In the years 1996-2002 evaluation of herbicides' efficacy used in low doses was tested. For investigations several herbicides recommended for weed control in cereals were selected. The results of experiments indicate on possibility of reducing of herbicides' doses by about 25 to 3 7.5%, and still obtaining good effects ofweed control without significant decrease of yielding of cultivation plants. The dose is depended upon sensitivity of weed species, growth stage of weeds and their infestation, density of crop and the weather conditions. Low doses of herbicide can be applied where weeds are in early growth stage, where there is low infestation ofweeds, and weeds show susceptibility to used herbicides, moreover under correct crop density and good weather conditions.

In the years 2000-2002 the evaluation of herbicides' efficacy used in lowered doses was conducted. Six herbicides recommended for weed control in spring cereals were used for investigation. The majority of species of weeds occurring in spring wheat and spring barely reacted with a strong (above 90%) decrease of the fresh weight to the treatment with the herbicides applied in the doses reduced by 25%-50% in relation to the recommended ones. Polygonum convolvulus L., Polygonum persicaria L. and Thlaspi arvense L. were very sensitive species as they were very good controlled by tested herbicides in the doses decreased by 50%-75%. Veronica hederifolia L. and Viola arvensis Murr. were characterised by a low level of sensitivity and were controlled only by full recommended doses of tested herbicides. The significant statistical decrease on yield of spring wheat on the objects treated with the herbicides Aurora Super 61,5 SG (mecoprop-P+carfentrazone-ethyl), Granstar 75 DF (tribenuron-methyl) and Grody! 75 WG (amidosulfuron) in the doses lowered by 50% in relation to the recommended ones and Starane 250 EC (fluroxypyr) and Chwastox Trio 540 SL (mecoprop+MCPA+dicamba) in the dose lowered by 50%-7 5% was not observed. In the case of the herbicide Aminopielik D 450 SL (2,4-D+dicamba) the reduction of the dose by 25%-50% also did not cause decrease on yield of spring wheat. In the spring barley, the significant statistical decrease of yielding was not observed on all treatments with tested herbicides applied in the doses reduced by 50%-75%.

The influence of bean seed surface lipids on infestation of seeds by Acanthoscelides obtectus Say was investigated. The experiments were performed in dual-choice bioassays on three bean varieties: Blanka, Bor and Longina. The collected data for natural and solvent washed seeds concerned the number of ovipositions, embryo mortality, lack of seed-boring activity, dead larvae inside seeds and developed insects. The results clearly indicated that bean seed surface lipids are involved in all infestation stages, and could be used to distinguish resistant and non-resistant varieties of been. Chemical analyses revealed the following groups of surface lipids: wax esters, long chain primary alcohols, n-alkanes, sterols, fatty acids, squalene, aldehydes, monoacylglycerols, ketones and fatty acid esters. Quantitative composition of surface lipids was analysed using selected chemometric procedures to determine correlation with bioactivity. Cluster analysis of surface lipid composition enabled to distinguish resistant and non-resistant varieties. Fatty acids and monoacylglycerols were found to deter bean weevil infestation, while alkan-1-ols acted as attractants.

The red-banded stink bug, Piezodorus guildinii, is an important pest in soybean. Information on its distribution is needed to determine the most effective timing for pest control and strategies to avoid yield losses, such as adequate monitoring. The present study was aimed at examining the temporal variation and spatial distribution of P. guildinii in soybean. The experimental design comprised an area of 5400 m² planted with soybean, with 54 plots of 100 m² each, in which plants were examined weekly for nymphs and adults of P. guildinii with a beating sheet. Evaluations were carried out from soybean emergence to harvest; however, P. guildinii occurred only during the reproductive stage. Based on aggregation indices, theoretical frequency distributions, and semivariograms, nymphs and adults were randomly distributed at the beginning of infestation but, tended to be aggregate during pod setting and seed filling. Our findings have a contribution to improving pest sampling systems and infestation mapping, including future semiochemicals studies.