FUNGI IMPERFECTI 317 



Volutella Dianthi Atk. 1 is not uncommon on carnations in 

 moist situations. It attacks particularly those parts more or less 

 in contact with a damp soil. In favorable conditions the fungus 

 may spread with great rapidity and so weaken the plant as to 

 materially inhibit the production of flowers. It may, however, 

 be more severe on the cutting bench, especially when sufficient 

 ventilation or drainage is not provided. 



XXII. DRY ROT OF POTATOES 

 Fusarium oxysporum Schl. 



SMITH, ERW. F., and SWINGLE, D. B. The Dry Rot of Potatoes due to Fu- 

 sarium Oxysporum. Bureau Plant Ind., U. S. Dept. Agl. Built. 55 : 1-64. 

 pis. 1-8. 1904. 



Much confusion has prevailed concerning the organisms caus- 

 ing some of the diseases of potatoes both in this country and in 

 Europe. Various types of potato rot have been ascribed to a large 

 number of different organisms, oftentimes upon insufficient proof, 

 or sometimes merely from a single observation indicating the as- 

 sociation therewith of a particular fungus. 



It is very probable that many of the diseases described under 

 the name of dry rot, end rot, bundle blighting, etc., are due to the 

 fungus here discussed. Smith and Swingle have, by careful cul- 

 tural and inoculation experiments, demonstrated the causal con- 

 nection of a Fusarium with these types of disease, and they have 

 taken as the name of the species here discussed the earliest de- 

 scribed species of Fusarium associated with such diseases, namely, 

 the one given above, and they would regard as probably synony- 

 mous with this species half a dozen or more names subsequently 

 applied to fungi described as producing more or less similar types 

 of disease in the potato. 



Symptoms. The effect of this fungus upon the host is prima- 

 rily to produce a wilt, although previous to the wilting the affected 

 plants have a tendency to lie prostrate on account of the gradual 

 destruction of the root system by the fungus. The fungus ap- 

 parently gains entrance through the roots, and from these parts 



1 Halsted, B. D. The Carnation Anthracnose. N. J. Agl. Exp. Sta, Kept. 14; 

 385-386. 1893. 



