May 17,1924 
Rots of Strawberries 
645 
nucleus, sometimes as many as five; two or three being the common numbers. 
The nuclear wall is not very distinct in stained preparations but the large 
nucleole is always plainly visible, surrounded by a clear place in the cytoplasm 
(PI. 2, A, 6). 
ARTIFICIAL INOCULATIONS ON STRAWBERRIES 
Strawberries growing in pots in the greenhouse at the Arlington experiment 
farm, Virginia, were readily inoculated by laying pieces of agar bearing mycelium 
on the soil beneath half-grown berries. In every case the berries developed the 
characteristic rot within three or four days. The fungus penetrated the soil at 
the point attacked so that when the berry was removed some of the soil was 
attached to it. The fungus was recovered from such diseased berries by trans¬ 
fer of pulp from points well below the surface. Greenish berries from the 
Washington market have also been inoculated in damp chambers by placing 
bits of agar covered with hyphae from test-tube cultures on the bottom of damp 
chambers and then laying an apparently sound berry on the piece of agar. The 
brown rot developed in every case within two days (PI. 1, G). Since the epi¬ 
dermis of a strawberry is so liable to rupture from all sorts of causes it is not 
certain that the fungus actually penetrated the unbroken epidermis. 
Sections of berries artificially inoculated show that the hyphae crowd in 
between the akene and that part of the receptacle in which the akene is partly 
sunken. It may be that the fungus finds a film of moisture in this region where 
the walls of the epidermis are also easily penetrated. The most noticeable 
effect upon the host tissue is a swelling and clearing of the cells between which 
the hyphae are pushing. The cell contents take very little stain. The fungus 
apparently does not seek out any particular part of the berry. Hyphae are 
found in every tissue in the region attacked. The sieve tubes or long conduct¬ 
ing cells of the vascular bundles leading to the “seeds” are pushed aside and 
hyphae crowd in between them or run along between these cells in all directions 
(PI. 3, A). Hyphae also pack in between the small cells of the pulp between 
the akenes and crowd up close to the cells of the sclerotized and thickened cell 
walls (PI. 3, B). No living tissue appears to be immune. If nuclei were present 
in the diseased pulp cells examined, they did not take the stain. The nuclei of 
the fungus, however, appeared very distinctly (PI. 2, A, b; B). 
THE TAN BROWN ROT OF STRAWBERRIES 
An excellent description of the Pezizella brown rot of strawberries was pub¬ 
lished by Stevens and Peterson * 3 in connection with their account of the organism 
causing the disease. They described this fungus as Patellina fragariae although 
it had already been described under a great many different names. 4 The region 
attacked by the fungus is marked on green berries by the appearance of small 
sunken spots. These spots are tan colored, slightly sunken, and enlarge only 
slowly. When a ripe berry is attacked, the rot spreads much more rapidly 
but the color of the spot is about the same (PI. 1, H). The fungus grows into 
the pulp of the berry so that the rotted portion is deeper than its diameter. 
The core of the region attacked is consumed and the host tissue is replaced by 
mycelium so that the decayed portion finally presents a spongy dry texture. 
The host tissue immediately surrounding the diseased area, although devoid of 
mycelium, becomes soft and wet and its cells separate from each other. As the 
core of the rotten spot is very tenacious it can easliy be removed intact. This 
* Stevens, F. L., and Peterson, A. some new strawberry fungi. Phytopathology. 6: 258-267, 
illus. 1916. 
4 Shear, C. L., and Dodge, B. O. the life history and identity of ** Patellina fragariae,” 
"LEPTOTHYBIUM MACROTHECIUM” AND “PEZIZA OENOTHERAE,” MyCOlOgia, 13:135-170. pi. 8-10. 1921. 
