DANGEROUS INTERNATIONAL FOREST TREE DISEASES 49 



tion and retention in quarantine until all latent infections have had 



time to appear. 



Range : In Japan it is common from Hokkaido south to the Tohoku 



District. 

 Hosts: Pinaceae (species listed in order of susceptibility) — 



Larix decidua (Planted in Japan) 



L. gmelini var. olgenis (Planted in Japan) 



L. gmelini var. japonica 



L. leptolepis 

 Literature : 



Sawada, K. Fungi inhabiting conifers in the Tohoku District II. 



Fungi on various conifers except "Sugi*'. (Japanese with Latin 



Diagnoses) Bui. Govt. Forest Expt. Sta. 46: 111-150. 1950. 

 Uozumi. T. Shoot blight of larch in Hokkaido (Japanese) . Forest 



Protect. News (Tokyo), 7: 156-158. 1958. 



Anthracnose of Acacia 



GJomerella acaciae (K. Ito & Shibukawa) K. Ito (syn. Phy sa- 

 les pora acaciae K. Ito & Shibukawa). Symptoms of the disease first 

 appear on the plant as punctate brown lesions, which later enlarge 

 and attain 5-10 mm. in diameter and become dark brown in color. 

 The disease attacks all of the above ground parts of Acacia seedlings 

 including leaves, stems, petioles, and branchlets. During wet periods 

 the lesions elongate, coalesce, and very frequently girdle entire stems 

 and petioles, causing a rapid wilting, early defoliation, and subse- 

 quent death of the shoot. The fungous invasion of the young suc- 

 culent shoot is especially rapid and severe. A number of the affected 

 seedlings have dead tops with a few basal living branchlets. Len- 

 der moist conditions, conidial masses of salmon pink color are abun- 

 dantly produced on the lesions. About the end of October small dark 

 brown to black perithecia are irregularly scattered on the surface 

 of the dead area. 



Acervuli erumpent, scattered or gregarious, 100-140/* in diameter, 

 conidiophores hyaline, cylindrical or fusoid. 6-15 X 2-3/*, setae among 

 conidiophores. 1- or 2-celled, few or numerous, dark brown tapering at 

 the apex 24-72 X 3-6/*, conidia hyaline, straight with round ends. 

 12-18 X 4r- 6/*. 1-celled. Perithecia single or in groups, partially erum- 

 pent. globose, slightly papillate. 54-141 X 60-114/*, asci ovate-oblong 

 with a collar extending into the apical wall, 8-spored. 36-60 X 6-9/*, 

 paraphyses broad in width, acute in apical portion, 39-55 X 3-8/x, 

 ascospores hyaline, ovate or elliptical, arranged irregularly, 1-celled. 

 10-15 x 3-6/*\ 



This is the most serious disease of Acacia seedlings (especially A. 

 deaJhnfa) in Japan. Losses are very heavy, more than 90 percent mor- 

 tality in some nurseries. 



One of the most important features of this disease is the penetration 

 of the pathogen into the seed, where it may pass the winter as a dor- 

 mant mycelium. The fungus is usually detected in about 5 percent of 

 the seeds collected in Kyushu. The infected seeds are thus the most 

 important sources of the primary infections, which appear in the nurs- 

 eries. It has been thought that the causal organism might be im- 

 ported from abroad with seeds into Japan. In importation of .4- 



