The disease white rot, also called sclerotinia, is most commonly caused by the marsupial fungus Sclerotinia sclerotiorum. A variety of crops are susceptible to this disease, such as cabbage, carrots, potatoes, sunflowers, Jerusalem artichoke, peas, grapes, and other plants, both wild and cultivated. It is found everywhere in the middle latitudes.
Peculiarities of white rot
White rot occurs most actively in greenhouses and hothouses because indoor conditions are most favorable for the growth of the pathogen fungus, namely high humidity and poor ventilation. The disease actively develops also in storage.
Both underground and above-ground parts of the bush suffer from sclerotinia. Thus, withering of shrub upper parts, decaying of shoots in the root area, discoloration of leaves, their watery appearance and white patches on their surface is observed. On a cut of the shoot of the affected plant, black fungal sclerotia are clearly visible, and in some cases they also appear on the surface of the organs. As a rule, the plant is affected through the soil, and the disease actively develops in cool (12 to 15 degrees) conditions of high humidity and sudden temperature changes.
White rot control
To get rid of white rot, the problem must be approached comprehensively.
If you only use chemicals to combat it, you will not achieve a long-lasting effect. To maintain the health of the plant, you must necessarily adhere to the agrotechnical rules of culture, properly care for the plant and do not forget about the prevention of the disease. The fact is that plants with a very strong immune system are quite rarely affected by various diseases.
In the affected bushes, conduct treatment of the diseased areas with a healing composition, which can be prepared with your own hands, for this purpose, combine a strong solution of manganese and chopped chalk. Before proceeding to treatment, first cut out all the problem areas with the capture of healthy tissue.
If the affected areas on the bush are very numerous or occupy too much surface area of the bush, experts advise that such a plant should not be treated but dug up and burned.
For spraying sick plants use such means as: Euparen multi, copper sulfate, Hom, Rovral, Bordeaux liquid, Oxyhom, Abiga-Pic or other fungicides containing copper. Also very effective against white rot are such means as: Topaz, Topsin, Previcur, Ridomil Gold, Profit Gold, Skor, Fundazol, Ordan, Acrobat MC, but use them through the season, otherwise habituation may develop.
Since increased humidity promotes sclerotinia, make sure it is not higher than necessary and that the plants are well ventilated. Since pathogenic fungi are in the soil, it must be disinfected before sowing or planting.
If planting house plants, the potting soil can be disinfected in the oven or microwave. And the soil in the garden or vegetable garden should be poured a solution of Fungistop or Fondazole, it should be done three days before planting. When planting any crop in the open ground should always stick to the scheme, which is recommended by experts. Emerging seedlings most often need thinning, because dense plantings are easily affected by various fungal diseases.
Garden and garden plot should be timely cleared of weeds, as well as do not forget to systematically carry out preventive spraying of crops against harmful insects and diseases.
When the harvest is complete, remove all plant debris from the surface of the plot and recultivate it. Be sure to disinfect the storage area before putting the crop in storage. Also, do not forget to sort the fruits, for storage choose absolutely whole and healthy. Periodically check the fruits in storage during the winter, and remove those that show signs of spoilage.
Cucumber diseases in the greenhouse.
White rot of cucumbers.Garden World Website
Treatment of fruit crops
Grape white rot
It happens that the summer after a long hot dry period the rains start and then the hot weather sets in again. It is under these conditions that the conigthyrium diplodiella fungus affects grapes and the development of the disease has two stages: first, the fruits look boiled and later the bushes begin to shrivel up. During the first stage, intensive reproduction of mycelium is observed, and during the second stage, which lasts much longer, the appearance of pycnidia of the fungus on the surface of fruits and leaves occurs. In white rot infested grapes, the appearance of diseased leaves does not change much, they dry out and become darker, but the leaves do not fall off the shrub.
Necrotic ring-shaped spots appear on the affected crop stems, as well as ulcers and longitudinally located cracks. And on diseased fruits, yellow spots initially appear, as the disease progresses they change their color to bluish-brown. Fruits lose turgor, the skin on them surges, and under it appear cavities which contain air, because of this it may seem that the grapes are covered with white plaque. Sclerotinia affects firstly fruits that are outside, but just four days the disease can kill the whole bunch. The diseased grapes will fall off and remain in the ground where the pathogenic fungi can overwinter undisturbed and become active again as spring arrives.
What to do if the first signs of white rot in grapes are discovered? First, try to completely eliminate all contact of the bunches with the surface of the ground. After that, cut off all the diseased areas from the bushes and within 24 hours, treat all the grapes, as well as the surface of the ground under the bushes, you can use fungicides containing copper. The soil on the plot must be treated without fail, otherwise the fungus in it can overwinter undisturbed and in early spring it will again actively attack the vine bushes.
White rot on strawberries
Sclerotiniosis can also affect strawberries (garden strawberries) under certain weather conditions. Such a berry crop is most often affected by gray rot, but sclerotiniosis is no less dangerous for it.
You can tell that the bush is affected by white rot by the white cotton wool-like plaque with irregularly shaped sclerotia of black hue. During the development of the disease, all diseased berries become watery and rot appears on them.
It is very difficult to cure strawberry bushes affected by sclerotinia, as the first thing to do is to make sure that no fruit comes into contact with the ground. A good preventive measure in this case will be to grow such a berry crop in a hanging structure or on the film. If your garden strawberry grows on an ordinary bed, then first cut out all the affected parts of the bushes, and then treat the surface of the soil and plants with a solution of a fungicidal drug.
Finish by covering the soil surface of the plot with a layer of mulch (any organic material).
White rot on cucumbers
White rot in cucumbers damages both the above-ground parts of the bush and the roots. Soggy spots form on the affected shoots that first appear in the root area and then gradually spread to the entire stem. After that, a cotton-like outgrowth of fungus appears on the surface of the spots, and mucus is systematically excreted from it, which runs off the bush and affects the still healthy plants. Over time, the shoots become soft and slimy, with black sclerotia appearing on the fungus.
The diseased plants wither, and their leaves lose their turgor and wither. Fruits that look healthy can not actually be eaten, they quickly rot away, even if they are subjected to heat treatment. Sclerotinia can cause most damage to cucumbers if grown in the same place every year, as well as to bushes growing in unheated greenhouses that are not well ventilated. Thickening of the plantings also accelerates the development of the disease.
At the first signs of white rot, you must begin to fight the disease immediately:
- Remain the humidity level by not watering or feeding the cucumbers for at least 7 days.
- Cut off all diseased parts of the bush.
- Treat the cucumbers with a warm solution of Oxychome or Topaz, choose a dry, windless, but cloudy day for this purpose.
- After treating cucumbers growing in the greenhouse, be sure to ventilate the greenhouse, but be sure to observe the air temperature (as recommended on the fungicide package).
If the disease is just beginning to develop, it is recommended to cut out the affected areas as quickly as possible using disinfected secateurs, making sure to capture the healthy tissue. The root area and the place of cutting should be covered with lime-powder or carbon powder.
When the bush is treated, it is fed on the leaves, using a solution consisting of a bucket of water, 2 grams of copper sulfate, 10 grams of urea and 1 gram of zinc sulfate. If the plant is very badly affected, it should be dug up and destroyed.
Sunflower White Rot on Cucumber
White Rot on Sunflower
Sunflower seedlings affected by sclerotinia rot the root system or the subseedling knee. Adult plants affected by the disease develop brown rotting spots on the surface of the stem covered with a white coat. As the disease progresses, soaking and breaking of the stem occurs.
Wet, dark-colored spots also appear on the basket and are covered with a felt-like fungus infestation. Both cap and inflorescence seeds rot away.
To prevent the disease, you must follow the rules of crop rotation, cultivate varieties resistant to fungal diseases, clean the area after harvesting and in autumn you must dig over or plow the soil. During the growing period Pictor is used to treat sclerotiniosis in sunflowers.
White rot, septoriosis and fomopsis in sunflowers.
Methods of fungicide control
White rot on tomatoes
Sclerotiniosis on tomatoes is caused by the pathogen Sclerotinia libertiana Fuckce. It enters bushes through mechanical damage, and the pathogenic fungi become active in cooler, more humid, and denser plantings. Tomato can be infected by the disease both through shoots and leaves, and through fruit. Affected tissues turn yellow, mucus and white flaky coating appear on their surface, their softening is also observed, and cracks are formed on the skin of diseased fruits. Pathogenic fungi can persist in the soil and also on plant residues.
Therefore it is necessary to remove the remains of bushes from the plot after harvesting the fruit, as well as to recultivate the soil.
To preserve the harvest and prevent white rot of tomatoes, follow the recommended preventive measures:
- Use proper crop rotation;
- To keep optimal humidity and temperature levels in the greenhouse;
- do not overgrow the plantings.
White rot on pepper
Sclerotiniosis can also affect peppers, resulting in stem destruction at the root part. In the beginning, a white coating appears on the surface of the stem, and over time black sclerotia form on it, and then the fungus also appears, which poisons the entire plant. The disease develops most actively in a cool environment (about 15 degrees) with high humidity.
- Before planting pepper seedlings, the soil must be disinfected and the distance between bushes must be such that each is well blown with air.
- Warm water is used for watering.
- Plants affected by sclerotinia are dug up and burned as soon as possible. The bushes left on the bed and the soil surface are sprayed with the same preparations as those used when tomatoes are affected (see above).
White rot on garlic and onions
The onions and garlic are also susceptible to sclerotinia both when grown on the plot and in storage. You can tell that onions are affected by white rot by the foliage, which begins to turn yellow at the tips and then dies off altogether. In affected garlic, the development of chlorosis on the leaves is from the bottom up.
Both garlic and onion scales then develop a fungal plaque that looks a lot like absorbent cotton. Under this plaque, a slimy rot appears. Numerous small black fungus sclerotia appear on the diseased bulbs. As the disease progresses, the plant dies. Weakened bushes that are watered with cold water die most often.
If white rot affects already mature bushes, the bulbs rot in storage, in which case a white-colored fungus with black small sclerotia forms on the fundus. If only one garlic clove is diseased, the death of the whole head is inevitable.
If the humidity is high and the temperature optimum for the infection, it develops most rapidly in slightly acidic soil (pH 5.5). But both garlic and onions should be grown in slightly alkaline or neutral soil, so it is advisable to neutralize acidic soil when preparing the bed for planting.
Also, do not forget the rules of crop rotation: on a site where onions and garlic grew, these cultures can not be planted for several years. Before sowing or planting garlic cloves and seedlings should be disinfected for 30 minutes in a solution of Fundazole (2%) or within 5 minutes they are treated with a suspension of TMTD (3%). The newly emerged seedlings should be inspected systematically and at the first signs of disease all diseased plants should be dug out and destroyed, and the area where they were growing should be covered with a thin layer of lime.
White rot preparations (fungicides)
As mentioned above, white rot is combated with fungicide preparations, so a brief description will be given below:
- Abiga-Pic. This is a broad-spectrum agent containing copper.
It is used against many fungal and bacterial diseases.
- Acrobat MC. The drug is distinguished by its systemic-local action. It is used for various fungal diseases such as sclerotinia, alternariosis, mildew, phytophthorosis, peronosporosis, etc.
- Bordeaux mixture.
Such a contact fungicide is characterized by a wide spectrum of action. It is used not only for treatment but also to protect cucurbits, fruits, flowers, berries, vegetables, citrus and ornamental crops from many diseases.
- Copper sulfate. This copper-containing contact agent is used to treat plants for many different diseases and has a broad spectrum of action.
This broad-spectrum systemic contact agent is used to treat those diseases caused by fungi of the oomycete subclass.
- Ordan. This contact-system agent is used to treat various plants affected by fungal diseases (for example, white rot and phytophthorosis). It can be used both in the greenhouse and in the open ground.
This fungicide is characterized by its systemic properties. It is used as a protective agent against peronosporosis and various rots as well as a growth-stimulating agent.
- Profit Gold. A systemic contact preparation used to control fungal diseases.
- Ridomil Gold.
This fungicidal agent having contact-systemic action is also often used to treat plants affected by fungal diseases.
- Rovral. This is a contact agent characterized by high efficiency and used against the whole complex of diseases.
- Skor. This systemic preparation used in the control of fungal diseases is characterized by a pronounced therapeutic and long-lasting preventive action.
- Topaz. This systemic agent is used in most cases for preventive treatment of plants against fungal diseases at the very beginning of the growing season.
- Topsin-M. This systemic agent is used both for prophylaxis and treatment of various diseases. In preventive treatments with the remedy before the first signs of disease appear, it has very high protective properties.
- Fundazol. Such systemic broad-spectrum drug is also used as a dressing agent for soil, seeds, planting material. It has both therapeutic and protective effects.
- Hom. A fungicide of contact and systemic-local action is used to treat plants against various diseases.
Native remedies used in the fight against white rot are very few, or rather, it is only one. To prepare it, combine 3.5 liters of water, half a teaspoon of copper sulfate and one and a half liters of milk whey. Spray the affected bushes with the mixture.