1. Grape Vine Fungal Trunk Diseases

2. Meet “Botryosphaeria”
A fungus living in your vines
Causes spur, cordon and vine death
Was previously unknown here (?)
Is spreading world-wide

3. Botryosphaeria
Can be confused with virus, or nutritional deficiencies.
Vascular discoloration is typical, including brown/black streaks (necrosis in the xylem tissue)

4. About Botryosphaeria One of several fungi causing trunk disease
Spreads by infection of pruning and other wounds via air-borne spores
Spores are produced in wet weather, maybe high humidity
Can quickly make vineyards uneconomical because of loss of bud break, and vine deaths
May be a cause of low yields in Midwest

5. Symptoms caused by Trunk Disease Fungi
Trunk and cordon
Wedge-shape lesions when cut in cross-section (Eutypa)
Dieback described as ‘dead arm’ and loss of spur positions
Shoots
Stunted appearance during the spring
Bud burst
Delayed or lack of growth in one or more spur positions
Canes
Bleached
Buds
Necrotic

6. Fungal Disease Management
Late pruning
Prune as late as possible before bud break
Double pruning
First pass is done in the winter
Prune to two buds in early spring before
bud break
Fungicide treatments and wound protection
(VitiSeal, B-Lock, Topsin M, etc.)

7. Fungal Disease Management
Remedial surgery and sucker training
Vine training
Cane pruning
Reduces disease severity
Spur/cordon pruned
Disease levels may increase
Avoid large cuts during pruning
Vine debris MUST be removed from site

8. But it can be controlled
Protect all pruning wounds by painting/spraying fungicides/paint mixtures as are used in CA
At first symptoms in vineyard, begin saving trunk shoots, as low as possible
Train up 1-2 new trunks, remove old cordons and trunks
Remove pruning debris (a good practice for many problems, e.g. grape cane borer, other pests, disease inocula)

9. Avoid stress that can weaken vines
Correct planting, irrigation, fertilization
Avoid early fruit production/harvest
Avoid stress that can weaken vines

10. Life Cycle of Botryosphaeria
pycnidia
conidia
over winters
on diseased wood
pseudothecia
prevent new infection
ascospores
on cankers
Break
Disease
Cycle
rain splash and wind spread
conidia and ascospores
remove inoculum source
canker
fresh wound
around initial
infection point
wood necrosis
vascular system
damaged
by fungal growth
conidia germinate and
invade woody tissue
via xylem
dead arm,
vine death
Life cycle of botryosphaeria dieback in grapevines showing the key points for
management options to break the disease cycle.

11. Cultivar Avg. Disease Intensity Petite Pearl 2.75 Sabrevois 3.10
Brianna
3.30
Frontenac Blanc
3.45
Frontenac Gris
3.50
Lemberger
3.60
Norton
3.62
La Crescent
4.00
Aromella
4.10
Chambourcin
4.88
Cayuga White
4.96
Noiret
5.60
St Croix
5.62
Chardonel
5.73
Vidal Blanc
5.75
Lacrosse
5.76
Bianca
6.00
Grafted Chambourcin
6.20
Frontenac
6.33
Edelweiss
6.40
Niagara
DeChaunac *
Leon Millot
6.66
Vignoles
6.80
Corot Noir
7.60
Traminette
8.10
* Known that it is very susceptible but was not in our evaluation

12. Don’t ignore Trunk Diseases
DO NOT PANIC!!!!
Learn to recognize symptoms
TREAT EARLY
You will be rewarded with old, healthy vineyards
Read “Don’t let trunk diseases ruin your day, and your vineyard” The Grapevine, May June 2018