Exam I

Question 1

What microorganisms can infect via direct penetration?

Answer 1

Fungi

Question 2

Hydathode

Answer 2

opening at end of leaf

Question 3

What microorganisms can infect via natural openings?

Answer 3

fungi and bacteria

Question 4

Koch’s Postulates

Answer 4

1. pathogen must be associated with disease
2. isolate suspected pathogen in culture & describe characteristics
3. pathogen must be inoculated onto healthy plants of same species and produce same disease
4. pathogen must be re-isolated from inoculated plants and have characteristics identical to step 2

Question 5

When did Koch’s postulates come about?

Answer 5

mid-1800’s

Question 6

Winter Burn

Answer 6

occurs when leaves want to transpire but the roots are still frozen; usually affects conifers; usually affects one side

Question 7

Frost-Cracks

Answer 7

woody parts expand and crack

Question 8

Frost band

Answer 8

similar to russetinf

Question 9

Frost heaving

Answer 9

occurs when repetitive patterns of freezing and thawing cause the clay to expand and sever the vascular system

Question 10

Blossom end rot

Answer 10

caused by a deficiency in Calcium

Question 11

Etiolation

Answer 11

caused by a deficiency in light. results in weak, long stems, and smaller, chlorotic leaves.

Question 12

Iron deficiency

Answer 12

tips of branches and leaves chlorotic and necrotic

Question 13

Nitrogen deficiency

Answer 13

old growth chlorosis

Question 14

Phosphorus deficiency

Answer 14

purplish discoloration

Question 15

Potassium deficiency

Answer 15

pale, necrotic spots around margin

Question 16

What is an example of a disease complex

Answer 16

crown rot of alfalfa. plant initially has mechanical damage done that allows a secondary pathogen to enter.

Question 17

Four plant disease control methods

Answer 17

exclusion, eradication, host resistance, direct protection

Question 18

1912

Answer 18

first quarantine laws introduced in US

Question 19

1957

Answer 19

Federal Plant Pest Act

Question 20

Four quarantine categories

Answer 20

1. restricted: usually inspect/treat seeds
2. post-entry period: can enter after quarantine
3. completely prohibited: not allowed
4. unrestricted: dead specimens allowed

Question 21

Evasion

Answer 21

a method used to control plant disease where the plant is grown in particular geographic or regions or at particular times in order to avoid pathogen. (i.e Barley Yellow Dwarf, Black Rot of Cabbage)

Question 22

disinfectant

Answer 22

used when pathogen is INSIDE seed; bayleton

Question 23

disinfestation

Answer 23

used when pathogen is OUTSIDE seed; captan, thiram

Question 24

Protectant

Answer 24

used when pathogen may not be present-preemptive; captan, thorium.

Question 25

Temp required to kill ALL microorganisms in heat treatment

Answer 25

176 F

Question 26

Temp required to kill fungi in heat treatment

Answer 26

100-130 F

Question 27

Temp required to kill bacteria in heat treatment

Answer 27

140-160 F

Question 28

1885

Answer 28

Millardet discovers first fungicide after spraying grapes w/ Copper sulfate and lime.

Question 29

Bordeaux mixture

Answer 29

3:1:100 CuSO4:Lime:H20; first fungicide

Question 30

heterocyclic compounds

Answer 30

interferes w/ proteins; Capatan

Question 31

Agrobacterium

Answer 31

gram negative, rod shaped with 1-4 flagella; colonies are slimy on carb media, non pigmented and smooth. soil inhabitants

Question 32

Clavibacter (corynebacterium)

Answer 32

Gram positive, slightly curved rod, generallynon-motile

Question 33

Erwinia

Answer 33

Gram negative, several flagella; facultative anaerobes: amylovora-no pectic enzymes, necrotic or wilt disease. carotovora-produces pectic enzymes, causes soft rot

Question 34

Pseudomonas

Answer 34

gram negative, common inhabitants of soil, H2O, marine. Fluorescent-produce yellow/green diffusible fluorescent pigments on low iron media. Nonflourescent- no pigments

Question 35

Xanthomonas

Answer 35

gram negative straight rods, polar flagellum. colonies usually yellow. all are plant pathogens, usually found only on plant/plant material.

Question 36

Xyella

Answer 36

Gram negative, straigh rods, no flagella. no pigments, small colonies. habitat is in xylem

Question 37

Streptomyces

Answer 37

gram positive and filamentous. colonies has smooth surface that may become powdery. variety of pigments, used for abx

Question 38

Lethal Yellowing of Coconut Palm

Answer 38

CA: Mollicute
S: premature coconut drop, yellowing/death of lower leaves, top of tree falls off
D: plant hopper
C: remove and burn palms, plant resistance, tetracycline

Question 39

Western X Disease of Cherry

Answer 39

CA: Mollicute
S: enlarged stipules, die back of branches, small, flat, pointed, bitter greenish/white cherries
D: Grafting, leafhoppers
C: plant resistance, remover infected trees, remove chokecherries from around orchards, disease free buds

Question 40

Bacterial Wilt of Alfalfa

Answer 40

CA: Clavibacter michiganense pv insidiosum
S: stunting, yellowing of leaves, wilting and browning of vascular tissue
Resting Stage: alfalfa seed and live or dead plants
Control: crop rotation, resitance

Question 41

Black Chaff of Wheat

Answer 41

CA: Xanthomonas campestris pv tranlucens
S: water soaked lesions, become necrotic spots/streaks
Resting Stage: Straw or winter wheat
D: lead contact, sprinkler, wind/rain, seed
C: uninfected seed, reduce irrigation

Question 42

Bacterial Ring Rot of Potato

Answer 42

CA: Clavibacter michiganense pv sepedonicum
S: late in growing sense, chlorides, upward necrotic leaves, creamy mass of bacterial juice in vascular tissue
R: infected tubers, machinery, sacks
D: Infected seeds, knives
C: certified seeds, disinfect equipment using sodium hypochlorite