Journal Article

Incidence of coverd smut disease on grain sorghum and re-evaluation of the efficacy of Thiram and Raxil in Controlling the disease in Gezira and Gadarif Sudan

Ahmed, Aziza I, Zaroug, Mohammed S, Abbasher, Abbasher A

2013

Overview

Sorghum is the main staple food crop for most of Sudanese people. It is attacked by many fungal diseases including smuts of which covered smut is the most important. In Sudan, Thiram 25% and Raxil 2% were recommended against the disease for more than two decades. Therefore the main objectives of this study were: To determine the incidence of covered smut disease on some sorghum varieties in rainfed and irrigated areas; and to ensure the efficacy of these two fungicides in controlling the disease. The surveys conducted in Gadarif State revealed that sorghum variety \"Arfa-Gadamak\" is highly resistant to covered smut disease with 0.0% incidence disease. Sorghum varieties \"Feterita and Mugud\" were tolerant (4.5% and 7.7%, respectively), while \"Zahrat Elgadamblia\", \"Tabat and Wad-Akar\" were susceptible (15.7%, 12.0% and 11.7%, respectively). The most susceptible varieties encountered were \"Corokolo\" and \"Wad-Ahmed\" (27.2% and 26.5%, respectively). In Rahad region, Wad-Ahmed was susceptible to the disease (10.3% - 20.0%), whereas, \"Tabat\" was protected from the disease when it was treated (0.5%) compared to (10.9%) when untreated. Where treated seeds used routinely in irrigated areas (Gezira Scheme), the disease incidence was zero. In laboratory experiments, germination of covered smut spores was inhibited profoundly by treating with Thiram at 4 and 8 ppm (85% and 100%, respectively). However, Raxil gave 65% germination inhibition at a higher rate of 900 ppm. In field experiments, treatments of Raxil at both rates tested (recommended (3 g kg־¹ seeds) and lower than recommended rate (2.75 g kg־¹ seeds)), gave 100% and 99.3% disease reduction. Whereas Thiram at both rates gave 97.5% and 94.1% disease reduction, respectively. Analysis of variance showed significant differences between the treatments and the control in weight of sorghum seeds per head. Thiram increased the seed weight/head by 213.0% and 211.8% at both rates tested, whereas Raxil at both rates increased sorghum seeds weight per head by 270.0% and 249.0%, respectively compared to the untreated control. The findings reveal that Raxil and Thiram are still effective in controlling covered smut disease and the variety \"Arfa-Gadamak\" was the most resistant among the tested sorghums.

• Publisher: جامعة سنار
• Subject: الإنتاج الزراعي / التقاوي الزراعية / المبيدات الفطرية / محصول الذرة