Agriculture Reference
In-Depth Information
Table 19.8
Effects of Post-harvest Treatments with Pyrimethanil and Iprodione on
Botrytis cinerea
Inoculation-Induced (1 × 10
4
Spores/ml) Disease Severity (Scores:
1
Mycelial Matting), Flower and Leaf
Abscission (Debris, as % Initial Stem Weight) and Flower Vase Life of Geraldton
Waxflower cv. CWA Pink Packaged and Kept at 20°C for Six Days
=
None, 2
=
Trace of Mycelium, and 3
=
Debris (% initial
Score weight)
Flower vase
life (days)
Treatment
Disease Severity
water (control)
3.1
24.5
1.7
iprodione (1.0 ml Rovral/l)
1.4
2.7
3.5
pyrimethanil (1.5 ml Scala/l)
1.4
5.7
3.0
pyrimethanil (2.0 ml Scala/l)
1.7
6.2
3.3
Source: Compiled from Taylor
et al
. (1999).
be implemented. It is similarly important to adhere
strictly to product use advice and other information on
the label.
care in application. Methyl bromide is being banned from
many uses because it depletes ozone in the atmosphere.
Dichlorvos has a degree of vapour-phase activity. In addition
to concentration, the efficacy of insecticide treatments is
strongly influenced by the time by temperature interaction.
That is, control is generally enhanced at higher temperatures
and upon longer exposure to insecticides. Physical treat-
ments, such as hot-water dips, may prove useful for tolerant
cut flowers (Seaton & Joyce 1988; Hansen & Hara 1994).
Irradiation is attractive as it leaves no pesticide residues, but
the doses needed to kill insects also damage flowers. Even
the lower doses needed to sterilise insects cause damage
(Seaton & Joyce 1992; Nell & Reid 2000).
Miscellaneous treatments
Fresh dyeing or tinting of some cut flowers, such as
carnations, is practised to extend the product range
(Wills
et al
. 1998; Reid 2002). Light-coloured (e.g.
white) blooms are pulsed with food-grade water-soluble
dyes. Blue dye is often used (Plate 19.3). With a view to
reducing the risk of physical damage during packing and
transport, kangaroo paw inflorescences may be pre-
wilted. Provided that the treatment is not excessive,
rehydration is readily achieved later. Hygiene is an
important issue with all cut flowers. Good hygiene
involves washing and disinfection of containers and
other equipment (e.g. secateurs) with an approved
chemical (often chlorine based). Light after harvest is
important for the quality of some flowers. For example,
some protea species suffer leaf blackening in darkness.
Supplementary lighting equivalent to bright room or
office lighting conditions (30 μmol/m
2
/s) markedly
reduces blackening (Jones
et al
. 1995b). Leaf blackening
of protea can also be reduced by only growing species
that are not prone to blackening, watering before picking,
cooling, avoiding water condensing on leaves, glucose
pre-treatments, and rapid marketing (Jones
et al
. 1995b;
Stephens
et al
. 2001; Faragher
et al
. 2002). Gravitropic
bending can be reduced by holding flowers vertically
and keeping them cold. Fluoride injury can be avoided
by using rain, good quality bore or dam water, or
deionised water. Some flowers cause allergies to people
handling them. For example, the hairs on kangaroo paws
Disease treatments
Disease control is usually achieved using fungicides,
such as iprodione or pyrimethanil for botrytis control
(Wearing
et al
. 1995; Taylor
et al
. 1999; Table 19.8).
Fungicides are applied as dips or sprays (see Figure
19.8). Biological control agents may have commercial
potential for botrytis management (Hammer & Marois
1989), as may treatments with compounds (e.g. methyl
jasmonate) that enhance natural defence processes (Meir
et al
. 1998; Darras
et al
. 2005; Dinh and Joyce 2007).
Calcium treatments may also help restrict botrytis (e.g.
roses; Volpin & Elad 1991), albeit not for all flowers (e.g.
Geraldton waxflower; Taylor
et al
. 2003). GA treatment
inhibited botrytis development in some rose cultivars
(Shaul
et al
. 1995).
The regulations covering the use of specific insec-
ticides and fungicides vary between jurisdictions. Thus,
the relevant governing rules must be read and under-
stood before pest and disease management programs can
