50 U.S. DEPT. OF AGRICULTURE MISC. PUB. 9 39 



seeds, seed treatment with disinfectants or hot water bath is necessary 

 for anthracnose-free countries. 



Range : Central and southern districts of Japan. 

 Hosts: Leguminosae — 



Acacia dealbata 



A. mollis sima 

 Literature: Ito, K., and Shibukawa, K. Studies on some anthrac- 



noses of woody plants — III. A new anthracnose of Acacia with 



special reference to the life history of the causal fungus. Bui. 



Govt. Forest Expt. Sta., 92 : 51-64. 1956. 



Leaf Blotch of Poplar 



Septotinia populiperda Waterman & Cash. Symptoms first appear 

 in early spring as small brown spots on the young leaves, frequently at 

 or near the margin, but also at any point on the leaf blade. The spots 

 usually increase rapidly in size, soon become gray at the center, and 

 have an irregular but sharply defined margin. On the most susceptible 

 species and hybrids, large areas of the leaf blade become invaded by 

 the fungus. 



On the lower surface, the leaf blade and particularly the veins in 

 the affected area become dark brown with white sporodochia. On 

 the upper surface, small white masses of conidia appear, usually de- 

 veloping in concentric circles. Along the margin of the blotch, white 

 mycelial fans are frequently formed just below the cuticle of the upper 

 leaf surface. Two or more of the spots may coalesce, resulting in al- 

 most complete invasion of the leaf tissue. Early defoliation usually 

 follows, and the young shoots of the most susceptible poplars may thus 

 be entirely defoliated by late summer. On the fallen diseased leaves on 

 the ground, thin, small, black sclerotia of the fungus are abundantly 

 produced in late October. For morphological characteristics of the 

 pathogen, see Waterman and Cash (1950) . 



In 1956, the first collection of this disease in Japan was made in 

 Tokyo. Since that time, further surveys showed a more extensive 

 distribution of the disease. Now, the fungus is distributed widely 

 throughout Japan almost everywhere poplars are cultivated. Leaf 

 blotch is the most important disease of poplar leaves and causes severe 

 damage. Japanese pathologists believe that the pathogen was prob- 

 ably imported with cuttings from Europe or America to Japan after 

 World War II. 



International spread is chiefly by cuttings, and imported cuttings 

 must be surface sterilized before planting. 



Distribution : Japan, North America, Europe. 



Host : Salicaceae. 



Susceptible: Populus simonii, P. koreana, P. davidiana X P. canes- 

 cens, P. tremula X P. trerruuloides, P. canadensis. P. serotina, P. 

 regenerata, P. marilandica, "Rochester" poplar, P. euramericana, 

 1-455, 1-214, 1-154, 1-293, LK-79, LW-42, "Wettstein" poplar, 

 "Jacometii" poplar, P. japonogigas, P. eugenii, P. berolinensis. 

 (All planted in Japan) . 



Very susceptible: P. nigra X maximowiczii (Kamabuchi-1,2), P. 

 charkowiensis X trichocarpa, P. robusta, P. gelrica, "Leipzig" 

 poplar, P. nigra Xlauri folia (All planted in Japan). 



