Gerbera & Roses growing article January 2006
Vase life flowers / bacteria growth;
Good quality flowers are flowers with a
long vase-life. Short vase-life can be caused by water shortage due to a
blockage of the veins in the flower stem. These blockages are caused by
bacterial growth in the stems. Bacteria are normally not growing in the flower
stems when they are still growing on the plant. Harvesting or/and bad quality
water can contaminate the flowers. When the bacteria are introduced to the stem
they begin to multiply, making the blockage.
In cold rooms, at low temperatures, the
bacteria growth is very slow, but at a temperature of 20 degrees (at the
customer) the bacteria are growing fast. The bacteria can sometimes be seen as
dreads of slime in the water. The bacteria blockage can result in wilted flowers
within 2 to 3 days, and this makes sure that the customer is not satisfied with
his purchase.
A few important things to keep in mind
when the temperatures are high in summer;
- Hygienic working conditions.
- Use of clean buckets.
- Put the flowers after harvest straight
in water.
- Bright sun and draughts make it
difficult for the flower to uptake water.
- Use the correct flower treatment
products (chloride and/or Chrysal)
Labour issues;
There could be money saved on labour
when the way of picking and packaging of flowers are done more efficient. Most
growers don't know exactly how much time and money is spend on processing of the
flowers. The labour cost are rising and the production increase each year a few
percent, if nothing is done the labour cost get a (too) high percentage of the
cost and it would be harder to make a profit.
My suggestion is to start to count the
flower production per M2 per week / month and also how much flowers are
processed per hour. By doing this over a longer period you could find out the
progress in the coming years.
Over the last few months I have seen by
a few growers gerbera plants affected with Sclerotinia and Tomato spotted wilt
virus;
Sclerotinia;
The symptoms are that the plant wilt
and white mould with black style pellets (sclerotiorum) in the crown of the
plants. Most of the time the plants survives even it loses all of its leaves,
after a while you see new leaves coming but the result is that you have lost
production for a 3 – 6 months period. If you don't treat the sclerotinia it will
affect a large number of plants, most of the time the sclerotinia will affect
varieties with a lot of leaves which prevent airflow around the heart of the
plants.
What could you do to prevent
sclerotinia?
Do regularly crop maintenance to keep
the crop open, especially by varieties which have a lot of foliage.
Use bottom pipe heating to avoid low
temperatures and a dead climate between the plants.
Remove the leaves of the affected
plants and spray a fungicide when you see the first symptoms of Sclerotinia, for
the best result you have to repeat the fungicide spray after 10-14 days.
Tomato spotted wilt virus (TSWV);
Infection by TSWV resulted in a variety
of symptoms of which concentric rings and leaf necrose are most common. Other
symptoms are decreased flower quality and slow down in growth when infected in
an early stage.
Remove and destroy all infected plants
because they cannot be cured and can affect surrounding plants.
Try to keep thrips numbers low because
thrips could spread the virus.
Because many weeds carrying the virus,
remove weeds both inside and outside the greenhouse.
***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.
