Grape Diseases

Downy mildew

Plasmopara viticola

Powdery mildew

Erysiphe nector

Black rot

Guignardia bidwelli

Botrytis bunch rot

Botrytis cinera

Crown gall

Agrobacterium vitis

Pierce’s disease

Xylella fastidiosa

What is the causal agent of downy mildew?

Zoospores

What is the causal agent of powdery mildew?

Ascospores

What is the causal agent of black rot?

Ascospores

What is the causal agent of botrytis?

Conidia

What is the causal agent of crown gall?

Bacterium

What is the causal agent of Pierce’s disease?

Bacteria

What is the causal agent of grapevine yellows?

Phytoplasma

Two flagella of unequal length

Heterokont

What differentiates oomycete cell walls from true fungi?

Cellulose

What is an obligate parasite that feeds on living host tissue?

Biotroph

What structure facilitates sporangia nutrient absorption from host?

Haustoria

What is the abaxial side of a leaf?

Underside

What are the sexual fruiting bodies in powdery mildew?

Chasmothecia

Infected buds with downy mildew may overwinter and in spring produce…

Flag shoots

Specialized hyphae that produce conidia…

Conidiophores

Specialized hyphae that produce sporangia…

Sporangiophores

Galls are caused by the overproduction of…

Auxin and cytokinin

An incompatible reaction between these two leads to resistance.

R gene receptors and avr gene elicitors

What does RNAi stand for?

RNA interference

What is the purpose of the RNAi process?

Destroys mRNA before it can make proteins

What tissues are affected by black rot?

Leaves, shoots, fruits

How do berries affected by black rot appear?

Mummified

Why are mummified berries significant for overwintering?

They are inoculum sources

What structure produces ascospores in black rot?

Pseudothecia

What appears as black “pimples” within a black rot leaf lesion?

Pycnidia