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Questions and Answers
What was responsible for the near complete loss of the American chestnut?
What was responsible for the near complete loss of the American chestnut?
- A bacterial infection
- A plant parasitic nematode
- A viral outbreak
- A fungal disease (correct)
How was chestnut blight introduced to the United States?
How was chestnut blight introduced to the United States?
- Through native tree species
- Imported Chinese chestnut trees (correct)
- Via contaminated soil
- Through agricultural practices
What management strategies are currently used against chestnut blight?
What management strategies are currently used against chestnut blight?
- Chemical pesticides exclusively
- Genetic modification of the trees
- Planting only native species
- Sanitation and fungicides (correct)
What role did the French wine industry play in disease management?
What role did the French wine industry play in disease management?
Approximately how many acres of chestnut trees died due to the chestnut blight?
Approximately how many acres of chestnut trees died due to the chestnut blight?
Which of the following statements about Chinese chestnut trees is true?
Which of the following statements about Chinese chestnut trees is true?
What type of pathogen mainly caused the devastation of the American chestnut?
What type of pathogen mainly caused the devastation of the American chestnut?
After the introduction of chestnut blight, how did the landscape of American forests change?
After the introduction of chestnut blight, how did the landscape of American forests change?
What is the primary function of sexual spores produced by water molds?
What is the primary function of sexual spores produced by water molds?
How often can sporulation occur in water molds during a growing season?
How often can sporulation occur in water molds during a growing season?
What is one visible example of a fungal disease mentioned?
What is one visible example of a fungal disease mentioned?
Which of the following pathogens cannot survive winter in Kentucky?
Which of the following pathogens cannot survive winter in Kentucky?
How can the variation in fungal spores assist diagnosticians?
How can the variation in fungal spores assist diagnosticians?
Which type of fungal fruiting structure is produced sexually?
Which type of fungal fruiting structure is produced sexually?
What is a common symptom of cucumber infection by the cucurbit downy mildew pathogen?
What is a common symptom of cucumber infection by the cucurbit downy mildew pathogen?
Where are spores of the cucurbit downy mildew pathogen typically produced?
Where are spores of the cucurbit downy mildew pathogen typically produced?
What is a characteristic of exposed or unprotected fungal spores?
What is a characteristic of exposed or unprotected fungal spores?
What happens to a fungal spore once it makes contact with a suitable plant surface?
What happens to a fungal spore once it makes contact with a suitable plant surface?
How do spores of downy mildew spread to new tissue?
How do spores of downy mildew spread to new tissue?
What is required for plant disease to occur according to the Disease Triangle?
What is required for plant disease to occur according to the Disease Triangle?
Which of the following diseases primarily affects solanaceous crops?
Which of the following diseases primarily affects solanaceous crops?
What is the typical overwintering site for the late blight pathogen?
What is the typical overwintering site for the late blight pathogen?
Which of the following fungi’s reproductive strategies involves both sexual and asexual processes?
Which of the following fungi’s reproductive strategies involves both sexual and asexual processes?
Which structure is a common asexual fruiting body produced by fungi?
Which structure is a common asexual fruiting body produced by fungi?
What structures do plant parasitic nematodes use to pierce plant tissues?
What structures do plant parasitic nematodes use to pierce plant tissues?
Which of the following symptoms is NOT commonly caused by nematode feeding?
Which of the following symptoms is NOT commonly caused by nematode feeding?
How do plant parasitic nematodes primarily disseminate over long distances?
How do plant parasitic nematodes primarily disseminate over long distances?
What does the presence of female nematodes at a feeding site indicate?
What does the presence of female nematodes at a feeding site indicate?
Which type of nematode feeds while remaining on the exterior of plant roots?
Which type of nematode feeds while remaining on the exterior of plant roots?
What reproductive method can female nematodes use to produce eggs?
What reproductive method can female nematodes use to produce eggs?
What is a common result of severe root loss due to nematode feeding?
What is a common result of severe root loss due to nematode feeding?
What differentiates the feeding behavior of dagger nematodes from that of soybean cyst nematodes?
What differentiates the feeding behavior of dagger nematodes from that of soybean cyst nematodes?
What is the primary way bacteria infect plants?
What is the primary way bacteria infect plants?
Which of the following symptoms are commonly caused by bacterial infections?
Which of the following symptoms are commonly caused by bacterial infections?
What facilitates the movement of bacteria to infect plants?
What facilitates the movement of bacteria to infect plants?
What reproductive process do bacteria undergo for rapid multiplication?
What reproductive process do bacteria undergo for rapid multiplication?
How long can some bacteria survive in soil?
How long can some bacteria survive in soil?
What happens to plant tissue once bacteria begin to reproduce inside it?
What happens to plant tissue once bacteria begin to reproduce inside it?
Which of the following is NOT a common bacterial disease mentioned?
Which of the following is NOT a common bacterial disease mentioned?
What might indicate a serious bacterial infection in plants?
What might indicate a serious bacterial infection in plants?
Powdery mildew is known to cause a white powdery appearance on infected plants.
Powdery mildew is known to cause a white powdery appearance on infected plants.
Cedar-apple rust can complete its life cycle using only one host.
Cedar-apple rust can complete its life cycle using only one host.
Spores of the powdery mildew fungus survive winter on healthy plant tissues.
Spores of the powdery mildew fungus survive winter on healthy plant tissues.
Armillaria root rot is particularly aggressive towards newly transplanted and older stressed trees.
Armillaria root rot is particularly aggressive towards newly transplanted and older stressed trees.
Rust pathogens are only found in dry climates.
Rust pathogens are only found in dry climates.
Cedar-apple rust produces different spore types during different seasons.
Cedar-apple rust produces different spore types during different seasons.
Infection by the powdery mildew pathogen occurs when rain splashes spores onto new plant growth.
Infection by the powdery mildew pathogen occurs when rain splashes spores onto new plant growth.
The unique structure known as galls is produced by cedar-apple rust on apple trees.
The unique structure known as galls is produced by cedar-apple rust on apple trees.
Viruses in plants often lead to immediate death of the host plant.
Viruses in plants often lead to immediate death of the host plant.
Insects can transmit plant viruses multiple times during a growing season.
Insects can transmit plant viruses multiple times during a growing season.
Rose rosette virus is transmitted by insects such as thrips.
Rose rosette virus is transmitted by insects such as thrips.
Plant viruses can move in and out of plant tissue as easily as fungal and bacterial pathogens.
Plant viruses can move in and out of plant tissue as easily as fungal and bacterial pathogens.
Tomato spotted wilt virus can infect a wide variety of plant species.
Tomato spotted wilt virus can infect a wide variety of plant species.
The tobacco mosaic virus primarily infects only tobacco plants.
The tobacco mosaic virus primarily infects only tobacco plants.
Symptoms of rose rosette infection can appear immediately after infection.
Symptoms of rose rosette infection can appear immediately after infection.
Once a plant is infected with TSWV, it does not transmit the virus to insects.
Once a plant is infected with TSWV, it does not transmit the virus to insects.
Infected seeds or pollen can contribute to the spread of plant viruses.
Infected seeds or pollen can contribute to the spread of plant viruses.
Infected plants can sometimes exhibit lesions on stems as a symptom of TSWV.
Infected plants can sometimes exhibit lesions on stems as a symptom of TSWV.
Chlorosis is a symptom commonly associated with plant viral infections.
Chlorosis is a symptom commonly associated with plant viral infections.
The mites responsible for spreading rose rosette virus can move through wind currents.
The mites responsible for spreading rose rosette virus can move through wind currents.
Certain viruses can remain viable in dormant plant tissue for extended periods.
Certain viruses can remain viable in dormant plant tissue for extended periods.
Once inside an insect's gut, plant viruses can only be carried for short periods.
Once inside an insect's gut, plant viruses can only be carried for short periods.
Virus-infected plants do not provide a source for vectoring mites after they are infected.
Virus-infected plants do not provide a source for vectoring mites after they are infected.
Thrips acquire the tomato spotted wilt virus during their adult stage.
Thrips acquire the tomato spotted wilt virus during their adult stage.
Mosaic symptoms on plants are characterized by a uniform green color throughout.
Mosaic symptoms on plants are characterized by a uniform green color throughout.
Mottle symptoms present as an irregular pattern of light and dark areas on plant leaves.
Mottle symptoms present as an irregular pattern of light and dark areas on plant leaves.
Mummy refers to soft, wet tissue on fruits caused by pathogens.
Mummy refers to soft, wet tissue on fruits caused by pathogens.
Necrosis is the death of plant tissue and is a symptom associated with multiple pathogen groups.
Necrosis is the death of plant tissue and is a symptom associated with multiple pathogen groups.
Stunting symptoms indicate that a plant is growing larger than normal.
Stunting symptoms indicate that a plant is growing larger than normal.
Vein clearing symptoms manifest as yellowing of the entire leaf surface.
Vein clearing symptoms manifest as yellowing of the entire leaf surface.
Watersoaking involves wet, dark, or greasy lesions that are typically sunken.
Watersoaking involves wet, dark, or greasy lesions that are typically sunken.
Scab lesions are characterized by a smooth surface appearance.
Scab lesions are characterized by a smooth surface appearance.
Witches’ broom symptoms involve an abnormal brush-like shoot development.
Witches’ broom symptoms involve an abnormal brush-like shoot development.
Wilt symptoms are associated with drooping leaves and reduced plant health.
Wilt symptoms are associated with drooping leaves and reduced plant health.
Exclusion techniques aim to prevent pathogen introductions to areas where they currently exist.
Exclusion techniques aim to prevent pathogen introductions to areas where they currently exist.
Fungicides are usually pathogen-specific and are effective in managing only fungal pathogens.
Fungicides are usually pathogen-specific and are effective in managing only fungal pathogens.
Resistance refers to selecting plants with increased tolerance to pathogens.
Resistance refers to selecting plants with increased tolerance to pathogens.
Avoidance strategies include the practice of using diseased plants for crop rotation.
Avoidance strategies include the practice of using diseased plants for crop rotation.
Fungicides can reverse disease symptoms once applied to affected plants.
Fungicides can reverse disease symptoms once applied to affected plants.
Reducing plant stresses can be an effective common practice for pathogen avoidance.
Reducing plant stresses can be an effective common practice for pathogen avoidance.
Quarantine is a common practice used in the avoidance strategy to manage plant pathogens.
Quarantine is a common practice used in the avoidance strategy to manage plant pathogens.
Antibiotics are primarily used to manage fungal pathogens in plants.
Antibiotics are primarily used to manage fungal pathogens in plants.
Powdery mildew is known to infect numerous landscape and garden ______.
Powdery mildew is known to infect numerous landscape and garden ______.
Spores of the powdery mildew pathogen survive winter on infected plant ______.
Spores of the powdery mildew pathogen survive winter on infected plant ______.
Organisms that cause disease are referred to as ______.
Organisms that cause disease are referred to as ______.
Cedar-apple rust is caused by a group of fungi known as ______.
Cedar-apple rust is caused by a group of fungi known as ______.
A plant disease is an abnormality caused by a living ______.
A plant disease is an abnormality caused by a living ______.
The pathogen of cedar-apple rust overwinters as galls on ______.
The pathogen of cedar-apple rust overwinters as galls on ______.
One of the most notable historical impacts of plant disease was caused by the late blight of ______.
One of the most notable historical impacts of plant disease was caused by the late blight of ______.
The galls produced by the cedar-apple rust release slimy 'horns' comprised of ______ during spring rains.
The galls produced by the cedar-apple rust release slimy 'horns' comprised of ______ during spring rains.
Plant pathogens utilize hosts for nutrients and/or reproduction at the hosts' ______.
Plant pathogens utilize hosts for nutrients and/or reproduction at the hosts' ______.
In late summer, apple lesions produce another spore type that infects ______.
In late summer, apple lesions produce another spore type that infects ______.
Armillaria root rot is particularly aggressive towards ______ and older stressed trees.
Armillaria root rot is particularly aggressive towards ______ and older stressed trees.
Disease-causing organisms include fungi, oomycetes (water molds), bacteria, viruses, and ______.
Disease-causing organisms include fungi, oomycetes (water molds), bacteria, viruses, and ______.
Throughout the season, powdery mildew produces additional ______ causing subsequent infections.
Throughout the season, powdery mildew produces additional ______ causing subsequent infections.
On a global scale, plant diseases cause an estimated ______ billion in annual losses.
On a global scale, plant diseases cause an estimated ______ billion in annual losses.
Affected plants are referred to as ______.
Affected plants are referred to as ______.
Saprophytic organisms obtain nutrients from ______ organic material.
Saprophytic organisms obtain nutrients from ______ organic material.
The American chestnut was nearly wiped out by a fungal disease known as ______.
The American chestnut was nearly wiped out by a fungal disease known as ______.
Chinese chestnuts are tolerant to the ______, while American chestnuts are not.
Chinese chestnuts are tolerant to the ______, while American chestnuts are not.
Disease management strategies against chestnut blight include the use of resistant ______.
Disease management strategies against chestnut blight include the use of resistant ______.
The first fungicide used in the wine industry was the ______ mixture.
The first fungicide used in the wine industry was the ______ mixture.
Approximately ______ million acres of chestnut trees died due to chestnut blight.
Approximately ______ million acres of chestnut trees died due to chestnut blight.
Fungi, bacteria, viruses, and ______ are examples of different types of pathogens that affect plants.
Fungi, bacteria, viruses, and ______ are examples of different types of pathogens that affect plants.
In urban areas, American chestnut trees once provided high-quality ______ for construction.
In urban areas, American chestnut trees once provided high-quality ______ for construction.
In the late 1800s, chestnut blight was accidentally introduced to the United States through imported ______ trees.
In the late 1800s, chestnut blight was accidentally introduced to the United States through imported ______ trees.
Plant disease diagnostics begins with the observation of ______.
Plant disease diagnostics begins with the observation of ______.
Fungi and bacteria can cause leaf spots that are similar to those caused by ______.
Fungi and bacteria can cause leaf spots that are similar to those caused by ______.
To confirm diagnoses, identification of signs such as mycelial growth and fruiting structures requires the use of a ______.
To confirm diagnoses, identification of signs such as mycelial growth and fruiting structures requires the use of a ______.
Examination of surrounding plants can provide vital information regarding disease ______.
Examination of surrounding plants can provide vital information regarding disease ______.
Patterns of injury or symptoms can give clues as to whether variety- or species- specific infections are ______.
Patterns of injury or symptoms can give clues as to whether variety- or species- specific infections are ______.
Information regarding soil makeup, disturbances, and soil drainage patterns can assist in differentiating ______ maladies from diseases.
Information regarding soil makeup, disturbances, and soil drainage patterns can assist in differentiating ______ maladies from diseases.
Diagnosing plant problems may require submitting samples to a ______ laboratory for further analysis.
Diagnosing plant problems may require submitting samples to a ______ laboratory for further analysis.
Several steps to disease diagnostics include examining vital site information and examining ______ tissue.
Several steps to disease diagnostics include examining vital site information and examining ______ tissue.
A single plant species can have numerous cultivars or ______, which can vary in many traits.
A single plant species can have numerous cultivars or ______, which can vary in many traits.
Symptoms may differ with plant species or ______, which is vital for diagnosis.
Symptoms may differ with plant species or ______, which is vital for diagnosis.
Critical information like irrigation practices and ______ date can aid in making accurate diagnoses.
Critical information like irrigation practices and ______ date can aid in making accurate diagnoses.
In some cases, symptoms develop on plant parts that are different from the infected ______.
In some cases, symptoms develop on plant parts that are different from the infected ______.
A root rot pathogen may cause symptoms like dieback and ______, indicating potential troubles with the plant.
A root rot pathogen may cause symptoms like dieback and ______, indicating potential troubles with the plant.
It may be necessary to submit symptomatic plant samples to a diagnostic ______ if the cause cannot be determined.
It may be necessary to submit symptomatic plant samples to a diagnostic ______ if the cause cannot be determined.
Determining if a problem is present can depend on assessing normal versus abnormal plant ______.
Determining if a problem is present can depend on assessing normal versus abnormal plant ______.
Collecting additional information can lead to a more complete ______ of plant health issues.
Collecting additional information can lead to a more complete ______ of plant health issues.
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Study Notes
History and Significance
- American chestnut trees were devastated by chestnut blight, a fungal disease introduced in the late 1800s through Chinese chestnut imports.
- Approximately 30 million acres of American chestnuts died within 40 years due to their lack of tolerance to the blight.
- Disease management strategies now include resistant varieties, sanitation, and fungicides.
Pathogens
- Fungi reproduce via spores which can be created sexually or asexually; their variation helps in pathogen identification.
- Fungal reproductive structures can be visible (e.g., mushrooms) or microscopic (e.g., pycnidia, acervuli).
- Downy mildew and late blight are diseases caused by water molds, which are host-specific.
Conditions for Disease Development
- Plant disease is influenced by a susceptible host, a viable pathogen, and a favorable environment, forming the Disease Triangle.
- Spores germinate on contact with a plant surface under optimal conditions, leading to infection.
Fungi
- Fungi require suitable conditions to grow; sporulation can happen multiple times in a season when water is available.
- Water molds can produce spores prior to dormancy and can survive harsh conditions.
Water Molds
- Downy mildew affects various plants; infection results in angular leaf spots and can cause defoliation.
- Late blight primarily infects potatoes and tomatoes, characterized by water-soaked lesions that lead to defoliation.
Bacteria
- Around 200 bacterial types are known to cause plant diseases; they are single-celled and reproduce rapidly through binary fission.
- Common bacterial diseases include bacterial wilt and fire blight, with symptoms such as leaf spots and wilting.
- Bacteria spread via water, wind, and insects, often requiring wounds or natural openings to infect plants.
Plant Parasitic Nematodes
- Nematodes are microscopic roundworms that primarily infect plant roots, causing stunted growth and reduced yields.
- Infestation symptoms include chlorosis, root galls, and dieback due to their feeding on plant cell contents.
- Key examples include soybean cyst nematodes and stubby-root nematodes, which can feed externally or penetrate tissues.
Plant Diseases Overview
- Powdery Mildew: A fungal disease affecting many plants; spores survive winter on infected debris. Spring rains facilitate spread to new growth, leading to a white, powdery appearance.
- Cedar-Apple Rust: A fungi-induced disease requiring multiple hosts; galls on juniper overwinter, producing spores in spring that infect apple trees, creating lesions that later infect junipers.
Armillaria Root Rot
- Affects recently transplanted and stressed trees, causing root decay.
Viruses
- Extremely small pathogens necessitating powerful magnification for observation. Viruses can persist in host plants for years, avoiding rapid mortality.
- Common vectors include insects which acquire and transfer virus particles during feeding, enabling multiplication of viruses inside insects.
Common Viral Diseases
- Tobacco Mosaic Virus: Named after the first observed symptoms in tobacco, infects over 100 plant species, leading to symptoms like mottling and stunting.
- Rose Rosette Virus: Carried by rose leaf curl mites, causing witches' broom, leaf reddening, and excessive thorn development.
- Tomato Spotted Wilt Virus (TSWV): Infects thousands of species, transmitted by thrips. Symptoms include wilting, lesions, and mottling on fruit.
Symptoms of Plant Pathogens
- Mosaic and Mottling: Nonuniform coloration often seen with viral infections.
- Necrosis: Tissue death observed in various pathogens.
- Stunting: Reduced plant growth affecting size and vigor, ensuing from viral or nematode infections.
- Wilt and Scorch: Common symptoms related to both fungal and viral infections.
Plant Disease Diagnostic Techniques
- Techniques include prevention (exclusion), pathogen management (avoidance), and selection of resistant plant varieties.
- Exclusion: Prevent pathogen entry through quarantine and inspection, utilizing disease-free plant materials.
- Avoidance: Use certified plants, inspect before planting, reduce stress, and rotate crops.
Protection Against Plant Diseases
- Implement protective measures tailored to specific pathogen threats. Fungicides mainly serve to limit fungal infections but do not cure existing diseases.
- Resistance: Selecting disease-resistant plant varieties to mitigate the impact of common pathogens.
Understanding these principles aids in the identification and management of plant diseases, enhancing plant health and productivity.
Plant Diseases Overview
- Pathogens causing plant diseases include fungi, water molds (oomycetes), bacteria, viruses, nematodes, phytoplasmas, and parasitic seed plants.
- Major historical impact example: Late blight of potato led to the Irish potato famine in 1845, resulting in about one million deaths.
- Losses from plant diseases globally are estimated at $38 billion annually.
American Chestnut and Chestnut Blight
- The American chestnut was nearly wiped out by chestnut blight, a fungal disease introduced in the late 1800s through Chinese chestnuts.
- Approximately 30 million acres of American chestnut trees died within 40 years due to their susceptibility.
- Management of chestnut blight now includes resistant varieties, sanitation, and fungicide applications.
Disease Development and Symptoms
- Symptoms of plant disease arise after a pathogen infects a host and may result from complex interactions between biotic and abiotic factors.
- Common disease indicators include notable symptoms on specific plant parts, which can mislead diagnostics if not appropriately assessed.
- Examples of diseases:
- Powdery mildew: Infects various plants, characterized by white powdery growth.
- Cedar-apple rust: Requires multiple hosts; overwinters on juniper and affects apple trees in spring.
Plant Disease Diagnostics
- Diagnosis begins with observing affected plants and the environment, often necessitating microscopic examination.
- Recognizing the impact of abiotic factors (e.g., weather, soil conditions) is crucial for accurate diagnosis.
- Key diagnostic steps:
- Examine the site for clues about environmental conditions affecting plant health.
- Ask questions about plant history, caretaking practices, and unusual occurrences (herbicide applications, irrigation practices).
- Identify the specific plant parts exhibiting symptoms, as issues may not originate from the visibly affected areas.
Management and Research
- Disease management strategies evolved significantly since the introduction of the Bordeaux mixture fungicide to tackle issues in agricultural systems.
- Continuous research is being conducted for better management options against persistent diseases, like chestnut blight.
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