grapevinetrunkdiseases - 1 JANUARY/FEBRUARY 2005...

JANUARY/FEBRUARY 2005
BY
W. D. Gubler, P. E. Rolshausen,
F. P. Trouillase, J. R. Urbez, T. Voegel
Dept. of Plant Pathology,
University of California, Davis, CA
G. M. Leavitt, University of California
Cooperative Extension, Madera, CA
E. A. Weber, University of California
Cooperative Extension, Napa, CA
G
rapevine trunk diseases are
responsible for significant eco-
nomic losses to the wine industry
worldwide. Symptoms of these
diseases include dead spurs, arms, and
cordons and eventual vine death due
to canker formation in the vascular tis-
sue. In Eutypa dieback, deformed
leaves and shoots occur as the
pathogen invades spur positions. As
cankers develop, yield reductions
occur due to the loss of productive
wood. The impact of grapevine wood
diseases can be significant in older
vineyards, and usually becomes more
severe as vineyards become older.
Eutypa dieback, caused by Eutypa lata
was originally thought to be responsible
for most canker development in California
vineyards. However, recent findings have
highlighted the importance of other fungi
involved in the death and decline of
grapevines in California. In this regard,
Botryosphaeria species have also been
recovered from cankers, and were
determined to be the main cause of canker
diseases in some California vineyards.
Recent research has also indicated the
occurrence of several new fungal trunk
disease pathogens of grapevine belong-
ing to the family Diatrypaceae (the same
family as Eutypa ). These include Eutypa
leptoplaca, Cryptovalsa ampelina , Diatrype
species, and Diatrypella species. We will
present current information on the epi-
demiology and control strategies of fun-
gal organisms responsible for grapevine
spur, cordon, and trunk dieback in
California.
1
G R A P E G R O W I N G
RESEARCH UPD A TE
Grapevine trunk diseases
in California
Figure I: Fruiting bodies (perithecia) of E.
lata on a grapevine previously grafted for
variety change. The large pruning wound
favored formation of E. lata perithecia on
the dead trunk of the old variety.
Figure II: Black stroma bearing perithecia (fruiting bodies) of E. leptoplaca on dead trunk of
big leaf maple collected in St. Helena, Napa County, CA.

JANUARY/FEBRUARY 2005
Eutypa dieback
Eutypa dieback was responsible for
a loss in net income for California wine
grapes estimated to be over $260 mil-
lion in 1999. Many growers consider
Eutypa to be the most significant dis-
ease of grapevines.
Typical symptoms of E. lata include
formation of a wedge-shaped canker
and stunted shoots with cupped, tat-
tered, chlorotic, and necrotic leaves
that are best seen in spring time. Foliar
symptoms are due to toxins produced
by E. lata. Differences in susceptibility
of grapevine cultivars to infection have
been reported, although no cultivars
are immune. Cankers develop down-
ward at a faster rate than toward the
end of cordons and also increase in
diameter over time. Extended infection
of grapevines by E. lata leads to vine
death.