The Most Common and Economically Significant Carrot Diseases
Black Rot
(Alternaria radicina)
Black rot typically infects specific parts of the carrot before spreading throughout the entire root. Signs of infection are characterized by clearly defined zones of healthy and diseased tissue, which are easily noticeable. The infected tissue parts are distinctly dark (black). The disease is introduced from the field. Carrots become infected through diseased leaves, with the pathogen moving down to the root or directly from the soil. Black rot is often present in seed carrots and usually spreads through infected seeds.
Powdery Mildew
(Erysiphe heraclei)
In recent years, powdery mildew has emerged as a significant disease in carrots. It thrives in warm weather with high humidity, often present in conditions of intensive production due to irrigation. Initially, powdery mildew appears as very small patches that can be washed off the leaves during irrigation. However, if the mildew occurs extensively, it covers the entire leaf mass and petioles, giving them a white, flour-dusted appearance. The leaf then rapidly deteriorates, and the symptoms may be mistaken for black spot (Alternaria).
Since the fungus can persist on a large number of wild plants in and around carrot fields, it is important to detect symptoms early. It is recommended to inspect crops before irrigation.
Leaf Blight
(Alternaria dauci)
This disease is caused by several species of the genus Alternaria spp., with A. dauci being the most significant in our region. It causes the appearance of black spots, initially on the leaf edges, which then spread to cover the entire leaf, extending to the petioles, causing the whole leaf to wither and die. Once the disease affects the entire leaf mass, it significantly reduces yields and causes the roots to lose flavor quality.
An important protective measure is the use of at least a two-year crop rotation and the sowing of treated seeds. However, intensive carrot cultivation is not possible without fungicide protection. Regular field inspections determine the timing of the first treatment, with subsequent spraying intervals depending on daily infection levels and the susceptibility of the carrot variety or hybrid to the disease.
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