Miklós Nádasy

The role of allelopathy in host-virus relations

Introduction The term allelopathy was introduced by Molish (1937) at the first time. Earlier it was considered as a type of interference among higher plants, where products of secondary metabolism inhibit (less promote) the development and physiological processes of neighbourhood plants (Rice 1984). The term allelopathy has been extended recently, including not only plant-plant, but also plant microorganism interactions. It is considered as a new alternative way for biological weed control (Duke et al. 2002, Dikic et al. 2003), in order to reduce environmental pollution (Nemeth Konda 2003). Plant viruses make up about 15-30% out of the whole plant diseases. Virus particles create extremely close biological units with the host cell. The biosynthesis of viruses is done by the organelles of the host cell. Therefore chemical protection against viruses is unsuccesful in vivo and causes the death of the host plant cell at the same time. In spite of this, some natural substances are known to inhibit the replication and cellto cell movement of viruses and to reduce virus concentration (Moraes et al. 1974, Baranwal and Verma 1997, Manickam and Rajappan 1998, Vivanco et al. 1999). The mode of action of natural substances is not yet known exactly, but it can be presumed, that these substances may modify special receptor places on the plant cell surface, therefore adhesion of virus particles can not be happened (Gaborjanyi and Tobias 1986). The aim of our investigations was to study the effect of allelopathic weed extracts on host-vims relations.

Damage determination of western corn rootworm (Diabrotica virgifera virgifera leconte) in soil disinfected, continuous corn

Introduction Corn is one of the most important cultivated plants of Hungary (Varga and VargaHaszonits 2003), for the last years its sowing area can be said unchanged ranging from 1.1-1.2 million ha. In the last decade its yield per ha increased considerably, between 2003 and 2005 the average quantity of corn harvested on one ha was 7.52 t and the total corn yield of Hungary surpassed 9 million t (Hingyi 2006). Easy to see that disclose the biotic yield decreasing factors of this economically important crop is an essential task. The success of corn production in Hungary is fundamentally determined by the American origin invasive western corn rootworm (WCR). Since its first Yugoslavian description in 1992 (Baca 1993) the pest has extremely rapidly spread and settled in Europe. According to a survay made in 2004 the species has caused economic losses in an area of 300000 km 2 in Europe (Ripka 2004). The successful European acclimatization of the pest can be explained partly by the soil cultivation base of crop production (Bayar et al. 2003, Jug et al. 2006), partly by the optimum Middle-European climatic conditions required for its development and spreading (Ilovai et al. 1998). The WCR’s damage in the field may show a wide range from a 100% yield loss due to a total lurch to the economically negligible leaf peeling (Ivezic et al. 2006, Hatalane Zseller et al. 2004). The manifestation of these symptoms in a given area is greatly influenced by the pressure of the pest (Keszthelyi 2005), the actual annual precipitation conditions (Hadi 2004, Riedell 1994) and the agrotechnical operations of the corn field (Hatalane Zseller et al. 2004), However, it can be declaired that without soil disinfecting insecticides used in the case of monocultures successful corn production is today is almost unimaginable (Little et al. 1992).

The effect of the weather on the light-trap’s data of the cotton bollworm in Hungary

Introduction The global warming was mentioned more and more in the last years mainly in the extreme hot and dry year: 2003. The mean temperature of the Earth rose 0.6°C in the last 100 years, the number of droughty years with extreme weather conditions increased in the last one and half decade (storms, rainstorms, hails). Not only the weather data, like daily mean temperature but also the number of the drought and hot preferring animals has shown the changing of our climate. The latest insect of this sort is the cotton bollworm (Helicoverpa armigera Hiibner 1808) in Hungary. This pest is spread in North-Africa, in South-Europe and South-Asia and in Australia (Scsegolev, 1951). Its defusing area corresponds to the cotton growth regions. The ecological factors are favourable to the pest in the droughty years in Hungary too. It was detected more than 60 times in our country (Szeoke et al., 1987). The most significant enemy of the cotton bollworm is the cold and rainy weather (Voros, 2004). High ratio of the worms perishes through infection of viruses and bacteria (Aerobacter cloaceae, B. thuringiensis, E. coli, Micrococcus luthens, Ps. fluorescens, Serratia marcescens) (Lipa et al., 1972). The moth can be found in the light-traps with various numbers since 1993 in every year. The warming can be one of the main reason of the pests permanent presence by us. The winters will be milder, the mean temperature in July is increasing, and the precipitation is decreasing, so the climate will be more and more ideal for the cotton bollworm. The pest can be detected with light-traps and sexferomon-traps too. The butterflies of the second generation fly well to the light (Hoffmann et. al., 2004). In our present study we processed the meteorological and light-trap data of the Plant Protection and Soil Conservation Services of Borsod, Csongrad, Fejer, Komarom-Esztergom and Tolna Counties.

Larval feeding of the western corn rootworm ( Diabrotica virgifera virgifera leconte) on roots of several weeds and its effect on crop rotation

(L) P.B. /ECHCG/, Setaria viridis (L) P.B. /SETVI/, Triticum aestivum L. /TRIES/, Abuthilon theophrasti Medic. /ABUTH/, Datura stramonium L. /DATST/ and Amaranthus retroflexus L. /AMAREJ to feed larvae. We used 1.-3. stage instars separately for the observations. In every observations we set three treatments in 3 Petri dishes. First dish contained 20 pieces of Li instars second and third also contained 20-20 L2 and L3 instars. Development of larvae feeding on weeds was compared with larvae living on roots of com. We measured the width of head capsule of larvae to check the pass of stages. Mortality was evaluated on every third days (Table 1.). Dishes and their content were sterilized under laboratory UV lamp. Results and discussion

Effect of a soil microbe preparation (EM-1) on the damage of Western Corn Rootworm (Diabrotica virgifera virgifera LeConte)

Oil rape is a valuable fodder because in early spring and late autumn it produces green forage used for the nutrition of domestic animals. It has been replacing sunflower and soy in colder and wetter regions. It is additionally advantageous because it leaves behind more nitrogen in soil, which is beneficial to other plants in plant rotation. There are some possible ways for the fixation of nitrogen in soil and they are as follows: by the means of oil rape straw ; by relatively long roots ; by the action of nitrogen bacteria, which perform the nitrogen synthesis within their root system, which is the case in some leguminous plants. Oil seed rape is expected to be wider used in crop rotation of West and Middle Europe, Croatia included. Due to this various sorts have been introduced and potential positive impacts have been studied in order to boost the process. This paper presents information on barley and wheat yield in case when they were sown after oil seed rape and corn. The aim of the research is to determine the presence of positive impacts upon the soil with special attention paid to a potential increase of nitrogen content after oil seed rape was grown. The preceding crops had statistically significant effect. Rape yield was significantly higher compared to the one with corn as preceding crops. Very similar results were obtained in 2007.The maize hybrids seed from three different FAO groups (FAO 400, FAO 500 and FAO 600) in four fractions (KO, KP, SO and SP) produced in two climatically different years (extremely dry 2000 and extremely wet 2001) had been different in quality and chemical composition. The effects of year, genetic specifity and seed fraction at the kernel mass, chemical composition (starch, proteins, cellulose, oil and moisture content) and seed vigour have been evaluated. The influence of agroecological conditions during two production years have been exposed at seed chemical composition and vigour indicators (cold test – CT and bulk seed electrical conductivity - EC). The genetic specificity and seed fraction had significant influence at all tested indices, with the exception of the influence of the fraction at the starch content

The effect of walnut cultivation on pest insects

Effects of different site conditions on insects were remarkable. In case of codling moth, the result was evident: with intensive cultivation, the abundance and damage of the codling moth were decreasing. As a contrary to this, there was no considerable difference between the damage of leaf weevils in the orchard and the home garden trees. The main impact on their abundance was the age of the orchards and not the chemical control. An increasing population of white peach scale was observed in the orchards while no insects were found on the home garden trees.

Usability of a cellulose base binding material in control of WCR (Diabrotica virgifera virgifera Leconte, 1868).

Cellulose pearl was tested for years in our laboratory. Insecticide binding ability, retard of the action of bioactive agents, usability against the Western Corn Rootworm (Kysan es Miller, 1986) and other early stage pests (e.g.: Corn Weevil /Tanymecus dilaticollis Gillenhal/) was investigated. Our aim was to the pearl being able to bind water-base pesticides on its porous build and could be able to emit these agents under vegetation continuously. It could be useful to reduce the amount of soil insecticides and the soil pollution by pesticides. With soil pesticides get many active chemical agents in the fields and the plants. Plant protection experts have the duty to reduce the risk of environmental pollution, which are caused by using of insecticides and fertilizers. We have to find new methods to protect our crops because of conservation. Greenhouse screenings and field experiments were started to investigate all the favourable abilities of the pearl.