ESTIMATION OF THE INFLUENCE OF HERBICIDES AND PGR OF ZEASTIMULIN ON WEEDING AND YIELD OF CORN
Authors: Okrushko Svitlana 
Published: December 2020

The system of protection of cultivated plants from the negative effects of weeds is an important element in the technology of growing corn. The application of the chemical method allows to effectively and for a long time get rid of the agrophytocenosis of weeds. Weeds significantly impair the growing conditions of cultivated plants and prevent them from realizing the opportunities inherent in the genetic potential of the crop. Maize has a low level of competitiveness against weeds.
The aim of the article was: to substantiate the application of insurance herbicides Laudis and Stellar for weed control and their joint use with PGR Zeastimulin to increase corn grain yield.
Medium-early maize hybrid PR39T45 FAO 250 was grown. It is characterized by good cold resistance and drought resistance. The size of the registered area of plots is 20 m2, repeated three times with a systematic arrangement of options. The predecessor of corn was potatoes. Herbicides and PGR Zeastimulin were applied in the phase of 3-4 leaves in corn.
After treatment of crops with Laudis herbicide, weed accounting showed a decrease in the number of weeds by 89,7% compared to control. At the time of maize harvesting, Laudis reduced the level of weeding by 94,7% in quantity and by 655 g/m2 of mass compared to the natural background without the introduction of herbicides and growth regulator. The application of Stellar herbicide allowed better control of the number and weight of weeds, due to its effect on perennials. The decrease in weed numbers was 93,5% during the first survey, 97,0% during the second and 97,9% during the third.
In the experimental variants, where herbicides were applied together with PGR Zeastimulin, no decrease in the number of weeds was observed, and only a slight decrease in the above-ground air-dry mass of weed plants was observed.
The height of maize in the phase of 7-8 leaves on the herbicidal background was higher by 17,3% (var. 2) and 19,8% (var. 4) than on the control variant. Treatment of crops with Zeastimulin provided an increase of this indicator by another 2 cm. Due to the positive effect of the growth regulator, the length of maize cobs increased from 17,9 cm to 18,6 cm in the version of weed control by Laudis (0,5 kg/ha), and from 18,3 cm to 19,4 cm in the variant of herbicide application. Stellar (1,1 l/ha). In maize, the diameter of the cobs increased due to a decrease in the negative effects of weeds and under the influence of PGR Zeastimulin.
Weed control in maize agrophytocenoses with Laudis herbicide (0,5 kg/ha) provided better conditions for cultivated plants, which gave a grain yield increase of 2,9 t/ha, and Stellar herbicide (1,1 l/ha) - for 3,1 t/ha. The application of Zeastimulin to maize crops increased the yield by 9,5% in the Laudis herbicide variant (0,5 kg/ha) and by 9,2% in the Stellar herbicide variant (1,1 l/ha).
Further studies are planned to continue the assessment in maize agrophytocenoses of the effects of Laudis and Stellar herbicides on weed and PGR Zeastimulin under different weather conditions during the growing season.
Key words: corn, weeds, herbicides, plant growth regulator, yield.