68 U. S. DEPARTMENT OF AGRICULTURE. 



Without a microscope it is quite difficult at times to differ- 

 entiate the various rots of mature tomato fruits caused by 

 Phoma, Colletotrichum, and other fungi. This is especially 

 true when secondary rots have set in and covered up or con- 

 fused the typical clear-cut symptoms. 



It appears, however, that anthracnose and other fruit rots 

 are more common on over-ripe fruit, and occur in southern 

 stock later in the season than does the Phoma rot. The 

 slimy, orange-pink spore masses of anthracnose aid in dif- 

 ferentiating it from Phoma rot. In Phoma rot, slimy spore 

 masses appear very frequently at the openings of the pycni- 

 dia, but these are whitish rather than pink in color. 



This disease is most marked in southern winter-grown 

 tomatoes; that is, the Cuba, Florida, and California crops. 

 It was exceedingly destructive to Cuban tomatoes during 

 the winter of 1917-18, and to Florida tomatoes during April 

 and May of the same season. 



The disease occurs on the vines, where it is known as 

 Phoma blight or black spot. It is not known definitely 

 whether the original infection of the fruit destroyed in tran- 

 sit occurs in the field or in the packing house. The disease 

 develops in transit and in the ripening rooms, and is favored 

 by a warm, moist atmosphere. 



Affected fruit is subject to infection with bacteria and 

 other fungi. 



No satisfactory control of the disease in transit and in the 

 ripening rooms has been worked out. 



Ref. (32); (56); (60). 



TOMATO: SOIL ROT. 



Cause: A fungus (Rhizoctonia). 



In its early stages, soil rot on green or ripe fruit is char- 

 acterized by firm, brown spots which may be marked with 

 concentric rings. Later they increase in size and generally 

 a brown, firm mat of mold covers the older lesions. On 

 mature fruit in the market, soil rot lesions are large, brown, 

 water-soaked areas not sunken and not concentrically 

 marked. 



Soil rot progresses and spreads very rapidly in transit and 

 storage, the fungus passing from one fruit to another 

 through the wrappers. The most striking characteristic 

 under these circumstances is the plentiful development of a 

 coarse, white, and later, brown mycelium with small brown 

 sclerotia. The growth of the hyphae is of a peculiar radiat- 

 ing type, resembling densely crowded spokes of a wheel, 

 and is often further characterized by concentric zones. Very 

 often the mycelium, the sclerotia, and the paper wrapper 

 form a thick, dry and hard mat, or the hyphae may hold the 

 wrapper quite firmly to the fruit so that shreds of it remain 

 when the fruit is unwrapped. Examination of decayed fruit 

 in the market often reveals the original soil rot lesion with 

 its firm, brown and concentrically marked center surrounded 



