Achievements and problems in the weed control in grain sorghum (Sorghum Bicolor Moench.)

Gr. Delchev*, M. Georgiev

1Department of Plant Production, Faculty of Agriculture, Trakia University, 6000 Stara Zagora, Bulgaria (Manuscript received 28 November 2016; accepted for publication 21 March 2017)

Abstract. Chemical control has emerged as the most efficient method of weed control. Herbicides combinations and tank mixtures of herbicides with adjuvants, fertilizers, growth regulators, fungicides, insecticides are more effective than when applied alone on sorghum crops. Their combined use often leads to high synergistic effect on yield. The use of herbicide antidotes for the treatment of seeds in sorghum is a safe way to overcome its high sensitivity to many herbicides. Data regarding herbicide for chemical control of annual graminaceous weeds in sorghum crops are quite scarce even worldwide. Problem is the persistence of some herbicides used in the predecessors on succeeding crops, which is directly related to the weather conditions during their degradation. Most of the information on sorghum relates to the conventional technology for weed control. There is no information about the new Concep technology in grain sorghum. A serious problem is also the volunteers of the Clearfield and Express sun sunflower. They have resistance to herbicides different from that of conventional sunflower hybrids. There is no information yet in scientific literature on control of these volunteers.

Еvaluation of perspective sorghum breeding forms in their reaction to some diseases in field conditions

M. Georgieva – Andreeva, K. Tanova, S. Raykov
Abstract. During the period 2009-2010 a phytosanitary evaluation of 17 breeds of sorghum from breeding experiment of Agricultural Institute – Shumen, grown at different density, has taken place. The development of bacterial diseases – bacterial leaf streak and bacterial leaf stripe, fungal leaf blight and non-infectious chlorosis have been reported. Regardless of plant density, the fungal leaf blight develops strongest (from 16% to 34%), with a tendency of increasing in dense sowing. Regarding bacterial leaf streak, the selection materials have shown mediocre resistance with maximum intensity 38% for thin sowing and 36% for dense sowing. The non-infectious chlorosis occurs depending on origin with disease development from 0 to 48%.