Bud Drop: The typical sign of thrips is a bud that grows
large, turns an off-color before opening, and then falls from the plant at the
slightest pressure. Buds may sometimes fall before turning color, but often
that sort of rotten color happens before the buds fall. The reason for this change
in the big, healthy bud is that the thrips have been scratching around inside
the bud as well as laying eggs inside of it. When the bud falls, the young
thrips are then able to leave the bud and burrow into the ground where they
change into adult thrips that are capable of flying back up to new buds to
continue the cycle.
Scratch Marks: Some varieties of
hibiscus do not react to thrips by losing their buds. In that case you can see
the thrips damage as scratch marks on the flower petals. Sometimes it looks
almost natural, like the spots and markings that some of our varieties produce
as part of their interesting flower coloring. Other times you can see how it
badly mars the beauty of the flowers. Even though these varieties do not lose
their buds they can still be treated in order to obtain flawless blooms free of
COMMENTS on disease
Thrips are insects that lay their eggs inside the buds of hibiscus,
roses, and other species that make big buds before flowering. The thrip is
small but visible if you look for it. The easiest way to see thrips is to take
an open flower and shake it over a white piece of paper. Thrips will fall out
of the flower onto the paper, looking like small, black pencil lines on the
paper. They are much longer than they are wide, and their dark color stands out
against a piece of white paper.
For fast and full results, it is best to remove
all rotten buds from the plants and the ground and dispose of them in the
trash. In order to keep thrips under control, you will need to use a product
called Spinosad. This
chemical needs to be sprayed over the tops of the plants, covering the buds and
upper leaves of the plants. Use Spinosad for three treatments, 5-7 days apart.
but you may repeat this treatment series if you need to. You can also drench
the potting mix or soil around a hibiscus with a systemic pest control product.
This will kill most of the live thrips that are living in the ground in the
juvenile form, and it will speed up control of this pest.
Organic Treatment: If you don`t want to use
pesticides, an organic approach is to spray in the same way with any product
containing "Neem oil," a natural product obtained from the Neem tree.
It may require more treatments to control thrips, but is a good alternative
approach if combined with gathering up all rotten buds and spent flowers so the
thrips do not reach the ground around the plant .