Cercospora Radish Management: Treatment of Cercospora Leaf Spot on Radish Leaves

Radishes are one of the easiest crops to grow. From seed to harvest, it often takes only a handful of weeks. But, as with any plant, radishes can develop disease symptoms that can affect the crop. Radish leaf spot is one such disease that can cause seedlings to die or, in older plants, reduce the size of the edible root. The disease is present in the soil and in cruciferous plants. Find out how to manage Cercospora radish and what you can do to prevent the disease.

Recognize the cercosporeal stain on radishes

If you had a penny for every potential disease or pest problem that could affect your garden, you’d be rich. Radishes are fairly hardy plants, but even they are prone to disease. One of the most common diseases is hedge leaf spot in radishes, also known as early blight. Unfortunately, it is similar to many other leaf spot diseases and can be difficult to diagnose. Fortunately, it is fairly easy to prevent.

A fungus causes the radishes to have a stain on the leaf of the hedge. The disease starts on the leaves but moves quickly to the petioles. Leaves develop large round grey or brown lesions with dark edges. The

The petioles become infected and show long grey-green lesions. Lesions on the leaves become lighter in centre as they mature.

As the infection progresses, the whole leaf turns yellow and eventually dies and falls off. This is a highly contagious fungal disease that can spread quickly to all the leaves of a plant. The lack of photosynthesis to direct cell formation means that root size is greatly reduced. Shortly after leaf fall, the plant dies.

Management of radishes with cercosporeal spot

The fungus Cercospora lives in the soil or in plant waste. It can survive the winter in this way. It can also survive on volunteer plants, some weeds and wild crucifers such as wild mustard. The fungus also affects other members of the cruciferous family, such as cabbage, but it can also infect watermelons, beets and many other vegetable crops.

Spores of the fungus form on the leaves and survive as fallen foliage. Even when the leaves have been composted, the soil can still support the fungus. Temperatures of 55 to 65 degrees Fahrenheit (13 to 18 C.) favour spore growth. The spores are splashed on the plants during rain or watering. They can also be carried by the wind or during cultivation. Good sanitation practices are essential for the management of horseradish cercospores.

Leaf spots on radish can be controlled by cultural and sanitary methods. Several fungicides are also useful if used early in the disease cycle. Copper sulphate is one of those that can be used safely on food crops.

Other useful practices to prevent infection are crop rotation for 3 years and sanitation of equipment. Deep tillage under plant debris can help reduce the risk of infection because radishes do not grow very deep in the soil. At the end of the season, remove all plant material, even if there has been no infection in the current year.

During the growing season, remove any plants that show symptoms. Remove weeds and keep other cruciform vegetables away from the radish crop. Provide good spacing between radishes to promote air circulation and prevent infected plants from spreading the disease throughout the crop.

Fences can infect other types of products, so early detection is essential to control the spread of the disease.