23
VI.
Codacide Oil Increases Adhesion and Retention:
The efficacy of spray retention by targets depends mainly on the velocity and size of the impacting
droplets and their intrinsic physico-chemical properties and those of the target surface.
In addition
to improving velocity and optimum droplet size uniformity (refer Section. IV.), Codacide Oil
’
s
physico-chemical properties are of a similar composition to leaf and insect cuticle wax (both are
triglycerides) which assists adhesion and retention efficacy.
Holloway
et al
(2000) examined adjuvant effects on fluorescein retention by field bean, pea and
barley foliage after application with an even spray nozzle.
This showed that Codacide Oil (10 g l
-1
)
with a Deposit per Unit Emission (DUE) mean of 2,703 increased retention by over 41% compared to
water alone (DUE 1909) and some 20% more than compared with the mineral oil Actipron.
Table 1:
Ajuvant effects on fluorescein retention by field bean, pea and barley foliage after
application with an even spray nozzle.
Additive
Mean Deposit per Unit Emission (DUE) Values
a
Field Bean
Pea
Barley
None
7.41 (1657)
4.80 (121)
4.88 (131)
Actipron
7.58 (1961)
5.34 (208)
5.01 (149)
Codacide Oil
7.57 (1931)
6.24 (513)
5.56 (259)
Note:
a
In values for statistical analysis; back-transformed values in parenthesis
As seen in Table 1, Codacide ability to improve adhesion and retention is especially apparent for
hard-to-wet foliage such as young barley foliage (due to their dense covering of microcrystalline
epicuticular wax), and for waxy, water repellent surfaces of pea foliage than for the easily wettable
foliage of field beans (Holloway
et al
, 2000).
Balsari
et al
(2001) at the University of Torino, Italy, also showed how Codacide improved adhesion
and retention on different vine cultivars (Moscato, Pinot Nero and Barbera) especially for cultivars
with a higher presence of hairs on the leaves (Pinot Nero and Barbera) with a 17% and a 27%
increase for Pinot Nero and Barbera consecutively compared to pure water alone on the upper leaf
surface of vine cultivars (as determined by spray deposit ul/cm
2
).
As examined by Scanning Electron Microscope (refer Fig. 1), droplets applied to wheat leaves (using
Hamilton Syringe) that contained Codacide and the growth regulator chlormequat were found to
maintain their amorphous state and find their way past the finger-like protrusions of microcrystalline
epicuticular wax forming a solid interface and bond between the physico-chemically similar target
surface and Codacide to improve adhesion and retention (Baker, 1994).
Amorphous state of Codacide maintained and microcrystalline finger-like protrusions of
epicuticular wax penetrated for improved interface, adhesion and retention.
Fig. 1:
Droplet of chlormequat applied with Codacide on wheat
PPP+Codacide Oil
Small droplet contact angle and strong interface
with PPP available for target surface interaction.
