Dip Irrigation In California

HORTSCIENCE 47(3):368–373. 2012.

Drip Irrigation in California
Strawberry Nurseries to Reduce
the Incidence of Colletotrichum
acutatum in Fruit Production
Oleg Daugovish
University of California Cooperative Extension, Ventura County, 669 County
Square Drive, Suite 100, Ventura, CA 93003
Mark Bolda
University of California Cooperative Extension, Santa Cruz County, 1432
FreedomBoulevard, Watsonville, CA 95076
Sukhwinder Kaur
Department of Plant Pathology, University of California, Davis, CA 95616-8680
Maren J. Mochizuki
University of California Cooperative Extension, Ventura County, 669 County
Square Drive, Suite 100, Ventura, CA 93003
Daniel Marcum
University of California Cooperative Extension, P.O. Box 9, 44218 A Street,
McArthur, CA 96056
Lynn Epstein1
Departmentof Plant Pathology, University of California, Davis, CA 95616-8680
Additional index words. anthracnose, crown, cultural control of disease, Fragaria ·anassasa,
daughter plant, quantitative PCR, sprinkler irrigation
Abstract. Strawberry anthracnose caused by Colletotrichum acutatum is often asymptomatic on plants in sprinkler-irrigated nurseries but destructive after transplantation
intofruiting fields. This study evaluated the impact of strawberry nursery sprinkler and
drip irrigation in the presence or absence of C. acutatum on post-transplantation plant
growth, mortality, and fruit yield in fruiting fields in California. In a 2005 nursery at
Tulelake, CA, dip infestation of mother plants with C. acutatum reduced early-season
mother plant canopy size by 21% and delayed runnerproduction in mother plants but
otherwise had no obvious disease symptoms. In comparison with sprinkler-irrigated
treatments in the nursery, drip irrigation of infested nursery plots reduced plant losses in
fruit production fields by 86% at Watsonville, CA, in 2005 and 50% and 75% at Oxnard,
CA, in 2005 and 2008. Transplants from infested nursery treatments had a 33% to 60%
smaller canopy and 11%to 42% lower yield than transplants from uninfested nursery
treatments. However, transplant canopy size and yield from the infested and then dripirrigated nursery treatment were similar to the sprinkler-irrigated, non-infested nursery
treatment. Quantitative polymerase chain reaction measurements of C. acutatum in
crown tissue of fruiting field plants seven weeks after transplanting showedsignificantly
more C. acutatum (’11·) in their crowns in sprinkler-irrigated than drip-irrigated,
infested nursery transplant treatments. During the course of fruit production, the
amount of C. acutatum in crown tissue increased in all treatments. However, at the end of
the fruit season, there was still significantly more (’8·) C. acutatum in the crowns of the
plants produced by sprinkler irrigationthan by drip irrigation in the nursery. These data
suggest that if C. acutatum is present in the nursery, drip irrigation can reduce
subsequent plant stunting and yield losses in strawberry production fields.

Received for publication 16 Nov. 2011. Accepted
for publication 17 Jan. 2012.
We thank Conroy Farms, University of Calif.
Hansen Trust, California Strawberry Commission,
University ofCalif. Core Issues Grants, and University of Calif. Intermountain Research and Extension Center for financial support and R. Kim for
excellent technical assistance.
1
To whom reprint requests should be addressed;
e-mail lepstein@ucdavis.edu.

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Each year, California strawberry nurseries transplant ‘‘mother’’ plants into 1,000 ha
to produce over one billion runner plants
(daughters) foreither out-of-state sale or
for 15,620 ha of California fruit production,
valued at %$1.8 billion (Calif. Dept. of
Food and Ag., 2010). Nearly all (greater
than 95%) transplants originate from individual axenic tissue-culture plants that
are used to produce daughters in hanging pots

in a greenhouse followed by a generation in
pathogen-free soil in a screenhouse and finally
a series of...