Abstract: [Objective] The strain Stenotrophomonas maltophilias Smal-007 was isolated by Nanjing Forestry University and developed as a biocontrol agent for controlling pine wilt disease. In order to verify the control effect of Smal-007 in the southern forest regions of China, a large-scale experiment was performed in forest in Sanming city, Fujian Province.[Method]A total of 363.6 hm² pine forests locating at four regions of Sanming city (Meilie district, Sanyuan district, Fenggang subdistric and Qingzhou town of Shaxian county) were used for the experiment. In Meilie district, the experiment forest was 103.3 hm² of Pinus massoniana pure forest, including 65.1 hm² treated with the bacterial spray and 38.2 hm² as control area. In Sanyuan district, the experiment forest was 100.0 hm² mainly with mixed forest of P.massoniana and broad-leaved trees, including 51.7 hm² treated area and 48.3 hm² control area. In Shaxian Fenggang, the forest was 82.4 hm² mainly with P. massoniana pure forest, including 56.5 hm² treated area and 25.9 hm² control area. The area of forest at Qingzhou, Shaxian County was 77.9 hm², mainly with P.massoniana and broad-leaved trees, including 53.6 hm² treated area and 24.3 hm² control area. The forest in Melie district was sprayed by atomizing machine with Smal-007 culture at the concentration of 12-15 kg·hm^-2, while the forest in Sanyuan district and Shaxian county were sprayed by a light aircraft at a concentration of 6-7 kg·hm^-2. The spraying was performed for once a year, in May of 2014 and 2015, respectively. The dead trees caused by pine wood nematode was counted from June to December every year.[Result] The number of wilting and dead pine tree was significantly reduced in Melie district and Sanyuan district. The control efficiency in Melie district was 90.9%and 100% for 2014 and 2015, respectively. The control efficiency in Sanyuan district was 93.4% and 92.7% for 2014 and 2015, respectively. Due to heavy rain soon after spraying, the control effect in Shaxian county was not as good as the last two districts. The control efficiency in Fenggang, Shaxian county was 30.5% and 69.4% for 2014 and 2015 respectively, while the control efficiency in Qingzhou, Shaxian county, was 26.7% and 20.1% for 2014 and 2015, respectively.[Conclusion] When treated with the biocontrol Smal-07 culture, under the condition of no rain for 48 h after spraying, the pine wood disease can be efficiently controlled in the southern forest regions of China. Our result shows that the bacterial Smal-007 biocontrol agent can be successfully used in epidemic area of the pine wilting disease in northern Fujian.

Key words: pine wood nematode, smal-007, biocontrol bacteria, control effect