Diseases

Question 1

What are the sizes of fungal spores, bacteria, and virus particles

Answer 1

-Fungal spore 10 µm
-Bacterium 1-3 µm
-Virus particle 0.2 µm (200 nm)

Human hair 100 µm

Question 2

Is bacterica carried by wind or rain?

Answer 2

Look this us in your notes

Question 3

Ways that bacteria is spread

Answer 3

-insects
-contaminated seeds
-infected plant material
-animals
-boots
-equipment

Unsure about rain, wind, and water being a spreading method and need to figure out why

Question 4

Botrytis cinerea

Answer 4

 Biology: Necrotrophic, facultative fungus (i.e. invades living tissues and lives on dead material)
 Invasion: injuries (biotic (animals) /abiotic (climate/human)
 Optimal temp. 20-24 °C
 This skins are more susceptible
 Economic relevance: sour rot und noble rot
 Redvarieties: colour is less intense

Question 5

How do bacteria move inside the plant? Apoplast or Symplast?

Answer 5

Both. Apoplast and symplast in the epidermis and cortex and then in the endodermis where this casparian strip is, it transitions to symplast only, through the pericycle and into the xylem

Question 6

Factors that make botrytis infection easy

Answer 6

-wax layers
-bunch compactness
-injury:

abiotic injury:
–hail
–mechanical
–excess N fertilizer
–berry burst from rain
–berry splitting

biotic:
—insect feeding
—fungal infection

Question 7

How can you tell the difference between necrosis on a leaf from botrytis and from black rot

Answer 7

black rot will have pycnidia (tiny black spots) within the necrosis

Question 8

How can you tell the difference between botrytis verus phomopsis on canes

Answer 8

Botrytis:
-swollen sclerotia (width of cane)
-black spots not shapes
-cane normal in color

Phomopsis
-shrunken scletotia
-round/oval black spots
-cane color bleached

Question 9

What are the two factors leading to berry-cracking and in what climactic environment is it most likely to happen?

Answer 9

Factors:
-look arrangement of subepidermal cells
-thinner cuticles and epicermal cells

Climate:
-most common in some varieties following a heavy rainfall after drought stress

Question 10

How does high nitrogen levels in the vineyard effect botrytis?

Answer 10

It increases the risk by producing more compact, full (higher vigor) clusters

Question 11

Effects of black rot on vines

Answer 11

-on leaves, small nectotic spots with pycnidia
-petiols become black and dry, the leaves may fall
-tendrils dry and shrivel
-shoots become black with pycnidia due to necrotic acres
-berries develop brown areas that grow larger until they shrivel and are covered with pycnidia (asexual) & perithecia (sexual

Question 12

What is pycnidia and perithecium, what time of year do the form, and how are their spores spread?

Answer 12

perithecium: the fruiting bodies in the sexual form that contain ascospores. Infect new frowth during spring.

pycnidia: the fruiting bodies of the asexual form that contain conidia. Repeating cycles during summer rains.

conidia spores dispersed by rain
ascospored dispersed by wind

Question 13

What are the three diseases that dry grapes and how can you tell them apart?

Answer 13

Downy mildew: “leather berries”, violet in color, entire cluster willl be dry

Black rot: “fruit mummies”, black berries, hard to touch, sporadic berries effected within the cluster

Esca: Berries not black, maintain some purple, speratic on cluster

Question 14

What is the difference between pycnidia and perithecia

Answer 14

pycnidia = asexual
perithecia = sexual

Question 15

What measures can be taken to control black rot

Answer 15

-emove mummified berries
-good air circulation
-low susceptibility varieties
-protective fungicides in wet seasons (typically controlled with DM/PM fungicides)
-curative fungicides (only under high infection)

Question 16

What are the sexual and asexual spore names for
1. Downy mildew
2. Powdery mildew
3. Grey rot
4. Black rot

Answer 16

1. Downy mildew
   sex = oospore
   asex = zoosporangium
2. Powdery mildew
   sex = cleistothecium
   asex = conidia
3. Grey rot
   sex = apothecium
   asex = conidia
4. Black rot
   sex = perithecium
   asex = condidia in pycnidium

Question 17

Green rot (Penecillium) is the second invader to which fungus

Answer 17

botrytis cinerea (primary invader)

Question 18

What are the toxins in wine from penicillium, are they stable or unstable, and what type of damages do they cause

Answer 18

Ochratoxin - stable during fermentation, cause kidney damage and/or cancer

Patulin - degraded by fermentation and sulfur (unstable), cause problemd in juice and fresh wines

Question 19

Trichothecium roseum (Pink rot)
-what does it do during AF
-what does it cause to humans

Answer 19

Trichothecin: toxin that inhibits the alcoholic fermentation. Not metabolized by yeast during the alcoholic fermentation.

Sufficient amounts can be carcinogenic!

Question 20

Coniella petrakii (White rot)
-what does it do to wines

Answer 20

Wines produced from infected berries have bitter notes and the total acidity increases

Question 21

Explain the two ways that grape clusters can be infected with sour rot by insects,
and the steps of the process leading to acetic acid

Answer 21

Unwounded grapes are damaged by hail or birds (for example), insect D. melanogaster will lay eggs and larvae inside the berry = yeast and bacteria growth

The spotted wing drosophila can damage the grapes themselves to lay their eggs/larvae, then the D. melanogaster insects will come and lay theirs too = HEAVY yeast and bacteria growth

Process:
flies > Acetobacter from flies into wounds > interact with yeasts > acetic acid

Question 22

Is sour rot
a. bacteria
b. yeast
c. decaying fungi
d. all of the above

Answer 22

d. all of the above