What is carrot black rot? Why are my carrots turning black? Let’s find out about black rot of carrot symptoms and treatment control guidelines!
Table of Contents
Black Rot of Carrot Definition
Black rot of carrot meaning – What is black rot of carrot?
Even though this disease is important as a carrot storage disease, it also causes seedling damping-off, foliar and crown infection, and umbel blight. There are times when many crops are lost, but black rot is less of a problem when carrots are kept and stored in the field instead of being picked and put in cold storage. All of the main places where carrots are grown have black rot. The disease also affects parsnips and other important Apiaceae crops.
Black Rot of Carrot Causes
What causes the black rot of the carrot? What is the most common cause of the black rot of carrots?
Black rot is caused by a fungus called Alternaria radicina. The spores of A. radicina are either single or in chains of two. They are ellipsoid to oval, measure 20–50 x 10–25 μm, and have seven to eight lateral septa. There may also be one or two longitudinal septa in each segment of each spore. The conidia don’t have the long beaks of many other Alternaria species. Alternaria radicina also attacks the crowns, petiole bases, and roots of celery and celeriac, as well as the leaves of caraway, dill, fennel, parsley, and parsnip.
Black Rot of Carrot Symptoms
Signs and symptoms of black rot of carrot – What are some symptoms of black rot of carrot?
At first, small brown spots on the leaves with green rings get bigger and become black lesions. These lesions are similar to those caused by Alternaria dauci, but they tend to be bigger and leave dark brown or black spots at the base of the petiole. The crowns and upper roots of the new seedlings get weaker and darker as they grow. In the field, crown symptoms are usually black spots that go down into the soil. Secondary black spots can also form on the taproot, especially if broken or split. A. radicina causes dry, black, sunken lesions with sharply defined edges after the harvest. During long storage, roots can grow into each other.
Carrot Black Rot Disease Cycle
Alternaria radicina is often found on the surface of seeds and in the pericarp and testa. The pathogen can live for at least 8 years in crop residues and in the soil without debris. Microsclerotia are structures that help A. radicina stay alive. When it’s warm (above 20º C) and wet for a long time, diseases are more likely to grow. ºThis pathogen can grow at temperatures between -0.5 and 30º C, but it does best at 28º C. Crops can be affected at any stage, but leaves that are about to die are the most likely to be hurt. Infections on the crown come after infections on the petioles.
Black Rot of Carrot Treatment Guidelines
Treatment of black rot of carrot – What is the best treatment for black rot of carrot?
Use seed that doesn’t have a lot of the disease-causing agent. Fungicides or hot water can treat small amounts of seed infection. Plant resistant cultivars. Rotate your crops to cut down on soil-borne inoculum. Foliar fungicides used to treat Alternaria leaf blight should have some effect on the spread of black rot, but specific recommendations for field use have not been made. When harvesting and washing carrots for crops that will be kept for a while, be careful not to damage the roots. During storage, keep the temperature cool (0–1º C) and the relative humidity high.
I hope you understand about black rot of carrot symptoms and treatment control guidelines.