| Pythium aristosporum | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Clade: | Diaphoretickes |
| Clade: | SAR |
| Clade: | Stramenopiles |
| Phylum: | Oomycota |
| Order: | Peronosporales |
| Family: | Pythiaceae |
| Genus: | Pythium |
| Species: | P. aristosporum |
| Binomial name | |
| Pythium aristosporum Vanterp., (1938) | |
Pythium aristosporum is a species of pythium under the class oomycota (often referred to as water molds) that causes root dysfunction in creeping bentgrass.
Pythium aristosporum causes root dysfunction in creeping bentgrass. [1] Creeping bentgrass is a cool season grass that is found mainly on the putting greens, fairways, and tees of golf courses in the Northern United States due to its ability to be cut at very low heights (an eighth of an inch) and survive winters relatively unharmed. [2] It is ideal for golf courses because it grows stoloniferously (with above ground shoots). This allows the grass grow laterally relatively quickly and form dense ground covers, making it ideal for golf courses.
Like the disease name suggests, Pythium aristosporum affects the roots of creeping bentgrass. While there are no macroscopic signs, there are a few above and belowground symptoms that plants infected with this disease will exhibit. Aboveground, there will be dieback on the tip of the grass blade and the grass will turn from the lush green to a yellow/brown color typically in circular patches. Symptoms aboveground are secondary, and a result of the necrosis of the roots. Belowground, the roots will die back, turn a pale tan color, and lose their root hairs. [3] These symptoms are systemic, as they involve the whole plant, [4] and the mass of root tissue that is lost is a primary symptom because it is a direct result of the pythium. Listed are all macroscopic symptoms, or ones that can be seen without the use of magnification.
Microscopically, hyphae are visible. The primary survival structures of pythium are oospores and sporangia. [5] Oospores and sporangia are circular in shape. Antheridia and oogonia would also be present on hyphal cells. The oogonium is in the shape of a circle that is connected to the hyphae and the antheridium looks like a branch of hyphae that connects to the oogonium to produce oospores. [5]
Pythium aristosporum infects plants in a variety of ways such as through wind, water, overwintering in soil, equipment, and infected plants. [6] For the sake of this cycle, the overwintered oospore will be the starting point. Oospores on a plant can use a germ tube to get into the cell of a plant. If not already on a plant cell, the oospore will release a zoosporangium that releases zoospores. Zoospores have two flagella (one tinselated and one whiplash) and are motile, needing water to move and spread. They then encyst on a cell and develop haustoria as a way to leach nutrients from the cell. Once established in the cell, mycelium spread throughout the plant. Sporangia are then able to arise from the mycelia and either directly infect a cell or release zoospores to infect. From there, mycelia are able to spread and the cycle repeats. Because this is able to happen more than once per crop cycle, it is a polycyclic disease. [7] After conditions are no longer conducive to growth and survival (very dry or cold conditions) or the plant has died, haploid antheridia and oogonia from the hyphae fertilize together to create diploid oospores.
Environment plays a key role on whether the disease develops in a plant or not. While the host plant and microbe may be present, if the environment is not conducive, then there will not be disease. Pythium root dysfunction develops in the roots of creeping bentgrass in the fall, winter, and spring when mean soil temperatures are between 50-70°F. [3] This pathogen reduces the ability of roots to absorb water and nutrients from the soil, which makes the disease much more harmful during times of stress, such as low fertility, low soil oxygen levels, and especially drought. Because of this, symptoms are most common during warm periods in the summer when soil temperature is within key range. [5]
Due to the disease impacting the roots so heavily, creeping bentgrass in sand-heavy soils fare even worse as sandy soils have excellent infiltration and percolation. [1] Turf in soils that are high in organic matter content fares better (once infected) because of the soils ability to retain nutrients and moisture, which allows the hindered roots to be able to absorb them better than if in a very well drained soil. While the soils that retain a higher plant available moisture content allow the plant to survive better once infected with the disease, the best way to prevent it is just the opposite-having soils that allow water to drain well and prevent long periods of pooling. Saturated conditions allow zoospores to spread and infect turf root cells, so it is ideal to prevent the ground from being saturated for too long.
Insects, like billbugs, can also act as vectors by transferring spores or by feeding on roots and creating openings-allowing the oomycete to enter more easily. [8]
Pythium is a genus of parasitic oomycetes. They were formerly classified as fungi. Most species are plant parasites, but Pythium insidiosum is an important pathogen of animals, causing pythiosis. The feet of the fungus gnat are frequently a vector for their transmission.
Phytophthora sojae is an oomycete and a soil-borne plant pathogen that causes stem and root rot of soybean. This is a prevalent disease in most soybean growing regions, and a major cause of crop loss. In wet conditions the pathogen produces zoospores that move in water and are attracted to soybean roots. Zoospores can attach to roots, germinate, and infect the plant tissues. Diseased roots develop lesions that may spread up the stem and eventually kill the entire plant. Phytophthora sojae also produces oospores that can remain dormant in the soil over the winter, or longer, and germinate when conditions are favourable. Oospores may also be spread by animals or machinery.
Aphanomyces euteiches is a water mould, or oomycete, plant pathogen responsible for the disease Aphanomyces root rot. The species Aphanomyces euteiches can infect a variety of legumes. Symptoms of the disease can differ among hosts but generally include reduced root volume and function, leading to stunting and chlorotic foliage. Aphanomyces root rot is an important agricultural disease in the United States, Europe, Australia, New Zealand, and Japan. Management includes using resistant crop varieties and having good soil drainage, as well as testing soil for the pathogen to avoid infected fields.
Phytophthora cactorum is a fungal-like plant pathogen belonging to the Oomycota phylum. It is the causal agent of root rot on rhododendron and many other species, as well as leather rot of strawberries.
Phytophthora medicaginis is an oomycete plant pathogen that causes root rot in alfalfa and chickpea. It is a major disease of these plants and is found wherever they are grown. P. medicaginis causes failure of stand establishment because of seedling death. Phytophthora medicaginis is part of a species complex with Phytophthora megasperma.
Phytophthora nicotianae or black shank is an oomycete belonging to the order Peronosporales and family Peronosporaceae.
Pythium irregulare is a soil borne oomycete plant pathogen. Oomycetes, also known as "water molds", are fungal-like protists. They are fungal-like because of their similar life cycles, but differ in that the resting stage is diploid, they have coenocytic hyphae, a larger genome, cellulose in their cell walls instead of chitin, and contain zoospores and oospores.
Pythium ultimum is a plant pathogen. It causes damping off and root rot diseases of hundreds of diverse plant hosts including corn, soybean, potato, wheat, fir, and many ornamental species. P. ultimum belongs to the peronosporalean lineage of oomycetes, along with other important plant pathogens such as Phytophthora spp. and many genera of downy mildews. P. ultimum is a frequent inhabitant of fields, freshwater ponds, and decomposing vegetation in most areas of the world. Contributing to the widespread distribution and persistence of P. ultimum is its ability to grow saprotrophically in soil and plant residue. This trait is also exhibited by most Pythium spp. but not by the related Phytophthora spp., which can only colonize living plant hosts.
Phytophthora erythroseptica—also known as pink rot along with several other species of Phytophthora—is a plant pathogen. It infects potatoes causing their tubers to turn pink and damages leaves. It also infects tulips (Tulipa) damaging their leaves and shoots.
Pythium aphanidermatum is a soil borne plant pathogen. Pythium is a genus in the class Oomycetes, which are also known as water molds. Oomycetes are not true fungi, as their cell walls are made of cellulose instead of chitin, they are diploid in their vegetative state, and they form coenocytic hyphae. Also, they reproduce asexually with motile biflagelette zoospores that require water to move towards and infect a host. Sexually, they reproduce with structures called antheridia, oogonia, and oospores.
Pythium graminicola is a plant pathogen infecting cereals.
Pythium myriotylum is a soil-borne oomycete necrotroph that has a broad host range, this means that it can infect a wide range of plants.
Pythium volutum is a plant pathogen infecting wheat, barley, and turfgrass. It is known to be sensitive to some of the compounds typically present in selective media commonly used for isolating Pythium spp., so isolation may require alternative methods.
Sclerophthora macrospora is a protist plant pathogen of the class Oomycota. It causes downy mildew on a vast number of cereal crops including oats, rice, maize, and wheat as well as varieties of turf grass. The common names of the diseases associated with Sclerophthora macrospora include "crazy top disease" on maize and yellow tuft disease on turf grass. The disease is present all over the world, but it is especially persistent in Europe.
Phytophthora plurivora is a very aggressive soil-borne plant pathogen, with worldwide distribution and a wide variety of hosts.
Phytophthora quercina is a papillate homothallic soil-borne plant pathogen causing root rot of oak tree species in Europe. It is associated with necrotic fine roots.
Globisporangium sylvaticum is a plant pathogen, an oomycete known to cause root rot and damping off in a multitude of species. These species include apples, carrot, cherry laurel, cress, cucumber, garlic, lettuce, pea, rhododendron, and spinach. Symptoms of infection include stunting, wilt, chlorosis, and browning and eventual necrosis of roots. The pathogen can by identified by the presence of thick, microscopic, round spores within the cells of the root.
Pythium porphyrae, is a parasitic species of oomycete in the family Pythiaceae. It is the cause of red rot disease or red wasting disease, also called akagusare (赤ぐされ) in Japanese. The specific epithet porphyrae (πορφυρα) stems from the genus of one of its common hosts, Porphyra, and the purple-red color of the lesions on the thallus of the host. However, many of its hosts have been moved from the genus Porphyra to Pyropia.
Black rot on orchids is caused by Pythium and Phytophthora species. Black rot targets a variety of orchids but Cattleya orchids are especially susceptible. Pythium ultimum and Phytophthora cactorum are known to cause black rot in orchids.
{{cite web}}: CS1 maint: multiple names: authors list (link)