Broomrape control and phytotoxicity of imidazolinone herbicide in IMI sunflower genotypes and influence on seed yield

Abstract

Imidazolinone herbicides are one of the most feasible methods for broomrape control, especially in intensive agriculture. In this, trial we evaluated the resistance of seven different sunflower genotypes of F1 and F2 generation and five commercial hybrids to imidazolinone herbicides and also their effect on broomrape control. The experiment was conducted in field conditions in Svetozar Miletić locality (North Serbia), a naturally highly infested plot. Race E was determined in this region ten years ago for the first time in Serbia. The analysis of the population, which was done by a set of differential lines, showed that broomrape in that locality still belong to race E of the parasite. Sunflower was treated with imidazolinone herbicide (Pulsar-40) with 1.2 l/ha (at a concentration rate 0.25%) at three-leaf stage. Controls were the same non-treated genotypes and commercial hybrid NS-H111 which is susceptible to broomrape and IMI herbicides. Evaluation of herbicide effect was done 14 days after application when sunflower plants were at the beginning of the budding stage. The reaction of sunflower genotypes to applied herbicide was evaluated according to the reaction of plants. The phytotoxicity of herbicide was expressed by the following symptoms: total plant deterioration, severe chlorosis and slightly yellowing. Intensity of phytotoxicity varied depending on the observed genotype.Percentage of dead plants ranged from 13-68%, plants with severe chlorosis and curly leaves ranged from 0-35% and symptoms of slightly chlorosis were observed on up to 20% percentages of evaluated plants. Plants which expressed susceptibility to applied herbicide such as chlorosis and yellowing totally recovered during the time but the phytotoxicity had influence on the yield and quality of seeds. Seed yield of plants with symptoms has been decreased from 43,7 to 90,1% related to control. Although we obtained good results in broomrape control in sunflower by one application of IMI-herbicide, we recommend two split applications of IMI herbicides.