Exploring the Phenomenon of White Spot: Unraveling the Mystery of its Origin and Potential Impact


White spot, also known as Alternaria leaf spot, is a common fungal disease that affects a wide range of crucifers within the Brassicaceae family. It is characterized by the formation of small, round lesions that have a yellow halo around them. These lesions can be found on the leaves, stems, and even the flowers of affected plants.

This disease is caused by the fungus Alternaria brassicicola, which uses moisture and cool temperatures to thrive. It is commonly found in areas with poorly drained soils or in fields where crucifers, such as turnips and rapes, are grown. The fungus can overwinter in plant debris or in the soil, and can also be seedborne, leading to its spread from one season to the next.

Infected plants show symptoms such as yellowing leaves, wilting, and premature fruit drop. The disease can also cause stem girdling, leading to the death of affected plants. In commercial crops, white spot can result in significant yield loss and economic damage.

There are several management practices that can help control white spot. Crop rotation, for example, can reduce the incidence of the disease by preventing build-up of the fungus in the soil. Proper sanitation, including the removal and disposal of diseased plant debris, is also important in preventing the spread of the disease. Fungicide sprays can be used to control white spot, although it is important to monitor for resistance and use a combination of different fungicides to prevent this.

In conclusion, white spot is a common disease that affects crucifers, including turnips and rapes. It can cause significant damage to crops, resulting in yield loss and economic loss for growers. By implementing proper management practices, such as crop rotation and sanitation, this disease can be controlled and its impact minimized.

Turnip Mustard

Turnip Mustard, which is also known as Brassica rapa subsp. rapa, is a white spot organism that is commonly found in turnip and mustard crops. It hosts various cole crop pests and can cause significant damage to fields.

Turnip mustard overwinters in soil and can be used as a green manure crop to improve soil health. It is best to rotate turnip mustard with other crops to reduce the risk of disease and pest infestation.

This plant is used for multiple purposes, including oilseed production, livestock forage, and culinary uses. It can be sprayed with water to retain moisture and promote healthy growth.

One of the common diseases that affect turnip mustard is verticillium wilt, which causes yellowing and lesions on the stems and leaves. Another disease is fusarium wilt, which results in stem shredding and yellowing of the plant. If not managed properly, these diseases can cause severe yield losses.

In addition to diseases, turnip mustard can also be affected by other pests such as wirestem, blackleg, and downy mildew. These pests can be managed through proper crop rotation, timely harvesting, and the use of appropriate fungicides and pesticides.

Turnip mustard is commonly grown alongside other cruciferous vegetables, such as cabbage and broccoli. This helps in managing diseases and pests and promotes healthy growth. The harvested leaves of turnip mustard can be used in salads and as a table vegetable.

Fusarium wilt, blackleg, and damping-off are the common diseases that affect turnip mustard. These diseases can be managed through the use of disease-resistant varieties, proper sanitation practices, and the introduction of beneficial organisms.

Another disease that affects turnip mustard is powdery mildew, which can cause premature yellowing of leaves and the formation of white spots. It is important to monitor and manage this disease to prevent its spread and minimize damage.

Sclerotinia, also known as white mold, is another disease that can infect turnip mustard. Once a field is infected with sclerotinia, it can cause rot in the pods and damage the stems. Proper crop management practices, such as rotation and timely harvesting, can help minimize the impact of this disease.

White Spot

White spot is a disease that affects members of the Brassicaceae family, such as turnips and mustards. It is caused by the fungus Leptosphaeria maculans and can be a significant issue in crop production.

The disease is characterized by the appearance of white lesions on the upper surface of the leaves, stems, and fruit. These lesions may develop a gray or brown color as the disease progresses. In severe cases, the leaves may become yellowed and wilted, leading to premature plant death.

White spot can be spread through wind-blown spores, contaminated seed, or by infected crop residues. The disease thrives in cool and wet conditions, but can also persist in dried plant material. Crop rotation, managing weed hosts, and reducing leaf wetness can help to control the disease.

To prevent white spot infection, it is important to follow good management practices. This includes using disease-free seed, practicing crop rotation, and applying appropriate fungicide sprays. It is also important to remove and destroy infected plants to prevent the spread of the disease to nearby crops.

In conclusion, white spot is a common disease that affects turnips, mustards, and other brassicaceae crops. By following good management practices and implementing preventative measures, farmers can reduce the impact of white spot and protect their crop yields.

Comments on the Disease

White Spot, also known as Alternaria Leaf Spot or Blackleg, is a common disease affecting crucifers, including turnips. The disease is caused by the fungus Alternaria brassicicola and can lead to significant crop losses. It is characterized by the presence of small, dark brown to gray lesions on the leaves, stems, and roots of infected plants.

The disease is favored by cool, moist conditions, and can spread rapidly in fields with poor drainage or excessive irrigation practices. It is commonly observed in early spring and late fall when temperatures are mild and moisture levels are high. The initial symptoms of the disease include the wilting and yellowing of the leaves, followed by the development of soft, water-soaked lesions.

White Spot can also cause girdling of the stem, which restricts the movement of water and nutrients, leading to the stunting and death of the plant. The disease can also infect the pods, resulting in rot and the production of black spore masses. Infected plants may also exhibit downy growth on the undersides of leaves and stems.

Management of White Spot involves the use of cultural practices and resistant varieties. Crop rotation, proper drainage, and the removal of diseased plant debris can help reduce the incidence of the disease. Additionally, applying fungicides and maintaining adequate spacing between plants can limit the spread of the fungus.

Other diseases that can affect crucifers and turnips include Sclerotinia, Verticillium Wilt, Fusarium Wilt, and Clubroot. These diseases can cause similar symptoms, including wilting, yellowing, and root rot. Proper sanitation practices and the use of disease-resistant varieties can help prevent the spread and severity of these diseases in growing fields.

In conclusion, White Spot is a common disease that affects turnips and other crucifers. It is caused by the fungus Alternaria brassicicola and can cause significant damage to crops. Proper management practices, including crop rotation and the use of resistant varieties, can help control the disease and minimize crop losses.


White spot management involves implementing various practices to prevent the spread of the disease.

Firstly, farmers should practice crop rotation, as the white spot fungus infects brassicaceae crops, such as mustard, turnip, and crucifers. By planting non-host crops in between, the spread of the disease can be minimized.

Weed management is also crucial in preventing the spread of white spot. Weeds surrounding the planted crops can act as hosts and facilitate the infection process. Therefore, farmers should practice regular weeding to remove potential hosts.

Additionally, adopting good sanitation practices is important. Infected plant stems, roots, and foliage should be removed and destroyed to prevent the disease from spreading. Regularly cleaning and sterilizing tools and equipment can also help minimize the risk of infection.

Fungicides can be used in commercial settings to control the white spot disease. However, it is best to consult with experts to determine the appropriate fungicide and application method.

Other fungal and bacterial diseases, such as clubroot, fusarium wilt, and bacterial spot, can also affect crucifer crops. Following similar management practices as those for white spot can help minimize the impact of these diseases as well.

In conclusion, implementing proper management practices, such as crop rotation, weed control, sanitation measures, and the use of appropriate fungicides, is essential in preventing and controlling white spot and other related diseases in crucifer crops.

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Dr Heidi Parkes

By Dr Heidi Parkes

Senior Information Extension Officer QLD Dept of Agriculture & Fisheries.