Plant pathology is the study of plant diseases.
• Fungi
• Bacteria and
• Viruses.
Detecting the less-obvious symptoms is more difficult when the diseased plant is the only specimen of its kind in the particular area and cannot be compared with a healthy one.
Normally Nonparasitic plant disorders are not included in the study of diseases, but it is still important to recognize them.
Nonparasitic plant disorders may include :-
• Improper planting depth
• Nutrient imbalance
• Temperature extremes
• Toxic chemicals
• Mechanical injury
• Water imbalances and
• Air pollution.
Most environmentally induced problems tend to be uniform but disease may show up in spots throughout a site.
I’m Tapsendra Patel and in this article we will review the Types of Pathogens and Abiotic Disorders of plants.
If we want to diagnose plant diseases effectively, so it is necessary to understand the biology of the microorganisms ( fungi, bacteria, viruses )
which cause disease to plants.
The very 1st is an organism that causes disease,
the 2nd one is a host plant susceptible to the pathogen and
the last 3rd one is an environment conducive to disease development.
These three conditions, commonly known as the “Plant Disease Triangle” and all must exist at the same time and in the same place. When the three conditions above occur at the same time, the pathogen infects the susceptible host and the disease starts. The disease continues until a change in the environment works against the pathogen.
Fungi are multi-celled microorganisms that may be seen without a microscope during certain stages of their life cycles. Fungi have no chlorophyll and their cell walls are composed of chitin and other polysaccharides but not of cellulose. Many species of fungi can be identified by the microscopic spores ( reproductive structures )they produce that aid in dispersal and survival. Some fungi develop masses of hyphae, collectively referred to as mycelia, and spores that are readily visible. Some fungi have no spores, such as Rhizoctonia, which can be identified microscopically.
Symptoms for fungi may be :-
• Wilt
• Chlorosis
• Yellowing
• Stunting
• Leaf spots or
• Blights.
Signs for fungi including spores may be :-
• Rust or powdery mildew spores
• Mycelium
• Sclerotia
• Mushrooms and
• Conks.
• Wind
• Runoff water from rainfall or irrigation will also move fungal spores from one plant to another plant.
• Fungi that live in the soil and can move from plant to plant by growing along intermingled roots.
• Fungi can also be spread by human activity, through movement of already diseased plants or by the use of gardening tools. While fungi may enter a plant through its natural openings, or through wounds, they can also penetrate directly through the plant’s epidermis (cuticle).
• Water is the chief means by which bacteria are transmitted.
• Another important means of dispersal is through human contact. Many bacterial diseases can be spread simply through the process of touching an infected plant and then touching a healthy plant with hands or pruning tools. Bacteria cannot penetrate the cuticle of plants but they can enter the plant through a wound or natural opening to initiate disease.
Pseudomonas and Xanthomonas are common bacterial organisms that cause disease in plants.
Bacterial diseases can be divided into 2 types:-
• Systemic
• Localized.
Systemic bacterial diseases - can invade plant tissues that carry water and nutrients. Then the disease spreads throughout all parts of the plant.
Localized bacterial diseases - Under certain conditions,the bacterial pathogen may grow in only one area of the infected plant.
This is localized infection and can cause :- Stem rots, Leaf spots and Blights, Wilts, and Root rots.
Some other symptoms includes :- Galls, Cankers, Wilts, and Soft decay.
Many of these symptoms are the same as those that fungi causes to plant. This makes a very challenging task to identify the pathology of that disease unless you send a plant sample to a laboratory.
Viruses are usually spread from diseased to healthy plants by :-
• Insects
• Mites
• Nematodes
• Fungi and
• Even humans.
Viral disease symptoms include :-
• Curling leaves
• Stunted growth
• Wilting
• Mosaic patterns of spots on leaves
• Mosaic patterns of spots on fruit
• Deshaped leaves and
• Chlorotic leaves.
These environmental factors include:-
• Extreme temperatures
• Strong winds
• Too high moisture
• Too low moisture
• High or low soil pH
• Poor air quality
• Too much or too little light
• Nutritional problems and
• Human activities such as :- pesticide and fertilizer applications.
If one or more of these factors goes above or below the optimum range for a given plant species, plant growth might be abnormal or will be adversely affected.
• Pests are more likely to infect plants which are dependent in plants for Nutrients.
• Analkaline pH - Because of this alkaline pH, some essential nutrients unavailable for plant roots up take.
• Too much water - After an abundance of rain, plant roots may not be able to absorb oxygen because water fills the space that usually holds air. Feeder roots die, which can damage the plant. This problem can occur in compacted soils, too.
• Soil fungi - that cause root disease may easily infect a plant’s roots.
• Light and temperature problems - Plants can get sunburned . A rapid drop in temperature close to or below freezing kills soft herbaceous plant tissue. Cold temperature scan damage new growth, branches, stems, and trunks of woody plants.
• Not enough water - Plants will often wilt and leaves will scorch when temperatures are high and the soil is deficient of moisture.
These plants are more likely to be injured if they do not have any mulch around their base, since mulch helps prevent the equipment from contact.
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Diseases are caused by microorganisms such as :-• Fungi
• Bacteria and
• Viruses.
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Some disease symptoms, such as leaf spots and wilting, are easily seen or measured. Others are difficult to observe.Detecting the less-obvious symptoms is more difficult when the diseased plant is the only specimen of its kind in the particular area and cannot be compared with a healthy one.
Normally Nonparasitic plant disorders are not included in the study of diseases, but it is still important to recognize them.
Nonparasitic plant disorders may include :-
• Improper planting depth
• Nutrient imbalance
• Temperature extremes
• Toxic chemicals
• Mechanical injury
• Water imbalances and
• Air pollution.
Most environmentally induced problems tend to be uniform but disease may show up in spots throughout a site.
I’m Tapsendra Patel and in this article we will review the Types of Pathogens and Abiotic Disorders of plants.
If we want to diagnose plant diseases effectively, so it is necessary to understand the biology of the microorganisms ( fungi, bacteria, viruses )
which cause disease to plants.
Disease Triangle
Three conditions are required for a disease to develop in plants:-The very 1st is an organism that causes disease,
the 2nd one is a host plant susceptible to the pathogen and
the last 3rd one is an environment conducive to disease development.
These three conditions, commonly known as the “Plant Disease Triangle” and all must exist at the same time and in the same place. When the three conditions above occur at the same time, the pathogen infects the susceptible host and the disease starts. The disease continues until a change in the environment works against the pathogen.
Fungi
Plant diseases are majorly caused by fungi ( approx 85% of total )Fungi are multi-celled microorganisms that may be seen without a microscope during certain stages of their life cycles. Fungi have no chlorophyll and their cell walls are composed of chitin and other polysaccharides but not of cellulose. Many species of fungi can be identified by the microscopic spores ( reproductive structures )they produce that aid in dispersal and survival. Some fungi develop masses of hyphae, collectively referred to as mycelia, and spores that are readily visible. Some fungi have no spores, such as Rhizoctonia, which can be identified microscopically.
Signs and Symptoms
With pathogens, you can see signs (physical evidence of the pathogen ) and symptoms (physiological changes to the plant as a result of the disease) in the infected plantSymptoms for fungi may be :-
• Wilt
• Chlorosis
• Yellowing
• Stunting
• Leaf spots or
• Blights.
Signs for fungi including spores may be :-
• Rust or powdery mildew spores
• Mycelium
• Sclerotia
• Mushrooms and
• Conks.
Dispersal
Spores can be carried for miles by :-• Wind
• Runoff water from rainfall or irrigation will also move fungal spores from one plant to another plant.
• Fungi that live in the soil and can move from plant to plant by growing along intermingled roots.
• Fungi can also be spread by human activity, through movement of already diseased plants or by the use of gardening tools. While fungi may enter a plant through its natural openings, or through wounds, they can also penetrate directly through the plant’s epidermis (cuticle).
Bacteria
Bacteria are one-celled microorganisms that are so small they can be seen only with a powerful light microscope. Most plant pathogenic bacteria do not produce spores. Although some bacteria can survive in the soil in decaying plant material for a time, they usually need a host to survive.Dispersal
Bacteria are dependent on outside agents for dispersal from plant to plant.• Water is the chief means by which bacteria are transmitted.
• Another important means of dispersal is through human contact. Many bacterial diseases can be spread simply through the process of touching an infected plant and then touching a healthy plant with hands or pruning tools. Bacteria cannot penetrate the cuticle of plants but they can enter the plant through a wound or natural opening to initiate disease.
Pseudomonas and Xanthomonas are common bacterial organisms that cause disease in plants.
Bacterial diseases can be divided into 2 types:-
• Systemic
• Localized.
Systemic bacterial diseases - can invade plant tissues that carry water and nutrients. Then the disease spreads throughout all parts of the plant.
Localized bacterial diseases - Under certain conditions,the bacterial pathogen may grow in only one area of the infected plant.
This is localized infection and can cause :- Stem rots, Leaf spots and Blights, Wilts, and Root rots.
Some other symptoms includes :- Galls, Cankers, Wilts, and Soft decay.
Many of these symptoms are the same as those that fungi causes to plant. This makes a very challenging task to identify the pathology of that disease unless you send a plant sample to a laboratory.
Viruses
Viruses are the smallest in all three pathogens described here, and can only be seen with an electron microscope. Virus is connecting link between living and non-living. They are made up of genetic material ( DNA or RNA) which is usually wrapped in a protein coat. They require a living host in order to reproduce, because they use plant host cells in the reproduction process. Most fungi and bacteria reproduce independent of the plant host but viruses use host machinery for reproduction.Dispersal
The organism spreading the virus is referred to as a vector.Viruses are usually spread from diseased to healthy plants by :-
• Insects
• Mites
• Nematodes
• Fungi and
• Even humans.
Sign and Symptoms
Viral diseases are recognized by the symptoms on the plant. Symptoms depends on the type of virus, plant and environmental conditions.Viral disease symptoms include :-
• Curling leaves
• Stunted growth
• Wilting
• Mosaic patterns of spots on leaves
• Mosaic patterns of spots on fruit
• Deshaped leaves and
• Chlorotic leaves.
Abiotic Disorders
“Abiotic” literally means without life. Abiotic plant disorders are non-biological factors, usually associated with the plant’s environment that affect plants adversely.These environmental factors include:-
• Extreme temperatures
• Strong winds
• Too high moisture
• Too low moisture
• High or low soil pH
• Poor air quality
• Too much or too little light
• Nutritional problems and
• Human activities such as :- pesticide and fertilizer applications.
If one or more of these factors goes above or below the optimum range for a given plant species, plant growth might be abnormal or will be adversely affected.
• Pests are more likely to infect plants which are dependent in plants for Nutrients.
• Analkaline pH - Because of this alkaline pH, some essential nutrients unavailable for plant roots up take.
• Too much water - After an abundance of rain, plant roots may not be able to absorb oxygen because water fills the space that usually holds air. Feeder roots die, which can damage the plant. This problem can occur in compacted soils, too.
• Soil fungi - that cause root disease may easily infect a plant’s roots.
• Light and temperature problems - Plants can get sunburned . A rapid drop in temperature close to or below freezing kills soft herbaceous plant tissue. Cold temperature scan damage new growth, branches, stems, and trunks of woody plants.
• Not enough water - Plants will often wilt and leaves will scorch when temperatures are high and the soil is deficient of moisture.
In conclusion
Recognizing the causes of these stresses and eliminating them helps protect plants from diseases caused by plant pathogens. Be careful when you use lawnmowers, as this equipment can cause wounding.These plants are more likely to be injured if they do not have any mulch around their base, since mulch helps prevent the equipment from contact.
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