ASCOMYCETES 



243 



to some extent the cambium and the young wood. Much of the 

 injured bark peels off, and as the mycelium is perennial, extending 

 further each season, large cankers may be produced. 



Unicellular microconidia generally appear first. These are fol- 

 lowed, usually on areas killed the previous season, by pale stro- 

 matic cushions of fertile hyphae producing macroconidia. The 

 latter are twice or more septate, sickle-shaped, and are apparently 

 most important in the distribution of the fungus during the 

 summer. The perithecia develop late in the season, or the fol- 

 lowing spring, arising in clusters on the stromata. 



Control. The fact that this fungus seems to follow other injuries 

 suggests that prevention (where preventive measures are necessary), 

 especially in the case of susceptible plants, may be practiced by 

 simply covering up the wounds with a thorough application of 

 Bordeaux mixture or white paint. For example, immediately after 

 a hail storm or after pruning it might be desirable to use the 

 measures indicated. 



XXXV. STEM ROT OF SWEET POTATO AND EGGPLANT 



Nectria Ipomozce Hals. 



Halsted, B. D. The Egg Plant Stem Rot. N. J. Agl. Exp. Sta. Rept. 12: 

 281-283. 1891. 



This fungus has been described as the cause of the stem rot 

 of the sweet potato (Ipomcea Batatas). It is also considered to 

 be responsible for a disease marked by the poor development and 

 unfruitfulness in eggplant in New Jersey. The affected plants 

 manifest the presence of the fungus by a general unhealthfulness, 

 finally yellowing and wilting. An examination of the living plants 

 may disclose a creamy white mycelium near the base of the stem. 

 This mycelium, according to Halsted, bears spores typical of the 

 form genus Fusarium, or the macroconidia of other species of 

 Nectria, that is, curved, hyaline, and pluriseptate. Later the peri- 

 thecial stage appears in clusters at the base of the stem. Genetic 

 connection between these spore forms has been verified by arti- 

 ficial cultures and by cross inoculation. A comparative study of 

 the spore forms indicates that the disease upon sweet potato and 

 eggplant is produced by the same fungus. 



