Page 58 - Grapevine July-August 2019

Around The Vineyard

ed blocks and move workers to infected blocks at
the later part of the day.

Controlling the spread of viruses requires strict
protocols for handling vines and performing cul-
tural practices in the vineyard and nursery. Hot
water treatment of vine cuttings and grafted
vines are effective controlling the movement of
mealybugs from one site to another. Other recom-
mended practices include establishing wind traps,
planting insecticidal cover or border crops, using
site dedicated clothing and/or shoes for workers,
and avoiding the use of potentially contaminated
equipment in the vineyard.

Ultimately, the removal of infected vines or
entire blocks will be key to reducing the source
of infection. Guidelines call for rouging (removal
of individual infected vines) if there is less than
25% disease incidence and entire blocks (greater
than 25% disease incidence). A common mistake is
the removal of a portion of the infected vineyard
block (see photo 2). This decision is made to avoid
production losses at the vineyard. However, in no
time, the newly planted vines will become infected
by the same virus present in the other portion of
the vineyard.

The control of leafroll spread needs to be based
on a concerted effort among growers. In California
the development of a network of neighboring
growers has allowed open discussion of infection
status of blocks and applied control measures. The
use of cultural practices (especially sanitation and
insect control applications) should be coordinated
and scheduled to include area-wide treatments as
grapevine viruses and their vectors do not know or
respect neighboring borders.

Judit Monis, Ph.D. provides specialized services
to help growers, vineyard managers, and nursery
personnel avoid the propagation and transmission
of disease caused by bacteria, fungi, and viruses in
their vineyard blocks. Judit (based in California) is
fluent in Spanish and is available to consult in all
wine grape growing regions of the word. Please
visit juditmonis.com for information or contact
juditmonis@yahoo.com to request a consulting
session at your vineyard.

Page 56 The Grapevine • July - August 2019 877-892-5332

Grapevine Main Pages GV070819_Layout 1-1 .indd 56 6/18/19 3:20 PM