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White Spot Fungus: Control Of Leaf Spot In Cruciferous Vegetables

White Spot Fungus: Control Of Leaf Spot In Cruciferous Vegetables


By: Jackie Rhoades

Cruciferous plant diseases are those that attack members of the Brassicaceae family such as broccoli, cauliflower, kale, and cabbage. White spot fungus is one such disease that favors the loose leaves of these vegetables and is therefore more of a threat to spinach, kale, and turnips than the tight head of cabbage or the flower heads of cauliflower and broccoli.

White Spot Fungus

This fungus is caused by a species of Cercospora and has become more common in recent years. White spot on leafy vegetables is one of several cruciferous fungal problems. It also goes by the name frogeye.

White spot fungus presents as circular to irregular spots that range from ¼ to ½ inch (.6 to 1.27 cm.) across and scattered across the leaf. It begins as light tan, dry spots and soon turns to papery white lesions on the leaf surrounded by a halo of yellow or pale green. The spots grow and merge. Chlorophyll production is decreased as the green area disappears and soon the leaf begins to yellow and die.

White spot on leafy vegetables can destroy a crop of seedlings or severely deform them. Older plants can survive the loss of their outer leaves.

Cruciferous fungal problems, such as the white spot fungus, are passed along from previously infected plants or surrounding weeds. They are borne on the wind and begin in the cool temperatures (55- 65 F./10-18 C.) and rainy weather of early spring, exactly when cruciferous vegetables should be planted. It becomes more severe as the temperatures rise.

Control of Leaf Spot in Cruciferous Vegetables

Control of leaf spot in cruciferous vegetables should begin as soon as this cruciferous plant disease is discovered. Because the fungus weakens the plant, it may encourage the growth of other cruciferous fungal problems. Fungicides or sprays containing copper appear to be most effective. Because fungicides deteriorate fairly quickly, repeated applications every week or two is necessary to keep cruciferous fungal problems at bay.

There are several things you can do for the control of leaf spot disease in cruciferous vegetables that have nothing to do with sprays or chemical treatments, and the first is sanitation. Fungal spores can overwinter on any organic matter left in the garden. For the smaller garden, this means that all garden debris should be cleared away and disposed of at the end of the season. For larger plots, crop debris should be plowed under after harvest so that the organic matter quickly decays.

While you have no control over rain or temperature, you can plant your seedlings with enough room between them to promote good air circulation and thus faster drying after rain. You can also discourage white spot on leafy vegetables by watering beneath the plants instead of overhead, and clear the ground around your garden plot of weeds that may carry the pathogens.

Crop rotation is another effective method of control of leaf spot in cruciferous vegetables and most other cruciferous plant diseases. Plant your vegetables in a different spot in the garden each year, leaving at least a two-year span before returning them to their original space.

One last tip to prevent the spread of white spot fungus: clean your garden equipment regularly and wash your hands after inspecting contaminated plants. This along with the other practices above should help you keep white spot fungus and other cruciferous plant diseases out of your garden.

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Why Are the Leaves on My Garden Plants Turning White & Dying?

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If plant leaves are turning white and dying, the underlying reason is most likely either sunscorch or powdery mildew. While both of these things can cause white leaves, they are very different in their appearance and treatment options. Prevention is always best, but good maintenance and cultural practices can help to improve your garden's outlook.


Disease emergence is favoured by wet leaves and cool temperatures. Temperatures of 10°C – 15.5°C (50°F -60°F) with moist conditions created by rain, dew or irrigation promote disease development.

The white leaf spot fungus survives on plant remains and seeds of infected plants, and its spores are spread by wind and water splash.

Primary infection spread – When prolonged wet weather conditions occur over autumn or winter (due to rain, dew or irrigation), and temperatures are between 10°C – 15.5°C (50°F -60°F), the lesions on the leaves produce sexual spores which are wind-borne and can spread over long distances.

Secondary infection spread – Later in the season, water splash caused by rain or overhead irrigation spreads asexual spores which will cause further disease in the next season.

The fungus can also survive by overwintering in self-seeded crops or brassica weeds such as wild mustard, wild radish, and shepherd’s purse, which can act as a source of infection to infect newly-planted crops.


Tips for Growing Brussels Sprouts in Winter

Brussels sprouts are a cool weather crop suitable for cultivation in USDA Hardiness Zones 3-9 and their flavor is improved by a light frost. But what about if a heavy freeze is in the forecast? Learn how to protect your brussels sprouts and enjoy a fresh winter harvest in this guide. Read more now.


Leaf Disease identification:

Many farmers may be wondering why some plants in their gardens may be having leaves appearing as though they have dark patches.

There is an easy way of identifying this kind of common plant disease by looking for small and dark spots that are raised occurring on leaves of plants.

By so doing, the farmer is able to take the correct action in order to ensure that the plant is well catered for.

The farmer is supposed to destroy the infected plants. Besides, the farmer should also apply a fungicide on the plant.

This will help in doing away with the small and black spots occurring on the leaves and hence ensuring that healthy plants are the result.

Bacterial wilt Plant Disease

Cause:
This kind of common plant disease is caused by cool and wet weather.

Leaf Disease Identification
Farmers should look up for large, yellow spots on leaves. Those yellow spots often change to a brown color.

Treatment
The appropriate corrective action that should be taken is removal of infected plants. On the other hand, farmers should ensure that they space plants correctly to prevent crowding.

Cucumber mosaic virus

Cause:
The cucumber mosaic virus is a disease caused by organisms called aphids.

Leaf Disease Identification:

Often, farmers might find yellow spotting on leaves of plants such as coffee plants. Also, leaves could appear streaking.

This is a clear sign of this kind of ailment.

Cucumber Mosiac Virus on leaves

Treatment
One corrective measure that should be taken is discarding the virus infected plant. In addition, farmers should maintain a strict aphid control practice.

Black root rot

This kind of Common Plant disease is also referred to as thielaviopsis.

Cause
It caused by damp soil with temperatures ranging between fifty five to sixty degrees Fahrenheit. This temperature is a bit not conducive for plant roots to do well.

Root Disease Identification:

The combination of high temperatures and the dampness of the soil, roots begin to rot.

They appear to have blackened areas. Also, foliage of these plants may appear stunted.

By checking on the foliage of plants for this kind of signs will be a sure way to discover this disease.

Leaf Disease Identification:

This disease usually occurs on ornamental s and soft fruits such as raspberries, blackberries as well as strawberries.

In addition, cabbages are also not left behind as they too may be found to suffer from this condition.

Treatment
This condition is corrected by ensuring improvement of the ventilation if growing plants under glass.

Also, farmers should ensure that they remove the affected areas the soonest the symptoms are detected so to ensure that the entire plant does not get infected.

Cylindrocladium
Cause
This kind of common plant disease is caused by humid environment as well as overhead irrigation.

Leaf Disease Identification:
It is commonly identified by dark brown spots occurring on leaves of plants.

Treatment
This disease is managed by removal of infected plants to ensure that the disease does not spread to other plant sections.

Rhizoctonia
Cause:
This disease is caused by warm and soil that appears to be overly moist.

Identification:
It is identified by the stem rotting at the soil line associated with brown to red lesions.


Treatment
It is best to ensure that the infected plant is removed and the application of fungicides.

Common plant diseases Angular leaf spot

Cause
This disease is caused by seed and plant debris.

Leaf Disease Identification:
It is identified by holes occurring in leaves.

Treatment The disease is managed by growing plants in arid climates. In addition, growing plants that are resistant to harsh conditions will help control the disease.

MealybugsCause:
This Plant disease is attracted by over watering of plants as well as soil with excess levels of nitrogen.

Leaf Disease Identification:
It is identified by small, white insects that have a white coating that appears fluffy.

Treatment The disease is managed by removal of affected plants manually using rubbing alcohol or using of insecticide.

To avoid spreading of disease try to avoid spreading of disease try to avoid working in the garden when plants are wet.

It is not recommended to compost infected leaves. To prevent overwintering of fungal spores.

Anthracnose : Cause
This disease is caused by seed and plant debris.

Leaf Disease Identification:
This disease is identified by leaf tips turning yellow and eventually turning to brown.

It is managed by removal of infected leaves as well as avoiding over watering of plants.

To avoid spreading of disease try to avoid working on the garden when plants are wet.

It is not recommended to compost infected leaves. To prevent over wintering of fungal spores.

Spider mites

Cause
It is brought about by warm heated temperatures. It is identified by fine webbing on the undersides of leaves.

This disease is managed by isolation of plants and pruning of the damaged leaves.

Also, cleaning of infected plants using soapy water may help. Application of insecticides does wonder when it comes to fighting this disease.

⦁ Downy mildew
This common plant disease is brought about by prolonged wetness on plants. It is clearly identified by white mildew on the underside sections of the leaves.

Treatment
This disease is managed by removal of infected plants to ensure that it does not spread to other sections of the plant.

The correct spacing should be done in between the plants to ensure that proper air circulation occurs between the plants.

Prune or Stake Plants for better air circulation.

Tip: Water in early hours of the morning to allow them to dry during the day.

Blight is a common plant disease that is responsible for most sudden deaths of leaves, flowers and stems of plants. There are various kinds of blight including

Fire blight

This is a bacterial disease that mostly affects fruits such as apples, pears, fruit trees and small fruits. Often, affected shoots are usually a bit blackened. Also, farmers may tend to notice lesions on branches as well as limbs oozing an orangish-brown fluid during extremely warm days.

Fire blight should be treated the soonest to ensure that it does not spread to the entire fruit tree as it may kill it.

The farmer should put on some protective gloves and add four cups of water to a bowl. Pour in a cup of bleach to the large bowl containing water slowly to ensure that it does not splash out.

Stir the mixture using a spoon. Go ahead and prune all the branches that are affected by fire blight using a pair of shears.

Immerse the shears in the bleach solution created after each cut so as to ensure that the infection is not spread.

Carefully cut off all the branches at least twelve inches below the last branch which appears wilted as well as discolored.

Gather all the branches that have been cut off and make sure to dispose them at least one hundred feet away from that particular tree being worked on.

Afterwards, put six cups of water into a one-gallon garden sprayer and to them, add about four cups of white vinegar.

Make sure to close the lid of the sprayer then shake vigorously to ensure that the contents mix well. Proceed to putting on protective glasses to ensure that eyes are not contaminated.

Pump the handle that is at the sprayer to exert pressure on the solution. Direct the nozzle towards the tree and it starting from the bottom to the top.

Spray on the leaves as well as under them. Take a step back, and spray the tree again beginning from the top the bottom.

Ensure that the tree is sprayed until the leaves are left saturated and start dripping off the solution. Spray thoroughly on the trunk of the tree that is affected.

Repeat this whole procedure after two weeks to ensure that the fire blight is completely eliminated.

Fungal blight is a disease that occurs on vegetables, shade trees as well as fruit trees. When fungal blight affects tomatoes, peppers or potatoes, it is referred to as early blight.

Farmers might be wondering why there could be brown or black colored spots on leaves which develop concentric rings.

When the blight is just too much, the leaves may dry up and eventually die as the spots grow close together.

First symptoms are usually on the lower leaves. For potato tubers, they tend to develop dark spots that seem sunken.

Early blight often occurs at any given time during the growing season with relatively high temperatures accompanied by wet humid conditions.

This causes it to spread rapidly.

The best thing to do is to prevent plants from suffering early blight. This is achieved by ensuring that disposing off of infected plants.

On the other hand, the farmer is required to space out plants in a way that they are able to breathe as air is able to circulate freely between the plants.

Also, seeds ought to be purchased from trusted sources to ensure that they are of high quality and healthy as well.

Plants should be checked frequently especially during wet climates to ensure that in case a sign of blight is detected then the corrective action is taken without allowing it more time to spread.

If a sign is detected then, the farmer should use an organic copper spray as it is considered relatively safe.

To avoid causing harm to bees, spraying should be carried out early in the morning before they start roaming around.

However, excessive quantities of copper may build up in the soil if sprayed in large amounts and result to toxicity. In case the farmer adds more copper, then they should consider shifting to another section and plant their crops there.

This common plant disease is known to infect flowers such as holly, lilacs, azaleas and rhododendrons. It causes dieback of shoots and stem cankers of these flowers.

On the other, late blight can also affect potatoes, tomatoes and peppers. The very first symptoms are occurrence of water-soaked spots on leaves that are on the lower sections.

This spots later grow bigger and are mirrored with a white downy growth on the under surface of the leaf.

In the case of potatoes, the black colored blotches often penetrate the flesh and may appear as though they are sunken lesions.

Occasionally, during the wet seasons, the affected plant will often rot and eventually die.

As prevention remains of key importance, treatment measures are also a necessity to prevent infected plants from dying.

The disease can be prevented by ensuring that during the wet seasons, branches of plants are kept off the ground by use of trellis and plant supports.

Use of mulch in plenty can also help to keep this disease away from plants.

It is also very healthy to spray plants from below and not above like most people do.

Also, watering should be done in the early morning hours to ensure that by night fall, the plants are already dry.

In the event of occurrence of blight, then the farmer is obliged to get rid of the affected plants and place them in a trash bag.

It is necessary that the farmer avoids composting the affected plants as this would only result to this contagious disease spreading quickly. And may even affect the plants in the neighboring gardens.

This disease is often identified by dead sections that are a bit discolored on the stems of plants.

Occasionally, they form on woody plants and appear to be cracks, sunken areas or raised areas of dead tissue or abnormal tissues.

These sections often ooze or result to girdle trunks or shoots that may at times cause total death of plants.

There are several types of cankers or forms in which cankers occur.

Cytospora cankers

This kind of cankers is as a result of fungal infections. It is known to affect spruces, stone fruits and popular. They are identified by circular discolored areas occurring on barks of plant.

Nectria cankers

This disease may attack hardwoods, shrubs as well as vines of some plants. However, it is known to cause much damage on maple trees. It is identified by areas that appear as sunken areas around the bark next to wounds.

Also, small and pink structures that produce spores may be seen indicating presence of this disease. Branches and twigs may die in the process while the disease may girdle trees of a tender age.

This disease can be controlled by removal of diseased branches and ensuring limitation of pruning cuts.

⦁ Rusts
This is a common plant disease that is caused by fungal infections and requires two different species of plants to use as hosts in order to complete their life cycle.

They are identified by light tan to rust-hued coating. They often appear on small twigs and needles and needles at first.

It is best to control this common plant disease by allowing plants free space that is adequate to allow free circulation of air. Besides, application of neem oil can be very helpful at preventing this disease because it is responsible for killing the spores on leaves.

In case the plant disease develops, the infected plants should be removed and eventually burnt when autumn season comes.

On the other hand, some types of rusts can be controlled by removing the alternate hosts as it would help to ensure that an outbreak does not occur.

These kinds of rust include white pine blister, wheat as well as cedar apple rust.

Wheat rust needs a barberry plant as an alternate host for the disease to thrive.

On the other hand, white pine blister needs a member of the family of currants while cedar apple requires a combination of both the apple and a relative of the juniper.

Elimination of the mentioned alternate hosts will therefore help to do away with this disease in case of infection of the mentioned plants.

Often, wilting is usually brought about by plants failing to get adequately watered.

However, permanent wilting may be brought about by cases where fungi or bacteria infect plants that are in the wilting process.

Permanent wilting will eventually lead to death of infected plants. There are different types of wilt including

⦁ Verticillium wilting

This refers to a fungal disease that is known to attack a variety of fruits, vegetables, ornamentals as well as flowers. This disease causes plants to wilt and the end result is usually causing them to turn yellow.

Occasionally, the infection enters plants via their roots and usually spreads through the vascular system of the plant. It causes the entire vascular system and the plant at large to die.

Treatment of this disease is impossible as it is incurable the moment it enters the plant. The only option is to ensure the removal of the affected plant and destroying them completely.

In cases where it’s the branch of a plant that is affected, then cutting off the infected region preferably the area below the symptoms would greatly help to slow down or rather reduce the spread of the disease.

However, it is important to note that the disease might remain in the soil even after complete removal of the infected plants.

It is therefore necessary that another area is used for planting other plants lest they also get to suffer from the same disease.

Stewart’s wilting

This is a bacterial caused disease that is usually widespread on sweet corn often grown in the eastern regions of the United States of America as well as Canada.

It is usually identified by decaying of the crown, bleached or yellow streaks on the leaf as well as the internal vascular discoloration.

Often, bacterial slime usually oozes out of the stalks or leaves once they are cut.

The end result is usually death of the plant.

If the plant survives death then, it might end up being sufficiently stunted to an extent that no ears are produced.

This is a common plant disease that often affects vegetables that are in the family of cabbages. It is usually caused by fungi.

Often, plants usually wilt during the day and become revived again during the night while yellow leaves that are older will drop off.

Occasionally, roots usually appear swollen or even distorted. This disease causes the plants to lower their yields or eventually die.

Treatment
Prevention of this disease can be done by ensuring that the garden is clean as well as rotating of crops. Also, controlling of weeds like shepherd’s purse and mustard will help to prevent the club root infection

. In the cases where the plants are infected, then they should be removed with so much caution.

The garden tools used to remove them should be sterilized using a solution of four cups of water and a cup of bleach both combined.

In addition, if club root has been encountered before, the best solution is to adjust the soil pH to a more alkaline level of about 7.2 or at least to a level of at least 6.8 prior planting of plants newly.

However, the spores of this particular disease can persist in the soil for a period of up to twenty years.

In such a case then, the farmer is advised to solarize his or her farm soil in order to get rid of this disease.

⦁ Leaf curl

This is a fungal disease that causes leaves of many trees to appear distorted. There are different types of this kind of plant disease such as the peach leaf curl.

Often, it attacks almonds as well as peaches and is identified by pale new leaves and failure of the midrib to grow along with the leaves thus causing them to curl and pucker as they expand.

The fruit may also get damaged and unfortunately the tree may eventually die as a result of leaf curl disease.

Leaf blister

Oak leaf blister can kill oak trees. It is identified by yellow bumps on the upper surface of the leaves as well as gray depressions around the lower surfaces of the leaves.

Leaf curl and leaf blisters can be prevented by using a dormant oil spray that is usually safe for the tree, pets, humans and the environment.

Also, there is a great dormant oil formula to manage the disease. This oil formula contains two table spoons of canola oil and one table spoon of baking soda which is mixed into a gallon of water.

In order for it to be effective, it is necessary to treat the tree during stages when the tree is dormant. The dormant stages are usually between November and early spring but before breakage of the bud.

The farmer is supposed to fill up the spray bottle with the homemade spray and coat the tree or rather the trees thoroughly.

The stems as well as both sides of the leaves should also be sprayed with the oil. Application should be done only when the fruit tree is dry and not during times when the temperatures are below freezing.

⦁ Black spot

This is a common plant disease that usually affects roses. This spots appear on the leaves of the rose plant up to a half inch across with margins that are of yellow color.

In occasions where they are left unchecked then, an entire rose bush may end up totally defoliating.

Often, when a rose bush is attacked by black spot fungus, then its markings are present until the leaves that are marked fall off and a new leaf is finally generated.

However, the fungus that is responsible for causing the disease can be killed in order to prevent further damage to the foliage and causing death to the entire plant. The marks will remain for a particular amount of time.

Treatment
Prevention remains the key but this disease can be treated in various ways. It can be prevented by ensuring an adequate planting site that is at a position to receive plenty of sunlight as well as circulation.

In addition, frequent pruning as well as using of resistant cultivars. Besides, mulching can also help to prevent dirt and spores from being splash upwards and falling on the plant.

Some people also prefer to use a baking powder spray. This helps to change the level of pH of the leaf surfaces. As a result, this will cause it to be more difficult for the black spot to infect the plants.

An organic solution can be made by mixing a number of tablespoons of baking soda with a particular amount of water. The farmer should proceed to spraying on both sides of the foliage

. This application process should be repeated after every week or after it happens to rain. Neem oil can also be used as it is known to help manage many other rose pests also.

If black spot happens to develop, the farmer should destroy all the dropped leaves.

Pruning should also be applied to plants to control them from contracting these diseases.

This condition occurs commonly on woody branches of shrubs as well as trees. During periods of high rainfall or even watering the plants, a fungus known as coral spot that lives on dead wood might be spread in the course. It appears as pink pustules occurring on the branches of woody shrubs and trees.

It is necessary to ensure that corrective action is partaken the soonest the condition is detected.

Often, the controller should heavily prune the shrub of the tree and ensure that they cut out all the regions that are affected and proceed to burning the parts that have been chopped off so as to prevent the disease from spreading.

In conclusion, it is clear that plants are affected by diseases that are many in numbers. However, treatment is possible to save plants from dying down if carried out effectively basing on the above discussion.


Blackleg (Leptosphaeria maculans)

Blackleg fungus commonly affects the stems and leaves of vegetable brassicas. Stem damage can lead to cankering and severing of the plant at the base. The lesions are light brown with a purplish outline which often contain pinhead-sized, black dots. The lesions tend to be linear and irregularly distributed. Wet and windy conditions favour development of the disease.

Blackleg is predominantly carried over on crop residues but can also be on seed. Once present in the crop, it can be spread by irrigation and rain water splash, or by wind dispersing the spores from the lesions. It can also be spread by farm machinery and equipment.

Clubroot (Plasmodiophora brassicae)

Clubroot causes galls to form on roots of infected plants. The galls interfere with the plant’s uptake of water and nutrients. Under warm conditions, plants often wilt which is usually the first sign of clubroot infection. Wilting plants should be removed from the ground to check for galls on the roots.

The clubroot fungus can remain in infested soil and water for many years. Care should be taken not to confuse clubroot infection with galls that are formed by root-knot nematode. Considerable research into the management of clubroot in vegetable brassica crops in Western Australia has been done. More information is available at Managing clubroot in vegetable brassica crops.

Damping off (Fusarium or Pythium species)

Damping-off disease can occur before or after emergence and typically is associated with wet cold conditions. Obvious signs are missing plants or wilting of newly-emerged seedlings. There may be a wet rot of the stem and seedling stems may become constricted. These fungi are soil-borne and survive in soil without a host being present. They have a wide host range and can survive on alternative non-brassica hosts.

Downy mildew (Hyaloperonospora parasitica)

Downy mildew causes damage from the seedling (cotyledons) to the harvest stage of growth. Leaf symptoms appear as yellowish, irregular areas on the upper surface corresponding to a white fluffy growth on the undersides of leaves. Older lesions become dry, brown and papery in texture and may cause the entire leaf to drop. Cool, moist conditions favour the disease and the head of broccoli and cauliflower curds may be infected with black spots within or on the surface.

The peak period for spore release is after sunrise. Downy mildew is spread by the wind although leaf wetness is required for infection. This fungus-like (oomycete) disease can survive on brassica weeds, in crop debris or soil for several months, even in the absence of a host.

Leaf spot/target spot (Alternaria species)

Two closely related species of the Alternaria fungus (A. brassicae and A. brassicicola) cause this disease. The circular leaf spots vary from mid to dark brown to black. The spots often have a target-like appearance as a yellow halo surrounds the sunken centre.

As well as affecting the leaf, the disease can cause blackening of cauliflower curds. The disease occurs when conditions are moist. The fungus can be carried over on crop residues and brassica weeds.

Powdery mildew (Erysiphe cruciferarum)

Powdery mildew is a fungus that produces a white powdery mould on the top surface of leaves. The disease can occur through to crop maturity and its development is favoured by warm dry weather. The powdery mildew fungus, which is spread by the wind, survives on living tissue and Brussels sprouts, swedes and cabbages are mainly affected.

Ring spot (Mycosphaerella brassicicola)

Leaf spots caused by ring spot fungus look similar to those caused by Alternaria species. The main difference is that ring spot lesions are grey and contain black, pinheads dots in concentric rings. This spot does not damage cauliflower curds or broccoli heads but can render cabbage heads unsaleable unless heavily trimmed.

Severe ring spot on leaves can reduce growth, delaying harvest and damaging crops that are harvested in leaf.

Cool moist conditions are favourable for development of ring spot. The fungus is spread by wind and water splash and survives on crop residues in the soil when a host is absent.

White blister (Albugo candida)

White blister has several strains which can infect different vegetable brassicas. The disease mainly affects the green material although systemic infections can produce symptoms throughout the plant. White blisters form on the undersides of leaves, with a corresponding yellow patch on the upper surface.

The blisters contain white spores, which can be spread by infected produce, crop debris, wind and water splash. Systemic infections can cause distortion of the plant stem as well as formation of galls on leaves. Distortion of broccoli heads can occur, making them unmarketable.

White blister can survive on brassica weeds and on crop residue in the soil. More information is available at White blister disease in vegetable brassica crops.

White leafspot (Pseudocercosporella capsellae)

White leafspot disease is relatively common on Chinese cabbage and mustard-type brassica vegetables but has also been detected on cauliflower leaves. The spots on older leaves are usually circular, about 2mm and larger across and pale brown to white with a papery texture.

Lesions on cabbage tend to be less regular in shape, larger and darker with well defined margins. Spores can be spread by wind and water splash. The fungus can survive on brassica weeds which can be a source of infection in newly-planted crops.

White mould (Sclerotinia species)

White mould fungus attacks a wide range of crops and weeds. There are two species, Sclerotinia sclerotiorum and Sclerotinia minor.

First signs of the disease are water-soaked areas which later become covered by a fluffy white mould. At the late stage of Sclerotinia sclerotiorum infection, black sclerotes about the size of rice grains may be seen in the white mould or inside the stem of the plant.

Sclerotinia minor infection produces smaller black sclerotes (0.5-2mm) that are more rounded. Above-ground parts of the plants can be affected and Sclerotinia can survive in soil for several years without a host being present.


How to Prevent White Spot on Mustard Green Leaves

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Mustard greens (Brassica juncea) are annual plants grown in gardens for their nutritious, edible leaves. Mustard is a cool-season crop that thrives in any ordinary garden soil and is sown from early spring to August for summer and fall harvesting it can be sown in fall for an early spring crop. Although mustard greens are simple to grow and do not have many problems, they are susceptible to fungal diseases, such as white spot, which is persistent in moist conditions. Fortunately, taking certain measures can help prevent white spot.

Plant mustard greens in well-draining soil, or amend the soil by adding a 3- to 6-inch-thick layer of compost over the planting area and using a digging fork to turn the compost into the soil. Mustard greens thrive in rich, moist soil, but poor draining soil can encourage fungal diseases, including white spot.

Keep weeds suppressed around the mustard green plants. Weeds can harbor diseases that are spread to desired plants through wind and rain.

Avoid overhead irrigation. It can encourage fungal disease. Water plants at the base of the stems, preventing moisture from contacting mustard leaves.

Follow a two- to three-year crop rotation plan when growing mustard greens and other non-cruciferous plants. This procedure includes changing the layout of the garden each season so that members of the Brassica family grow in only a certain area once every two to three years.