MARKET DISEASES OF FRUITS AND VEGETABLES 41 



affected stock. When the insects extract the sap out of the surface 

 cells of the pod these cells die and become grayish or silvery white. 

 The silvery marks, streaks, and etched areas constitute a superficial 

 blemish that is generally overlooked by the trade unless the appear- 

 ance of the lot as a whole is greatly injured (pi. 11, B). 



No decay has been observed to follow thrips injury on peas. 



PARSLEY FAMILY 



Within the botanical family of plants known as the Umbelliferae, 

 or parsley family, are found in addition to many wild species a 

 number of important cultivated plants. Chief among these are anise 

 (Pimpinella anisum L.), caraway (Carum carvi L.), carrot (Daucus 

 carota L.), celery (Apium graveolens L.), dill (Anethum graveolens 

 L.), finocchio (Foeniculum vulgare L.), parsley (Petroselinum hor- 

 tense Hoffm.), and parsnip (Pastinaca sativa L.). As a group they 

 are characterized in part by the possession of abundant volatile oils. 

 Consequently, many are used for the flavoring value of their seeds or 

 for the flavoring and garnishing value of their leaves. Others are 

 eaten for the flavor and food value of their leafstalks or taproots. 



Carrot 



The carrot (Daucus carota L.) is grown for its elongated edible 

 crown tuber or fleshy taproot. The most desirable types have a 

 slightly tapering or nearly cylindrical root of moderate size. Any- 

 thing that impairs the appearance, flavor, or crispness of the root 

 reduces the marketability of the crop. 



Carrots pulled while immature are usually tied together in bunches 

 of four or five and marketed immediately with the tops on; but 

 sometimes they are topped. Those allowed to mature in the field 

 are pulled, topped, and marketed either immediately or after several 

 months in storage. 



The carrot is subject to a number of diseases that affect the foliage 

 in the field; chief among these are bacterial blight (Phytomonas 

 carotae Kendrick), cercospora leaf blight (Cercospora apii Fres. var. 

 carotae Pass.), downy mildew (Plasmopara nivea (Ung.) Schroet.), 

 Macrosporium leaf blight, and yellows. (See Celery, Mosaics and 

 other Virus Diseases, p. 53.) 



Diseases that affect the root in the field include primarily bacterial 

 soft rot, rhizoctonia crown rot, root knot (Heterodera marioni 

 (Cornu) Goodey), sclerotium rot (Sclerotium rolfsii Sacc). (See 

 Beans, Sclerotium Rot, p. 30) , and watery soft rot. 



The most important diseases of carrots in transit, storage, and on 

 the market are bacterial soft rot, black rot, fusarium rot, gray mold 

 rot, rhizoctonia crown rot, rhizopus soft rot, and watery soft rot. 



(See 181, 215.) 



BACTERIAL SOFT ROT 



(Erivinia carotovora (Jones) Holland) 



Bacterial soft rot of carrots is of most importance on roots that 

 have been topped and held in farm storage, although it may occur 



