MARKET DISEASES OF FRUITS AND VEGETABLES 35 



by the coming of dry weather. When such fruit reaches the packing 

 house much of the external fungus growth is removed by the brushes 

 and again the damaged fruit may be packed along with sound fruit. 

 In either of these cases the spots become a potential source of trouble 

 during transit and on the market, because of the danger of renewed 

 growth of the fungi through the weakened rind whenever conditions 

 become favorable. 



Water spot is found in highest percentage in groves sprayed with 

 oil. except where the spray mixture consists of miscible oil and lime- 

 sulfur. On trees where this combination is used and on trees given 

 other spray treatments, water spot develops in comparatively small 

 amounts only. When weather conditions are favorable the spot may 

 be expected from about the middle of January to the end of the navel 

 orange season. 



See 35, . k3,!fi.) 



WATERY BREAK-DOWX 



(See Grapefruit. Watery Break-down. p. 10.) 



OTHER SUBTROPICAL FRUITS 



Avocados 

 anthracnose (black spot) 



{Coiletotrich um gloeosporioides Penz.) 



OCCUBKEWCE, SYMPTOMS. AND EFFECTS 



Anthraenose. or black spot, is the most frequently observed rot of 

 softening avocados on the market. It occurs on fruit from all 

 commercial-growing sections and is found on all commercial varieties. 



Spots appear over the surface of the fruit as small light-brown, cir- 

 cular discolorations of the skin. They enlarge very rapidly, and the 

 color changes through dark brown to black in the center of the spot. 

 Usually a light -brown border of fresh decay can be seen surrounding 

 the dark central portion. A single lesion may cover the entire side of 

 a fruit or scattered lesions may coalesce to cover even larger surface 

 areas. These large decayed areas are found only on overripe fruit. 

 If the fruit is in a moist atmosphere pink waxy spore masses are 

 formed on the spots in ma— - a covering. These turn black 



with age. 



The decay penetrates deeply into the flesh, eventually extending to 

 the seed in the form of a hemisphere. The decayed tissue is firmer than 

 the surrounding flesh and is easily separated from it. leaving a fairly 

 clean cavity. Immediately beneath the center of the spot the flesh is 

 black, but this color fades at the edges into a shade of tan only slightly 

 darker than the healthy flesh. 



CAUSAL FACTORS 



The causal fungus. CoUetoirk-hum gloeosporioides, also causes an- 

 thraenose decays of mangoes (p. 45) and citrus fruits (p. 3). It 

 attacks leaves and twigs of the avocado, from which organ- the >p<>res 

 are washed onto the fruit. The fungus is weakly parasitic, attacking 

 only ripe fruits and requiring openings or breaks in the rind to gain 

 entrance. On Florida fruit it very commonly enters through blotch 

 lesions. 



