6 MASS. EXPERIMENT STATION BULLETIN 427 



Species of Alternaria and Macrosporium on the Caryophyllaceae 



Several species of Alternaria and Macrosporium have been described on mem- 

 bers of the Caryophyllaceae, and they all appear to be distinct from Alternaria 

 dianthi (Table 1). Macrosporium nobile Vize was found in dead stems and leaves 

 of Dianthus at Forden, England, by Rev. J. E. Vize and originally reported 

 by M. C. Cooke (17, 18). Later British accounts of Macrosporium nobile (19, 

 41, 42) described the fungus as being definitely parasitic to carnations in England. 

 The type specimen, Vize, Micro Fungi Brit. No. 63, however, bears only the 

 fungus Heterosporium echinulatum (Berk.) Cke., a prevalent fungus on Dianthus 

 associated with small gray leaf spots. The Macrosporium described by Vize 

 may be regarded as secondary and saprophytic. The name appeared once in 

 the American literature (20). 



Cash (12) reported Alternaria dianthi on blighted foliage of Lychnis chalcedonica 

 L. collected at Sitka, Alaska. The writer's examination of this material re- 

 vealed an abundance of Cladosporium, apparently parasitic, also some Hetero- 

 sporium, and a trace of Alternaria which was inadequate for identification and 

 might more properly have been ignored in the naming of the specimen. Seymour 

 (55) listed Cladosporium herharum (P). ex Lk. on many species of Dianthus and 

 Lychnis, and apparently the same fungus is involved in the specimen in question. 

 Bisby and others (7) reported Alternaria dianthi on Dianthus barbatus Linn. 

 The specimen also bears the fungus Heterosporium echinulatum (Berk.) Cke. 

 in much greater abundance. The fascicles of conidiophores arising from the 

 stomata and dotting the blighted foliage belong to Heterosporium. 



Inoculations of Dianthus caryophytlus and cabbage with conidia of Alternaria 

 dianthi were readily successful on Dianthus and unsuccessful on cabbage (26). 

 So far as is known, the fungus is restricted to the genus Dianthus. It has been 

 reported on D. tristus Vel., D. barbatus Linn., D. plumarius Linn., D. chinensis 

 var. heddewigii (Linn.) Regel, and D. Allwoodii Hort. (6). 



Root and Crown Rot 



This disease, caused by the fungi Fusarium avenaceum (Fr.) Sacc, F. cul- 

 morum (W. G. Smith) Sacc, F. poae (Pk.) Wr., etc., is featured by a progressive 

 wilting, collapse, and browning of the entire plant. The roots gradually rot 

 away to the root head. The base of the stem is invaded and rotted. Reddish 

 areas appear among the brown decayed stem and roots. The generalized rotting 

 of roots and crown which characterize this disease is caused by many species of 

 Fusarium, of which the three mentioned are most commonly responsible. These 

 organisms also cause a serious rotting of the snags and nodes in the branches, and 

 wilting of the parts above the infection centers. The disease can be bad in two- 

 and three-year-old flowering stock. These organisms also cause a common soft 

 basal rot of cuttings during the rooting period in the sand bench and after trans- 

 planting. Frequently complete failures result among rooted stock. 



Destructive occurrences of the disease are frequent in July and August among 

 newly benched plants, especially in wet, poorly drained soil. The disease has 

 been the subject of extensive studies by Dowson (24), White (71-75), and Wickens 

 (77, 78). 



Branch Rot or Fusarium Wilt 



This disease, caused by the fungus Fusarium dianthi Prill. & Delacr., is charac- 

 terized by browning of the conductive tissue, wilting, yellowing, and gradual 

 rotting of the stem and branches, and straw-colored dead remains (Fig. 6). 



