松针褐斑病在湿地松幼林中的发展

<正>湿地松(Pinus elliottii)幼林中松针褐斑

DEVELOPMENT OF BROWN-SPOT NEEDLE BLIGHT IN SLASH PINE PLANTATIONS

This paper reports on the results of investigations of brown-spot needle bligt (Lecanosticta acicola) in slash pine (Pinus elliottii) plantations in the northern region of Fujian province, China. The conidia of brown-spot fungus were released and spread by the splashing of the rain. From a 1.7m high affected tree, most splashed conidia landed within the range of 0-3.4 meters, never exceeding 8.5 meters, when the wind velocity is less than 1m/s. In a slash pine plantation, from November 1982 to April 1985, the average distance of the spreading of disease from an infectious center was 8 meters, the ratio of the infected trees increased by 50% and the disease index increased by 23. The disease developed all the time from March to November, the heaviest infection occured between late April and late June, with the period of September and October coming next. The optimum temperature for disease development was 20-25°C in average for a period of ten days.