Sometimes plants get sick and no matter how much you talk to your plant, they won’t talk back. The initial step in determining if a plant has a disease is to look at the signs and symptoms. This can give you a clue about what’s going on.
Read full article about | Types of Plant Pathogens and Abiotic Stresses | Click here |
Hello I'm Tapsendra Patel and this article will provide you a background on plant diseases and the signs and symptoms common for plant pathogens.
A disease is any abnormality that alters the looks or function of a plant. Plant functions are effected by this physiological process. Disease can also reduce yield and quality of harvested product. Disease is a process or a change that occurs over time. It does not occur instantly. Infectious plant diseases are caused by living organisms that attack and acquire their nutrition from the plant they infect. The parasitic organism that causes a disease is a pathogen. Numerous fungi, bacteria, viruses, and nematodes are pathogens of crops and plants. The plant invaded by the pathogen and serving as its food source which are referred as a host. Pathogens are capable of manufacturing infection and causing a disease. Fungal spores, bacterial cells, virus particles,and nematode ( juveniles or adults ) are some samples of plant pathogens.
Fungi (multi-celled microorganisms that may be seen without a microscope during certain stages of their life cycles) are the most common plant pathogens. Fungi group causes about 85% of total plant diseases. Fungi have no chlorophyll, and their cell walls are composed of chitin and other polysaccharides. Many species of fungi can be identified by the microscopic spores ( reproductive structures that aid in dispersal and survival) they produce. Some fungi haven't any spores, like Rhizoctonia,which can be identified microscopically by the very characteristic. Wind often disperses many fungal pathogens. Spores can be carried for miles by wind, water, rainfall or irrigation runoff from plant to plant. Fungi that live in the soil can move from plant to plant by growing along in the soil. Some fungi (e.g., Rhizoctonia) can survive on their own for long periods of time without a number by living in plant debris or soil. Fungi also can be spread by act , through movement of already diseased plants, or the utilization of contaminated gardening tools. While fungi may enter a plant through its natural openings like stomates ,or through wounds, they can also penetrate directly through the plant’s cuticle as well.
Bacteria are single celled microorganisms that are so small they can be seen only with a powerful microscope. Most plant pathogenic bacteria do not produce spores. Although some bacteria can survive in the soil in residues plant material for a time, they usually need a host to survive. Bacteria are dependent on environment for dispersal from plant to plant. Bacteria are transmitted through water, wind, irrigation runoff, etc. Another important means of dispersal is thru human contact. Many bacterial diseases are often spread simply through the method of touching an infected plant then touching a healthy plant with hands or pruning tools. They cannot penetrate the plants cuticle ,but can enter through a wound or natural opening to cause disease. Some groups of bacteria require an insect host for there transmission and entry into the plant. One such example is that the citrus disease Huanglongbing (also referred to as HLB or citrus greening).
Viruses are the littlest of the three pathogens described here and may only be seen with an microscope . They are made up of genetic material surrounded with a protein coat. Genetic material can be DNA or RNA. They must have a living host so as to breed ,because they use plant host cells within the reproduction process. Most of the fungi and bacteria have independent reproduction from there plant host. Viruses spread from infected to healthy plants by insects,mites, nematodes, fungi, and even humans. The organism spreading the virus is referred as a vector.
Nematodes are microscopic, non-segmented,round, slender worms. Several thousand species of nematodes are found in soil, in fresh and salt water, in animals, and within or on plants all over the world. Most feed on dead or decaying organic material. Also some of them can be parasites on plants, insects, animals or even fungi. A single acre of cultivated soil may contain many many nematodes. Most of parasitic nematodes cannot be seen with naked eyes. They sometimes exceed 1/8 of an inch and maybe smaller than 1/64 of an inch. Nematodes inject substances into host plant cells through their stylets and then suck nutrition from the plant cells. The life cycle of a nematode includes an egg, 3 or 4 juvenile stages, and an adult. The average life cycle of a nematode is 20 to 60 days. Nematodes feed in or on plant roots. Some nematodes live a neighborhood or all of their lives inside plant roots. Most important plant-parasitic nematodes prey on plant roots and directly interfere with water and nutrient uptake by the plant.
Any detectable changes in color, shape, or functions of the plant in response to a pathogen or disease-causing agent is a symptom. Leaf spots or blights, discoloration of plant part , stunting, and wilting are symptoms which will be evidence of disease. Symptoms can occur throughout the plant or they can be restricted to localized areas. Well certain symptoms are characteristic of a particular disease, a number of pathogens may produce the same or similar symptoms. Symptoms often change over time and their expression is influenced by environmental conditions and plant varieties. Signs of plant disease are physical evidence of the pathogen like fungal bodies, bacterial , or nematode. Signs can help with plant disease identification.
The abnormal features which indicates that something is wrong in plant's health is called Symptom. It is important to learn the proper name for a symptom. A Spot is just an another one, a spot. If there are spots on the leaves, they will be called leaf spots; spots on the fruit are fruit spots. The technical term for a spot is “lesion,”which means a localized diseased area or wound.
As spots grow together, the symptom is called a Blight and this is different from a spot because it damages more numbers of grouped cells.
Galls, or tumors are masses of undifferentiated tissue growth which may be found on stems, roots,and leaves. These are similar to cancerous tumors alike humans cancer.
A simple degradation in plants tissues by pathology is ROT
A Wilting is water stressed condition for a plant which causes symptoms like white, off-white or light-green vascular tissue. Wilt can also be caused by nematodes since they feed on and damage the root system.
Damping-off is the rotting of seedlings and they may emerge from the soil or potting mixture. There are two types of damping-off diseases. One is Pre-emergence damping-off which occurs when a germinating seed is infected.
And the another one is Post-emergence damping-off which occurs when a fully grown seedling gets infected from soil sources and ultimately dies.
The symptoms discussed above are mainly associated with fungal or bacterial pathogens.
Symptoms of viral diseases include fading the color of leaves and fruit , yellowing of leaves, misshapen leaves, yellow or necrotic rings on leaves or fruits. Too often, symptoms of specific diseases and some abiotic disorders overlap sometimes. To properly identify a fungal or bacterial disease, we must look for the signs of the pathogen, the most significant way to find out may be - it should be viewed with the unaided eye ,a magnifying lens, or microscope. With fungal diseases, one can often see the actual fungal growth like mycelium, sporemasses such as molds or rusts, and mushrooms.
In order to obtain a definitive diagnosis of a virus, samples must be sent to a clinic that has the special equipment and materials necessary to do the proper tests. Additional help is available through several plant diagnostic clinics run by university plant pathologists around the state. .
In summary, the major plant pathogens responsible for disease development in plants are fungi, bacteria, viruses, and nematodes. We should have a clear cut the difference between a sign and a symptom to understand the key of identifying a plant disease.
- TAPSENDRA PATEL
Read full article about | Types of Plant Pathogens and Abiotic Stresses | Click here |
Read full article about | Types of Plant Pathogens and Abiotic Stresses | Click here |
Hello I'm Tapsendra Patel and this article will provide you a background on plant diseases and the signs and symptoms common for plant pathogens.
A disease is any abnormality that alters the looks or function of a plant. Plant functions are effected by this physiological process. Disease can also reduce yield and quality of harvested product. Disease is a process or a change that occurs over time. It does not occur instantly. Infectious plant diseases are caused by living organisms that attack and acquire their nutrition from the plant they infect. The parasitic organism that causes a disease is a pathogen. Numerous fungi, bacteria, viruses, and nematodes are pathogens of crops and plants. The plant invaded by the pathogen and serving as its food source which are referred as a host. Pathogens are capable of manufacturing infection and causing a disease. Fungal spores, bacterial cells, virus particles,and nematode ( juveniles or adults ) are some samples of plant pathogens.
Fungi (multi-celled microorganisms that may be seen without a microscope during certain stages of their life cycles) are the most common plant pathogens. Fungi group causes about 85% of total plant diseases. Fungi have no chlorophyll, and their cell walls are composed of chitin and other polysaccharides. Many species of fungi can be identified by the microscopic spores ( reproductive structures that aid in dispersal and survival) they produce. Some fungi haven't any spores, like Rhizoctonia,which can be identified microscopically by the very characteristic. Wind often disperses many fungal pathogens. Spores can be carried for miles by wind, water, rainfall or irrigation runoff from plant to plant. Fungi that live in the soil can move from plant to plant by growing along in the soil. Some fungi (e.g., Rhizoctonia) can survive on their own for long periods of time without a number by living in plant debris or soil. Fungi also can be spread by act , through movement of already diseased plants, or the utilization of contaminated gardening tools. While fungi may enter a plant through its natural openings like stomates ,or through wounds, they can also penetrate directly through the plant’s cuticle as well.
Bacteria are single celled microorganisms that are so small they can be seen only with a powerful microscope. Most plant pathogenic bacteria do not produce spores. Although some bacteria can survive in the soil in residues plant material for a time, they usually need a host to survive. Bacteria are dependent on environment for dispersal from plant to plant. Bacteria are transmitted through water, wind, irrigation runoff, etc. Another important means of dispersal is thru human contact. Many bacterial diseases are often spread simply through the method of touching an infected plant then touching a healthy plant with hands or pruning tools. They cannot penetrate the plants cuticle ,but can enter through a wound or natural opening to cause disease. Some groups of bacteria require an insect host for there transmission and entry into the plant. One such example is that the citrus disease Huanglongbing (also referred to as HLB or citrus greening).
Viruses are the littlest of the three pathogens described here and may only be seen with an microscope . They are made up of genetic material surrounded with a protein coat. Genetic material can be DNA or RNA. They must have a living host so as to breed ,because they use plant host cells within the reproduction process. Most of the fungi and bacteria have independent reproduction from there plant host. Viruses spread from infected to healthy plants by insects,mites, nematodes, fungi, and even humans. The organism spreading the virus is referred as a vector.
Nematodes are microscopic, non-segmented,round, slender worms. Several thousand species of nematodes are found in soil, in fresh and salt water, in animals, and within or on plants all over the world. Most feed on dead or decaying organic material. Also some of them can be parasites on plants, insects, animals or even fungi. A single acre of cultivated soil may contain many many nematodes. Most of parasitic nematodes cannot be seen with naked eyes. They sometimes exceed 1/8 of an inch and maybe smaller than 1/64 of an inch. Nematodes inject substances into host plant cells through their stylets and then suck nutrition from the plant cells. The life cycle of a nematode includes an egg, 3 or 4 juvenile stages, and an adult. The average life cycle of a nematode is 20 to 60 days. Nematodes feed in or on plant roots. Some nematodes live a neighborhood or all of their lives inside plant roots. Most important plant-parasitic nematodes prey on plant roots and directly interfere with water and nutrient uptake by the plant.
Any detectable changes in color, shape, or functions of the plant in response to a pathogen or disease-causing agent is a symptom. Leaf spots or blights, discoloration of plant part , stunting, and wilting are symptoms which will be evidence of disease. Symptoms can occur throughout the plant or they can be restricted to localized areas. Well certain symptoms are characteristic of a particular disease, a number of pathogens may produce the same or similar symptoms. Symptoms often change over time and their expression is influenced by environmental conditions and plant varieties. Signs of plant disease are physical evidence of the pathogen like fungal bodies, bacterial , or nematode. Signs can help with plant disease identification.
The abnormal features which indicates that something is wrong in plant's health is called Symptom. It is important to learn the proper name for a symptom. A Spot is just an another one, a spot. If there are spots on the leaves, they will be called leaf spots; spots on the fruit are fruit spots. The technical term for a spot is “lesion,”which means a localized diseased area or wound.
As spots grow together, the symptom is called a Blight and this is different from a spot because it damages more numbers of grouped cells.
Galls, or tumors are masses of undifferentiated tissue growth which may be found on stems, roots,and leaves. These are similar to cancerous tumors alike humans cancer.
A simple degradation in plants tissues by pathology is ROT
A Wilting is water stressed condition for a plant which causes symptoms like white, off-white or light-green vascular tissue. Wilt can also be caused by nematodes since they feed on and damage the root system.
Damping-off is the rotting of seedlings and they may emerge from the soil or potting mixture. There are two types of damping-off diseases. One is Pre-emergence damping-off which occurs when a germinating seed is infected.
And the another one is Post-emergence damping-off which occurs when a fully grown seedling gets infected from soil sources and ultimately dies.
The symptoms discussed above are mainly associated with fungal or bacterial pathogens.
Symptoms of viral diseases include fading the color of leaves and fruit , yellowing of leaves, misshapen leaves, yellow or necrotic rings on leaves or fruits. Too often, symptoms of specific diseases and some abiotic disorders overlap sometimes. To properly identify a fungal or bacterial disease, we must look for the signs of the pathogen, the most significant way to find out may be - it should be viewed with the unaided eye ,a magnifying lens, or microscope. With fungal diseases, one can often see the actual fungal growth like mycelium, sporemasses such as molds or rusts, and mushrooms.
In order to obtain a definitive diagnosis of a virus, samples must be sent to a clinic that has the special equipment and materials necessary to do the proper tests. Additional help is available through several plant diagnostic clinics run by university plant pathologists around the state. .
In summary, the major plant pathogens responsible for disease development in plants are fungi, bacteria, viruses, and nematodes. We should have a clear cut the difference between a sign and a symptom to understand the key of identifying a plant disease.
- TAPSENDRA PATEL
Read full article about | Types of Plant Pathogens and Abiotic Stresses | Click here |
Comments
Post a Comment