492 DISEASES OF CULTIVATED PLANTS 



the following season, when they germinate and infect the 

 roots of young tomato plants. 



These conidial stages obviously belong to the life-cycle 

 of a Nectria closely allied to N. solani, if not identical with 

 it, but I have not succeeded in obtaining the ascigerous 

 condition, which probably only occurs on quite old, dry, 

 dead portions of the stem or root. 



The Diplocladium has erect branches bearing two or three 

 whorls of branchlets ; the hyaline, elliptical, i-septate, conidia 

 are borne singly at the tips of the branchlets, 5-6x1 "5 fi, 

 but somewhat variable in size. 



Fusarium conidia, fusiform, curved, 5-7-septate, hyaline, 

 45-80 x 4-5 \>. Chlamydospores or resting-spores, globose, 

 hyaline, or tinged amber at maturity, terminal or interstitial, 

 18-35 /'- diam. 



As infection takes place underground, spraying is of no 

 service. Plants should be removed and burned on the 

 first clear symptoms of the disease, otherwise the Fusarium 

 conidia, which are produced in immense numbers, are 

 readily dispersed and infect other plants, and an epidemic 

 is set up which it is most difficult to check. I have not 

 succeeded in infecting a plant with the Diplocladium conidia. 

 There is a tendency on the part of some growers to allow 

 diseased plants to remain, arguing that half a crop is better 

 than none ; this, however, is false economy. Many growers 

 firmly believe that the germs of the disease are carried 

 in the seed. I have never been able to find mycelium 

 in the seed, but I have frequently found Fusarium spores 

 embedded in the glairy mass that surrounds the seed. Such 

 spores, if placed in the soil along with the seed, would 

 probably give origin to the disease. It is very risky using 

 the soil that has produced a diseased crop for future crops; 

 but remembering the great cost of removing and replacing 

 soil in a house, suspected soil should be thoroughly mixed 

 with gas lime, after which it should be allowed to remain . 

 for certainly ten weeks before anything is planted in it. 

 Seed obtained from diseased fruit, or from a diseased area, 

 should not be used. 



Collenette, Roy. Hort. Soc, 19, pt. 1 (1895). 

 Massee, Gard. Chron., June 8, 1895. 

 Massee, above repeated in /burn. Soy. Hurt. Soc, 19, 

 pt. . (1895). 



