Black Mold

Disease

Black Mold

Alternaria brassicae

fungi

In a Nutshell

    Grayish-brown, circular spots of different sizes appear on leaves, often with a chlorotic haloOver time, the centers become thin and papery, eventually dropping out to give a shot-hole effectLeaves become chlorotic and defoliation can ensue in severe casesDamping-off of the newly emerged seedling growing from infected seeds

Hosts: %1$s

· Turnip · Cabbage · Radish · Canola · ·

Symptoms

All aerial parts of the plant may be attacked and different degrees of susceptibility can be found in different crops. Usually grayish-brown, circular spots develop first on older leaves. These range from small discrete black specks to large zonate lesions up to 12 mm diameter with brown centers. These lesions may have a sooty mass of spores in their centers and be surrounded by a chlorotic halo. Over time, the centers become thin and papery, eventually dropping out to give a "shot-hole" aspect to the lamina. Leaves become chlorotic and defoliation can ensue in severe cases. In seedling growing from infected seeds, the pathogens usually cause damping-off of the newly emerged plants. Spots can also appear on pods or at the base of the stem, causing the symptom known as blackleg.

Trigger

The symptoms vary slightly depending on the crop in question and are caused by the seed-borne fungus Alternaria brassicae, a common pathogen of cabbage and other species of Brassica. Another related species of fungus, namely Alternaria brassicola, may also be encountered in some of these crops. The main way of transmission of these pathogens is through infected seeds. They may have spores on the seed coat or fungal threads in the internal tissues. In both cases, the fungus gradually colonizes the developing plant and lead to the appearance of symptoms. The fungus can also overwinter on susceptible weeds or non-decomposed crop debris. In that case, the spores landing on healthy plant enter the tissues through the natural pores on leaves or through wounds. In any case, humid conditions, windy rain and warm temperatures (optimum 20-24°C) favor the infection process.

Biological Control

No biological treatment or method seems to be available to fight this pathogen. Please contact us if you know of any.

Chemical Control

Always consider an integrated approach with preventive measures and biological treatments if available. Monitoring and correct diagnosis are essential to understand the need of an application with fungicides. Seed treatment is strongly recommended. Foliar sprays in the field once the the first symptoms have been detected is another way to control the disease. Finally pre-storage dips may be employed in some cases to avoid the development of the disease during storage. There is a variety of compounds that could be used, depending of the scope of the treatment, the crop in question, and the environmental conditions. These include: anilazin, chlorothalonil, difenoconazole, iprodione, mancozeb, maneb, vinclozolin. You can also spread Calcium Cyanide.

Preventive Measures

    Make sure to use healthy seeds from certified sourcesIn turnip, some degree of resistance to this pathogen is available in some varietiesLeave sufficient space between plants when planting to allow for a good ventilationRegularly monitor the field for signs of the diseaseRemove and collect old leaves that are in contact with the soilRemove infected debris after harvestRemove weeds in and around the field, particularly weeds from the Brassica family




Features

Regional Weather

Get detailed forecast and actual weather data.

Plantix offers detailed weather information on the following issues:

Precipitation

Humidity

Air Pressure

Temperature

Wind speed

Plantix Community

Get in touch with experts around the world.

Post your questions

You can post your questions and pictures and get feedback from other farmers or gardeners. Plantix' experts will answer your questions related to plant diseases and pests.

MyCommunity

Exchange with Plantix users around you, in your language and related to the crops you grow.

Global Community

Connect to farmers, gardeners, experts and interested people around the world that discuss plant diseases, remedies and best practice for sustainable farming.

AI-Driven Disease Detection

Instant diagnostics and solutions based on your picture

Image Recognition

Plantix analyzes your picture within a few seconds and gives you instant feedback on your plant problem.

Customized Management Options

On top of the detection result, Plantix offers you a detailed description of possible solutions - both biological and conventional.

Preventive measures

Plantix offers information on preventive measures to protect your crop from the next attack.