Sezonska dinamika Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) u Zemun Polju (Srbija)

The abundance of imagoes of the species Diabrotica virgifera virgifera LeConte 1858 was monitored by the application of yellow sticky traps in a three-factorial trial with long-term continuous cropping of maize in Zemun Polje in 2004. The present study shows the dynamics of eclosion of this species during the July-October period and abundance of imagoes on the field in correlation with application of manure, application of NPK mineral fertilizers, and the amount of crop residues in the soil.Vrsta Diabrotica virgifera virgifera LeConte, oligofagna štetočina, dospela je na naše prostore slučajnom introdukcijom devedesetih godina prošlog veka. Za ovu vrstu svojstveno je da formira ekonomski nivo populacije samo u monokulturi kukuruza. Ogled u kojem je praćena brojnost kukuruzne zlatice je trofaktorijelni zasnovan na eksperimentalnoj parceli Instituta za kukuruz u Zemun Polju 1972. godine. Obuhvatao je 54 varijante, šest kombinacija mineralnih đubriva, tri načina postupanja sa žetvenim ostatcima i tri doze primene stajnjaka. Odabrano je 12 varijanti, praćena je brojnost imaga na žutim lepljivim klopkama marke Pherocon AM. Prva pojava imaga u našim uslovima počinje krajem juna, porast brojnosti događa se u julu, maksimum u julu i avgustu mesecu. Brojnost populacije analizirana je po varijantama na osnovu vremena praćenja i povoljnosti vremenskih uslova za gajenje kukuruza. Tokom tromesečnog perioda (juli, avgust, septembar 2004.) ukupno je uhvaćeno 317 jedinki, brojnost se kretala od nule na početku jula do maksimalnih 76, registrovanih 6. avgusta. Nakon ovog perioda brojnost se znatno smanjila i od početka septembra nije više registrovan ni jedan primerak. Pad brojnosti u drugoj polovini avgusta može se tumačiti migracijom jedinki na susedna polja sa svežom svilom ili polenom u cilju dopunske ishrane. Po varijantama ogleda iznosila je od svega osam u varijanti sa najmanje hraniva, do 52, u varijanti sa najviše hraniva. Možemo konstatovati da je nedostatak vlage u avgustu uslovio brže sazrevanje svile, sušenje zemljišta, masovniju migraciju i skraćenje dužine života imaga, što se odrazilo na pad brojnosti i manjeg broja položenih jaja, što se potvrdilo u 2005. godini

RESULTS OF TESTING OF RESISTANCE OF SOME SWEET CORN INBRED LINES AND THEIR HYBRIDS TO THE EUROPEAN CORN BORER

The resistance of sweet corn to the European Corn Borer is lower than in field corn. The chemical treatment by the insecticides should be done in the short period, from the attack of the Borer to the technical ripening of the cobs. This is particularly the case when it becomes necessary to repeat the treatment against the second generation of the Borer. The appearanc of the second generation is becoming more and more widespread in Vojvodina and Slavonija. The larvae attack manily the cobs. Cur investigation were carried out under artificial infestation of the plants in 1972 and 1973 in Zemun Polje. The results are obtained on the base of the data for 6 experimental hybrids and 8 inbreds, their parental components

Effects of harvest residues and mineral fertilisers on yield and lodging of maize plants caused by larvae of Diabrotica virgifera virgifera Le Conte

Monitoring of plant lodging and yield response was performed with the aim to quantify the maize plant response to WCR larvae root damage. Results of plant lodging ranged from 5.39% to 22.26%. Ploughing down of harvest residues slightly decreased percentage of the plant lodging from 12.92% to 15.24% comparing to the removal of harvest residues. Yield response to CR was followed by 565 kg ha-1 prior to and 586 k /ha-1 after the WCR appearance. Yield differences were 2.861 t ha-1 and 2.840 t ha-1, percentage of yield losses was 35.6% and 33.0% in CRO and CR1, respectively

Efekat tretiranja semena kukuruza imidaklopridom i tiametoksamom na sklop biljaka i prinos zrna

The abundance of pests and the rate of plant damages are controlled by the maize seed treatments with insecticides, as a preventive measure and a measure leading towards the lower population. It is expected that insecticides are efficient when used in relatively small dosages and that are not phytotoxic to seeds and young plants. The aim of the present study was to test the efficiency of imidacloprid and thiametoxam via both, the maintenance of plant spacing and obtained grain yield and also to check the response of certain hybrids to the seed treatment with systemic insecticides. Eight commercial ZP hybrids, four medium early maturity and four full season hybrids, were selected to test imidacloprid (Gaucho 350 FS - 1.0 l per 100 kg seeds) and thiametoxam (Cruiser 350 FS in the amount of 0.6, 0.9 and 1.0 l per 100 kg seeds). Seeds of all hybrids, including the control, were treated with the fungicide Maxim XL 035-FS (150g/100 kg seeds). Strip trials were performed in six locations in south Banat in the 2004-2007 period. The number of plants ha-1 at harvest and grain yield (t ha-1 at 14% moisture), in four replications of 10 m2 each, were recorded and then indices of plant spacing and grain yields for each hybrid over locations and years were calculated. The indices were estimated by the formula of values of plant spacing and the yield in treatments/ values in the control. Plant spacing: the average number of plants in the treatment with imidacloprid Gaucho 600 FS (63 hybrids/locations) and the control was 48,627 ha-1 and 47,812 ha-1, respectively, while the positive difference amounted to 815 plants ha-1 in the treatment. The index of plant spacing was 103.2, and it varied over hybrids, locations and years from 74.9 to 161.4. The corresponding values in the treatment with Cruisera 350 FS (70 hybrids/locations) and the control were 49,945 ha-1 and 49,749 ha-1, respectively. A positive difference in favour of the treatment amounted to 196 plants ha-1. The index of plant spacing was 100.4, and it varied from 82.6 to 132.7. Grain yield: the average grain yield in the treatment with 600 FS and the control was 9,306 t ha-1 and 8,942 t ha-1, respectively. An average positive difference in favour of the treatment amounted to 364 kg ha-1. The index based on the average grain yield amounted to 104.1. The corresponding values in the treatment with Cruisera 350 FS and the control were 9,601 t ha-1 and 9,031 t ha-1, respectively, which means that the positive differences was 570 kg ha-1. According to the average values of obtained plant spacing and grain yields for both insecticides, it can be concluded that a positive response of maize to the seed treatments (364 to 570 kg ha-1) was established under the conditions of a low abundance of soil pests, particularly western corn root worm, during the 2004-2007 period. Although all eight hybrids expressed tolerance to both observed insecticides, it should be stated that the inconsistence of results can create a different impression.Nakon prelaska sa višegodišnje monokulture na gajenje kukuruza u plodoredu, pa i u ponovljenoj setvi, brojnost populacije kukuruzne zlatice se smanjila ispod ekonomskog značaja. Ostale su aktuelne samo autoktone zemljišne štetočine.Tretiranje semena kukuruza insekticidima, predstavlja preventivnu meru zaštite od žičnjaka i grčica, kao i od ptica koje vade klijance. Cilj ispitivanja bio je, da se testira efikasnost imidakloprida i tiametoksama preko očuvanja sklopa, ostvarenog prinosa zrna i proveri reagovanje osam hibrida na tretman semena navedenim sistemičnim insekticidima. Sklop biljaka: kod imidakloprida Gaucho 600 FS na 63 (hibrid x godina x lokalitet) pozitivna razlika iznosila je 815 biljaka/ha a kod tiametoksama Cruisera 350 FS 196 biljaka/ha. Indeks sklopa bio je 103.2, kod prvog i 100.4 kod drugog insekticida. Prinos zrna: primenom imidakloprida Gaucha 600 FS ostvarena je pozitivna razlika od 364 kg/ ha, a kod primene tiometoksama Cruisera 350 FS 570 kg/ha. Na osnovu prosečnih vrednosti ostvarenog sklopa biljaka i prinosa zrna može se zaključiti da su svih osam hibrida pokazali tolerantnost na oba ispitivana insekticida, uz napomenu da nekonzistentnost rezultata treba šire analizirati

European corn borer (Ostrinia nubilalis Hbn) population fluctuation at Zemun Polje between 1986 and 2005

The European corn borer (ECB) (Ostrinia nubilalis Hbn) is one of the most important pests of maize in Serbia. Therefore, it has been and continues to be an attractive subject of research. The flight of ECB adults has been monitored by light traps at the Maize Research Institute in Zemun Polje, Serbia since 1966. Significant qualitative changes in the ECB voltinism occurred during the last three decades of the 20th century. ECB used to be extremely univoltine with 80-90% moths of the first generation, but lately it has become predominately bivoltine. During these 20 years of monitoring, a total of 52,450 specimens were captured (32,382 females and 20,068 males) and their population varied between 351 moths per year recorded in 2001 and 8,347 recorded in 1987. Ratio between the first and the second generation has been changed so that the larger number is the second generation: on the average 1:5.94 (first: second generation), and ranged between 1:0.34 recorded in 2004 and 1: 21.6 recorded in 1987

Effect of planting dates on the level of European corn borer (Ostrinia nubilalis hbn.) Infestation, and crop injury and grain yield of maize (Zea mays l.)

Proper planting date is important for maize production. Therefore, field studies were conducted from 1995-2005 to determine the most suitable planting date for six maize hybrids (FAO 300-700 maturity groups) as influenced by infestation level of European corn borer (ECB), Ostrinia nubilalis (Hbn). Significant differences in the levels of ECB infestation, level of damage and grain yield were observed between the planting dates, and the years. The total plant infestation by both generations ECB over the planting dates ranged from 47% to 60%. Plant damage rating was on the average of 2.2 and slightly differed across the planting dates. Yield results indicated that the planting period for maize production in the Vojvodina province was from April 15 to May 5, but the Most Suitable date was the beginning of the third week of April

Evaluation of Serbian commercial maize hybrid tolerance to feeding by larval western corn rootworm (diabrotica virgifera virgifera leconte) using me novel 'difference approach'

Since the discovery of the pest in 1992, western corn rootworm (Diabrotica virgifera virgifera LeConte (WCR)) populations in Serbia have successfully been kept low with crop rotation. This has reduced the efficiency of screening maize for WCR resistance. A cooperative project between Iowa State University and the Maize Research Institute, Zemun Polje evaluated 13 Serbian commercial maize varieties in Ames, Iowa over a two-year period using the difference approach. Maize hybrids were planted on trap crops where high WCR populations were assumed. Hybrids were evaluated for WCR resistance using a randomized complete block design with four replications. Treatments were paired-rows arranged in split plots with one row in each pair treated with insecticide and the other row left untreated. WCR injury was evaluated using a rating of root size and root re-growth (1-6 scale), root injury (0-3 Node-Injury Scale), root mass, lodging, and yield. The results indicated significant differences among the Serbian hybrids in the presence of moderate-to-high levels of western corn rootworms. The relative benefit of insecticide treatments for maize hybrids was a useful tool in evaluating resistant germplasm. However, conducting analyses on relative differences between insecticide treated and untreated plots was not as effective at detecting differences as comparing the plots independently

Factors contributing to the population changes of major maize pests in Serbia

Changes in pest populations occur on a regular basis and can be influenced by various biotic and abiotic factors, including human activites. The objective of this article was to outline several factors that contributed to the population changes in major maize pests over a 50 year period as reported in Serbian literature. Populations of economically important insects, pathogens and weeds were influenced by changes in agronomic practices and introduction of new species. Examples of new pests included: insect species such as western corn rootworm, weed species such as common ragweed and marshelder, and various pathogens including races of Exserohilum turcicum and Bipolaris zeicola. There was also an increase in maize dwarf mosaic virus and barley yellow dwarf virus