CHEMICAL AND NONCHEMICAL CONTROL OF WEEDS IN THE CULTIVATION OF LEMON BALM FOR SEEDS

Abstract

The fight against weeds in the organic cultivation of herbal plants, both raw and for seeds, is a big challenge for growers. The paper compares the chemical (bentazon, 960 g·ha–1 and fluazifop-P-butyl, 150 g·ha–1) and nonchemical (scattering mustard seed meal in two doses 1.5 and 3.0 t·ha–1) control of weeds in the cultivation of lemon balm for seeds. Additionally, the influence of these factors on the yield of fresh herb and seeds of lemon balm and the sowing value of seeds was evaluated. The best method to control weed infestation was to use mustard seed meal in an amount of 3.0 t∙ha–1. Scattering of mustard seed meal in that dose reduced the number and weight of weeds on average from two years of research by 52.1 and 60.2% in relation to unweeded control. Slightly less effective methods were successively: bentazon and application of mustard seed meal in quantity of 1.5 t·ha–1. The largest yield of fresh lemon balm herb was collected from plots where mustard seed meal was used in an amount of 3.0 t∙ha–1. Seeds harvested from plots, on which mustard seed meal was used in a larger quantity was characterized by the lowest sowing value determined by the lowest energy and capacity of germination and the highest share of nongerminated seeds. Lowering the amount of used mustard seed meal to 1,5 t·ha–1 significantly improved their sowing value. Although this method was less effective in counteracting weeds than using larger dose, it provided comparable effects of reducing the number and weight of weeds in relation to chemical protection.

Keywords

• lemon balm seed
• mustard seed meal
• herbicide
• weed control
• germination