All sugar beet (Beta vulgaris) cultivars tested were susceptible to different extents against the infection with Uromyces betae. 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 Kawemira). The LS cvs. produced higher dry matter, root length, root diameter and fresh and dry weights of sugar beet roots then the 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) that 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 while yield particularly root fresh weight and sucrose percentage in roots was maximized by using the less susceptible “LS” cvs Farida combined with spraying plants with the recommended dose of the fungicide Caramba just at the first appearance of rust disease symptoms or garlic extract (0.3%) just at the first appearance of rust disease symptoms. Also, spraying plants with IAA (300 ppm) after 70 days from sowing, using the 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. |
