. Recent research on foliage diseases : conference proceedings : Carlisle, Pennsylvania, May 29-June 2, 1989. Leaves Diseases and pests United States Congresses. Figure 1.—Distribution of Dothistroma septospora in Yugoslavia Table 1 lists the Pinus species on which this fungus has been detected in Yugoslavia. Of the highly suscep- tible species, four species (P. contorta Dougl., (Grev.) Balf., P. ponderosa Laws., P. nigra var. maritima (Ait.) Melville) are exotic plants, and their distribution is relatively limited in Yugoslavia. In Yugoslavia great economic loss is caused by D. sep
. Recent research on foliage diseases : conference proceedings : Carlisle, Pennsylvania, May 29-June 2, 1989. Leaves Diseases and pests United States Congresses. Figure 1.—Distribution of Dothistroma septospora in Yugoslavia Table 1 lists the Pinus species on which this fungus has been detected in Yugoslavia. Of the highly suscep- tible species, four species (P. contorta Dougl., (Grev.) Balf., P. ponderosa Laws., P. nigra var. maritima (Ait.) Melville) are exotic plants, and their distribution is relatively limited in Yugoslavia. In Yugoslavia great economic loss is caused by D. septospora only in P. nigra plantations. Plantings between 5 and 25 years of age are especially endangered. Damage has also been detected on P. mugo Turr., but only on park trees. This species is never attacked by D. septospora in natural habitats. The main reason for the above is that the ecol- ogic factors prevailing in natural habitats of P. mugo are very unfavourable for the development of the fungus. Dothistroma septospora has never been recorded in Yugoslavia at the elevations higher than 900 m. As for P. sylvestris, it is very resistant to this fungus and even mild infections are very rare. Table 1.—Pinus species that are hosts of Dothistroma septospora in Yugoslavia Host Susceptibility P. contorta Dougl. +++ P. halepensis Mill. + P. jeffreyi Grev. Balf. +++ P. nigra Am. +++ P. nigra var. maritima (Ait.) Melville +++ P. ponderosa Laws. +++ P. mugo Turr. ++ P. sylvestris L. + +++ = High susceptibility; ++ = Moderate susceptibility; + = Low (or very low) susceptibility Disease Symptoms The first symptoms of the disease on needles infected during the current year appear by the end of September and during October, but they are quite distinguishable during November and December. The infection occurs most often on the previous year's needles, and more rarely on current-year needles. The first symptoms of the disease are the discoloration of needle tips. The upper half of the
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