336 



Pomona College Journal of Economic Botany. 



Description of Plates 



PLATE I. Carnation plant in which the shoots on the right appear healthy, 

 and those on the left are aflfected by the Fusarium disease, showing difference in the 

 condition of the affected part, particularly in the appearance of the leaves. 



PLATE IL Photographs of poured plate cultures twelve days old growing on 

 nutrient agar (M4). Natural size. Fig 1, Culture of Fusarium oxysporum strain 

 (H). The mycelium is depressed and slightly yellow in appearance. Fig 2, Culture 

 of Fusarium (E) isolated from a diseased carnation. The concentric zone effect is 

 due to the different degrees of density and height of the aerial growth. The my- 

 celium corresponding to the inner light zone is purple (Saccardo Chromotoxia). 



PLATE IIL Photographs of poured plate cultures twelve days old growing on 

 nutrient agar (M4). Natural size. Fig 1, Culture of Fusarium (R) isolated from a 

 diseased carnation. The growth is cottony and has a very slight pink coloration in 

 the central part of the plate. Fig 2, Culture of Fusarium (IV) isolated from a 

 diseased carnation. The growth is cottony and has a slight yellowish tinge. 



PLATE IV. Photographs of tube cultures twenty-three days of age. Tubes 

 a, d, e, and f are growing on beet agar (M2). Tubes b and c are growing on nutrient 

 agar (M4). Natural size. The tubes labeled (IV), (R3), (E3), and (E2) represent 

 different strains of carnation Fusarium. The tube labeled (H) is a culture of F. oxy- 

 sporum. All the strains from the carnation show a vigorous aerial growth and an 

 abundance of color. The clearly defined pellicle at the surface of the slant is due to 

 a deep wine-red coloration of the medium. This color shades into a lighter pink im- 

 mediately above, but the central parts of the cultures have a sulphur yellow colora- 

 tion and the upper portions remain white. The tube containing the F. oxysporum 

 culture shows a depressed growth and a very pale salmon coloration in all parts 

 except in the slight growth extending above the upper point of the slant; this is 

 cottony and white. 



PLATE V. Drawings to show various stages in the development of the 

 Fusarium fungus. 



Figures 1-8 represent various stages in the development of the carnation 

 Fusarium. Figure 1, Macroconidia being cut off from a short lateral hypha. XICXX). 

 F«gure 2, Macroconidia being cut off from a terminal hypha. XICXX). Figure 3, 

 Typical macroconidia developed in cultures on rice. Length 40 u., diameter 5 u.-7 u. 

 X500. Figure 4, Typical macroconidia taken from a cluster of spores that developed 

 on the stem of a diseased carnation in the field. Length 25 U.-60 u., diameter 4 u.-5 u. 

 Their most common length is 35 u.-50 u. X500. Figure 5, A typical chlamydospore 

 formed by the terminal swelling of a hypha. XIOCX). Figure 6, A germinating macro- 

 conidium forty-eight hours old. X500. Figure 7, A germinating macroconidium 

 twenty-four hours old. XIOOO. Figure 8, A simple sporodochium showing the forma- 

 tion of spores. X500. I-'igures 9-11, Drawings to represent various stages in the devel- 

 opment of the potato Fusarium. Figure 9, Microconidia being formed on a short 

 luteral hypha. They vary in size from 5 u.-lO u. in length by 2.4 U.-3.4 u. in diameter. 

 XIOOO. Figure 10, Typical macroconidia formed in a culture on potato; they vary 

 from IS U.-35 u. in length by 3.2 u.-5 u. in diameter. They are commonly 20 u.-30 u. 

 in length. X1(XX). The constrictions at the septa are often conspicuous. Figure 11, 

 a, Chlamydospore produced by a terminal swelling of a hypha. b, Chlamydospores 

 produced by intercalary swellings of the hypha. c, A mature chlamydospore. XIOOO. 

 The chlamydospores are usually 10 u.-12 u. in diameter. 



