CORNELL UNIVERSITY EXPERIMENT STATION BULLETINS. 313 



A NEW ANTHRACNOSE OP THE PRIVET. 



4/ 



A few twig:s of the privet {Ligustrum vulgare) received from Penn Yan 

 Tiaving the appearance of blight were communicated to me by Prof. Bailey. 

 From 12 to 18 inches or more of the terminal portion of some of 

 the twigs was dead, the point where the dead portion joined the 

 healthy presenting the depressed line observable on twigs of pear 

 and ajjple affected with the blight. The resemblance to blight, 

 however, was only superficial and confined to twigs in the final 

 stage of the disease. Other twigs presenting an apparently 

 healthy terminal portion were found to be diseased at a point 

 about 12 to 18 inches from the end where a depressed area of 

 diseased tissue was observed, oblong in outline, the longer diam- 

 eter being parallel with the longitudinal axis of the stem. A 

 comparison of the different specimens showed that this diseased 

 area, quite small primarily, and seated only upon one side of the 

 twig, gradually increased in size until eventually it extended 

 entirely around the twig completely girdling it. The supply of 

 nutriment thus being cut off from the terminal portion of the 

 twig, death of that portion followed. 



Seated in the original diseased areas, whether extending partly 

 or entirely around the stem, are minute black elevated points 

 which can be seen with the unaided eye. Figure 1 a and 6 rep- 

 resent portions of twigs, a with the diseased area extending 

 partly around the stem, while h is girdled. In the diseased areas are 

 shown these small black elevations. The disease is produced by a fungus 

 which grows within the stem. These black elevated points are centers 

 where pustules of the fungus are developed, containing its reproductive 

 bodies, or spores. 



Figure 2 represents a very thin section, across one of 

 these pustules, magnified to show the structure of the 

 pustule and the form of the spores. The growth of the 

 pustule has ruptured the epidermis of the stem. In the 

 opening between the broken parts of the epidermis are 

 shown some of the spores. Beneath these are numerous 

 parallel short fruiting threads, or basidia of the fungus, 

 at the end of which the spores are developed. The 

 basidia can be seen to arise from the blackened stroma 

 of the fungus which consists of quite a compact associa- 

 tion of irregular cells, The black color of the pustules 

 comes from the stroma. 



Following the analogy of other anthracnoses these 



spores falling upon other stems would spread the disease. 



. ^ The practical question is, of course, how to prevent the 



^9^0l^^^^^ spread of the fungus, or the starting of the disease 



mur^l^fJi another year. The suggestion might be made to trim 



'^ S the hedge with the shears below the affected parts of 



twigs, and burn the trimmings. It might also be well in the spring just 



before the buds swell to thoroughly spray the hedge with the Bordeaux 



mixture to kill any spores which may have remained during the winter. 



Method of sej)aratio7i of the fungus. — To study the development of the 

 fungus it was necessary to separate it from other common forms of fungi 

 40 



