Diseases

Help me! I’m dying.

Disease

• Disease is a plant disorder caused by an

infectious pathogen or agent

Groups of pathogens

• Bacteria

– Single-celled organism

– Must remain in host or

under debris

– Actively divide to spread

• Fungi

– Multi-cellular

– Eats on plants and hurts

them in the process

– Produces spores that

spread

• Viruses

– Ultramicroscopic parisites

– Attack plant tissues

– Should destroy plant

completely if found

• Parasitic plants-

– A plant that attaches to

another plant

– Ex. mistletoe, dodder,

lichens

Plant Disease

• Must be identified

before they can be

treated

• Warm temperatures

and moist conditions

in greenhouse plant

production make most

horticulture plant

diseases worse

Disease

• Prevention through

sanitation and insect

control is much easier

than treating the

disease.

Diseases

• Blight

• Canker

• Damping off

• Galls

• Leaf spot

• Mildew

• Mosaic

• Rots

• Rust

• Smut

• Wilt

• Chlorosis

Blight

• Infectious bacterium

• Cause plant to quickly

turn brown or black as if

they had been burned

• One specific blight is fire

blight-devastating apple

crops

• Prune 6-8” below

infection

Chlorosis

• Normally green tissue

is pale, yellow, or

bleached. It results

from failure of

chlorophyll to develop

because of infection

by a virus

• Happens from

fertilizer, cold

weather, water, etc

Canker

• Bacterial disease

• Causes open wounds

on woody plant stems

Damping off

• Fungal disease

• Causes young plants

and seedling to rot

off at soil level

• Need clean containers

and soil and plenty of

air circulation between

plants

Galls

• Round swelling or

growths on plants

• Usually caused by an

insect that vectors the

disease

Leaf spot

• Rings of different

shades of brown,

green, or yellow

• Looks like dots or

circles

Mildew

• Fungus

• Grows on leaf surfaces

• Appears as white, gray or

purple spots

• Example is powdery

mildew

• Homemade remedy= 2 tsp

baking soda +

horticultural oil with 1 gal

water

Tobacco Mosaic & Mosiac

• Caused by a virus

• Leaves have irregular

mottled areas with

patterns

• Ranges from dark

green to light green to

yellow to white

Rots

• Fungus

• Causes plants to decay

and die

• Usually has a unique

smell

• Improve drainage for

the plant to prevent

Rust

• Fungus

• Causes small spots on

leaves

• Resembles yellow,

orange, brown or red

rust

• Mainly on

underneath of leaf

Smut

• Black powdery

disease

• Causes blisters that

burst open

• Releases black spores

• Grows on aphid’s

honeydew

Wilt

• Fungus

• Disease that blocks

the uptake of water

in plants stems

• Causes plants to look

constantly wilted even

when adequately

watered