6 MISC. PUBLICATION 5 41, U. S. DEPT. OF AGRICULTURE 



Marketability of the buds depends upon their stage of maturity, 

 their freshness, and their freedom from disease and insect injuries. 

 The buds must be harvested before they are too mature; otherwise 

 the receptacle and scales will be tough and lack flavor. Toughness 

 and drying-out may also occur in small buds produced on old plants 

 or in buds that are held too long or in a dry place after harvest. 



Of the relatively few diseases to which globe artichokes are subject 

 the more important are gray mold rot, leaf spots (Oercospora obscura 

 Heald and Wolf, and Ramularia cynaras Sacc), powdery mildew 

 (Erysiphe cichoracearum DC), root rot (Phytophthora megasperma 

 Drechs.), and the virus diseases mosaic and yellows. 



The only market disease of significance is gray mold rot. Buds 

 damaged by bruising, by field freezing, and by feeding of the arti- 

 choke plume moth larvae (Platyptilia carduidactyla (Kiley)) are 

 frequently seen on the market. 



(See 70, Ml.) 



Freezing Injury 



Globe artichokes freeze when exposed to temperature below about 

 29° F. Severe freezing kills the buds and causes them to turn black 

 soon. Slight freezing results in breaking, cracking, and blistering of 

 the epidermis on the exposed parts of the outer bracts. The loosened 

 areas of the epidermis are whitish, and the bud as a whole may be- 

 come somewhat browned. This detracts considerably from the 

 market appearance of the buds. 



(See HI, 157.) 



Gray Mold Rot 



{Botrytis sp.) 



OCCURRENCE, SYMPTOMS, AND EFFECTS 



Gray mold rot is at times an important field disease and is regularly 

 the most prevalent market disease of globe artichokes. It also occurs 

 on the market on all the other vegetables included in the present 

 publication. 



Under humid conditions the lesions of gray mold rot are moist to 

 wet, odorless, and reddish brown or brown (pi. 3, A and C). The 

 borders are definite and slightly water-soaked. Under dry conditions 

 the advancing edge is not water-soaked and the affected tissues are 

 dark brown, dry, and firm. Decay lesions can be distinguished from 

 bruised areas by the deeper penetration of the discoloration. 



Lesions may appear anywhere on the bud. Commonly they origi- 

 nate at the cut surface of the stem and at the tips of the bracts where 

 splitting has occurred (pi. 3, C). Under humid conditions the de- 

 cayed areas become covered with the grayish mycelium and the 

 velvety, grayish-brown spore masses of the pathogen, in themselves 

 characteristic signs of the disease (pi. 3, B). 



CAUSAL FACTORS 



Gray mold rot is caused by a species of Botrytis of the cinerea type. 

 The fungus is found wherever vegetables are grown, since it is able to 

 live on plants of many kinds. Spores produced abundantly under 



