All sugar beet (Beta vulgaris) cultivars tested were susceptible to different extents against the infection with Uromyces betae Tul Kick. They were categorized as less susceptible “LS” cvs. (Farida, Gloria, Top and Toro), moderate susceptible “MS” cvs. (Negma, Gazail and Pleno) and the high susceptible “HS” cvs. (Raspoly, Lola and Kawmeia). The LS cvs. produced higher dry matter, root length, root diameter and fresh and dry weights of sugar beet roots followed by MS and HS cvs. The rust disease severity (DS) on sugar beet strictly correlated with sowing time. DS was higher on the early sowing (15th August) than the late sowings (15th September, 15th October and 15th November). Regardless sowing date, the disease was very low at 15th February then increased gradually until reached its maximum at 15th April. The DS recorded minimize levels on sowings performed at 15th October and/or 15th November.
The DS was minimized and yield was maximized by using the less susceptible “LS” cvs Farida combined with spraying plants with the recommended dose of the fungicide Caramba or garlic extract (0.3%) just at the first appearance of rust symptoms. Also, spraying plants with IAA (300ppm) after 70 days from sowing, using N and P fertilizers together at rate of 60 kg N and 30 kg P2O5 per feddan, respectively and sowing sugar beet seeds at the proper distance between both rows (60cm) and plants (30cm) each alone gave satisfactory results.
In fact, using the N fertilizer alone at rate of 100 kg (N)/feddan significantly increased DS and root fresh weight while decreased total soluble solids % (TSS) % and sucrose content in roots increased comparing with the other N levels including control receiving no N fertilization. However, the P fertilizer used alone at 15 and 30 kg (P2O5)/feddan gave the best disease control in both seasons comparing with the control receiving no P fertilization.
Intercropping sugar beet with broad bean (Vicia fabae) significantly increased both DS and fresh weight of sugar beet roots meanwhile decreased total soluble solids (TSS %) and sucrose content in roots in comparison with the control (sugar beet alone). Intercropping the two crops at rate 1:3 and 3:1 resulted in the highest decreases in both later criteria, respectively.
Key words: Sugar beet, Rust, Uromyces betae, Cultivars, Sowing date, Fungicides, Garlic, IAA, Intercropping,
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