Localisation and seasonal positions of wireworms in soils.

Dominance of dangerous Agriotes species was detected with pheromone traps in the Transdanubian region of Hungary in the examined period. The trapped species showed the following rates: A. lineatus 71%, A. sputator 19/o, A. ustulatus 5%, A. obscurus 3% and A. rufipalpis 2%. The volumetric quadrate method was found to be the most suitable method for soil sampling, as it resembled the natural conditions best, with a digging gripper and forestry hole digger. Occurrence of larva populations was surveyed. Sample areas were previously identified with GPS. Soil temperature, density and water content of dug samples were measured. Density of weed species growing in sample areas was determined. R-value amounted to 0.9200 between the occurrence of wireworms in different soil profiles and soil temperature. 0.7650 R-value was calculated between the depth of occurrence (cm) and the number of wireworms. This fact demonstrates the seasonality of larva occurrence in different soil profiles. The experiments were carried out in different locations and at different times. On the basis of the measurements data show between population and soil density R-values of 0.8637, 0.8006, 0.6294. There was a close regression between population and soil moisture R-values were at 0.5129, 0.9185, 0.7354. Besides data maps show the relationship between soil density and the number of wireworms. This fact proves the local positions of pests. Soil moisture supports the relationship, but its dominance is eliminated by saturation under rainy weather conditions (2005). Weed spots are related to soil density, moisture and population. They all influence adults in looking for best egg-laying places, which contributes to offspring care resulting in later local occurrence. Precision plant control can be applied together with geo-positioning studies. The method enables us to save costs and reduce pesticide stress.

Role of mites and thrips in the agrobiocoenosis of the soybean.

Soy beans dangerous pests are mites and thrips, that is why the present paper aims at the examination of the changes in their numbers and dominance relations of some varieties of different maturity groups. The small plot experiments were conducted in Kisalföld region with the following soybean varieties: early ripening Bólyi 38, Evans, McCall, middle ripening Bólyi 45 and late ripening Eszter, Zsuzsanna and Borza, in Mosonmagyaróvár. Mites and thrips were collected every week with Berlese-extractor. It was observed that Tetranychus urticae Koch, the dominant mite species on soybean, developed its peak-numbers at the end of August. The number of mites was 20 % higher on the late ripening varieties, than on the early ripening ones. Predatory mites (Typhlodromus pyri Scheuten, Amblyseius andersoni Chant) and thrips (Scolothrips longicornis Priesner, Aeolothrips intermedius Bagnall) could not reduce the number of Tetranychus urticae due to their low density. Among the thrips Thrips tabaci Lindeman was the main pest of the soybean leaves, but Frankliniella intonsa Trybom was dominant in the flowers. The blooming of the soybean primarily influences the dynamics of phytophagous thrips. The peak-number of pests reached the highest rate a week later and more thrips were counted on the late varieties as well. Early ripening soybean varieties are recommended to be grown in the Kisalföld region since they are less affected by mites and thrips.

Interaction between nutrient supplies and aphid numbers on potato (2001-2002).

We set up our experiment on 11 potato varieties with 4 treatments and 4 replications in Hungary in 2001 and 2002. The aim of the experiment was to investigate the interaction between the nutrient supplies of potato and the change in the numbers of aphids feeding on the potato plant. In our experiment we sorted 4 nutrient levels according to the recommendations of soil analyses and variety holders. During the growing period we counted the numbers of aphids feeding on the potato leaves every week and controlled the virus infestation with ELISA-method after harvesting. Using the data we concluded that there is an interaction between the nutrient supplies of the potato plant and the numbers of aphids feeding on the leaves. The numbers of aphids on the plots with good nutrient supplies exceeded the numbers of aphids counted on the control plots. In 2001 and 2002 we counted 1150 and 1205 aphids per 100 plants on plots with nutrient supplies in the peak time of swarming compared to the control plot with numbers of 799 and 978. Beside nutrient supplies weather conditions influenced the numbers of aphids, too. Different temperature and rainfall conditions in both years affected the intense and progress of swarming. This can be the reason for the appearance of the first aphids (in the last week of April in 2001 and in the first week of May in 2002) and the time of swarming (15-18 June in 2001 and 28-31 May in 2002). Summer heat and hot days lowered the numbers of aphids. In 2002 following the heat in June and July the population escalated. After harvesting we confirmed our hypothesis from the tuber samples by ELISA-method: The virus infestation was higher on plots with intensive growing practice than the virus infestation on the control plots. In 2001 the rate of PLVRV infestation on Agria variety of the control plot yielded 18.7%. At the time of the 3rd treatment it increased to 37.2%. In 2002 the control had an infestation rate of 12.6% and 40.2% at the time of the 3rd treatment. In 2001 the rates of PVY infestation were 15.2% and 23.4% respectively and in 2002 they were 14.8% and 18.2% respectively. As the interaction between nutrient supplies, changes in the numbers of aphids and the virus infestation are not yet well known, further experiments are required.

Individual number change of Empoasca spp. cicadas species in potato.

We investigated the individual number change of Empoasca spp. cicadas species that are living in potatoes for 3 years. We applied the "100 plants" method for the determination for the individual number once per week. Based on the data determined that the settling of adult begins on the last days of May, and valid presence will be followed till the end of the breeding-season. The individual number was gradually increased during the settling, and reached the peak in 1990 on 23 July, in 2000 on 6 August and in 2001 on 22 July. We determined the individuals gathered during the collection. In the population of Empoasca spp. The E. solani Curtis and the E. decipiens Paoli played the dominant role. The E. vitis Göthe was also present with insignificant individual number. Beside the adults many larvae and nymphs were living on the potato which means that the Empoasca spp. Can reproduce also on the potato. At the time of peak individual number in 1999 1876 larvae, 344 nymphs and 400 adults were present on 100 plants, in 2000 (according to the previous order) 3340, 580, 1280, and in 2001 there were 954, 786 and 285. The rainfall in Hungary was disadvantageous in the investigated period, especially the year 2000. During the rain-free period the temperature was high and the relative humidity of the air was low. However, we could state that the increase of the cicada individual number was not restrained by the heat (30-35 degrees C) days. The decrease was in connection with the ageing of the plant stock.

Effect of subsoiling on the yield of sugar beet under conditions of rhizomania infection.

The rhizomania is known in Hungary since 1982. The causal agent, Beet necrotic yellow vein benyvirus (BNYVV) is transmitted by a soil-borne fungus Polymyxa betae Keskin. A field experiment was done under rhizomania infested and non-infested conditions to compare the yield parameters of five tolerant and four sensitive sugar beet hybrids. Tolerant varieties produced higher root yield under rhizomania infected conditions. The root yields of the sensitive varieties were similar to the tolerant ones on the uninfested field, but the root mass of some tolerant varieties exceeded the production of the former group. Subsoiling was carried out in two strips of a heavily infested field, while conventional soil cultivation was done on the other parts. There was not any other difference in the cultivation of the treated and control areas. Sugar beet root samples were collected at the time of harvesting from the subsoiled and control plots. Beet necrotic yellow vein virus (BNYVV) infection was tested by means of ELISA. Virus content, yield and yield parameters of samples were compared. There were no significant differences in virus infection between sugar beet roots derived from subsoiled and untreated plots. Ratio of BNYVV infected plants was about 90% in both areas. However, yield and yield parameters showed remarkable difference. Root yield of treated plots, calculated from average individual root weight and 80,000 plant/ha plant density exceeded by 140% the yield of control. Sugar content was 2.6% higher and the harmful non-sugar content was lower on the subsoiled plots. Owing to the favourable chemical and technological value of beet the white sugar content was approximately three-times higher on the treated area.