Ibolya Hatala Zseller(1); Endre Szel(2); Krisztina Mucsi(1)
1 Laboratory for Biological Control and Quarantine Development Plant Health and Soil Conservation Station of Csongrad County 6801 Hodmezövasarhely, P.O.B. 99 Hungary
2 Cereal Research Institute; 6701 Szeged, P.O.B. 391;
Diabrotica virgifera virgifera is present on the corn experimental field of Cereal Research Institute since 1996. The population of the pest increased every year according to the results of pheromone trapping of flight activity. Previous years no economic root damage was registered, but high number of lodged plants appeared in 1999.
Small plot (50 m2) trial was carried out for testing the effect of soil and seed-dressing insecticides against the larvae of WCR in the field where corn has been grown continuously for 20 years. Sowing and treatments took place on April 30. Evaluation of biological efficiency was based on modified "IOWA" (Hills-Peters) rating scale on July 19.
High rate of root damage (4,23) was observed in the untreated control. Results showed that neither soil insecticides nor seed-dressing treatments reduced considerably the root damage on the plots.
Best effect was obtained on the plots treated with fipronil granulate and liquid applications used in furrow. The other soil insecticides resulted none or moderate reduction in root damage. Seed-dressing treatments were even less effective.
Experience of these results indicate that effective control of WCR larvae is very difficult in continuous corn cultivation by using insecticides. Crop rotation seems to be the most reliable way to avoid the economic damage.