A dangerous fungal disease that can harm plants and completely destroy the crop.
How to protect plants from it?
Powdery mildew is caused by various types of microscopic powdery mildew fungi. It usually affects plants in warm, humid weather at + 18 ... + 25 degrees. The fungus actively develops at high humidity on a dry surface of tissues in dry weather, without precipitation.
At high average daily temperatures, it also develops in conditions of low air humidity.
Spores do not need liquid moisture to germinate, so rain, watering, and washing the leaves can stop the spread of the disease.
Powdery mildew affects many crops. The symptoms of the disease (as the principles of dealing with it) are the same in each case. Each of the pathogens specializes in only one or a few plant species. Therefore, you should not be afraid that powdery mildew of oak will migrate to phloxes, gooseberries and cucumbers.
What is dangerous powdery mildew
Powdery mildew always appears on young plant tissues - leaves, green shoots, petioles, green berries. Further development of the disease leads to a deterioration in decorativeness, poor winter hardiness, and in berry bushes - loss of yield.
The mycelium, which looks like a thick cobweb, grows rapidly, the spores easily scatter in the form of a white powder, similar to flour. With the development of powdery mildew during flowering, normal pollination does not occur, so the berries are formed ugly, covered with bloom, acquire a mushroom taste and smell.
The concentration of spores in the air and the risk of infection of plants from spring to mid-years is constantly increasing. However, in most plants, by this time the leaves are covered with a protective wax coating - cuticola, and it becomes difficult for fungi to infiltrate living tissue. If timely measures are taken, the disease can be stopped. The infection persists in plant debris and in the root of the affected shoots.
Powdery mildew prevention
- Mixed planting of unstable crops (phlox, roses, delphinium), refusal to grow monoculture in one place.
- Creating conditions for plants for free air circulation. Be sure to break out the extra shoots, garter.
- Timely removal of shoots with signs of disease, plant debris, fallen leaves.
- Deep tillage for annual flower and horticultural crops, as well as between rows.
- Balanced supplements. From the second half of summer - a decrease in the dose of nitrogen fertilizers. During an outbreak of powdery mildew activity (as a rule, the end of June - the beginning of July), it is better to feed the plants with phosphorus-potassium fertilizers, foliar microelements, and add wood ash.
- Regular watering, sprinkling of leaves and crowns can weaken and even stop the disease. Leaf resistance decreases in drought or due to lack of watering (for example, caragana, common barberry, maple get sick faster on sandy soil with a lack of moisture).
- Preventive autumn and early spring tillage in near-stem circles with copper-containing preparations.
- Selection of resistant varieties.
- Before flowering and immediately after harvesting, spraying plantings with a soap-copper emulsion (20 g of soap and copper sulfate per 10 liters of water).
- At the initial stage of defeat by powdery mildew on shrubs and roses, ash helps a lot: the bush is sprayed with water, powdered with ash, after a couple of hours the plant is again thoroughly washed with water.
- ! During the ripening period of berries, do not use chemicals. Potassium permanganate (5g per 10 liters of water) - let it be for a couple of days, but stop the disease just before ripening.
Control measures
To combat powdery mildew, sulfur preparations have been very effective and have long been used. In a fine dispersed form, sulfur is absorbed by the cells of the fungus and, turning into hydrogen sulfide, acts on them as a toxin. Before the leaves open, treat the plant with Thiovit Jet or Cumulus DF. Treat bushes with sulfur-containing preparations in the morning or evening hours, as hot weather can cause burns on leaves and berries. Good for the prevention of "Talendo" and "Karatan".
The development of powdery mildew can be suppressed by spraying plants with special preparations based on triazoles (Topaz, Horus, Skor), before treatment, diseased leaves are preliminarily removed.
The easiest way to deal with powdery mildew- a weak solution of urea. You need to spray in the evening after sunset on the lower and upper sides of the leaves.
Repeated spraying with fungicides is carried out after 10-14 days. For greater effectiveness, it is recommended to alternate drugs. Pay special attention to clipped hedges and plants at risk.
Folk remedies for the fight against powdery mildew
1. 10% aqueous solution of milk or (to save) whey - spray grapes and fruit bushes once a week. Milk fat, or possibly whey protein, then serves as food for microorganisms that compete with powdery mildew for space and eat its spores.
2. Daily infusion of ash(half a bucket of ash per 7 liters of water). Before spraying, dilute with water (1:1) and add 100 g of "green soap" as an adhesive. Pour the bushes from a watering can, wetting the leaves and clusters well. Some colleagues do not insist on ashes, but boil for 20 minutes.
3. Concentrate of saprophytic microflora. In the spring, pour 1/3 of the sown humus into a 100 l barrel, fill it with warm (+20 ... + 25 degrees) water, cover with burlap and keep warm for 5-6 days, constantly stirring. After 5-6 days, the concentrate is filtered through cheesecloth and poured into a sprayer. For prevention plants are treated in the "green cone" stage on cloudy days or in the evening. The second processing - in a week, one more - before flowering.
It is believed that this disease was brought to us at the beginning of the 19th century from America. However, the first mention of rose disease, which covers the leaves with flour, does not refer to America, but to Rome. It happened 300 years before our era. So people first encountered powdery mildew.
Classification of pathogens
The disease is caused by imperfect fungi of the class Marsupials ( Ascomycetes). The most common of them are Spheroteka ( Sphaerotheca) and Erisif ( Erysiphe). These are primitive organisms, the entire mycelium of which can consist of a single huge cell with a large number of nuclei.
- Erysiphe cichoracearum is an enemy of cucurbits, etc.
That is, if powdery mildew struck violets, it is not at all necessary that the nearby ficus is in danger.
How dangerous is a primitive enemy?
The phenomenal ability to mutate is the most important feature of all mushrooms. With powdery mildew fungi in agriculture and greenhouses, they fight by breeding hybrids. Since the hybrid is, in fact, a new type of plant, it is too tough for highly specialized fungi. For several years, you can safely breed hybrid plants. But then Sferoteka (or another fungus) mutates, attacks - and you have to breed the next hybrid...
The reproduction rate of powdery mildew mushrooms is unrivaled. Under favorable conditions (and this is just the microclimate of human habitation), the period from the first spores to the complete death of the host plant is from 5 to 7 days.
Young plants are extremely quickly affected - from shoots to the appearance of 2-3 true leaves. Their cell membrane is still thin, there is no proper level of immunity. In addition, flower seedlings are usually grown in mini-greenhouses. And this is an incubator for the development of powdery mildew. Therefore, special attention should be paid to the disinfection of seeds and soil for mini-greenhouses - after all, if spores of marsupial fungi get there, the seedlings will have no chance. Especially if the crops are thick. Bright and direct sunlight is detrimental to the pathogen - but it can also cause burns in young plants ...
Powdery mildew symptoms
The main symptom of the disease is reflected in its name - in the initial stages it looks like a white powdery coating. Single whitish spots appear on the upper side of the sheet, which are easily erased with the touch of a finger. But just a few hours later, the spots reappear, and their number and area increase. Then the spotting passes to the underside of the leaves, and eventually covers the plant with a continuous bloom.
Depending on the type of fungus, plaque can be white, whitish-pink, light gray, gray-brown, etc. The mycelium of the fungus grows, acquiring the appearance of felt. Then small spherical fruiting bodies - cleistothecia (conidiophores) are formed on its surface. The diameter of the fruit bodies is about 0.2 mm, they are clearly visible to the naked eye. When viewed under a microscope, the shape of the fruiting bodies resembles a bag, for which the mushrooms got the name Marsupials.
In one such bag there are several million conidia spores. Spores are easily spread by air - even a slight movement of air is enough, wind is not required. Conidia are also well spread with the help of water - it is worth wiping a diseased plant, rinsing a napkin in a basin - and all the water becomes infectious. At the spore stage, the pathogen is resistant to most drugs, because the spores are protected by a dense shell. Ascomycetes attack only living plants, and hibernate in the form of spores on dead plant debris.
In most cases, powdery mildew pathogens enter the house after summer "vacations" spent in the garden or in the country. The struggle must begin precisely from the infield:
- all plant residues are removed, regardless of whether signs of damage are seen on them or not;
- if organic residues are used as compost, they should be kept in the compost heap for at least 2 years, and preferably 3-5 years. During this time, the entire mycelium will be destroyed by bacteria that cause fermentation;
- on garden plants, the affected leaves and tops are broken off and burned;
- crop rotations are observed;
- weeds are removed in a timely manner;
- dense plantings are thinned out, especially those that grow in the shade;
- an overdose of nitrogen fertilizers with a deficiency of phosphorus and potassium is unacceptable;
- if measures have been taken to treat powdery mildew, then the next season must be started with preventive treatment of plants on the site.
Greenhouses is the main area of risk. Powdery mildew begins its reproduction most often there. Many gardeners put their houseplants in the greenhouse for the summer to "rest", unaware that this is sometimes fraught with consequences.
In order not to create comfortable conditions for the fungus, greenhouses must be ventilated. During the day, you need to make sure that condensation does not form on the walls of the greenhouses - in a humid atmosphere, the fungus multiplies with tripled force. A properly arranged greenhouse has one window at the bottom (usually at the bottom of the door) and one window at the top, on the opposite end. Thus, natural draft is launched and the owner does not need to worry about forced ventilation of greenhouses.
But sprinkling in a greenhouse, on the contrary, is useful. But it should be carried out in the morning so that the water on the leaves dries quickly. Spray water should be warm, it is useful to add potassium permanganate to it once a week (to a very slightly pink consistency) in order to carry out foliar feeding with potassium.
Pedlars diseases are pests. Aphids, scale insects, thrips spread powdery mildew spores and contribute to their penetration into the plant body, inflicting injections with their proboscis into the flesh of the leaf. Pest control is at the same time the prevention of the spread of powdery mildew fungi.
Powdery mildew control measures
A war is being waged against the marsupials:
- chemical;
- bacteriological;
- mechanical;
- genetic.
Chemical Measures struggle - these are all preparations, ranging from lye and Bordeaux mixture, and ending with the latest developments. The most effective today are Topaz, Bravo, Fundazol and other systemic drugs.
Dusting with colloidal sulfur is an effective measure, especially in the early stages. At the first symptoms of the disease, it is useful to spray the plant with a strong solution of laundry soap, or garlic tincture.
Most ascomycetes are unstable to an alkaline environment (like all fungi). The most accessible and harmless remedy is wood ash, diluted with water 1:10 and infused in the sun (or heated until boiling for 30 minutes). The solution should not boil, otherwise it will turn out to be strongly alkaline. Plants are sprayed with infusion of ash from all sides, or completely dipped into it.
Bacteriological measures include treatment with formulations containing fermentative bacteria. Lactic acid bacteria are a natural enemy of primitive fungi.
Of the available means, an infusion of mullein, an infusion of chopped wheatgrass, thistle or other weed is effective. Condition one - a mixture necessarily should ferment. To speed up the process, you can add a pinch of sugar, or a little yogurt.
Sour-milk products are commercially used by US farmers to combat powdery mildew in grapes.
In home and garden conditions, powdery mildew is removed by treatment with skim milk (whey), sour milk, curdled milk, etc. Dairy products are diluted with water 1:3. If the flower is small, you can simply dip it into a container. The advantage of this method is that the mixture is absolutely harmless to plants, animals and insects.
[!] Spoiled fermented milk products are very useful to add to compost to increase the level of beneficial bacteria there.
Mechanical Methods struggles are the most radical. All damaged organs are removed, fallen leaves, fruits and other residues are removed from the soil. The soil is dug up - once in the summer and always once in the winter.
[!] Regardless of whether chemical or other measures are used, the removal of the affected organs must be carried out.
Genetic Measures have been described above - this is the breeding of hybrids and powdery mildew-resistant plant varieties.
Powdery mildew is an aggressive but unstable disease. If the treatment is repeated 2-3 times, then with a high probability, it will be possible to get rid of it forever.
To prevent the pest from reappearing on flowers, you should observe newly acquired plants. Especially often the carriers of powdery mildew are roses - Tea and Repair, as well as saintpaulias.
[!] Very similar in symptoms to powdery mildew, it is an independent disease and is treated by other methods.
Powdery mildew yavl It is a fairly common harmful disease of both open and closed ground cucumbers.
The causative agent of powdery mildew on cucumbers:
cause two fungi from the class Euascomycetes, department Marsupials - Erysiphe cichoracearum DC and Sphaerotheca fuliginea Poll.Symptoms of powdery mildew on cucumbers:
real leaves are affected, less often cotyledons; on the petioles of the leaves and on the stems, a white powdery coating appears in the last stages of the disease. Initially, the disease manifests itself in the form of the appearance of small rounded spots, which soon merge, and the plaque occupies the entire surface of the leaf blade, which sometimes acquires a reddish color. If the disease enters the active stage, then the leaf blade of plants can be deformed and become concave, acquiring the shape of a bowl. Subsequently, the affected leaves dry up. On strongly oppressed plants, small fruits are formed.Development cycle of powdery mildew on cucumbers:
the pathogen overwinters in the stage of cleistothecia on plant residues
ah, but cucumber plants are affected by conidia during the growing season. Infection can enter greenhouses from open ground and vice versa. Failure to observe crop rotation in the open field and a temporary break between crops in the closed field can also lead to infection of cucumbers with powdery mildew. In addition, weeds such as comfrey, chicory, plantain, field sow thistle can serve as infection reservoirs. Powdery mildew can have 15 generations during the growing season, because. its incubation period is only 3-4 days.
Conditions for the development of powdery mildew on cucumbers:
the optimal conditions for the development of the disease on cucumber plants are temperatures from 16 to 20 ° C, high humidity, and insufficient lighting. With fluctuations in temperature and humidity, the disease can acquire a pathological course of development. Also, infection is facilitated by watering cucumbers with cold water, especially in hot and dry weather, when the turgor of plants decreases, and the pathogen can penetrate through the integumentary tissue.Measures to combat powdery mildew on cucumbers:
cultivation of resistant cucumber hybrids F1 - Katyusha, Kumir, Zodiac 499, Talisman, Pasamonte, Pasadeno, Ofix and Octopus (the last four hybrids were created by our partners - Syngenta company), etc., can significantly facilitate protective measures and achieve the desired yield. Removal of plant residues from the field, weed control and spatial isolation of cucumber crops are the main methods of controlling powdery mildew. On household plots and in small greenhouses, you can use the folk method of fighting infection: spraying cucumber plants with whey or skim water, which are diluted with water in a ratio of 1:10 (1 part whey or skim milk and 10 parts water). On an industrial scale, growing cucumbers requires the use of fungicides. To prevent powdery mildew, both outdoors and indoors, cucumber plants are sprayed with a fungicide. QUADRIS . At the first sign of the disease, fungicides are used.Powdery mildew of currant pathogen. Sferoteka, or powdery mildew on currants, is a fungal disease that is the most common and destructive for shrubs. Because of it, up to 90% of the berry crop is lost. Without treatment, the plant will inevitably die in a few years.
Consider in the article methods of dealing with this disease, folk methods and effective chemicals.
What you will learn from this article:
Powdery mildew on currants description
This is a widespread fungal disease that affects a large number of plant species, shrubs and trees. It is also called bel or ashtray.
The infection is often transmitted by sucking pests - thrips, scale insects, mealybugs, especially aphids. Also, spores of the fungus can get from when watering, from infected specimens through the air, or be transferred by humans through contact with them.
The development of a fungal disease is promoted by high humidity (60-85%), moderate air temperature (16-28 ° C), an excess of nitrogen and excessive planting density. In open ground conditions, the disease appears from the end of May and develops until late autumn. The peak of ashpel development is in June-July.
Powdery mildew prevention on currants
The fight against powdery mildew is carried out in a complex way - in addition to the chemical treatment of shrubs, it is necessary to take the following agrotechnical measures:
- water currant bushes only after the topsoil dries;
- remove and burn all plant residues in the fall;
- observe crop rotation;
- grow powdery mildew-resistant varieties and hybrids;
- do not overfeed currant bushes with nitrogen fertilizers, especially during the flowering period;
- do not forget to apply potassium-phosphorus fertilizers that increase the resistance of shrubs to the disease;
- carry out spring sanitary pruning of shrubs;
- carry out preventive treatment of shrubs with fungicides in early spring and after leaf fall.
Also, for preventive purposes, currant bushes are treated for powdery mildew with chemical means - for example, three or four times pollination with sulfur or three times treatment with Bordeaux liquid or other preparations of a similar action.
Powdery mildew of currant pathogen and control methods
Where to buy seeds and seedlings with delivery
Introducing powdery mildew with descriptions and photos. We list the causative agents of the disease on different plants, shrubs and trees and consider the signs of infection with a fungus. We will also consider downy mildew (peronosporosis) and its features.
Powdery mildew: description
This is a widespread fungal disease that affects a large number of plant species, shrubs and trees. It is also called bel or ashtray.
The infection is often transmitted by sucking - especially often tolerates. Also, spores of the fungus can get with water during irrigation, from infected specimens through the air, or be transferred by humans through contact with them.
The development of a fungal disease is promoted by high humidity (60-85%), moderate air (16-28 ° C), an excess of nitrogen and excessive planting density. In open ground conditions, the disease appears from the end of May and develops until late autumn. The peak of ashpel development is in June-July.
The causative agent of the disease
Microscopic fungi act as pathogens - the order Powdery mildew or Erysiphales (Erysiphales). In this case, the symptoms of the disease are similar when affected by different genera of fungi.
Common species of pathogenic fungi belong to the genera: Erysiphe, Microsphaera, Phyllactinia, Podosphaera (formerly Sphaerotheca) and Uncinula. Some species of them infect certain plants, shrubs or trees.
Worldwide, the most common causative agents of powdery mildew are the fungi Erysiphe cichoracearum and Podosphaera fuliginea.
- Blumeria graminis – cereals (cereals), lawn grasses
- Erysiphe alphitoides – oak
- Erysiphe cichoracearum - family Asteraceae. Aster, marigold, dahlia, calendula (marigold), daisy, sunflower and zinnia.
- Erysiphe cichoracearum, Podosphaera fuliginea, Podosphaera fusca - gourd family (watermelon, melon, squash, lagenaria, pumpkin and zucchini)
- Erysiphe cruciferarum – swede, cabbage, turnip, sugar beet
- Leveillula taurica – onion
- Microsphaera diffusa – soybean
- Moniliniafructigena, Podosphaerapannosa - rose family. Plum subfamily: apricot, quince, cherry plum, hawthorn, cherry, pear, peach, mountain ash, plum, cherry and apple tree. Rose family: strawberry, strawberry, raspberry, rose and rosehip.
- Podosphaera clandestina – apricot and peach
- Podosphaera leucotricha – pear, apple
- Podosphaeramacularis - hops
- Podosphaeramors-uvae – gooseberries, black and red currants
- Uncinulanecator - grapes (oidium - powdery mildew on the vine)
Signs of defeat
On the surface of the aerial part of the plant (usually leaves, young shoots and stem), white powdery spots with fungal spores are visible, they ripen and secrete liquid drops resembling dew.
In most cases, the disease occurs on leaves closest to the soil in the same way that fungi live in the soil. As the infection develops, the spots become larger and denser, a large number of spores are formed and the ashtray can move up or down the plant.
The fruits infected with the fungus crack and rot, and the flowers and buds fall off, and the plant stops growing.
Powdery mildew on a pumpkin leaf
Features of the lesion in various plants, shrubs and trees
Vegetables
Powdery mildew on cucumbers in greenhouses spreads with drafts and insufficient lighting against the background of a weakening plant. Most often, cucumbers near doors and vents are the first to become infected. A fungal disease can destroy vegetables very quickly. Vegetables from the Pumpkin family due to ashtray lose 40-60% of the crop, and the quality of the fruit also deteriorates.
Strawberry, strawberry, raspberry, rosehip and rose
In these species, the entire aerial part is affected, especially the leaves. Their edges are deformed, and the leaves become rough with a bronze tint on the inside. Powdery mildew-infected leaves stand out especially in August-September. On top of the berries and fruits, a powdery coating is visible and a specific aroma of the fungus is heard.
flowering species
In ornamental plants, the leaves darken and fall off from whites.
Gooseberry and currant
In the early 60s, powdery mildew pathogens from gooseberries moved to blackcurrants and since then gardeners have been fighting the disease on both shrubs. The infection bends the shoots and slows down growth, and the leaves become smaller and wither. Gooseberries still suffer from fruits - white spots appear on them, darkening with time.
To treat infection on gooseberries and currants, it is important to cut off the infected tips of the shoots in the spring. Before the flowering of the bushes and after picking the fruits, it is advised to spray them with preparations or folk remedies.
Pear, peach, plum, apple tree
On trees, a fungal disease attacks young shoots, leaves, flowers and fruits. Shoots and buds die in winter, and infection reduces the winter hardiness of the specimen. The leaves stop growing, deform and crumble.
The infection is especially active on old trees. Trees growing on the southern and southwestern sides of the hill suffer more from powdery mildew. It is important to prune the affected parts and spray with fungicides during the isolation of the buds.
Affected plants
Powdery mildew can infect a large number of plant species, bushes and trees. We list the species that the fungus affects most often.
- Greens: lettuce, dill, spinach.
- Cereal crops (cereals): wheat, barley.
- Ornamental crops (flowers): aster, marigolds (tagetis), dahlia, gerbera, hydrangea, delphinium, daisy, petunia, rose, september, phlox and chrysanthemum.
- Trees: apricot, quince, cherry, pear, oak, maple, peach, rowan, plum, cherry and apple.
- Other crops: watermelon, lawn grasses, peas, melon, calendula (marigold), mint, sunflower, rosemary, soybeans, tobacco, hops.
- Shrubs: barberry, hawthorn, grapes, honeysuckle, gooseberry, almond, lilac, currant, hazelnut (hazelnut, hazel) and dog rose.
- Vegetable crops: zucchini, cabbage, potatoes, onions, cucumbers, peppers, turnips, beets, tomatoes, pumpkins and garlic.
- Berry crops: strawberries, strawberries, raspberries.
- Indoor plants: balsam, gloxinia, potted gerbera, dracaena, kalanchoe, indoor rose, laurel, orchid, pedilanthus, violets (saintpaulia), ficus, yucca.
Powdery mildew on grapes
Downy mildew (Peronosporosis)
Mycoses of the disease outwardly resemble powdery mildew, but its causative agent is mushroom-like organisms from the Oomycetes class - the Peronosporaceae family.
Signs of defeat and where it comes from
The infection affects the leaves. At first, yellow spots of various forms are visible on their upper side, and on the lower side there is a gray coating of spores. With the development of downy mildew, the spots turn brown and brown (tissue necrosis) and increase in size, and the light coating of spores becomes dark.
Infected leaves shrivel, turn yellow and wilt. The disease destroys leaf tissue and rarely affects the stem or petioles.
1. Downy mildew 2. Powdery mildew
Downy mildew comes from unsterilized soil (especially with high levels of acidity and low air permeability) and undisinfected seeds.
The disease develops rapidly in natural conditions - cold nights with periods of long dew, and in a greenhouse with high humidity and poor ventilation.
This disease is more common in greenhouses, and in open ground conditions is much less common than powdery mildew.
ADDITIONS TO THE ARTICLE:
This concludes the presentation of fungal diseases. We hope that the above information will help you in determining the disease.
We wish that this disease does not disturb you either at home or in the garden / vegetable garden or greenhouse!
