Gerbera & Roses growing article July 2006
Insects;
In the coming weeks I would advice
growers to have a good look at the insects in their crops and take action to
reduce these insects. This is to make sure that the insects are under control
before the temperatures get higher and everyone gets busy on their farms with
harvesting the spring flush.
A weekly monitoring program is advised
for the early detection of insects and to evaluate the effectiveness of your
spraying. Yellow sticky cards can be placed in the greenhouse to see which
insects are in the greenhouse (rate of one per 500 M2). Keep records of
population on the yellow sticky cards to find out if the number of insects are
increasing or decreasing.
To get the best result with spraying
it's a good to know what the life cycle is of insects (higher temperature in the
greenhouse means a faster life cycle) and which chemical you have to use to get
the best result.
Botrytis;
Over the last few months quite a few
growers have contact me about botrytis in their flowers, hereby a few general
tips to prevent botrytis;
Make sure that the temperature in the
greenhouse is the same every where, if not use circulation fans to circulate the
air in the greenhouse.
Try to collect the drain water so the
ground stays dry, when there is no water on the ground the chance to get
botrytis is less.
Remove all the old and brown leaves
before the botrytis season start (early autumn / winter); make sure that the
crop is open so the airflow is good around the plant.
After removing leaves a lot of botrytis
spores are coming into the air, it's a good idea to spray the foliage with
Rovrall or Scala to kill these spores after removing leaves.
It doesn't matter where you grow
gerbera in Australia, but the use of heating pipes is the best way to reduce the
chance of botrytis. Quick temperature rises in the morning or high humidity on
dark days are the main course of getting botrytis.
A light spray / misting with Rovrall
over the flowers could help to prevent botrytis, but make sure you try this
first on a small area to see if you get spray damage.
Spraying for botrytis helps, but the
most important thing is to find the cause why you have botrytis in your flowers.
At the moment there are a few new chemicals on the market for botrytis, ask your
supplier for information about these new chemicals.
Planting gerberas;
Planting should be done in uniformly
moistened potting mix. Place the gerbera plant into the potting mix so the top
of the jiffy pot is 2-3 cm higher than the potting mix. If planted too high, the
plants might break at harvest. While planting too deep increases the risk of
disease (crown rot). Prevent root damage by carefully pressing the potting mix
against the pot. Under conditions with high daytime temperatures in the
greenhouse (> 30°C) and too much sunlight, it is recommended to plant early in
the morning or in the evening when the temperature and sunlight are less extreme.
To allow a good contact between pot and soil, it is recommended hand water very
soon after planting.
In the initial period after planting,
when light is a minor growing factor shading of the greenhouse is recommended.
Prevent direct wind. In the initial
period after planting, keep the humidity as high as possible.
Moistening of the plants after 2-3
weeks is not advisable, so wet leaf should be avoided.
As the plants are developing, the light
intensity and ventilation of the glasshouse may increase. The plants themselves
will have a major influence on the glasshouse climate by now (microclimate).
***Although we trust that this information
could be of considerable help to the success of the crop, we cannot accept any
liability for the results of your crop. All the information in this growing
newsletter is without committing ourselves.
This article is written by Job Roskam of Roskam
Young Plants Pty Ltd. and also published in the Australian flower industry magazine.
