Strawberry Phytophthora
Strawberry phytophthorosis is a plant disease. The causative agents are oomycetes of the genus Phytophthora. The most commonly identified are: Phytophthor a-Fragariae and Phytophthora cactus. Since the 1960s, the disease has spread widely in many countries [4] [6]. Phytophthora fragariae is contained in the “List of pests, diseases and weeds of punctual importance for the Russian Federation” and is a quarantine object [1].
Contents:
Symptoms of the disease
Symptoms of the disease appear on all organs of the plant: berries, buds, flowers, inflorescences. In years with high humidity, the tops of stems and growth points are affected [4].
The first symptoms can be found in late autumn on plant roots. They appear on terrestrial organs only in spring [1].
In spring, infected plants lag behind in development. Later, the lowest leaves of rosettes turn yellow, wither, and completely dry out. Damage quickly spreads to neighboring plants. Bushes in the hot spot area quickly die and form clumps. Damaged plants break off during reseeding, leaving most of the false horn and root in the ground. Most often, plants die during flower and fruit formation [6].
False horn and root neck – Necrosis of varying intensity, tissue examination or reddening of the axial cylinder of the root are formed on a longitudinal slice. Damaged areas are characterized by hard consistency and do not crumble [6].
Flower stems and leaves – necrotic spots are formed on the bases near the surface [6].
Roots – plants are damaged starting from the tips. In case of severe infection, the infection reaches the root neck [6].
Fruits – are infected at all stages of development. With green – brown spots develops on mature discolored areas. Affected tissues become softer and have a bitter taste. Sensitive mycelial plaque develops in high humidity. The berries gradually transfer and mummify [4] [6].
morphology
Mycelium is exophytic, in the form of a dense white badge. It develops on affected organs, in particular on berries [4] [8].
Zoospongiosis is large, light-colored, numerous. Up to 800 µm long [4].
Zoosporangia are oval, colorless. Dimensions 32-90 x 22-52 μm [4].
The oospores are globular. The protoplasm is granular with a large amount of oil. The shell is smooth, thick, colorless to golden brown. The diameter is 24-44 µm, on average about 33 µm [1] [4].
Mycelium is exophytic, in the form of a dense white badge consisting of long, branched, straight and curved GIFs, which often extend at right angles and are slightly swollen on the branches. The thickness of the GIF is 4-7 µm [8] [7].
Sporangia are simple or syndial, growing singly or in bunches [7].
Sporangia are ovoid, lyre-shaped, predatory, less frequently non-symmetrical, with a well-defined papilla. Dimensions are 20-55×17-46 µm [7].
Zoosporangia are ovoid, lemon-shaped, posteriorly propagated, sometimes asymmetrical, sizes 20-55×17-46 μm [7].
Oospores are globular, colorless, yellowish. The calyx is 1-2 micrometers thick [7].
Chlamydiospores are globular, colorless or yellowish, terminal and intercalary. They are 19-53 microns in diameter [7].
Pathogens that cause nodulation
biology
The causative agents are typical semi-representative phytopathogens hibernating as mycelium and oospores in tissues of diseased plants and as oospores in plant debris and soil. Oospores germinate in spring. Infection is carried out by zoospores that enter the plant through the epidermis. In infected plants, the phytopathogens develop sensitive mycelia. In the latter, conidia are formed that affect plants en masse during the vegetation period [4] [6].
Characteristically, the cell membrane in the places of haustoria penetration into a host plant cell is destroyed by enzymatic and mechanical effects, but the cell plaque remains undamaged. It penetrates the cell and encircles the anterior gate. At the same time, the plasmolemma does not adhere tightly to the coil of the house gate, but stands at a small distance. The space between the anterior gate of the house and the plasmolemma is filled with a matrix of extraautoria (an electron density substance). The width of the matrix varies depending on the type of host and phytopathogen, the physiological state of the cells, and the method of fixation of the test material. Outside the matrix, in some cases, another envelope is found, which is a product of the host secretions of the host system. It surrounds the entire haustoria or is only around its base in the form of a collar. The degree of development of this envelope depends on the host resistance to the phytopathogen. In resistant varieties and guys, it is well developed, surrounds the whole haustoria and isolates it from cell protoplasm. Vulnerable forms have no such cover [8].
Sources of infection are soil, diseased living plants, and their unreleased residues [4] [6].
Developmental conditions
Germination of oospores occurs over a wide temperature range, but the optimal range is from +14 °C to +18 °C. Infestation is most successful in cold or moderately warm weather in the presence of droplet-liquid moisture (dew, fog, heavy precipitation, watering). Water promotes transmission and development of zoospores and conidia. High temperature and water stress intensify the development of the pathological process and the manifestation of its symptoms [6].
Geographic distribution
Fitopluoru s-Wilde of strawberries – in Europe, North America, and Russia, the disease is widespread [1] [6] [8].
Phytophthora cactorum is widespread in Russia [1] [6] [8].
Harmfulness
Phytophthora cactorum is a harmful disease of the plant, namely strawberries. The infection affects all above-ground organs and causes the greatest damage to berries. With intensive development of the infection, complete destruction of the crop is possible [4].
Phytophthorosis of strawberries and raspberries
Very many diseases have been imported from other countries. The problem is that these diseases do not go around the country with a drumbeat. They creep in slowly and inaudibly, without flaunting themselves, but they can appear in any home at any time.
Late Blight Raspberry Disease.
The cause of strawberry death.
There are about 80 varieties of strawberries: it is not necessary to know everything, but it is worth to orient and understand the signs, what to do with sick plants and how preventive measures should be organized.
The spots on the leaves are clearly visible, so that every dacha can determine the disease, if there is a guide with a good description and photos. Problems with the roots are usually due to improper care: little or much water, frost or lack of nutrients.
Phytophthorosis of datesLephorosis starterica sadari and rams
Wilt or wilt. Plants are affected by Phytophthora fragariae var. fragariae Hickman. The pathogen specializes in strawberries and blackberries. The disease proceeds in two scenarios, chronic and transient.
The chronic course is slow. In the spring, bushes make themselves known in the beds, lagging behind the main mass of plants. Young leaves are darker than their vigorous neighbors, a grayish hue appears; old leaves wither and wither prematurely, but at first their edges become red, yellow, brown, which looks like a lack of nutrition. It is actually a lack of substance and water, but the starvation is caused by damage to the roots, which cannot nourish the plant. Therefore, the petioles of the new leaves are short. The bushes do not bear fruit or produce a tiny crop of low quality berries. There are few whiskers. Sometimes such an existence of the plant stretches for two or three years, if the time of infection is taken as a reference point.
Late blight disease of strawberries. In the lower right corner is the causative agent of the disease. Photo from vniikr.ru
Movie stills from trailer.zee18.com
Symptoms of the transient form first appear in stressed plants (when they live in areas where there is either reduced runoff or systematic accumulation of water. This form of the disease results in the death of stems, lower leaves, or sudden loss of all attachment.
What can be seen on the roots
Weak root system. There are very few lateral adventitious roots that feed the plant. Or they die off, starting at the tips: they darken, while their upper parts remain light for a while. By autumn they die off completely.
Root damage. Photo from shadez.us
On the main roots, the tips are gray or brown, bare (sometimes they are compared to a rat’s tail). A longitudinal section shows that the core (correctly the axial cylinder or stem) is colored in various shades of red.
You can tell the disease from the roots in the fall. Photo from omafra.gov.on.ca
These changes in the roots are clearly visible in the fall, but symptoms of the disease on the plant itself appear in the spring or early summer.
Predisposing factors.
Bald spots on strawberry orchards are the work of late blight. Photo from vniikr.ru
Infection occurs faster when there is plenty of water, it helps the pathogen to move in the soil (so if the plot is on a slope or in a lowland area, the spread across the plantation is faster).
These are spring and fall conditions. If spring is hot and dry (in such weather the fungus weakens its activity), and summer begins with coolness and rains, the beginning of the disease falls on the fertile period of late blotch – summer. And, of course, the presence of the pathogen in the soil. According to various data, oospores can persist in the soil for up to eight years, while Finnish experts say about twenty years.
Second face
Late blight of the leathery berry rot. Plants are attacked by Phytophthora cactorum. This fungus rarely penetrates the roots. All above-ground organs are affected, but the berries are the hardest. They appear as hard, leathery spots of brown or purple color. It is impossible to remove the seal from the pulp. The berries become bitter, and later they dry out.
Late berry leathery rot. Photo from libertarianinstitute.org
Irregularly shaped brown spots appear on buds and flowers. The rosette of leaves and the base of petioles die off. If humidity is high, a white, thick coating appears on all organs, and especially on berries. In winter, the fungus survives in the soil and on plant debris and rosettes.
- Grow healthy seedlings;
- Watch your crop rotation;
- Grow in an annual crop;
- Treat with Ridomil and Quadris.
Healthy Basis. Photo from Klubnika.org.ua page
Third Person.
Phytophthora basal rot (root neck and root rot). Plants suffer from phytophthorosis. This form of late Blight is perennial, with a menu of plants in 83 genera in which it develops on roots, stems, bark, fruit, and buds.
Strawberries are characterized by a variety of symptoms, the entire plant is completely affected. The disease is present in the Krasnodar, Moscow, Leningrad and other regions of Bashkiria.
How the lower leaves fade: they lie on the floor and touch the leaf plate with their tops. At the root neck, at the base of the stems and leaf petioles appear ring-shaped spots, then these places rot. Roots gradually die off, which does not lead to death, but the new leaves are deformed, they have thin petioles; Brown bluish spots appear in high humidity, and dry out in dry weather. Rosettes are deformed, unusual in shape and size.
Plants suffer from phytophthorosis. Photos site a-project.ncsu.edu The appearance is affected by Nematoda.
The middle can darken in flowers (the pistil dies). In the case of berries, late Blight root rot appears as follows:
Phytophthora basalis rot. Photo from bostane.ir
- The ovaries become covered with brown spots, stop growing, and wither.
- In immature berries, spots spread over the entire surface, the flesh becomes dense;
- Browning spots give the berry a bitter unpleasant taste.
- If you cut a berry longitudinally, you can see that the darkening of tissue comes from the stalk.
- To prevent the disease soak the planting material for a long time in medicinal solutions;
- Remember that young plants planted in the spring, can all summer and fall fade from the disease.
How to protect plants from disease
- The disease develops more in heavy soils, so plant plants in fertile, fairly light soils. Mulch the bushes annually.
- If you find plants with signs of the disease in the garden, remove all specimens, burn them, and refloor the garden. Give the crop away as late as possible (according to various sources after 4-8-20 years).
- Grow for former strawberry tribes for soil health (marigolds, calendula, rye, peas), which do not tolerate doing soil renewal after harvesting diseased plants.
- Don’t plant in damp places at all and don’t grow in clumps.
- Choose resistant varieties, buy seedlings from nurseries.
- Twice a year (in spring and fall) inspect bushes, study the condition of the roots.
Late blight of Raspberry.
The causative agent is phytophthora frafariae var. Rubi and not only it: as experts suggest, it is a complex of different types of late blight and fusariosis.
External signs of late blight on raspberry roots. Photo from Mazunenpictures.com
The first cases of the disease were reported in the 1950s, and in the 1990s, the disease appeared on cultivars in the device breeding plots.
The first cases of the disease were recorded in plants in the middle of the last century. Photo from bugwoodcloud.org
Not widespread in Russia and not common in the Baltic countries. Walk slowly …
Raspberry leaves dry and curl.
Affected leaves nearby. Still from Trailer.zee18.com
Temperature preferences of Phytophthora with high humidity, the soil should warm up to +5. +25°C, and the most favorable temperature corridor for Phytophthora is +10. +17 ° C with rainfall. But this is already the end of summer – beginning of autumn or spring. If you look from afar, you can see bare spots on raspberries, i.e. clear pockets with damaged plants. If you look closely, you can see that the dug-up roots are red in color.
Movie stills from trailer.zee18.com
- The buds do not open in the spring;
- the shoots first wither and then wither in a certain shape: it is thought to look a lot like a shepherd’s staff with a big hook, like in the movies about shepherds;
- the lower part of the shoots darkens to a height of up to 30 cm, spots appear, which grow in a ring around the shoot;
- if it is damp, humid, the darkened areas show the bloom of the fungus.
If you find late blight on strawberries or raspberries
- notify your local Rosselkhoznadzor office, as these diseases are quarantined.
- Remember that soil treatment with fungicides is ineffective.
- Uproot and burn diseased plants;
- Be careful when choosing a seller and buying seedlings.
Attention!
The film, footage from which we showed, created by the Federal Service for Veterinary and Phytosanitary Surveillance (Rosselkhoznadzor) and the All-Russian Center for Plant Quarantine.
Apparently, this disease is already widespread enough in our country, since such institutions create films about it and release them into wide distribution.
