Carrot Diseases and their Management

Abstract

Wherever carrots are grown, a variety of diseases reduces both the yield and the market value of the roots. Roots destined for the fresh market must be almost blemish-free; yet, at least three bacteria and twelve fungi cause lesions that reduce their value. Bunching carrots must have damage-free tops as well as roots but foliage, too, is attacked by a large number of pathogens. While tops are not an issue for bulk, cello-packed, or lightly processed carrots (e.g., ‘cut and peel’), healthy tops are critical for harvest since the undercut carrots are often mechanically picked up by the leaves. The presence of heavy infections causes inefficient harvesting and yield losses. Several viruses and phytoplasmas also cause damage to carrots both in the form of malformed roots and direct yield losses of plants. Because of the nature of the carrot root, damage caused by various nematodes is an important limiting factor in carrot production. Some nematodes, for example, have a ‘zero tolerance’ threshold, i.e., the presence of nematodes in soil at the start of the season will result in some crop loss. Various pest control strategies, including cultural practices, such as irrigation management, crop rotation, the production of clean seed, and bed preparation, in addition to chemical disease control, are used to limit economic losses to diseases.