. Recent research on foliage diseases : conference proceedings : Carlisle, Pennsylvania, May 29-June 2, 1989. Leaves Diseases and pests United States Congresses. Table 1.âSeasonal conidia production of Dothistroma septospora Period of the highest conidial production Period of Conidial production / Date of Stromata producing Degree of collection conidia conidial production3' % Dec. 14, 1982 0 25 0 Jan. 13, 1983 0 27 0 Feb. 19 0 Mar. 5 0 21 0 Apr. 2 45 + ~ ++ 23 60 + ~ ++ May 2 25 + 20 100 ++ June 4 100 ++ 21 100 H \-+ July 4 100 + ~ ++ 18 50 H h+ Aug. 1 25 + 16 0 Sept. 3 0 19 0 Dec. 14, 1
. Recent research on foliage diseases : conference proceedings : Carlisle, Pennsylvania, May 29-June 2, 1989. Leaves Diseases and pests United States Congresses. Table 1.âSeasonal conidia production of Dothistroma septospora Period of the highest conidial production Period of Conidial production / Date of Stromata producing Degree of collection conidia conidial production3' % Dec. 14, 1982 0 25 0 Jan. 13, 1983 0 27 0 Feb. 19 0 Mar. 5 0 21 0 Apr. 2 45 + ~ ++ 23 60 + ~ ++ May 2 25 + 20 100 ++ June 4 100 ++ 21 100 H \-+ July 4 100 + ~ ++ 18 50 H h+ Aug. 1 25 + 16 0 Sept. 3 0 19 0 Dec. 14, 1983 0 Jan. 2, 1984 0 18 0 Feb. 4 0 14 0 Mar. 5 0 20 0 Apr. 6 0 21 27 + May 1 67 + 18 100 + June 2 + ~ ++ 18 95 H h+ July 2 95 + ~ ++ 14 80 + ~ ++ Aug. 1 50 + ~ ++ 18 5 + Sept. 1 0 19 0 a) No production, +: Light production, ++: Heavy production. 1983 and 1984, respectively. Considerable rainfall, above 100 mm at an interval, was recorded at the time of the highest conidial production in both years. Laboratory experiments. â As shown in table 2, the epidermis of lesions was ruptured by the development of stromata at temperatures ranging from 10 to 30 C, with an optimum of 20-25 C. Conidia were produced at tem- peratures ranging from 15 to 25 C, with an optimum of 20-25 » a E a â p a> §°30 CD * 20 10 0 1984 p 1 ! "1 ! 1 ^^^^^^^^^ i i : . 111 11 i x i 1«1111 I I l_ J L 150 100 50 0 March April May June July August Figure 2.âRelationship between climatic conditions and production of conidia of Dothistroma septospora. Discussion Although symptoms of Dothistroma needle blight on P. thunbergii appeared in October, conidia of the causal fun- gus were produced from April to August of the following year, and peak production was in June in Shimane Prefec- ture. In order to control the disease, copper fungicides, which have been recognized as the most effective chemicals (4), should be applied during the period of conidial produc- tion. Control was not attempted
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