February 2019 - 25

RESEARCH
North Carolina. The results,
so far, have not indicated a
significant difference between
the two species of pine.
5. At 25 percent wood, growth
in both the 3-month-old
sawdust and shredded wood
were nearly identical to the
control treatments, and with
added fertilizer there was
only a 15 percent reduction
in growth with 50 percent
wood. The results indicate
that increased fertilizer
is beneficial with higher
fractions of wood.
6. When effective water capacity
is significantly less than
potential water capacity, a
container holds less water than
possible. Less water in the
pot means the plant dries out
to wilt sooner and can result
in the requirement for more
frequent irrigations at retail
and the development of water
stress symptoms of chlorosis
or necrosis if irrigations are
delayed. Adding a solution
with wetting agent prior to
shipping should be beneficial
in the retail market, especially
for plants grown in high wood
percentage substrates.
7. Plants in the high fraction
wood treatments did not
necessarily show unusual
visual symptoms other than
reduced leaf expansion and
sometimes reduced height.
Reduced height may be good,
but reduced leaf expansion
reduces photosynthesis
and growth. Inhibitory
compounds coming from the
wood act more like a growth
regulator than an herbicide.
It is important to note that
without plants growing in
a media without wood for
a side-by-side comparison,
the reduced growth might
not be apparent. Even with
a side-by-side comparison,
differences of 15 percent
fresh mass can be difficult
to visually detect. Finally,
even with reductions in
growth, the plants may still
be more than adequate for
sale as floriculture crops
often require the use of plant
growth regulators to reduce
size and height.
A UNIQUELY SENSITIVE
CROP
We have not yet studied
poinsettias, but the experience
of several growers suggests they
are uniquely sensitive to sawdust.
Interestingly, poinsettias appear
far more sensitive to sawdust than
to shredded wood. Some growers
report using up to 50 percent
shredded wood (HydraFiber)
without problems. High
temperatures during the shredding
process might be removing
inhibitory compounds.
Figure 8 shows poinsettias with
30 percentage fresh sawdust
compared to a peat/perlite control.
The plants with sawdust later
recovered following leaching and
high fertilizer applications and
were saleable, but the reasons for
the acute sensitivity of poinsettias
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For the full Danziger line as Rooted Liners and also in URC please contact:
Mike Fernandez at: mike@danziger.co.il, Tel. 315-396-6684
Lisa Heredia at: lisa.heredia@danziger.co.il, Tel. 239-248-0665
GREENHOUSE PRODUCT NEWS 25
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February 2019

Table of Contents for the Digital Edition of February 2019
