Naslov
Current status and results of the monitoring of western corn rootworm in 2003 in Croatia

Autori
Igrc Barčić, Jasminka ; Bažok, Renata

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
IWGO Newsletter 10th IWGO Diabrotica Subgroup Meeting and 9th EPPO ad hoc Panel and FAO Network Group Meeting / - , 2004

Skup
10th IWGO Diabrotica Subgroup Meeting and 9th EPPO ad hoc Panel and FAO Network Group Meeting

Mjesto i datum
Engelberg, Švicarska, 14.01.2004. - 16.01.2004

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
western corn rootworm; monitoring; Croatia

Sažetak
A progressive increase of adult population abundance was registered during seven-year monitoring of the occurrence, spreading and population density of the western corn rootworm in Croatia. For years the pest has been spreading on main corn growing area whithout any visible damage and farmers did not take the WCR a serious pest. The first economic damage caused by WCR occurred in 2002 in region of Baranja. In 2002, big yield reductions were observed only in fields with very heavy larval damages. Rainfalls occurred very often through July and August. Root regeneration was very intensive what diminished yield reduction. Yield loss on one field in Baranja according to the information of the farmer was 85%. In spite of the high attack of the WCR in 2002, the damages were not very visible in numerous fields. Favorable climatic conditions diminished yield loss caused by WCR, but the population level was increased. In 2003, monitoring of the WCR had 3 main tasks: to establish the furter spread of the pest ; to establish increase in population density and to establish economic population area and the average yield losses due the WCR larval attack. In 2003 Diabrotica virgifera virgifera LeConte was monitored following a common protocol. Monitoring of the WCR was conducted on 121 monitoring sites. On each site 1 pheromone and 1 Pherocon AM trap were place at least 50 m apart. Traps were palced in the field between June 10th and 17th. Each 7 days traps were checked and beetles collected. Significant spread of the pest in 2003 was recorded. The new line of the spreading of the pest is on the line Hodošan- Prelog- Donja Dubrava- Donja Stubica- Otok Svibovski- Hrašće- Mala Gorica- Dvor na Uni. WCR has infested an area of about 23.500 km2. In that area approximately 80 % of all Croatian corn production is conducted. Alltogether in monitoring action 31760 beetles were caught. Main ratio of beetles was caught on pheromone traps (93, 4 %) while only 6, 6 % of all beetles were caught on Pherocon AM traps. An increase in population density is occurred. Population growth index for the 2003 is 4, if it was calculated based on the data from all monitoring sites in all previously infested counties. The data from permanent monitoring sites show somewhat lower population growth index, 3. In 2003, on the 5 fields with visible symptoms of the attack of the WCR larvae, in order to evaluate the damages, root damage rating and plant lodging were conducted. Yield loss by yield weighting was predicted. The average root damage rate on all observed fields was over the economic threshold level. The percentage of the lodged plants was between 26, 3 and 91, 1%. Yield loss on the lodged plants was between 12, 9 and 49, 4 %. Extreme drought climatic conditions in 2003 caused very weak germination of corn. Low plant population together with unfavorable climatic conditions in 2003 caused an average yield loss of 30 % on all cornfields in corn production area. Yield loss caused by larval damage on observed fields was between 4, 8 and 45%. This yield loss should be added to the previously mentioned yield reduction. Some yield reduction was caused by silk clipping and during harvesting also. Correlation between root damage rate and yield loss in extreme climatic conditions is not so obvious as in regular climatic conditions. Damages caused by WCR larvae were recorded on the fields located in the Osječko- Baranjska, Vukovarsko- Srijemska, Požeško- Slavonska and Virovitičko- Podravska counties. This is an area of 12.500 km2. All damages were recorded on continuous cornfields, what stress again the importance of the crop rotation in future corn production. Economic population area from year to year is increasing and probability for the damages in continuous cornfields on larger area is growing.

Izvorni jezik
Engleski

Znanstvena područja
Poljoprivreda (agronomija)

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