PHYCOMYCETES 145 



in the packing house, and in storage conditions. From the 

 description subsequently given it may be readily distinguished 

 from forms of decay due to common mold fungi. It is most 

 serious in connection with lemon growing, but the fungus pro- 

 ducing the disease may also affect to a slight extent at least the 

 orange, pomelo, and other citrous fruits. In the orchard the dis- 

 ease may be found upon" fruit which has fallen, or that which 

 is hanging very close to the moist soil. It is most abundant 

 during wet weather, or follow- 

 ing irrigation, and is therefore 

 intensified where the soils are 

 heavy. It is estimated that under 

 favorable conditions for the fun- 

 gus a box of lemons per tree 

 is no extraordinary loss. 



Symptoms. The first indica- 

 tions of the trouble may be noted 

 in a brownish or purplish dis- FIG. 46. BROWN ROT OF LEMON 

 coloration of the rind, showing < After R " K Smith > 



light on the greener fruit, and darker on the yellow fruit. Both 

 young and old, vigorous and weak fruits alike are affected, and 

 the disease is particularly characterized by a marked and peculiar 

 odor, by its rapid spread from fruit to fruit, in the packing house, 

 or while stored in boxes, and by the presence of small flies 

 wherever the affected fruit is stored in quantity. After storage 

 for a week or ten days there may develop upon the affected 

 lemons a white mold-like growth (Fig. 46), and frequently upon 

 such affected fruit there is subsequently produced also the blue 

 mold, Penicillium. The blue mold alone, however, does not 

 spread rapidly, and has not the peculiar odor of the brown- 

 rot disease. The disease may appear upon fruit in storage, 

 which seemed to be perfectly colored and sound when passed 

 by the washer. 



The fungus. The fungus concerned in the production of this 

 decay is apparently one which was unknown until attention was 

 directed to this lemon disease, and which, while it is an active 

 parasite of citrous fruits, it is doubtless ordinarily a common sapro- 

 phyte found in moist soils and in water. The mycelium of this 



