Vine Diseases/ Insect Threats

Question 1

What four groups of diseases affect vines?

Answer 1

Fungal, Viral, Bacterial and Phytoplasma.

Question 2

Fungal diseases manifest as __ and __ and are typically in __ and __ climates.

Answer 2

Mildew and mold. Warm and Damp Climates.

fungal spores are spread by wind and rain.

Question 3

Fungal diseases attack which part of the vine system?

Answer 3

Fungal diseases attack the root system or canopy of the grapevine.

Fungal disease can threaten a whole vineyard

Question 4

What are some of the most worrisome fungal diseases?

Answer 4

Powdery and downy mildew.

Question 5

How are Viral diseases spread?

Answer 5

Viral disease is spread by Grafting or transmitted by insects.

Question 6

what are Phytoplasma reffered to as?

Answer 6

“Grapevine Yellows”

Question 7

What is Phytoplasma disease?

Answer 7

casused by phytoplasmas, pathogens similar to bacteria, yet work like a virus. spread by insect or grafting.

Question 8

What is Phylloxera?

Answer 8

An Aphid that feeds on the roots of vines.also know as Phylloxera root louse.

This aphid almost completely took out wine in Europe in 1860’s.

Question 9

is American Rootstock Naturally resistant to Phylloxera root louse?

Answer 9

Yes.

Question 10

What insects act as carriers of diseases?

Answer 10

Mealy bugs, Nematodes and glassy-winged sharpshooters.

Question 11

Name the 6 Fungal Diseases…

Answer 11

• Powdery Mildew (Oidium) - Uncinula Necator fungus
• Downy Mildew (Peronospora) - Plasmopara viticola
• Eutypa Dieback (Dead Arm) - Eutypa lata fungus
• Esca (Black Measles)
• Black Rot - Guignardia bidwelli fungus
• Bunch Rot

Question 12

Name the 3 Bacterial Diseases…

Answer 12

• Pierce’s Disease - Xylella Fastidiosa
• Crown Gall (Black Knot) - Agrobacterium tumefaciens bacterium
• Bacterial Blight - Xanthomonas Ampelina

Question 13

Name the 2 Viral Diseases…

Answer 13

• Leafroll Virus

- Fanleaf Degeneration

Question 14

Name the 1 Phytoplasma Disease…

Answer 14

Flavescence Doree

Question 15

Powdery Mildew (Oidium)

Fungal

Answer 15

A fungus that prefers densely shaded canopies and overcast weather. It affects all the green parts of the plant, marking grapes, leaves and shoot with a dusty white mildew.

Question 16

Downy Mildew (Peronospora)

Fungal

Answer 16

Attacks green portions of the vine, causing leaves to drop off the vine and limits the vines ability to photosynthesize. its first visible as oil spots on leaves and then a white, cottony growth on the underside of the leaf that survives on fallen leaves through winter and penetrates the soils affecting the vine.

Question 17

Eutypa Dieback (Dead Arm)

Fungal

Answer 17

Spores are carried by rain and enter the vine through pruning wounds. Infected vines may experience stunted growth as the fungus releases toxins, and and affected arm may die.

Fun fact : Australia’s d’Arenberd has a wine nicknamed after the disease called deadarm.

Question 18

Esca (Black Measles)

Fungal

Answer 18

Thrives in warmer climates with no known control or cure.
Spread by wind or pruning shears.

Esca is the result of a complex Fungi.
On young Vines - The Disease affects growth, berry development, and discolors leaves.
On Old Vines - the disease affects the wood, causing the interior pf the trunk and arms to soften and rot from the inside.

Question 19

Black Rot

Answer 19

Shows as a black spot on the vines shoots, leaves and berries. Known as Botrytis bunch rot, it will break down the skin of the berries and allow other yeast and bacteria to rot the grapes.

Question 20

Perice’s Disease

Bacterial

Answer 20

Transmitted by the glassy-winged sharpshooter- insect found near citrus orchards and oleander- this disease renders the vine incapable of producing Chlorophyll and killing it within five years.

There is no cure or control.

Question 21

Crown Gall (Black Knot)

Bacterial

Answer 21

When infected the vine develops tumors (galls) , on the trunk, essentially strangle the vine, killing the portions of the vine above. the bacteria thrive in colder climate living inside the grapevine.

the disease is spread through propagation of bacteria infected budwood.

Question 22

Bacterial Blight

Bacterial

Answer 22

Often kills young grapevine shoots, they develop dark brown streaks in early spring and eventually wither and die. spread by compromised tools and rain,

bacterial blight is controlled by hot water treatments or copper sprays.

Question 23

Leafroll Virus

Viral

Answer 23

responsible for 60% of the worlds grape production losses- this virus is made of 9 viruses. downward curling leaves signal diseases presence.

spread by the Mealy Bug or propagation of infected vines.

Question 24

Fanleaf Degeneration

Viral

Answer 24

A nepovirus spread by soil nematodes feeding on infected roots. leaves look like fans with yellow bands

Question 25

Flavescence Doree “Grapevine Yellows”

Phytoplasma

Answer 25

“Grapevine Yellows” is spread by leafhopper insects or propagations of infected vines.

the disease will cause pustules and cracks to form.

No cure exist.