Fig. 1. Cross sections through the trunk of a 25-year-old grape cv. Sangiovese vine affected by esca. The trunk was cut into 3- to 5-
cm-thick sections, which on the photograph show wood symptoms in a clockwise direction, starting from the trunk base up to the
portion where two large pruning wounds were made. The lowest trunk sections (A–C) show black spotting, brown-red wood, and
initial symptoms of white rot (slightly yellow in the picture) starting from the pith. The rotted wood gradually extends toward the
large wounds (D). In the upper trunk sections (E and F), yellowish, soft, and spongy rotted wood (white rot) predominate, being
bordered by a thick black line that in turn is surrounded by a marginal band of brownish red wood.
406 Plant Disease / Vol. 83 No. 5
Fig. 2. Pattern of wood colonization of a grapevine trunk by esca fungi (left, transverse
sections; right, median longitudinal section). The occurrence (percent isolation)
of three fungal species (Fomitiporia punctata [Fp], Phaeoacremonium chlamydosporum
[Pch], and P. aleophilum [Pal]), as found in a survey in central Italy, is reported
for each trunk portion. The white rot fungus, F. punctata, prevails in the completely
decayed wood and decreases toward the healthy wood as P. chlamydosporum
and P. aleophilum become dominant. These two fungi are mainly found in the black
streaks and brown-red wood, both in the wood portions around the pith and at the
margin of the decayed wood tissues. Green arrows, pruning wounds; BN, brown necrosis;
BRW, brown-red wood; AP, altered pith; BS, brown to black streaks, appearing
as black spots in cross section; DP, decayed pith; BL, black line bordering the decayed
wood; DW, completely decayed wood (white rot).
Fig. 3. Cracking of a grapevine trunk in
connection with a sector of decayed
wood.
Plant Disease / May 1999 407
Fig. 5. Effect of the absorption for a few hours of 15-day-old Phaeoacremonium chlamydosporum culture filtrate diluted 1:10 (left)
and of 5-day-old Fomitiporia punctata culture filtrate diluted 1:1 (right) on detached grape leaves. (photos courtesy F. Lops)
Fig. 4. Foliar symptoms of esca first appear as chlorotic spots that subsequently coalesce, turning dark red in some red cultivars
like Cabernet (A), and finally becoming necrotic. Dead tissues appear dark brown to red-brown, depending on the cultivar (B and
C). Symptoms often extend to the interveinal areas of the foliar blade, leaving a narrow strip of unaffected tissue along the main
veins (D), thus giving the leaves a characteristic tiger-stripe pattern. (photos courtesy G. Minervini, [A], and S. Frisullo [D])
408 Plant Disease / Vol. 83 No. 5
Fig. 6. Spotting of grape berries (black measles). Minute dark brown or purple spots on the berry skin can be scattered (A) or distributed
in bands (B). Cracks can also form on the berry. (photos courtesy S. Frisullo)
Plant Disease / May 1999 409
Fig. 7. A grapevine plant showing sectorial symptoms of apoplexy caused by esca
disease. Green, healthy-looking leaves and grape clusters quickly wither, drying completely
in a few days, but usually remain attached to the plant.
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Fig. 8. Cross section through the rootstock
stem of a 2-year-old grapevine
(Victoria/775 Paulsen) showing symptoms
of decline. The section shows
wood browning and black spots (which
appear as black streaks in longitudinal
section) due to the presence of dark
colored, gummy masses in the xylem
elements. The discolored wood was
found to be colonized by Phaeoacremonium
chlamydosporum.
Plant Disease / May 1999 411
Fig. 9. Colonies of Phaeoacremonium
chlamydosporum on malt agar plates.
The fungus developed from wood fragments
excised from black spots close to
the margin of a decayed trunk portion.
The colonies grow slowly in vitro, often
appearing first whitish and shiny (A),
and turning gray-olivaceous up to
blackish with age (B).
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Fig. 10. (A) Decayed wood in a grapevine branch inoculated with Fomitiporia punctata.
Two years after inoculation, white rot extended from the pith into the nonfunctional
wood. (B) Section through the trunk of a 6-year-old grapevine, 3 months after inoculation
with Phaeoacremonium chlamydosporum. Brown-red wood and brown to black
streaks developed from the inoculation site. From these areas, the fungus was reisolated
after 1 year up to 30 cm above and below the inoculation site with an average
80% success rate.
414 Plant Disease / Vol. 83 No. 5
Fig. 11. Esca spread, as estimated by external symptoms, in an old grape cv.
Sangiovese vineyard in central Italy in the period 1992 to 1995. In the portion of the
vineyard depicted on the map, the disease incidence was 19% in 1995, but it would
have been 49% if all plants showing symptoms at least once during the 4-year test
period had been counted. Diseased vines tended to be grouped together along the
rows of the vineyard.
Plant Disease / May 1999 415
Fig. 12. An efficient sanitation procedure to restore an esca-affected vine consists in
raising a basal shoot upon appearance of the first foliar symptoms of esca. The shoot
is then grown for the following 2 to 4 years while the vine, although showing symptoms,
usually remains productive. As soon as the new basal shoot is ready for grape
production, the affected trunk portion is removed. (photo courtesy E. Egger)
416 Plant Disease / Vol. 83 No. 5
Fig. 13. One of the oldest practices to
remit symptom appearance in the crown
of an esca-affected grapevine is to split
the trunk and insert a stone in the crack.
Plant Disease / May 1999 417
