NUT AND FRUIT TREE CROPS.
MACADAMIAS - A practical calibration.
There
are many lessons to be learned from this practical calibration
exercise so spend some time digesting the observations. Do the
calculations and see if my litres per tree are correct.
The mistblower
used is equipped with a set of ceramic hollow-cone tips all of the
same size. This is fine when spraying vines and small trees up to 4
or 5 metres. The Macs in this situation are about 8 to 9 metres high.
I will return to this aspect further on.
Checking the air flow.
I used 2 metre ribbons attached to the nozzle bodies. The top
centre-right is suspect. This method gives you a pretty good idea
where the air is going.
Water sensitive
paper. It is easy to say: 'staple
water-sensitive paper directly onto the leaves at the periphery and
inside the canopy at the top, in the center and lower part of the
trees.' In practice there are two problems; one is
getting there (mac leaves are tough and prickly and the branches are
brittle) and two; how many cards and exactly where to place them at
"random" to get a good idea of the spray distribution. If
you are undertaking a foliar feed or a light cover application it
won't be necessary to place the cards in the tree centre.
If the target pest
is an insect like stinkbugs on the macs then you would want a
fullcover spray and it would be essential to get to the tree centre. I decided to use a 5 metre aluminium 25mm square tube and attach the
ws-paper at 1 metre intervals. This was then fed into the tree as
close to the tree centre as possible. When testing
different nozzle arrangements one can use the same position and the
same tree.
A 5 m 25mm aluminium square tube accurately marked at 1 metre centres.
Here are the
results. The ceramic hollow-cones produced a heavy coverage at
2 and 4 metres while the AITX's (Air Induction ceramic tips) appear
to give a coaser droplet but more evenly distributed.
The mistblower was not very effective above 4 metres.
ATR tips distribution above. Water sensitive paper placed at 1 metres centres ; No 1 on left.
AITX tips distribution.
Speed. 50 metres was accurately
marked and the time recorded with a stopwatch. Tape on the ground lower left in image. In this case it took 1
min and 12 secs to cover the 50 metres. Speed in km/hr?
Nozzle arrangement.*** Nozzles
fitted ATR's each deliver 3.6 litres per minute at 20 bar. 12 were
used and 4 were shut off. Total delivery in l/min? It
would have been better to have tips of different sizes to achieve better
coverage. In my opinion I would aim for 30% to the top third, 45%
to the middle 1/3rd and 25% to the lower 1/3rd of the tree. Each
farmer will decide what's best.
Tree density. In this case the
inter-row is 10 m and the spacing intra-row is 2.5 m. There 41 trees
per 100 m and 10 rows per hectare. Trees per hectare?
*** Special notes relating to the
nozzles. It is clear that this mistblower is not going to cope
with the tree height. The problem with this particular nozzle-body
is that the capnut thread is 18mm metric so it was not possible to
test other nozzle types especially the Adjustable Conejet. To
increase the volume per tree, the rollover valves will have to be
replaced to allow for other higher volume nozzle-tips.
So how much
spray went onto each tree???
According to my calculations, the ATR
ceramic tips achieved 2.53 litres per tree.
The AITX 8004VK's each delivering
4.06 litres per minute increased the volume marginally to only 2.85
litres per tree.
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