bangla Agricultural University, Dhaka-1207, to identify the causal organism of white rust disease of red amaranth (Amaranthus tricolor L.) and for its suitable management for seed production during rabi and kharif seasons of 2018-19. Eight treatments including chemicals, botanicals, bio-pesticides viz. Ridomil gold 68WG (Mencozeb + Metalaxyl @ 0.2%), Autostin 50 WP (Carbendazim @ 0.2%), Dithane M 45 (Mancozeb @ 0.2%), Goldton 50WP (Copper oxychloride @ 0.2%), Bordeaus mixture (CaO + CuSO @ 1%), G-Derma ( Trichoderma sp.) @ 0.3%, Garlic bulb extract 1:1 (w/v) (Allium sativum @ 2%), and Allamanda leaf extract 1:1 (w/v) (Alamanda cathertica @ 2%) were considered for the management of white rust disease of Red amaranth (Amaranthus tricolor L.). Four foliar sprays were done at seven days interval, started from 7 days after disease appeared. The field experiments were conducted by following RCBD design with three replications. Obligate fungi Albugo candida was successfully identified by microscopic study as the causal organism of white rust disease of red amaranth. Among the treatments, Ridomil gold 68WG gave best result against white rust disease of red amaranth. Moreover, Allamanda leaf extract showed better effect and Autostin 50WP had moderate effect against the disease compare to other treatments. Growth and seed yield of red amaranth varied significantly among the treatments. In Rabi season of 2018, After 4 4 spray, the lowest plant incidence was recorded in Ridomil gold (24%) followed by Allamanda leaf extract (31%). Similarly, the lowest disease severity was found in Ridomil gold (1.83%) followed by Allamanda leaf extract (2.43%). Ridomil Gold reduced 63.07% plant incidence, 62.78% leaf incidence and 84.31% disease severity at 61 DAS over control. However, Allamanda leaf extract reduced 52.30% plant incidence, 52.78% leaf incidence and 79.17% disease severity over control. Similar results also found in kharif season of 2019 where after 4 th spray, the lowest plant incidence was recorded in Ridomil Gold (18.66%) which was statistically identical with Allamanda leaf extract (22%) and the lowest disease severity was found in Ridomil gold (1.93%) followed by Allamanda leaf extract (2.23%). At 57 DAS, Ridomil Gold reduced plant incidence (69.73%), leaf incidence (65.71%) and disease severity (88.41%) over control. However, Allamanda leaf extract reduced plant incidence (64.32%), leaf incidence (60.48%) and disease severity (86.61%) over control. Considering the overall performance of the treatments, Ridomil Gold 68WG showed the best effect in controlling white rust disease. Thus, Ridomil Gold 68WG could be used for seed production of red amaranth. Moreover, Allamnada leaf extract could be used as an ecofriendly approach for white rust disease management to ensure safe crop production.

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