505 Bulletin UASVM Agriculture, 66 (1)/2009 Print ISSN 1843-5246; Electronic ISSN 1843-5386 Integrated Weed Management for Maize Crop in Croatia Zlatko SVEČNJAK * , Klara BARIĆ, Dubravko MAĆEŠIĆ, Boris DURALIJA, Jerko GUNJAČA Faculty of Agriculture University of Zagreb, Svetošimunska 25, 10000 Zagreb, Croatia; * corresponding author: svecnjak@agr.hr Abstract. Concern about the effects of herbicides on the environment is the main stimulus to reduce their use in maize (Zea mays L.). Field research was conducted over two years to evaluate the efficacy of integrated weed management combining two seedbed practices at planting (no-till vs. tilled seedbeds), mechanical (0-3 inter-row cultivations) and chemical (none, band- and broadcast applied herbicide) methods on maize grain yield. Although seedbed practice had no effect on crop emergence, tilled seedbeds tended to produce larger grain yield than no-till seedbeds because of better control of early germinating weeds. Consequently, grain yield in no-till seedbeds consistently increased with each cultivation up to three passes because of improved weed control. However, the largest yield in tilled seedbeds occurred with two cultivations and then slightly decreased following third cultivation pass. Band herbicide application (50 % reduction in herbicide use compared to broadcast application) resulted in higher yield than one cultivation alone, whereas opposite responses occurred after multiple cultivation passes. Grain yield responded positively to one and two cultivation passes even when weeds were controlled by pre-emergence chemical method. Our findings indicated that banded herbicide application provided effective weed control in maize crop when complemented with two inter-row cultivations regardless of the method of seedbed preparation; thus making a viable option for Croatian farmers to lower herbicide load on the environment. Keywords: grain yield, inter-row cultivation; herbicide; band application; weed biomass. INTRODUCTION Maize, a warm season crop, suffers severe competition from early germinating weeds because of slow early development and wide row spacing (Subedi and Ma, 2009). Half a century ago, Vengris et al. (1955) found that the uncontrolled weed population can substantially reduce maize grain yields, particularly on fertilized plots. In Croatia, maize is the most important arable crop that occupies about 350 000 ha (Državni zavod za statistiku, 2007) and amounts to the greatest use of herbicides. Croatian farmers rely primarily on herbicides for weed control due to their effectiveness and ease of use. However, current environmental concern over the potential contamination of ground and surface waters has resulted in renewed interest in integrated weed management in maize production. One way to reduce herbicide use in maize production systems is to diminish the herbicide dose per hectare. The duration of weed control is shortened at reduced herbicide rates, but weeds emerging later can be easily controlled by inter-row cultivation. Mulder and Doll (1993) reported a minimum risk of maize yield loss when a 50-75 % reduction in herbicide was combined with mechanical weeding. Another method of reducing herbicide use is band herbicide application complemented with mechanical weed management. Inter-row cultivation alone has been reported to control weeds less effectively than herbicides, regardless of the number of passes (Hartzler et al., 1993). However, studies done by Buchholtz and Doersch (1968) showed that cultivation combined with broadcast herbicide