The herbicide tolerance levels of 49 Martonvásár inbred parents were examined in Martonvásár in a herbicide susceptibility trial in 2016. The normal dosage recommended in the permit documentations and double dosage were used for the 12 small-plot herbicide treatments performed in two repetitions. Spraying of early post-emergent herbicides w...as carried out in the 1–2-leaf stage, while post-emergent treatments were applied in the 7–8-leaf stage of maize. The extent of phytotoxicity was scored for the early post-emergent herbicides two and four weeks after treatments and for the post-emergent herbicides two weeks after treatments, respectively. Some of the herbicides examined are not approved in seed production; however it is important to know the reaction of maize parent genotypes for every type of herbicides. The active agent topramezone was withdrawn from the market in 2015, but it was included in the trials as its usage was allowed until stocks run out in 2016. The herbicide agents were examined as follows: mesotrione + S-metolachlor + terbutylazine; isoxaflutol + tiencarbazon methyl + cyprosulfamide; isoxaflutol + cyprosulfamide; mesotrione + terbuthylazine; tembotrione + isoxidifen-ethyl; mesotrione + nicosulfuron; prosulfu ron; nicosulfuron +prosulfuron + dicamba; bentazone + dicamba; nicosulfuron; topramezone; foramsulfuron + isoxadifen-ethyl.
Among early post-emergent herbicides, isoxaflutol + cyprosulfamide caused the less phytotoxic damage in the genotypes. The large amount of precipitation during the spring facilitated the infiltration of the active ingredient S-metolachlor, used regularly and successfully also in seed production, into the root zone, resulting in phytotoxic symptoms on susceptible inbred lines at the time of the first inspection. These genotypes recovered by the end of the vegetation period. The spring weather was cooler than usual, retarding the development of maize and thus led to the slower fermentation of herbicide active ingredients, accordingly, all of the post-emergent herbicides caused visible phytotoxic symptoms on some of genotypes. The most severe damages were generally caused by the double dosage of nicosulfuron + prosulfuron + dicamba, nicosulfuron, and foramsulfuron + isoxadifen-ethyl.
Field experiments were conducted to study affects of pH and hardness of spray water on efficacy of a herbicide combination (terbuthylazine + mesotrione) influenced by several pH adjusters and adjuvants in Debrecen, Hungary in 2008, 2009 and 2010. Favourable or unfavourable effects of pH and hardness of spray water could be observed under field...conditions. Evaluation of weed control efficacy is suitable for examination of affects of spray water pH and hardness on herbicides. The terbuthylazine and mesotrione herbicide combination is suitable to control monocotyledonous and dicotyledonous weed species, however, significant effects of hardness and pH of spray carrier was observed only in control of monocotyledonous weeds. Certain pH adjusters (e.g. ammonium nitrate) can lessen harmful affects of water hardness effectively. Significant loss of efficacy of sensitive herbicide was found in hard water (by about 50-60%), and surfactants was not able to eliminate that harmful affect. However, biological activity was the same as in soft water with ammonium nitrate which can overcome the antagonism of salts. That pH adjuster had a more significant affect on the efficacy of the herbicide than the surfactant had in that experiment.