Jasminka IGRC BARCIC, Renata DOBRINCIC,
Milan MACELJSKI
Faculty of Agriculture, Department for
Agricultural Zoology, Croatia, 10000 Zagreb, p.p.1,
As in the previous years the Department for Agricultural Zoology, Faculty of Agriculture, Zagreb has carried out the monitoring of the WCR in Croatia in 2000. The traps were placed on 133 sites. On each site one pheromon and one yellow trap (Pherocon or Multigard) were placed at least 100 m apart. Traps were placed in the field on June 20th. Traps were replaced by fresh ones each 25 days. Each 7 days traps were checked and beetles collected. 60% of sites (80 sites) were situated in previously infested areas and 40% of sites (53 sites) in areas which were not infested in 1999.
The results of monitoring the WCR in the period 1995-2000 are summarized in the following table:
Table 1: Results of monitoring of WCR in Croatia in period 1995-2000
| YEAR | MONIT. SITES | BEETLES CAUGHT | EVALUATION OF THE INFESTED AREA | ESTIMATED POPULATION GROWTH INDEX | ||
| total km2 | arable area 000ha | corn 000 ha | ||||
| 1995* | 41 | 1 | 1.200 | 30 | 10 | - |
| 1996 | 91 | 788 | 6.500 | 250 | 85 | - |
| 1997 | 123 | 3906 | 9.000 | 430 | 125 | 3,3 |
| 1998 | 136 | 5933 | 10.000 | 500 | 140 | 1,7 |
| 1999 | 117 | 15788 | 12.750 | 585 | 165 | 3,6 |
| 2000** | 133 | Cca 12000 | 14.500 | 700 | 200 | 2,5 |
The first beetle was found in soil on June 14th. The first beetle was caught on traps on June 20th, the same day when the traps were placed in the filed. The appearance of the beetles was 10-14 days earlier than in previous years. This fact can be explained with extremely dry and hot weather conditions in May and June.
The maximum catch was registered between July 10th and 20th what is also earlier than in previous years.
The spread of the WCR in the direction to the west was registered in northern and middle part of the infested area. In the northern part of the infested area WCR spread 35 km to the west. In the middle part of the infested area WCR spread about 20 km to the west, and in the southern part of the infested area no further spread was registered.
The spread of WCR in 2000 was faster along the river Drava than along the river Sava, similar to the situation in the last year. The farthest point of the WCR spread toward northwest is about 40 km from Slovenia.
At this moment the total area of 14500 sq km is infested on which area 200.000 ha of corn is grown.
The spread of the WCR in Croatia is shown in the map.
The estimated population growth index is about 2,5.
In our insecticide trials conducted at a site on the border with Yugoslavia, the mean root damage rate in untreated plots was between 3 and 3,5 (Iowa State University scale). The mean root damage rate in 1999. was between 2,5 and 3. On some plants minor goose neck symptoms appeared. The yield loses due to root damages in this trials were 5-25%. On one field in the region infested in 1997 on 10% of plants serious root damages occurred.
The investigation of biology and ecology of the WCR have been carried out for 4 years in the field and in the laboratory conditions also.
The results presented in this summary are preliminary, as only about 70% of data were collected at the moment of its submission.