By Stan V. Griep
American Rose Society Consulting Master Rosarian – Rocky Mountain District
In this article, we will take a look at thrips (flower thrips and even some known as the chili thrips) as one of the pests we may have to deal with in our rose beds. Thrips are tough customers when it comes to controlling them once they have set in upon our roses.
Identifying Thrips on Roses
Thrips are extremely active slender brownish yellow winged insects. They seem to favor the lighter colored blooms and will typically leave red spots and brown streaks on the petals. The flower buds are often deformed and typically will not open.
The chili thrips will attack the foliage and basically the entire host plant. The amount of damage they can do in a very short time is astounding! The chili thrips will kill the entire host rose bush or plant quickly if not treated immediately upon noticing the earliest stages of an attack upon the rose bushes or plants in the gardens.
Controlling Thrips on Rose Bushes
One of the reasons thrips can be so hard to control is that they live inside the buds and blooms of the roses and other flowering plants in the garden. Both the young and mature thrips feed on the sap within the petals by rasping the tissue of the petals to suck the sap out. The thrips usually start out breeding on various grasses and weeds. Once those sources are cut down, they move onto attacking the ornamentals in the garden.
The number of thrips attacking our gardens can grow very quickly once they have found the blooms of our gardens. The complete life cycle for the thrips can occur in two weeks time, so their numbers do indeed rise very quickly if a method of control is not started as soon as possible.
To gain control of a problem with thrips, using a systemic insecticide may prove to be the most effective. The systemic insecticides move throughout the tissues of the rose bushes treated, thus getting into even the most seemingly hidden tissues where the thrips love to attempt to hide, feed and breed. As always, the use of an insecticide is no light or easy choice. Using an insecticide that has the best chance of controlling the problem quickly will mean using less of it over time with hopefully less impact.
Take the time to read the labels well on the insecticides available in your area, and be sure that thrips are, in fact, listed as one of the insects controlled. Most insecticides will help in gaining control of the extremely nasty and tough chili thrip; however, the key is to spray frequently. Even though I do not like to use the insecticides, especially the systemic types, the amount of damage these pests can do in such a very short time warrants serious consideration. Staying on top of, or better yet ahead of, a major attack is extremely important.
Many people today use drip irrigation in their gardens or some form of automatic irrigation. The big problem with that is that the rose bushes or plants in our gardens, typically, do not get the close up inspection as when we water by hand. Thus, when an insect or fungal attack happens, it can gain control quickly and easily. By the time the problem is noticed, the choices are very limited as to what will gain control and do so quickly.
Remember, the garden grows best when the shadow of the gardener is there frequently. Take a garden walk to truly look over the foliage of your rose bushes and other plants at least weekly, even then a problem can get ahead of us.