MANAGEMENT OF SORGHUM COVERED KERNEL SMUT [Sphacelotheca sorghi (Link) Clint] THROUGH HOST RESISTANCE, BOTANICALS AND COW URINE AT SHERARO, NORTHWESTERN TIGRAY, ETHIOPIA

Abstract

Sorghum covered kernel smut (Sphacelotheca sorghi) is a predominate factor in reducing sorghum yield in Sheraro, northeastern Tigray, Ethiopia. Farmers in this area commonly use all available varieties regardless of their resistance or susceptibility to covered kernel smut and without any seed treatment. In view of this, two field experiments were conducted at Sheraro Experimental Station of Shire-Maitsebri Agricultural Research Center during 2016 main cropping season, with the objectives to: (1) evaluate the reaction of sorghum genotypes to Sphacelotheca sorghi; and (2) investigate the efficacies of some botanicals against covered kernel smut. The first experiment consisted of ten sorghum varieties (Birhan, Dagnew, Dekeba, Gubye, Melkam, Morowey, Tewzale, Tsa’eda chimrey, Wodi-Aker and Zer-Addis), which were inoculated artificially with Sphacelotheca sorghi spore at the rate of 2 gram spore per 1 kg seed. The second experiment also consisted of ten treatments: six botanicals (Eucalyptus, Garlic, Ginger, Feto, Neem, Papaya), one cow urine, one water treatment, all at the rate of 20 ml/200 g seed for 30 minute, and one fungicide (Apron star) at the rate of 10 g/4 kg seed, and one untreated or control check. The treatments were arranged in a randomized complete block design (RCBD) with three replications in each experiment. During the experimental activity, phenological data, grain yield (kg)/plot, 1000 grains weight (g), yield loss (%), yield loss reduction (%), covered kernel smut incidence and severity were collected. The analysis of variance showed that there was significant (p ≤ 0.05) difference among the tested sorghum varieties in their reaction to the disease. The lowest disease incidence (3.37%) was recorded on variety Birhan. The lowest disease severity (3.70%) was recorded on variety Dekeba. While the highest incidence (55.56%) and severity of 80.49% were recorded on variety Melkam. The highest yield (4291 kg ha-1) was recorded from the variety Dekeba, while the lowest yield (364 kg ha-1) was recorded on the variety Zer-Addis. The varieties Birhan, Dagnaw, Dekeba and Tsa’eda chimrey were found resistant to the disease. There was also significant (p ≤ 0.05) difference among seed treatments to manage the disease. Apron star, cow urine, neem and papaya leaf crude extracts had effectively suppressed the disease as compared to the other treatments, while the control, water treatment and feto were not effective. There was no covered kernel smut infection on the Apron star treated plots, while the highest incidence (30.30%) and severity of 69.14% were recorded on the control plots. The highest yield (3902kg ha-1) was recorded on Apron star treated plots, while the lowest yield (2005 kg ha-1) was recorded on the control plots. The highest net benefit (19109.90 birr ha-1) was obtained from the Apron star. While the highest marginal rate of return (87.13 birr for each one birr investing) was obtained from cow urine. Thus, as compared with other treatments, Apron star, Cow urine, neem and papaya leaf crude extracts were effective and economically feasible. The presence of resistant varieties and effective management methods seems to be promising. Therefore, farmers can use the resistant varieties and the effective management methods or a combination of them. Further investigation is needed on detail of the resistant gene of the resistant varieties and determination of the botanicals concentration.