MARKET DISEASES OF FRUITS AND VEGETABLES 43 



this condition show no signs of the disease on the outside, are difficult 

 to eliminate during the packing process, and consequently may some- 

 times reach the market. Badly "smutted" figs, when squeezed, give off 

 from the eye a black cloud consisting of the spores of the fungus. 



CAUSAL FACTORS 



Black mold rot is caused by the fungus Aspergillus niger. The same 

 species causes the black mold rot of onions and a decay of the fruit and 

 fruit stems of grapes. The fungus is widely distributed in nature and 

 is undoubtedly common on the soil surface and on vegetable debris; 

 it has also been found to live over from one season to the next on the 

 small twigs of fig trees. Infection is brought about by spores carried 

 through the eye of the fruit to the interior by ants, fruit flies, and vari- 

 ous beetles. Such insects are able to make their way into figs so green 

 that the eye still appears closed : they enter more easily of course when 

 the eye has begun to open, as in figs that are mature but still unshriveled. 

 Observations in the orchard show that most of the natural infections 

 occur in fruits that are in this condition. In figs fully mature and 

 shriveled, the sugar content of the pulp is so high that the fungus can- 

 not grow. 



CONTROL MEASURES 



Most of the infection takes place while the figs are still on the tree. 

 Some of it. however, seems to take place after the fruit has fallen, 

 especially if too long a time is allowed to elapse before it is picked up. 

 Naturally, under such conditions, greater opportunity is given for the 

 entrance of insects and the consentient introduction of the fungus 

 spores. More frequent pickings, certainly much oftener than once 

 every 2 weeks as sometimes happens, would prevent at least a part of 

 the "smutting*' and would at the same time give a cleaner, better 

 appearing product. No methods are known by which the fruit can 

 be kept free of the disease while still on the tree. 



(Sets 34, 56, 66, 86, 88, 107.) 



BLUE MOLD ROT 



(PenicUUum sp.) 



Blue mold rot, caused by PemcUlium sp., is sometimes found on fresh 

 figs on the market. Its development is relatively slow and the affected 

 tissues are only slightly softened. The disease is readily recognized 

 by the blue-green color of the fungus growth. 



CLADOSPORIUM SPOT 

 (Cladospofium hefbarum Lk. ex Fr.) 



Gladosporium Tierbccrum is the cause of occasional spotting of figs. 

 The spots appear first as dark olive-green specks that are particularly 

 noticeable on light-skinned varieties. As they enlarge they become 

 slightly depressed and finally turn to a yellowish-olive color. The 

 spots are found chiefly on overripe figs and are not of economic im- 

 portance. 



Methods of control are the same as recommended for alternaria spot 

 (p. 42). 



(See 25.) 



