Plant Injuries and Their Causes

Question 1

What is an injurious agent?

Answer 1

anything that impairs healthy growth/ maturation of a plant

Question 2

Define parasite

Answer 2

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

Question 3

What are the 5 kinds of plant parasites?

Answer 3

insects, bacteria, fungi, viruses, and nematides

Question 4

What must a landscaper know for effective control of insect damage?

Answer 4

• 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))

Question 5

Define pathogens

Answer 5

the bacteria, fungi, viruses and nematodes that cause plant disease

Question 6

What must a landscaper know for effective control of disease damage?

Answer 6

• 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

Question 7

How may plant pests be brought into a landscape?

Answer 7

plants purchased from a supplier, wind or water, animals, vehicles (from insects in the tires), and the soil

Question 8

Define symptoms

Answer 8

responses of plants to insects and pathogenic irritants (they can be physical or physiological)

Question 9

Define symptom complex

Answer 9

the sum of all symptoms expressed by a host plant from the time it is initially infected until it recovers or dies

Question 10

Symptoms in plants can be influenced by what factors?

Answer 10

• 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

Question 11

Define the plant symptom, wilting

Answer 11

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

Question 12

Define the plant symptom, color changes

Answer 12

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)

Question 13

Define the plant symptom, rotting

Answer 13

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

Question 14

Define the plant symptom, dwarfing

Answer 14

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

Question 15

Define the plant symptom, death of tissue

Answer 15

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)

Question 16

Define the plant symptom, increase in size

Answer 16

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

Question 17

Define the plant symptom, tunneling

Answer 17

borers and leaf miners commonly create this injury (lepidopterons)

Question 18

Define the plant symptom, holes

Answer 18

caused by insects/pathogens due to feeding

Question 19

How do you look for signs in a plant of an infectious irritant?

Answer 19

• 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

Question 20

When do pesticides need to be put on the plant?

Answer 20

before the pathogen or invader arrives, so it will die shortly after arrival

Question 21

What is the choice of pesticide formulation based on?

Answer 21

• 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

Question 22

What are the different kinds of pesticide formulations?

Answer 22

• 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

Question 23

Define biological controls of pest management and provide examples

Answer 23

• 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

Question 24

What is derived from the root of tropical legumes?

Answer 24

Rotenes

Question 25

What is derived from chrysthamumn?

Answer 25

Pyrethine

Question 26

Define weed

Answer 26

• 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

Question 27

What are the classifications of weeds?

Answer 27

• 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

Question 28

What are the principles of control?

Answer 28

• exclusion - includes all of the measures designed to keep a pest from becoming established in an area
• eradication (the removal)
• protection
• resistance

Question 29

What is the first principle of control?

Answer 29

exclusion

Question 30

What is the principle of control that sets up a barrier?

Answer 30

protection

Question 31

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?

Answer 31

resistance

Question 32

What occurs naturally where it is observed and then is reproduced by plant breeders or it is developer over time by plant geneticists?

Answer 32

resistance