Determination of the effectiveness of different methods used for the application of hypovirulent isolates for the biological control of chestnut canker (Cryphonectria parasitica)

The most suitable biological control method of chestnut canker caused by Cryphonectria parasitica is the application of hypovirulent isolates to active cankers. Usual application method of hypovirulent isolates is to place culture disks or pastes prepared from the isolates to the holes drilled on the bark around the cankers about 2-3 cm intervals. In the application of this method some difficulties, such as too steep land, large cankers and need of much work power, arises. For his reason, in order to facilitate the application of hypovirulent isolates, various methods were tested and their effectiveness was evaluated. The study area was chosen from İzmir and Aydın provinces where good quality chestnut production is high. Hypovirulent isolates were prepared as paste and diluted paste. Hypovirulent isolates were applied to the holes as hypovirulent paste to selected 24 cankers situated in the borders of Beydağ Forestry Management Chief of Bayındır Forestry Management Directory of İzmir while 18 cankers were treated by as paste application to the holes, diluted paste to the cankers wounded with a tool with pins, diluted paste directly to the cankers with a brush, six canker each in the Malgaçmustafa village of Sultanhisar town of Aydın province. After a year, healing of the cankers were observed on all the application methods. After two years from the applications, the number of the completely healed cankers increased. The results showed that all the applications were successful. In addition, especially in this region, Goat moth (Cossus cossus L.) which appeared intensively in July-August caused damage on the bark tissues of the application areas. For this reason, it was observed that hypovirulent applications in these areas should be done up to the middle of June.