Nah. I still don't wanna argue (but I guess I will -- a bit).
There may be 30 seconds some time in the course of a year when
conditions around ONE of my trees match the specs set out by MSU.
Dang! I wish I could figure out which tree it was.

The University of Florida has this to say:

"Foliar applications. In general, foliar applications of N, P, or
K have not been shown to be effective where a good soil fertility
program is followed. It is difficult to place enough of these
nutrients on the leaves, especially early in the growth cycle, to
be of benefit. Foliar applications of micronutrients can be
effective in correcting micronutrient deficiencies (Table 5 ).
Nutrients such as Ca and B, which are immobile in the plant,
should be applied in small amounts at high frequency rather than
in one application for correcting temporary deficiencies in some
leafy vegetables. . . ."

In another article, UF notes that foliar application of NPK to
leaves is useless, but says that iron deficiencies may be
corrected either by adding S to the soil or by frequent foliar
application of a weak Fe solution to the leaves.

So . . . In summary, for field-grown plants . . . Foliar feeding:
Maybe for a few micronutrient problems, IF you know which
micronutrient is causing the problem. Don't bother for general
feeding of the plant.

In bonsai (which was the subject of NONE of these studies (above
or below)) an every-two-week regime of regular fertilization with
a balanced fertilizer that contains the necessary
micronutrients -- and we all do at least that, don't we? -- will
make foliar fertilization, especially as described below, a waste
of money, time and effort (and fertilizer).

But since it is unlikely to do any damage, if you want to do it .
.. . have at it. I'll be resting in the shade drinking a Sam
Adams ale.

Jim Lewis - - Tallahassee, FL - Bonsaiests
are like genealogists: We know our roots!


In a message dated 6/24/2004 9:34:22 PM Eastern Daylight Time,
writes:

I was gonna say that, but people keep insisting that foliar
feeding is a valuable addition to growing bonsai, and I
didn't
feel like an argument. ;-)

Jim:

Let's argue a bit. );-)) The following is based on tests at
Michigan State University:

"FOLIAR FEEDING -
Foliar feeding is an effective method for correcting soil
deficiencies and overcoming the soil’s inability to transfer
nutrients to the plant. Tests have shown that up to 90 percent of
a foliar fed nutrient solution can be found in the smallest root
of a plant within 60 minutes of application. A project conducted
at Michigan State University, using radioÂ*active tagged
nutrients, proved that foliar feeding can be 8 to10 times more
effective than soil feeding.

The effectiveness of foliar applied nutrients is determined by
(1) The condition of the leaf surface, in particular the waxy
cuticle. The cuticle is only partially permeable to water and
dissolved nutrients and, as a result, it can limit nutrient
uptake. (2) The length of time the nutrient remains dissolved in
the solution on the leaf's surface. (3) diffusion, the movement
of elements from a high concentration to a low concentration. For
diffusion to occur, the nutrient must dissolve. and (4) The type
of formulation. Water-soluble formulations generally work better
for foliar applications as they are more easily absorbed when
compared to insoluble solutions. Water insoluble formulations
are generally slow acting because they must dissolve before they
can be absorbed and are more applicable for soil applications.

TIMING
The best time to foliar feed is late evening to early morning.
These are the times when the stomata (the small opening on the
leaves) are open.

Avoid foliar spraying when –
• When the temperature above 80F.
• When the weather is hot and dry and water vapor is leaving
the cells.

Foliar spray –
When the temperature is 72F or below.
• Early in the morning when the cells of the leaf are full of
water and dew has collected on the foliage.
• When air temperatures and humidity both equal 135 or less.
• When air temperature is cooler than soil surface temperature.

NOTE: A biological surfactant can reduce water tension and
improve the absorption rate of foliar sprays.

Where possible, the pH of a foliar spray should be between 6.2
to 7.0. To promote young plant growth a sweeter (alkaline)
solution (pH 7.0) is recommended. For established growth, a more
sour (acid) solution (pH 6.2) is recommended.

An effective foliar application can produce results in 2 to 6
days. A refractometer can detect results in 1 to 4 hours."

Nina: Thoughts?

Cordially,

Michael Persiano
members.aol.com/iasnob


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