Important
Tips for Foliar Feeding
The
value of foliar feeding was proven by research at Michigan
State University many years ago. A project partially funded
by the Atomic Energy Commission used radioactive tagged nutrients
to prove that a plant can feed through the leaves. In fact,
they proved that it is four to thirty times more effective
to feed a plant that way as far as the amount of nutrients
necessary to do the same job and there is no risk of ground
water contamination.
While we believe foliar feeding is useful and effective in
correcting deficiencies, we use it primarily to increase yield
and quality by overcoming the limitations of the soil and
its ability to transfer nutrients into the plant.
Best
Time To Foliar Feed
Between
7 and 10 am or after 5pm when the plant’s stomata (the small
openings on the leaves) are open. Stomata has very
little role to play in foliar absorption of nutrients.
All nutrients diffuse through minute pore (1nm size) on the
cuticle membrane. Cuticle is the outermost layer on
the leaf surface, which prevents excessive water loss.
The cuticular pores are lined with intense negative charge
that favours movement of potassium, calcium, magnesium, trace
elements and ammonium ions. Urea diffuse easily because
it is an electrically neutral molecule. Ions such as
phosphates, sulphate, nitrate move slowly, hence multiple
applications are required.
If
the temperature is 25°C or above at 7am don’t bother to spray,
as it will have little effect due to rapid evaporation of
spray droplets. The best temperature is around 21ºC.
If the weather is very hot and dry, then you may have to spray
between 2 and 4 am. The surface winds should be less
then or equal to 8 km/h to prevent spray drifts.
All
foliar sprays should have a pH between 4 and 6 where possible.
Usually you want sweeter (alkaline) sprays for young plant
growth and sour (acid) to make fruit, grain, ears etc.
If
foliar feeding is done correctly, you should see visual results
in approximately 48 hours. Always mix sprays as thoroughly
as possible; apply in as fine a mist as possible. The ultimate
sprayer is a mist sprayer that homogenizes the solution and
applies it in a fine mist across a large swath.
The
“law of little bits” always applies to foliar feeding. It
is better to spray small amounts of material more frequently
than it is to drench large amounts of material. Always be
careful of burning the leaf when bright sun is allowed to
shine on the spray. Many Spraygro Products have an organic
chelating agent therefore the inclusion of a wetting agent
may not be required as the chelating agent acts as a wetting
agent. It is also important to use a wetting agent with most
sprays to “spread” them out preventing beads of water from
forming on the leaves and to provide more even coverage.
