Damage and potential of fungus gnat as a Fusarium vector in the strawberry plants in Korea

Damage symptoms of fungus gnat on strawberry plants are similar to that of Fusarium wilt, anthracnose, and Phytophthora crown rot. Thus, strawberry farmers are often missing the time to control fungus gnat. In the present study, damage symptoms and occurrence pattern of fungus gnat were investigated, and the interaction between fungus gnat and diseases was identified. Damage symptoms of fungus gnat were found to be yellowing and deformation of new leaflets, reddish color on petiole, and ragged and rotted areas around the crown and root. Morphological and molecular analyses showed that the fungus gnat was Bradysia impatiens. Average damage caused by the fungus gnat was 13.1%, and the damage was higher in hydroponic culture than in soil culture. Occurrence time of fungus gnat was the highest from October to November and often occurred along with Fusarium wilt, anthracnose, and Phytophthora crown rot. Fusarium oxysporum f. sp. fragariae was detected in adult of fungus gnat. The results indicate that fungus gnat plays a significant role as a vector of Fusarium on strawberry plants in greenhouses, reinforcing the need for developing integrated disease and pest management.