Plant Injuries and Their Causes Flashcards
What is an injurious agent?
anything that impairs healthy growth/ maturation of a plant
Define parasite
lives in or on another organism (its host) and benefits when deriving nutrients and the host’s expense/ cannot manufacture its own food. they harm the plant’s tissue and maybe kill the plant
What are the 5 kinds of plant parasites?
insects, bacteria, fungi, viruses, and nematides
What must a landscaper know for effective control of insect damage?
- insects likely to attack a particular species
- stages of insects’ lives that do not damage plants
- parts of the plant that are affected by particular insects
- how to recognize the presence of insects
- how to match a type of injury with a specific insect (leaving marks, biting tissues, tunnels, virus attacks (necrotic tissues))
Define pathogens
the bacteria, fungi, viruses and nematodes that cause plant disease
What must a landscaper know for effective control of disease damage?
- the pathogens to which the landscape’s plants are most susceptible
- the environmental conditions most suitable for pathogen development
- the potential sources of pathogens in the landscape
- how to recognize the presence of pathogens and the onset of disease
- how to diagnose a specific disease
How may plant pests be brought into a landscape?
plants purchased from a supplier, wind or water, animals, vehicles (from insects in the tires), and the soil
Define symptoms
responses of plants to insects and pathogenic irritants (they can be physical or physiological)
Define symptom complex
the sum of all symptoms expressed by a host plant from the time it is initially infected until it recovers or dies
Symptoms in plants can be influenced by what factors?
- species of host plant
- environment (physical environment/nutrients available)
- quantity if infectious materials (certain amount of infectious material)
- insect population
- stage of development of insect of pathogen
Define the plant symptom, wilting
lack of water/ if pathogens attack a plant’s vascular system or if insects destroy the root system, the wilting is permanent/ fungi invading stem tissue, causes the damping-off diease (kill or weakening seeds or seedlings germinate), causes the plant to wilt
Define the plant symptom, color changes
widespread throughout most of the plant or localized as spots, rings, or lesions/ Etiolation/ Chlorosis (not the whole leaf or plant, but portions of the plant)
Define the plant symptom, rotting
results from the destruction of cells (roots, stem, leaf) causing a release of cellular fluids/ foul odor may be present/ may be dry or soft. result of plant disease or freezing
Define the plant symptom, dwarfing
reduced in size as a result of insects, nematodes, and other pathogens/Caused by a reduction of water uptake when new tissue is expanding. Insects and nematodes can contribute
Define the plant symptom, death of tissue
tissue dried, turned black or brown
- necrosis: dead tissue that may be located on leaves as spots or centered in young buds; blights encompass entire branches.
- necrosis is the final symptom in the symptom complex (insects, pathogens, environmental factors)
Define the plant symptom, increase in size
malformed in response to insect or pathogen irritants. As cells increase in size or number, symptoms are expressed as galls, witches brooms, swollen roots, abnormal shoot growth and scabe
Define the plant symptom, tunneling
borers and leaf miners commonly create this injury (lepidopterons)
Define the plant symptom, holes
caused by insects/pathogens due to feeding
How do you look for signs in a plant of an infectious irritant?
- insects, pathogens, and parasites leave signs of their presence
- at time the only evidence is the damage they leave behind
- pathogens are generally more difficult to recognize because they are smaller
When do pesticides need to be put on the plant?
before the pathogen or invader arrives, so it will die shortly after arrival
What is the choice of pesticide formulation based on?
- size of the landscape property being treated
- amount of active ingredient being applied
- other materials being applied along with the pesticide
- cost
- safety
- ease of application
What are the different kinds of pesticide formulations?
- solutions
- emulsifiable consentrates (tiny droplets will emulsify even though two will not mix (but will look like they did))
- wettable powders
- granules and pellets
- flowable suspensions
- dusts
- water-dispersable granules
- gels
Define biological controls of pest management and provide examples
- control techiniques that attempt to return some of the natural inhibitors of insects, pathogens, and weed injury to the landscape battlefield
- plant extracts, physical features, plant emissions, predators and parasites, alternative hosts
What is derived from the root of tropical legumes?
Rotenes
What is derived from chrysthamumn?
Pyrethine
Define weed
- plant having no economic value and/or growing where it is not desired (unwanted plants)
- do not rely on host plant for food
- compete with other plants for materials that both need to grow
- weeds host to insects and pathogens that are harmful to landscaping
What are the classifications of weeds?
- annuals: weeds that complete their lives in one year
- weeds that live for several years and may produce seeds numerous times during their extended lifespan
What are the principles of control?
- exclusion - includes all of the measures designed to keep a pest from becoming established in an area
- eradication (the removal)
- protection
- resistance
What is the first principle of control?
exclusion
What is the principle of control that sets up a barrier?
protection
What principle of control is an attempt to change the plant physically or genetically so that it will suffer less from disease and/or insects?
resistance
What occurs naturally where it is observed and then is reproduced by plant breeders or it is developer over time by plant geneticists?
resistance
