What is black stem rust?
Black stem rust, Puccinia graminis, is also sometimes referred to as wheat stem rust or stem rust of cereals. It is a heteroecious rust, meaning it requires two hosts to complete its life cycle. It is found world-wide including all 48 continental U.S. states.
What are symptoms of black stem rust of wheat?
Black rust Symptoms are produced on almost all aerial parts of the wheat plant but are most common on stem, leaf sheaths and upper and lower leaf surfaces. Pustules (containing masses of urediospores) are dark reddish brown - occur on both sides of the leaves, on the stems, and on the spikes.
What causes black rust?
Rust from Iron (III) oxides with limited oxygen and low moisture results in black rust. Black rust can be visually identified as a thin, black film which is the result of oxidation in a low oxygen environment.
What does stem rust do to wheat?
Wheat stem rust can attack all above-ground parts of the plant, including the stem, leaves and inflorescence. Infected wheat plants may also produce shrivelled grain. An untreated infection could reduce grain yield by up to 90 per cent.
How do you control black stem rust of wheat?
Use of high dose of potash is known to reduce rust infection. Apply balanced doses of nitrogen and potash as recommended. Damage by wheat rust may be minimized by spraying Zineb or Mencozeb 75 WP. Spraying is recommended only when a good crop of wheat is threatened by rusts.
Which plant is affected by the black rust disease?
The black rust disease is caused by the fungus Puccinia-triticina. The disease occurs wherever wheat, barley, and other cereal crops are grown.
What is black rust called?
Black Rust This layer is harder and thicker than red rust and can also be called magnetite. This rust will stay tightly bound to the to the base material and act as a partial protection from a further oxidization process.
What are 4 types of rust?
Types of rust:Yellow Rust. Iron oxide-hydroxide FeO(OH)H2O (high moisture) Yellow rust is present in metals that are found in large amounts of standing water. ... Brown Rust. Oxide Fe2O3 (high oxygen/low moisture) ... Black Rust. Iron (II)oxide – Fe3O4 (limited oxygen)
What are the type of rust in wheat?
Wheat is affected by three different types of rust diseases: leaf rust, stripe rust or yellow rust, and stem rust.
What causes stem rust?
Stem rust (caused by the fungus Puccinia graminis) can only survive from one season to the next on a living host. It does not survive on stubble, seed or soil. The most important hosts are susceptible wheat, but it can also survive on barley, triticale and some grasses.
How is stem rust transmitted?
Stem rust spreads rapidly within and between wheat crops. Spores can be blown by wind over very large distances from infected crops or cereal regrowth. Spores can also be carried on clothing.
Which organism causes rust of wheat?
Leaf rust, caused by Puccinia triticina, is the most common rust disease of wheat. The fungus is an obligate parasite capable of producing infectious urediniospores as long as infected leaf tissue remains alive.
What causes stem rust?
Stem rust (caused by the fungus Puccinia graminis) can only survive from one season to the next on a living host. It does not survive on stubble, seed or soil. The most important hosts are susceptible wheat, but it can also survive on barley, triticale and some grasses.
Which organism causes rust of wheat?
Leaf rust, caused by Puccinia triticina, is the most common rust disease of wheat. The fungus is an obligate parasite capable of producing infectious urediniospores as long as infected leaf tissue remains alive.
Which of the following wheat variety is resistant to black or stem rust?
thunbergii atropurpurea x B.
Which fungus is known as rust fungus?
The fungus that causes leaf rust is Puccinia triticina Eriks (formerly known as Puccinia recondita) and mainly attacks the leaves; the one that causes stripe rust is Puccinia striiformis f. sp. tritici and mainly attacks the leaves and the glume; and the stem rust is caused by the Puccinia graminis f. sp.
How to control wheat stem rust?
Several other fungicides such as sulphur, dichlone, zineb, maneb, etc. can effectively control the stem rust of wheat. In most cases, 5-10 applications per season are required for complete control of the rust.
What disease is on wheat?
Black stem rust disease appears on the wheat crop in all wheat growing countries throughout the world.
Why do pustules turn black?
In the later stage, as the plant approaches maturity, the reddish or rusty colour of the pustules turns black because the fungus produces teliospores instead of uredospores and uredia are transformed into black and smooth-walled telia.
What are pustules on plants called?
In later stages of plant growth. In later stages of plant growth, pustules may appear on the glumes and even the beards. Those pustules called uredia grow and fuse to form larger lesions of dark brown colour, the pustules vary in size from small to about 3 mm wide by 10 mm long.
What are the symptoms of wheat?
The symptoms on wheat appear at first as long, narrow, elliptical or oblong and brown pustules, parallel with long axis of the stem, leaf sheaths and leaves (lower surface mainly) of young seedlings or of plants at any stage of growth. In later stages of plant growth. In later stages of plant growth, pustules may appear on the glumes and even ...
Is wheat resistant to all races?
It is difficult to obtain resistance against all races in one wheat variety. Hence varieties that are resistant to most virulent locally existing races should be used in a particular area. (2) Excessive use of nitrogenous manures which influence the growth of rust fungi should be avoided.
Can wheat plants have telia?
Sometimes uredia and telia may exist on wheat plants in such great numbers that greater part of the plant appears to be covered with the ruptured areas which are filled with either reddish uredospores or the black teliospores or both. In severe attacks, plants, in general, look sickly and fail to form normal ears.
Where is wheat stem rust found?
Figure 8. Spread of wheat stem rust from winter wheat near the Gulf Coast to northern areas of wheat production where the stem rust fungus cannot survive the winter. Concentrations of wheat acreage are indicated by green shading.
What causes wheat stem rust?
To answers these questions requires a brief review of the biology of the wheat stem rust fungus ( Puccinia graminis f.sp. tritici ), the role of barberry in the stem rust epidemics, and the current status of stem rust in North America. Wheat stem rust is caused by a parasitic fungus that reproduces only in living plants. Symptoms of the disease in wheat consist of erumpent pustules primarily on the stems and leaf sheaths (Fig. 1). Each pustule is the result of an infection by a single rust spore. The initial infections produce no obvious symptoms until about 7-10 days after infection. Then the fungal mycelium, which has been growing within the plant tissue, masses directly under the plant epidermis and begins producing thousands of spores that rupture the epidermis and emerge as powdery, rust colored piles of urediniospores. Each urediniospore has the potential to produce a new infection that will cause similar damage on the same plant or another wheat plant. Multiple cycles of infection, sporulation, and re-infection can produce very destructive epidemics in wheat fields within just a few weeks.
How do barberry bushes prevent wheat rust?
Stem rust still exists, although at greatly reduced amounts, in the main wheat producing regions of the United States. Second, destroying susceptible barberry bushes reduced stem rust by getting rid of local sources of epidemics and, more importantly, by removing barberry as the breeding ground for new stem rust races. Limiting the development of new stem rust races allowed wheat breeders to develop new varieties with multiple genes for resistance to the remaining races of the pathogen. Third, it is important to realize that barberry will not stay out of wheat growing regions without active efforts to keep it out. The quarantine and selective eradication are still needed to keep stem rust susceptible bushes from being distributed and planted in the major wheat producing states. Even if susceptible barberry bushes are not planted next to wheat fields, they will produce berries with seeds that may be deposited by birds in fence rows or hedge rows near the fields. In a matter of years, this could undo the success that wheat breeders and pathologists have had in suppressing stem rust epidemics in wheat crops for more than 40 years. The result would be a return to cycles of major rust epidemics several times per decade such as currently occur with oat crown rust, except that the economic consequences would be far greater with losses from $50 million to $100 million or more in any given epidemic.
Why are barberry plants excluded from wheat?
The life cycle of P. graminis illustrates two reasons for wanting to exclude susceptible barberry plants from major wheat producing regions. First, barberry serves as the bridge to carry the fungus from one wheat crop to the next. During the interval between the harvest of one wheat crop and the emergence of the next wheat crop, P. graminis can survive as dormant teliospores, which through production of basidiospores, may give rise to new infections only on barberry. Without barberry, the teliospores represent a dead end in the fungus life cycle. When barberry bushes grow adjacent to wheat fields, they can serve as foci for the spread of stem rust into the wheat (Fig. 4) where the epidemic is sustained and spread by repeated cycles of infection and production of urediniospores. The second reason for excluding barberry is that, as the site of sexual reproduction of P. graminis, it serves as the breeding ground for new pathogenic races of the fungus. More will be said on this subject later.
Why is barberry rust quarantined?
Production and sale of various species and cultivars of Berberis (barberry), Mahonia, and Mahoberberis in the nursery trade in the United States are affected by the Black Stem Rust Quarantine, which was imposed to protect wheat crops in regions vulnerable to stem rust epidemics. For producers and distributors of barberry bushes, the quarantine is a burden that naturally raises the questions - Is wheat stem rust still a concern in the quarantined regions? - Is barberry still considered a threat?
What is the life cycle of a stem rust fungus?
Life cycle of the stem rust fungus, Puccinia graminis. The sexual stage of P. graminis, in which nuclei of + and - mating types are reunited, is completed on barberry. Pycnia, which result from infection on young barberry leaves by basidiospores, contain two key elements for the sexual process.
How many miles does a wheat stem rust survey cover?
Numbers of wheat stem rust collections made in farmers' fields per year in the Great Plains from Texas to North Dakota. Annual survey trips cover over 8,000 miles with stops at 300 or more fields per year. Reprinted from Leonard, 2001.
Why is grain shriveled?
Grain is shriveled due to the damage to the conducting tissue, resulting in less nutrient being transported to the grain. Severe disease can cause straw breakage, resulting in a loss of spikes with combine harvesting. Uredinia generally appear as oval lesions on leaf sheaths, true stem, and spike.
What is the color of uredinia?
Uredinia can appear on the leaves if other diseases have not killed them. Uredinia are brick red in color and can be seen to rupture the host epidermis, on the leaves uredinia generally penetrate to sporulate on both surfaces.
What is the effect of stem rust on wheat?
In Western Australia, stem rust typically causes losses of 10–50% in wheat, but this can increase to up to 90% when it occurs in early spring and is not controlled. Stem rust attacks wheat and triticale but barley can also be an important host during summer months. Stem rust produces large, reddish-brown oval to elongated spore masses on both sides ...
What is stem rust?
Stem rust produces large, reddish-brown oval to elongated spore masses on both sides of the leaf, on leaf sheaths, stems and outsides of heads. The pustules have tattered edges. The symptoms of stem rust and how the disease develops are discussed in detail on the Diagnosing stem rust of wheat MyCrop page. Stem rust requires living plants on which ...
How does stem rust survive?
To infect crops during the season it must survive summer by infecting volunteer cereals or grass hosts, known as the ‘green bridge’.
How does wheat stem rust start?
The disease cycle of wheat stem rust starts with the exposure of each new wheat crop to spores of Puccinia graminis f. sp. tritici, which are the primary inoculum. The source of the first spores that infect the new wheat crop differs depending on the region in which the wheat is grown. In warm climates, wheat is planted in late fall and harvested in early summer. The first spores to infect the young wheat plants in the fall are urediniospores. They generally come from infected volunteer wheat plants. Seed spilled in the field or on roadsides at harvest time often sprout and produce scattered volunteer plants. These plants can become infected from spores produced on late-maturing wheat plants still in the field. The infected volunteer wheat plants serve as a bridge that carries P. graminis f. sp. tritici through the summer to the next fall-sown crop of wheat.
What is the first rust spore to infect wheat?
The first rust spores to infect wheat in the spring in temperate regions may be aeciospores from barberry, the alternate host, or urediniospores from infected wheat in distant regions with milder winters. Therefore, we describe two disease cycles for stem rust - with or without barberry. Figure 12-map6a.
How does barberry eradication affect stem rust?
A single barberry plant can produce as many as 64 billion aeciospores. Second, it reduced the genetic variation in the fungal population by eliminating the sexual cycle, leaving only asexual urediniospores to maintain the fungus. Mutation is now the primary source of genetic variation. Consequently, there are no longer so many different races of wheat stem rust against which wheat breeders must seek resistance. Finally, epidemics are delayed by several weeks in many of the major wheat producing areas of the U.S. and Canada because aeciospores were released before the first arrival of urediniospores from the south.
What is the stem rust infection?
All stem rust infections of wheat or other grasses involve dikaryotic spores and dikaryotic mycelium. Over a period of days, the dikaryotic mycelium grows through the barberry leaf until a new structure, the aecium, breaks through the lower surface of the leaf to release the dikaryotic aeciospores ( Figure 10 ).
Why is the rust stage called the repeating stage?
In heteroecious rusts, this important spore stage is called the "repeating stage," because urediniospores are the only rust spores that can infect the host plant on which they are produced. Under favorable environmental conditions, multiple, repeated infections of the same wheat plant and neighboring wheat plants can result in explosive epidemics.
How do pycniospores help rust fungus?
Splashing raindrops also disperse pycniospores and aid in cross-fertilization. Fertilization of pycnia is critical in the rust fungus life cycle, because it gives rise to the dikaryotic mycelium. After the nucleus of the pycniospore joins that of the receptive hypha, the paired, haploid nuclei divide in tandem in the mycelium throughout the remaining stages of the life cycle. All stem rust infections of wheat or other grasses involve dikaryotic spores and dikaryotic mycelium.
Why is pycnia important in the life cycle of rust fungus?
Fertilization of pycnia is critical in the rust fungus life cycle, because it gives rise to the dikaryotic mycelium. After the nucleus of the pycniospore joins that of the receptive hypha, the paired, haploid nuclei divide in tandem in the mycelium throughout the remaining stages of the life cycle.
When does rust appear in wheat?
In India it appears at different times of the year in different parts of the country. It appears in the month of March in Northern India. In Southern and Peninsular India it appears very early in the 4th week of November.
What is stem rust?
The stem rust is a serious threat to wheat in India. It causes serious damage in moist areas and moist season. The nature and extent of damage varies from slight to almost complete failure of the crop.
Why do sori turn black?
Later in the season the sori turn black. This is due to the appearance of two- celled, black teleutospores or teliospores in the place of uredospores in the old uredia. When the grains are almost ripe, new and independent oblong to linear teleutosori make their appearance on the stem of the host.
How much wheat was lost in 1958?
Prasad (1960) reported that nearly one million tons wheat worth about Rs. 392 million was lost during 1958-59. The losses include reduction in the quantity of the thrashed grain (low yield), its poor quality and shrivelled lighter grains.
What are the measures to control stem rust?
Control Measures of Stem Rust Disease: 1. Cultivation of Rust Resistant Var ieties: The cultivation of varieties immune to the rust disease is an important means of combating the disease. Some rust resistant varieties of wheat are available in India. Np 710, Np 718 and Np 770 find favour with the farmers.
What is the effect of rust on plants?
Samborski and Shaw (1956) reported increase in the respiratory activity of rusted plants especially at the site of infection. Shaw and Colotelo (1961) found increase in total nitrogen, protein nitrogen, soluble nitrogen and the ratio of soluble to insoluble nitrogen as the rust develops. Prasad (1967), opined that amino acids and proteins are synthesized by the rust fungus itself.
Which part of the life cycle is passed on the grain host or the wheat plant?
The part of the life cycle which is passed on the grain host or the wheat plant represents the dikaryophase (H-L). During this phase each cell of the mycelium, each uredospore and each cell of teleutospore has a pair of nuclei called the dikaryon. One of these nuclei is of plus strain and the other of minus strain.
Stem Rust in Victoria
What to Look For
- Stem rust is characterised by reddish-brown, powdery, oblong pustules. The pustules have a characteristic torn margin that can occur on both sides of the leaves, on the stems and the glumes. Stem rust spores are much darker in colour than leaf rust spores, which are light brown and don't have torn margins. As the plant matures, the pustules produce black spores known as …
Economic Importance
- In Victoria, severe stem rust infections can reduce grain yield by more than 80 per cent in susceptible varieties and can reduce grain quality.
Disease Cycle
- Stem rust (caused by the fungus Puccinia graminis) can only survive from one season to the next on a living host. It does not survive on stubble, seed or soil. The most important hosts are susceptible wheat, but it can also survive on barley, triticale and some grasses. Carry over on wheat from one season to the next is greatest during wet summer a...
Conditions Favourable to Stem Rust
- Stem rust can occur in all regions of Victoria where susceptible varieties are grown. However, the likelihood of a stem rust epidemic is increased by several factors: 1. the build up of stem rust inoculum on volunteer wheat before sowing, both locally and in neighbouring states 2. the widespread planting of susceptible varieties 3. favourable weather conditions, which includes g…
Pre-Season Management of Stem Rust
- Stem rust can be managed using an integrated approach. This includes: 1. reducing the inoculum in a district by managing the green bridge 2. avoiding susceptible cultivars 3. close monitoring to enable timely fungicide sprays.
In-Crop Management of Stem Rust
- The effects of stem rust can be minimised with the timely application of foliar fungicides. As there is limited information on the management of stem rust in Victoria, the following recommendations for the in-crop management of stem rust are based on experience in Western Australia (Beard et al, 2004).
Rust Identification
- For rust identification, send rusted plant samples in a paper envelope (do not use plastic wrapping) to: Australian Cereal Rust Survey Plant Breeding Institute Private Bag 4011 Narellan NSW 2567