hort 301 exam 1

phytopathology

study of plant sufferring

What does phytopathology cover?

organisms/ factors that cause the disease*, mechanisms, local or global movement, and methods

What is a plant disease?

physiological malfunction of a plant and it is a continuous state

what is the cause of plant disease?

pathogenic agent or environment

How are diseases described?

taxonomically

What helps define diseases?

symptoms

What is meant by diseases are continuous?

the disease is prevalent until the plant dies

abnomormalities can be from _____ or _____?

damage, disease

damage abnormalities

short-term, mechanical

examples of disease abnormalities

insect feeding, wind, hail..

disease abnormalities

long-term, disturbance of plant metabolism

What are disease abnormalities caused by?

pathogens or suboptimal conditions

pathogen

evolving agent that causes plant diseases given specific environmental conditions

not pathogen examples

insects, mites, slugs, microbes hanging out on plants, or anything abiotic

see slides for disease definition

do viruses or leaf spots kill plants faster?

viruses. because they are in the vascular system of plants

what are leaf spots usually caused by?

fungus

fungus vs bacteria determination

oozing and stringing is fungus when leaf is cut and placed in water

pathogenic agents associated with plants

fungi, bacteria, protozoa, nematodes, viruses, and viroids

symptoms definiton

the change in appearance of the infected plant

examples of symptoms

yellowing leaves, wilting, leaf spota, dieback

symptoms are…

alteratoins in the host caused by a disease

symptoms are ____ and ____.

visible and measurable

“signature” symptoms

progression over time

How are symptoms associated with diseases?

they are characteristics of particular diseases

signs

structures that the pathogen produces on the surface of the host

examples of signs

spores, mycelia, or fruiting bodies

why worry about plant diseases?

losing money

trifecta of disease triangle

pathogen, host, and greenhouse environment

pathogen in disese triangle

bacteria, fungi, virus, nematode, mycoplasmas, and spiroplasmas

greenhouse environment in disease triangle

air flow, air temp, humidity, media temp, nutrition, watering, pH

host in disease triangle

crop, cultivar susceptibility

disease cycle

disrupted by disrupting one of the disease trifecta

disease cycle order

see slides

how does fusarium ipmact branches or leaves of tomatoes?

causes half of the branches and leaves to yellow

how does fusarium open the inside of tomato plants?

light brown streaks in the vascular tissue

what soil does fusarium thrive in?

warm soil (35-28C)

what soil pH does fusarium thrive in?

acidic (5.0-5.5)

what kind of pathogen is fusarium?

fungus

how to determine between a bacteria and fungi in water?

oozing, stringing, or cloudiness in the water

Are viruses soil-born?

viruses are not soil-born

Which two pathogens are soil-born?

bacteria and fungi

Which leaves will fusarium cause to wilt first?

lower leaves

Where do viruses transfer from?

seed, plant tissue, or vascular tissue from a plant

What do viruses and bacteria need to infiltrate a plant?

a wound

where do nematodes live?

in the soil

what do nematodes feed off of in plants?

sap

How does lime and calcium impact the soil?

increases pH

How do pine needles and sulphur impact the soil?

decreases pH

what other hosts does fusarium infect?

ginger…

What kind of pathogen is southern blight?

fungus

What are teh hosts of southern blight?

tomatoes…

How does southern blight affect stems and leaves of tomatoes?

brown to black lesions on stem and near soil line and wilting and dieback

What is the scientific name of southern blight?

Sclerotium rolfsii

What develops on the lesions from southern blight?

white hyphae

How does southern blight present itself on the soil near hosts?

tan to reddish-brown, spherical sclerotia

What pH does southern blight prefer

2-5 and is likely restricted 7>

SOP

standard operating procedure

H in disease trifecta

host

P in disease trifecta

pathogen

E in disease trifecta

environment

disease cycle

a squence of development from the initial interaction between the pathogen and the host that leads to the development and spread of the disease

Inoculation in disease cycle (1)

pathogen arrives and makes initial contact with a vulnerable part of the plant

Penetration in disease cycle (2)

the pathogen enters the plant tissues though natural openings (like stomata), wound, or by digging directly through the plant surface

Infection in disease cycle (3)

pathogen successfully invades the plant cells and establishes a harmful, parasitic relationship

Colonization (invasion) in disease cycle (4)

the pathogen grows, multiplies, and spreads inside the host plant

Dissemination (spread) in disease cycle (5)

the pathogen produces new reproductive units (like spores o bacterial cells) that travel via wind, water, or insects to infect other plants

survival (overwintering) in disease cycle (6)

the pathogen stays alive during harsh off-seasons in soil, crop leftovers, seeds, or insect carriers until a new growing season begins

What do fungi do during inoculation?

Pathogen produces some kind of infective units (spores, hyphae, sclerotia)

what do bacteria do in inoculation?

bacteria are single cells and do not make infected units since they are the infected units

what do viruses do during inoculation

entire capsulated virus is the infective unit

Fungus was the ___ ____ pathogen on a plant.

first identified

Oomycetes

more closely related to algae than fungi

When was fungi recognized as being different than plants?

1969

Many Opisthokonts have lost their ____.

flagellum

If Opisthokonts have flagellum, they are…

single and basal

How are mitochondria on Opisthokonts?

flat or smth idk

What are fungal cell walls made of?

glucan and chitin

How are fungal body plans?

single-celled or filamentous (mobile)

how does fungi reproduce and/ or infect

spores or hyphae

what is hyphae

cylindrical, branching filaments

tubular cell wall

multinucleate (but may be subdivided)

grow by tip elongation

most 2-10um un diameter

yeast

single celled fungi

how does fungi grow?

radially from tips

tip of hyphae has…

rigid wall and plastic, growing region

absorptive heterology

enzymes released from plastic region of hyphal tips

enzymes break down substrate

smth smth

two fungal features used for identification

hyphae and spores

hyphae can be identified from…

septation, branching, and pigmentation

spores identiied with

asexual, sexual, size

what is septa

cross-walls formed in hyphae

septae have ______ at regular intervals

cross-walls

aseptae do not have cross-walls, expect to delimit ______ structures or ___ ____.

reproductive, aging hyphae

hyuopal branching

occasionally useful characteristic

spores can be ____ or ____.

asexual, sexual

asexual stage (“anamorph”)

conidia and chlamydospores

sexual stage (“telemorph”)

defines the fungal Phylum:

zygospore- mucoromycota

ascospore- ascomycota

basidiospore- basidiomycota

oospore- oomycota (not fungi)

asexual spores conidia

dispersal and bearing structures

bearing structures

conidiophore= stalk

fruiting bodies

asexual chlamydospores

survival and made from existing hyphae

asexual fruiting bodies

pycnidium, acervulus, sporodochium

asexual pycnidium

enclosed, flask-shaped (sac)

pore +/- neck