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Spitzer T., Míša P., Bílovský J., Kazda J. (2015): Management of maize stand height using growth regulators. Plant Protect Sci., 51: 223-230.Effect in reducing maize plant height using growth regulators ethephon, chlormequat chloride (CCC), CCC + ethephon, and mepiquat chloride + prohexadione-Ca was studied in field experiments during 2010 and 2011. It was found that maize plant height could be reduced by as much as 125 cm (49% of control) using a double application of ethephon (576 g a.i./ha) at growth stages BBCH 18-19 and BBCH 34-36. The other growth regulators displayed weak or no influence. An optimum level of shortening was achieved using ethephon (576 g a.i./ha) at BBCH 34-36 (reducing plant height by 40-90 cm), but it is necessary to count upon yield loss of 0.5-0.6 t/ha.

During 2010–2012, we monitored flight activity of male and female stem weevils (Ceutorhynchus napi, C. pallidactylus) using yellow water traps, the effectiveness of various application dates for the insecticide thiacloprid (72 g active ingredient/ha), and the influence on yield. The first occurrence of beetles in traps was recorded after soil temperature at 5 cm reached 8°C in all experimental years. In all years, males of C. pallidactylus dominated in the traps and the times of beetles’ first occurrence. The most effective applications of thiacloprid at the stated rate were 14 days (2010), 6 days (2011), and 1 day (2012) after peak flight. Females with eggs appeared in bowls in 2010 and 2012 at first flight, while in 2011 no females were recorded. After the most effective applications, yields increased significantly in 2010 (+5% vs. the control) and in 2011 (+4%), and insignificantly in 2012 (+2%).

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Influence of plant growth regulators chlormequat chloride, chlormequat chloride + ethephon, ethephon, and mepiquat chloride + prohexadione-Ca + pyraclostrobin + ammonium sulphate (BAS67800F + BAS00800D) on decreasing sunflower height was evaluated. It was determined that sunflower height can be reduced by as much as 30 cm. In the case of BAS67800F + ammonium sulphate, there was a slight difference between application at BBCH 31–33 and BBCH 50–51, whereas for ethephon better application time was at BBCH 50–51. For chlormequat chloride, application at BBCH 31–33 was better, but height reduction did not endure until harvest. Flower head diameter shortly before harvest was not affected at any tested regulator. Flowering was delayed primarily at applications at BBCH 50–51.