Postharvest Biology and Technology 20 2000 115 – 124
Biological control of Botrytis, Aspergillus and Rhizopus rots on table and wine grapes in Israel
Tirtza Zahavi
a,
, Lea Cohen
a
, Batia Weiss
a
, Leonardo Schena
b
, Avinoam Daus
a
, Tania Kaplunov
a
, Johanan Zutkhi
a
, Ruth Ben-Arie
a
, Samir Droby
a
a
Department of Fruit and Vegetable Storage, Agricultural Research Organization, The Volcani Center, Bet Dagan
50250
, Israel
b
Dipartimento di Protezione della Plante dalle Malattie, Uni6ersita degli Studi di Bari, Via Amendola
165
A, Bari
70126
, Italy Received 20 December 1999; accepted 8 May 2000
Abstract
One hundred and twenty-nine strains of epiphytic micro-organisms, isolated from table and wine grapes in Israel, were screened for antagonistic activity against Botrytis cinerea on table grapes. Two isolates Candida guilliermondii,
strain A42 and Acremonium cephalosporium, strain B11 were further evaluated for the control of decay in grapes caused by Aspergillus niger and Rhizopus stolonifer. Decay incidence caused by Botrytis cinerea, Aspergillus niger and
Rhizopus stolonifer on wounded detached berries was reduced to 8, 14 and 22 respectively, by A42 and to 16, 82 and 60, respectively, by B11. On small clusters with intact berries, decay was reduced to 30, 22 and 22,
respectively, by A42 and to 48, 39 and 30 respectively, by isolate B11. Both strains survived well under local vineyard conditions and during storage at 0°C and maintained relatively high cell counts on the berries. Field
experiments were conducted in 1996, 1997 and 1998, with both table and wine grapes. Vines were sprayed with yeast suspension 2 – 5 times at 7 – 10 day intervals and decay was evaluated before harvest wine grapes or after storage
table grapes. A42 reduced decay caused by Botrytis cinerea in two of the three seasons in both table and wine grapes, and rots caused by Aspergillus niger in wine grapes were reduced significantly in 1997 and 1998. B11 reduced
Botrytis cinerea development in the two years it was tested in wine grapes but in table grapes only in 1996. Morever, it did not control decay caused by Aspergillus niger. © 2000 Elsevier Science B.V. All rights reserved.
Keywords
:
Vitis 6inifera; Yeast; Biocontrol; Grey mould; Candida guilliermondii; Acremonium cephalosporium www.elsevier.comlocatepostharvbio
1. Introduction
Botrytis cinerea, the cause of gray mold of grapes, is the dominant rot-causing pathogen in
most regions of the world Bulit and Dubos, 1988. In the warmer vine-growing areas of Israel
Aspergillus niger and Rhizopus stolonifer are also
Corresponding author. Tel.: + 972-3-9683613; fax: + 972- 3-9683856.
E-mail address
:
tirtzazyahoo.com T. Zahavi. 0925-521400 - see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 9 2 5 - 5 2 1 4 0 0 0 0 1 1 8 - 6
reported to cause decay and are of equal eco- nomic importance to B. cinerea Barkai-Golan,
1981. Rots caused by B. cinerea and R. stolonifer
usually begin to appear at the stage of ‘veraison’ fruit softening when sugar content in the berries
reaches 10 – 12 Hill et al., 1981; Marois et al., 1992. A. niger usually causes decay only at higher
sugar levels 15, although it is one of the fungi found on the surface of healthy grapes at all
stages Zahavi, unpublished data. The relative importance of the several rot-causing fungi, both
in the vineyard and in stored grapes, changes from one season to another, probably because of
differing climatic conditions. Since there is no way of knowing, at the onset of veraison the recom-
mended time to start chemical control programs, which pathogen will be predominant, it is difficult
to recommend a specific chemical control pro- gram in the vineyard. After harvest, SO
2
is gener- ally very effective in preventing the development
of decay Ben Arie et al., 1991, but effectiveness depends on the pathogen and the inoculum load.
Higher amounts of SO
2,
which might be more efficient, cause bleaching of the berries and an
off-flavour. Recently, SO
2
has been removed from the federal government’s ‘generally regarded as
safe’ GRAS list in the USA and its future use on grapes is therefore uncertain.
Public demand to reduce pesticide use, stimu- lated by greater awareness of environmental and
health issues, as well as development of resistance of some of the pathogens to the fungicides, limits
the application of chemicals on agricultural prod- ucts. In recent years much research has focused
on developing alternative control methods against pre- and postharvest decay in grapes as well as
other agricultural commodities Ferreira, 1990; Peng and Sutton, 1991; Wilson et al., 1991, 1993;
Filonow et al., 1996; Fokkema 1996; Harman et al., 1996; Leibinger et al., 1997.
In previous work, we evaluated the activity of the yeast strains, Kloeckera apiculata and Candida
guilliermondii strain U.S.7 in reducing posthar- vest decay of table grapes Ben Arie et al., 1991;
McLaughlin et al., 1992. When applied as a postharvest dip, both antagonists were found to
protect injured and artificially inoculated grape berries and also to reduce the incidence of decay
of naturally infected, non-injured grapes. How- ever, one of the important quality parameters of
table grapes is the presence of a bloom on the surface of the berry. A postharvest dip removes
some of the bloom, thereby adversely affecting the perceived quality of the treated fruit. Therefore,
the possibility of treating the fruit with antago- nists before harvest was evaluated Ben Arie et al.,
1991. The efficacy of the yeast C. guilliermondii in stopping disease development in the vineyard
and in reducing postharvest decay was demon- strated. However, the treatment did not retain its
effectiveness and the incidence of Botrytis decay increased considerably during 4 weeks storage at
0°C. This may be attributed to poor colonization and survival of this particular strain, which had
been isolated from the surface of lemon. We therefore decided to look in the vineyard for
effective antagonists of grape pathogens that are better adapted to the pre- and post-harvest
environment.
In the present paper we describe the isolation of natural epiphytic yeast antagonists from Israeli
vineyards, and the evaluation of their biocontrol activity against bunch rots under laboratory and
field conditions.
2. Materials and methods
