The Internet based 'Web-Blight' service (http://www.web-blight.net) was initiated to provide an online warning and prognosis system for potato late blight in the countries around the Baltic Sea. In order to obtain comparable results, methods were harmonized and a set of interacting PC and Internet applications were developed for use by the project partners. Results regarding monitoring of potato late blight and evaluation of variety resistance against late blight (field tests) are presented for Estonia, Latvia, Lithuania and Poland. The use of the Internet to collect and present data was very successful, because information were "on the fly", helping farmers in their decisions about the timing of first applications and choice of fungicide type. Results show that it was possible to find early attacks as primary attacks (spots in the fields). In most cases attacks were initially found in home gardens and later in conventional fields. The growth stage at first attacks was often higher than 3 7 (BBCH) indicating that very early attacks caused by oospores in the soil was not a widespread problem. Local varieties were tested for late blight resistance in untreated field trials against four test varieties (Sava, Oleva, Danva and Kuras), Primary disease data were uploaded to Web-Blight via the Internet, and applications on the Web-Blight server calculated epidemiological variables such as delay of first symptoms and RAUDPC. Results indicated the presence of race-specific resistance in some varieties, e.g. Kuras, and that some varieties were originally misclassified according to resistance scale, e.g. Sante. The network about observation trials clearly showed that field test of variety resistance against late blight in time and space is important, taking into account the rapid evolution of Phytophthora infestans populations in Europe.

As compared to 1977 potato acreage in Poland has decreased by about 1.4 million hectares and amounted to 958 thousand hectares in 2002. Potatoes are protected mainly against Leptinotarsa decemlineata Say, Phytophthora infestans and weeds. Number of chemical treatments against Colorado potato beetle fluctuated between 1.1. to 1. 7 per year, in average. In 1977-1987 mainly organophosphorous insecticides were applied, whereas in last years pyrethroids and nereistoxin were used. Chemical treatments against late blight fluctuated between 1.2 to 1.6 per year, in average. Observations performed in 1977-2002 showed that the application of contact fungicides considerably decreased. In weed control in potatoes only one treatment, in average, was performed using herbicides, mainly pre-emergence ones. Herbicides containing linuron and metribuzin were most frequently applied.

Preventive methods of plant protection used currently require a significant number of treatments throughout the season. Research results indicate a possibility of reduction of the number of treatments by halfwithout serious loss of effectiveness if the attack of pathogens has been recorded early enough. Limiting treatments to truly necessary ones means conserving chemicals, fuel and labour and consequently substantial financial savings for the farm. However, early warning requires full analysis of many factors that influence incidence, development and harmfulness of diseases, pests and weeds in relation with their impact on the yield. Such an analysis is beyond the power of the farmer alone. Appropriate models have to be used that utilize weather data and field observations in real time. At the present, due to frequent updating of the databases and sharing of the system by many users, in integrated plant protection the most efficient seem to be internet decision support systems. As of 2000 the Institute of Plant Protection in Poznań together with the Institute Soil Science and Plant Cultivation in Puławy in cooperation with the Danish Institute of Agricultural Sciences conduct a joint research project on development and implementation of an Internet Decision Support System for Integrated Plant Protection in Poland. Various modules of the system are already available on the Internet. Much like similar systems operating abroad, the Polish DSS also takes advantage of weather data utilized in disease models (the weather module). Nevertheless, an important addition to the system are strategically relevant data such as values and statistic distributions of elements of climate and potential yields (the agroclimate module), operation sheets, exploitation data and prices (the technology module) etc., which are important to the formulation and adoption of a particular line of action and risk evaluation in economic terms. When all modules are operational, the information relevant to decision making will be derived from on-line analyses based on cost calculation of different variants of plant protection applicable to the current situation.

The field experiment carried out in Winna Góra compared the efficacy of fungicide programs applied in accordance with the NegFry and Routine systems. The results of2002 validation achieved in Winna Góra showed that NegFry model forecasting the late blight occurrence is useful in Polish climatic conditions. Compared with routine treatment schemes, NegFry recommended fewer treatments without significant reduction of yield thus potato protection according to NegFry was more cost-effective than according to Routine system. Basing on these facts the NegFry decision support system can be recommended for Polish climatic conditions.

The outdoor pot experiments on the influence of weeds' growth stage and climate conditions on herbicides' effect were carried out in the Danish Institute of Agriculture Science in 2000-2001. The experiment concerning growth stage took into consideration three phases of Galium aparine: l, 2 and 3 whorls. The influence of temperature was performed using climate simulator running at three temperatures: 8/2°C, l 6.5/8°C, 24/16°C. The rain was applied using rain simulator 1, 3 and 6 hours after herbicides' treatment. Herbicides: Grody! 75 WG (amidosulfuron 750 g*kg-1), Aurora Super 61,5 WG (mecoprop 600 g=kg' + carfentrazone-ethyl 15 g*kt1), Lintur 70 WG (dicamba 65.9 g=kg', triasulfuron 4.1 g=kg') and Chwastox Trio 540 SL (dicamba 40 g*r1, MCPA 200 g"l', mecoprop 300 g*r') were applied in four doses: full recommended, 1/2, 1/4 and 1/8 of full dose on G. aparine. Grody! 75 WG and Aurora Super 61,5 WG were the most efficient to the youngest plants of G. aparine. Differences in susceptibility among three growth stages (1, 2, 3 whorls) to Grody! 75 WG were higher than to Aurora Super 61,5 WG. Effectiveness of tested herbicides tended to increase as temperature rose. The addition of adjuvant improved activity of herbicide Lintur 70 WG that showed satisfactory weed control even at four time reduced dose independently from temperature. The rain treatment 1, 3 and 6 hours after spraying caused reduction of Aurora Super 61,5 WG activity at 1/4 and 1/8 doses. The half dose gave a good result only when rain was applied 6 hours after treatment. Herbicide Grody! 75 WG was efficient after rain application (1, 3, 6 HAT) only at full dose.

The aim of investigations was to understand the effect of herbicides application on soil environment and residues in sugar beet. Field experiments were carried out during 1997-2001 on arable field near Wroclaw. Herbicides to weed control in sugar beet were applied at recommended dose alone and in mixture with adjuvants. Samples of soil, leaves and roots of sugar beet were taken on the day of harvest. Additional, soil samples were taken six weeks (in autumn 2000) and five months (in spring 2001) after harvest. All samples were analysed (herbicide residues) using the high-performance liquid chromatography (HPLC) with UV-detection and gas liquid chromatography (GLC) with ECD. Residues of active ingredient of herbicides determined in roots and leaves of sugar beet did not exceed acceptable values included in EU standards and herbicides use in normal agricultural practice should not present problems for following crops. Moreover, the addition of adjuvants caused an increase of the herbicide active ingredient residue in soil, leaves and roots of sugar beet samples in comparison with the treatments, where herbicides alone were used.

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%.

Some active ingredient of herbicides, after application, can create a risk for ground and surface water. The aim of investigations was monitoring of herbicidal pollution in ground and surface water on arable areas. The investigations were conducted in the years 2000-2002. The samples were collected (from stationary points located in the south-west Poland) twice a year (in spring and autumn about 3-6 weeks after nominal term of herbicide application). Surface water was sampled in 27 points and ground water in 18 wells. The residues of herbicide active ingredients (triazine and phenoxy acids) were determined using HPLC methods with UV detection and GLC method with ECD detection. The residues of active compounds in surface water (in spring and autumn) were detected. Residues at concentrations exceeding the EU safety standards were detected most frequently in springtime. The contamination levels in excess admissible limits were found in ca. 15% of surface water samples. In ground water (from wells) residues were detected sporadically and its level was very low (ca. 0.01- 0.1 mg=dm").

One of the most serious seed-borne diseases of flax is anthracnose or seedling blight caused by Colletotrichum lini (West.) Toch. This disease affects flax seedlings, leaves, stems, and fruit bags. It causes reductions in linseed germination power, stand density, stem and linseed yield, fibre output and quality. During 1999-2001 experiments were carried out at the Lithuanian Institute ofAgriculture Upyte Experimental Station to test the efficacy of seven fungicides used for seed dressing against flax anthracnose and other seedborne diseases. Experimental findings indicated that 19.0% to 34.0% of flax seeds were annually infected with C. lini (West.) Toch. causing flax anthracnose. As the disease can spread through the soil, on control plots sown with untreated with fungicides seeds 33.0% to 79.5% of seedlings showed symptoms of anthracnose. Seed treatment with Sportak 45 EC used at the dose 0.8 l f1 and Maxim Star 025 FS used at the dose 1.51 t-1 gave the best control of seedling blight causal agents. Their biological efficacy was as follows: against seed anthracnose 97.3% and 96.3%, at seedling stage, 76.5% and 76.3%, at 'fir-tree' stage - 67.8% and 60.4%. Biological efficacy of the other seed treaters was lower. The highest straw yield increases resulted from seed treatment with the Maxim Star 025 FS and Sportak 45 EC - 0.5 and 0.3 t ha" or 11.0% and 6.2%, respectively. The effect of fungicides used for seed treatment on linseed yield was similar. Maxim Star 025 FS increased the yield on average by 22.1%, and Sportak 45 EC and Premis 25 FS by 13. 7% and 13.3%. The other fungicides, except for Raxil 2 WS and Rovral FLO, also had a positive effect on flax straw and linseed yield, however, in all experimental years the increases were not higher than the least significant difference.

Zea mays originate from warm and tropical region of the world and needs high sum of effective temperature throughout vegetative period. On the Polish market varieties of maize differ in early maturing, provenance and temperature requirements. The foreign varieties react stronger to the sulfonylurea herbicides (nicosulfuron, rimsulfuron, foramsulfuron + jodosulfuron) than Polish maize varieties under unfavorable weather conditions. The trials were conducted in field conditions using 8 maize varieties. The aim of this experiment was evaluation of the influence of sulfonylurea herbicides on foreign and Polish varieties of maize under different weather conditions. The reaction of foreign maize varieties on herbicides was compared with reaction of Polish maize varieties in the years 2001-2002. Four early maturing varieties of maize were testing: AVENUE (FAO 220)-FR, JANNA (FAO 190)-USA, WIARUS (FAO 220)-PL, FIDO (FAO 220)-PL. It was proved that Polish maize varieties showed a higher toleration towards sulfonylurea herbicides. The later maturing varieties KRÓL (FAO 280)-PL, IMAN (FAO 300)-PL, KANZLER (FAO 300)-FR, MAGISTER (FAO 280)-CH responded in a similar way. In 2002 there were no differences in plant development between foreign and Polish maize varieties.

Amendment of VS juice agar and soil leachate with grapefruit extract resulted in the inhibition of colony growth and sporulation of Phytophthora ramorum. Zoosporangia were more susceptible to the extract than pathogen hyphae and chlamydospores. Spraying of rhododendron inoculated with P. ramorum with grapefruit extract at cone. 165 μglcm' inhibited 2-3 times the spread of necrosis on stems and leaves.