Page 7 - Vol.37-No.1 issue

CROP PROTECTION

Consumers increasingly demand or-
ganically produced fruit and vegetables
requiring zero use of chemical fungicide.
What’s the point in producing and eating
blueberries for health giving reasons if
they have previously been treated with
chemical fungicide is the clear thinking
behind this trend.
Strengthen the blueberry

Blueberry cultivation and production
using zero fungicide options are now
a reality because alternative disease
avoidance and management options are
available to growers. Research shows
that the manipulation of blueberry crop
nutrition can manage diseases like root
Calcium is the tissue rot caused by Phytophthora cinnamomi
strengthening nutrient which with particular nutrients playing specif-
maintains fruit f rmness from ic roles in strengthening plant tissues to
harvest and throughout storage boost yield and berry quality. By defini-
(Picture courtesy Omex) tion all plant nutrients are essential for
proper plant growth and development
Phytophthora cinnamomi shows multi- but one in particular stands out from the Treatment with Omex Calmax
host disease activity with the pathogen rest in blueberry cultivation and that nu- Gold signif cantly increased the
able to infect and cause disease in mas- trient is calcium. number of fruits borne on each
sive range of plant species including spur to give signif cant increases
other fruit crops like avocado and pine- Key to calcium as a bulwark for crop in yield (Picture courtesy Omex)
apple. It also has a propensity for high plants against adverse environmen-
disease activity within a wide range of tal conditions, whether abiotic (e.g. Soil calcium has been shown to dis-
climate. Phytophthora cinnamomi is trop- low temperature and drought) or biotic rupt the root infection process of north-
ical in origin and native to the Indian (pests and diseases), is this nutrient’s ern highbush blueberries in the Unit-
sub-continent where it was first identi- fundamental strengthening role in the ed States, but relying on soil calcium is
fied centuries ago on cinnamon trees growth and development. Calcium is not a fail-safe option. The soil may well
(hence the name), but now found world- first and foremost a tissue strengthening record a high level of calcium but the
wide infecting hundreds of different element and justifiably described as ‘the proportion present as soluble calcium,
species including chestnuts (Castanea) plant resilience nutrient’. Secret to the and as such available to the roots, may
in cool temperate climate like North strengthening role of calcium is in calci- be a different matter. A high proportion
America and Europe. High disease ac- um pectate a gelatinous compound con- of soil calcium is invariably locked up
tivity on blueberry which is essentially stituting the middle lamella which binds as insoluble salts such as calcium phos-
a cool temperate species is therefore no cellulose cell walls together in plant tis- phate especially when soils are alkaline
problem at all for Phytophthora cinnam- sue. with a correspondingly high pH. What’s
omi. more the divalent calcium ion (Ca2+)
is poorly mobile and shows a slow and
Fight the fungus tortuous passage from soil solution and
into the roots and from the roots up into
Root rot of blueberries has tradition-
ally been managed by using systemic, the stems, leaves and fruit. Supplement-
site-specific chemical fungicides but ing the soil with calcium is not the best
such options are decreasing as estab- option because most calcium-rich base
lished products lose their approval and fertilizers like lime (ground limestone)
are removed from the market. They do will excessively raise soil pH to the dis-
work and invariably well but at an envi- like and detriment of ‘acid loving’ blue-
ronmental cost as well as a financial cost. berries.
What’s more attempts to control Phytoph- The calcium solution
thora cinnamomi with such site-specific
action fungicides invariably proves un- Application of soluble calcium by foli-
sustainable in the longer term. The very ar feeding and rapid uptake of the nutri-
nature of their highly specific action on Manipulation of plant nutrition is ent by the leaves is secret to the success
the microbial pathogen populations used to manage root disease in in providing sufficient of this otherwise
means strains of the microbe resistant to blueberry poorly mobile nutrient to blueberry
their action eventually appear. (Picture courtesy Omex) bush crops. To find out more about calci-
um and its key role in blueberry produc-

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