The study was conducted in 2006-2009 in Rzeszów (50^o01’ N; 22^o03’ E) and Boguchwała (49^o58’ N; 21^o56’ E) (south-eastern Poland). Observations of the harmfulness of the European corn borer (ECB) to sweet corn (Zea mays var. saccharata) were carried out on Candle, Sweet Trophy and Sheba hybrids. In the study years the harmfulness of Ostrinia nubilalis was very high. During the analysed period caterpillars in both locations damaged from 58.0 to 97.5% of plants and from 55.0 to 92.7% of cobs. The risk to quantity and quality of cob yield was significant because from 1 to 15 caterpillars of the ECB eating out soft kernels were found on a single cob. Insecticides containing lambda-cyhalotrin and indoxacarb which were used for single and double spraying of plants demonstrated a high suitability for the protection of sweet corn against the ECB. The best results of chemical control of caterpillars were obtained by using two treatments with the studied insecticides during the growing season.

The study was carried out at the Research and Education Center Gorzyń with a branch in Brody (52°25’ N; 16°18’ E) in 2008-2009, in order to work out the effective way of weed control and protecting plantations against new weed emergences. Research combinations involved the herbicide Boreal 58 WG (flufenacet 48% + isoxaflutole 10%), Accent 75 WG (nicosulfuron 75%) and Mocarz 75 WG (tritosulfuron 25% + dicamba 50%) applied once at the dates and doses recommended by producers, 0.75 kg·ha^-1, 80 g·ha^-1 and 200 g·ha^-1, respectively, and in mixtures applied at two dates (at the stage of weed seedlings), in strongly reduced doses with an addition of the surfactant Trend 90 EC, Atpolan BIO 80 EC and ammonium nitrate. In divided treatments the single dose per hectare of herbicides Boreal 58 WG, Accent 75 WG and Mocarz 75 WG was 0.25 kg·ha^-1, 20 g·ha^-1 and 50 g·ha^-1, respectively. A dose of the adjuvant Atpolan BIO 80 EC was 1.5 dm³·ha^-1, Trend 90 EC was applied at a concentration of 0.1%, and ammonium nitrate in a dose of 2 kg·ha^-1. Carrying out one treatment often did not protect a maize plantation against secondary weed infestation. Applying mixtures of herbicides in reduced doses consisting Boreal 58 WG + Accent 75 WG + Mocarz 75 WG and an adjuvant based on methyl esters of acids or a non-ionic surfactant, with or without an addition of ammonium nitrate, in the system of divided doses, in two treatments, in comparison to a single treatment ensured a very high herbicidal efficiency and a full protection against secondary weed infestation. Lack of competition of weeds towards the crop created more favorable conditions for maize growth and development and favored a higher increase in grain yields. In spite of increased costs of protection against weeds, making the treatment two times ensured a higher profitability of maize grain production.

The aim of this study was to compare the herbicidal efficiency of mixture florasulam + 2,4-D (Mustang 306 SE) in spring wheat cultivar Bryza, spring barley cultivar Antek and oat cultivar Cwał sown in monocrops and two-species mixtures. Field experiments were carried out in 2005-2007 at the Experimental Station in Winna Góra (52^o12’ N; 17^o27’ E), owned by the Institute of Plant Protection – National Research Institute in Poznań. Herbicyd Mustang 306 SE was applied in a dose of 0.5 dm³·ha^-1 at 3-5 leaf stage of cereals using the knapsack sprayer Gloria. The analysis of weed infestation of cereal stand was made with the quantitative-weighing method twice in the growing period (3-4 weeks after the application and 7-8 weeks after the application). Efficiency of herbicide action in mixtures was compared with its effectiveness in monocrops of individual species. From the analyses made it follows that of the cereal mixtures, the barley-oat mixture was infested in the least degree, and the wheat-oat mixture in the most degree. Strongest effect of cultivation in mixtures on reduction of weed infestation was noticeable on the control treatments, where the herbicide was not applied, whereas the cereal cultivation system (pure or mixed sowing) not always differentiated the herbicide efficiency. Cereal grain yields in mixtures after the application of mixture florasulam + 2,4-D were significantly higher than yields of at least one of the component, and yields of mixtures harvested from the control treatments exceeded grain yields of both cereal species in monocrops.

In these studies, sugar maize requirements were estimated with respect to the level and method of nitrogen application and the application method of ammonium phosphate depending on the sowing date. The research was conducted near Poznań (52^o26’ N; 16^o45’ E) in years 2004-2007. It was shown that the most favourable sowing date for the yield size of cobs with covering leaves was the end of the third decade of April. Sowing delay until the third decade of May caused a significant decrease in sugar maize yield. Starter application of ammonium phosphate increased the yield of cobs with covering leaves and the number of cobs per area unit in relation to traditional spread fertilisation, although the effect of this factor depended on the weather course in the years of the research. The above fertilisation method gave positive effects particularly on the objects on which the entire nitrogen was used before maize sowing. Dose of 80 kg N·ha^-1 increased cob yield in relation to a dose smaller by a half, on condition that the entire nitrogen was used before sowing and maize was sown at the end of April. Delay in sowing time by about a month gave the opposite effect.

In these studies, the effect of the level and method of nitrogen and phosphorus application on the qualitative traits of sugar maize cobs was determined depending on the sowing date. It was shown that maize sowing on the earliest date (third decade of April) provided the highest yield of fully-grained cobs and their proportion in the total yield of cobs without covering leaves. Delay in sowing by a month caused a significant decrease in the values of these quality traits of sugar maize cobs. Application of starter fertilisation with ammonium phosphate increased the yield of grained cobs by 100% when the entire nitrogen dose was applied before maize sowing, regardless of its level. Starter fertilisation with ammonium phosphate had a positive effect on the proportion of fully-grained cobs in the case of the nitrogen dose of 40 kg·ha^-1 applied before sowing. Starter fertilisation decreased, in relation to spread fertilisation, the proportion of fully-grained cobs in the case of the nitrogen dose split into pre-sowing and top-dressing.

In this study, the economic assessment of production of maize for grain cultivated in monoculture was presented, with the use of two ways of pre-sowing tillage system (direct sowing, full ploughing tillage), as compared with cultivation in crop rotation. In the years of the study, large fluctuations in maize cultivation profitability occurred, resulting from the level of yield connected with the course of the weather conditions and grain prices. Prices of means of production in the analysed period were quite stable, whereas the market prices of maize grain fluctuated. The most favourable productive and economic effects in maize cultivation in Grabów (in the central-eastern part of Poland) were obtained in 2009, whereas in Baborówko (in the central-western part of Poland) in 2007. The most favourable economic effectiveness, measured by the value of gross margin, in Grabów in 2009 and in Baborówko in 2007, was provided by cultivation in crop rotation. This cultivation variant also provided the highest profitability of maize cultivation both per 1 ha and per 1 ton of grain, as well as the most favourable economic effectiveness of utilization of basic production factors (0.79 PLN per 1 PLN of direct costs incurred on average for both experimental treatments).

In years 2005-2007, sensitivity assessment of four maize hybrids took place – Gazelle, LG 3225, Lober, and PR 39H32, depending on the time and method of herbicide Mustang 306 SE application. Varietal experiment was established using the method of randomized blocks, in three replications, on soil classified as good wheat complex. Weeding was performed mechanically. Hybrids were sprayed with herbicide Mustang 306 SE at the dose of 0.6 dm³·ha^-1 at the 3-4- or 6-7-leaf stage, as well as with a dose limited by 50% at the 3-4- and 6-7-leaf stage. The objects on which the herbicide was applied were compared with the control (no herbicide used). In order to assess the yield variability of the analyzed maize hybrids within the realm defined by four variables (three variants of herbicide application + control), the methods of discriminatory analysis and cluster analysis were used. Gazelle hybrid was characterized by the highest yield variability depending on the date and dose of the applied herbicide in comparison with the control. Significantly higher yield stability was characteristic to hybrids LG 3225 and PR 39H32. Application of herbicide at the 6-7-leaf stage resulted in considerable yield reduction of all the studied maize hybrids (9.09 t·ha^-1). Maize hybrid yield on plots sprayed with split Mustang 306 SE herbicide doses at the 3-4-leaf stage (9.83 t·ha^-1) and 6-7-leaf stage (10.29 t·ha^-1) did not differ, however, from the yield obtained on the control (10.32 t·ha^-1).

Field experiments were carried out in 2008 and 2009 to develop an efficacious and cost-effective weed control program for maize. Herbicides containing terbuthylazine (Click 500 SC), nicosulfuron (Accent 75 WG) and tritosulfuron + dicamba (Mocarz 75 WG) were applied in tank-mixtures at reduced rates, sequentially at 14- to 18-day intervals with nonionic surfactant Trend 90 EC or methyleted seed oil adjuvant Atpolan Bio 80 EC. These standard herbicides were also applied once at recommended timing and rates, without adjuvant. Maize was infested mostly with Chenopodium album L., Polygonum convolvulus (L.).Á Löve and Echinochloa crus-galli (L.) P. Beauv. Broadleaf plus grass weed control with standard herbicide treatment of Click 500 SC, Accent 75 WG and Mocarz 75 WG was only 28, 6 and 21%, respectively. Herbicide tank-mixtures applied sequentially at reduced rates with adjuvants greatly increased weed control and weed control consistency that ranged between 92 and 99%. Atpolan Bio 80 EC was more effective adjuvant then Trend 90 EC. Sequential application of herbicide mixtures with adjuvants provided high increase of maize grain yield (as compared with the control by 9.36-10.38 t·ha^-1) and high net return (from 4037 to 4482 PLN·ha^-1). Benefits from standard herbicide treatments applied once at recommended rates without adjuvant were significantly lower (grain yield increase by 0.49-2.60 t·ha^-1 and net return from -6 to1080 PLN·ha^-1).

This paper deals with the achievements of domestic breeding programs of fodder maize (Zea mays L.) hybrids. This achievements include hybrids that were bred at Smolice – 68, at Kobierzyce – 21 and at Radzików – 4 varieties. In Poland, the first maize hybrid was Wiel-Wi registered in 1957. The first inbred line hybrid was registered in 1967 and it was a double cross hybrid – KB260 – bred at Kobierzyce from 4 foreign inbred lines. Next were IHAR 262 and IHAR 280 – registered in 1971 and 1972, respectively, also double cross hybrids, but created from inbred lines bred at Smolice only. Important stages in development of Polish maize breeding were also years 1977 – registration of the first three way hybrid SMTC 278, and 1994 – registration of the first single cross hybrids Deka and Avia – (all of them from Smolice). Breeding progress was presented as a general combining ability of grain yield of elite inbred lines that were used to create Smolice’s hybrids in years 1971-2006. The real breeding progress in maize breeding program in Smolice was calculated which, expressed as a grain gain from 1 ha, was 59.4 kg per year. Inbred lines S14 and S72, which were included in the formula of hybrid IHAR 262 registered in 1972, as well as the French line F2 which was extensively used 15-20 years ago, created hybrids yielding at a level of 10.0-10.5 t.ha-1 of grain. The newest inbred lines, including S61328, S41324A-2, S63322-3, S68911, S245 and S41796, were able to create hybrids outyielding the former ones by 1.5-2.0 t·ha-1. Present seed market share of domestic maize was discussed as well as prospects for the near future including expansion to foreign markets.