For The Scout
Scouting for thrips should entail a proper regimen, as always. And in this regimen growers can use a considerable variety of tools. Yellow sticky traps are one such tool. And if you’re using biocontrol agents to treat for or prevent other pests, which may be captured in yellow traps, then blue sticky traps are also very good at trapping thrips. Thrips, especially the larval stages, are, however, more difficult to count on blue traps. I prefer, when are where possible, to use yellow. I understand hot-pink traps are the best (based on a university study), but they are not, to my knowledge, commercially available. My guess is if hot-pink is your color, you’ll have to make your own traps-but that’s doable because insect trap coating products are available to growers for just such a purpose. A proper scouting regimen will also utilize single plant inspections. For thrips monitoring, use some plants which will bear a steady supply of flowers. These flowers may tapped or lightly shaken over a white sheet of paper — a drop-cloth, if you will — to facilitate easy detection. Like spraying, this should be done at high noon; but I encourage midday scouting, anyway. You may also lightly blow into open flowers as this will generally lure them out. They may be interested in what you had for lunch, perhaps. If you find your garlic-bread breath not only lures them out but kills them, keep it up, you may be on to something big.
One of the best ways to deal with thrips is to practice exclusion using an extremely fine insect screen and to carefully inspect incoming plant material, especially if it’s budding or flowering. Screening sounds pretty straightforward, but it entails planning because the material is so tightly woven, it will significantly reduce airflow. An airflow reduction can cause all sorts of problems. Burned-out exhaust fan motors just for starter; a fire as a result for finishers. Looser meshed (anti-virus) screens are probably the way to go as they do keep most thrips outside where they belong without such a dramatic airflow reduction. As another way to deal with these pests, in-house scouting becomes extremely important just in case they make it past security. (They, too, like many pests are opportunistic and will sneak in while the door is open and the guards aren’t looking. They’ll also grab a ride on employees coming and going during their duties.)
Using a trap crop is also a great idea for thrips. Blue flowers, like asters, work well. So do many other flowering plants. You may also choose to incorporate plants such as petunias and fava beans. These are especially important as they can be indicative of not only thrips, but the viruses they vector. Symptoms such as leaf spots, brown, oozing patches, necrotic leaves, concentric rings of various colors, and others, can all tell you a story about your local thrips-even if you don’t see the critters themselves. If you see some of the symptoms I’ve described, panic. No, not really, seek the help of a book containing color photos of these diseases on the varieties of plants you’re growing for a side-by-side comparison. Also, and don’t be afraid to do this, seek the assistance of professionals well-versed in identifying these problems. Start with your area university’s cooperative extension office. If you get an agent which tells you to give up biocontrol and IPM and to spray the whole damn house with something extreme, get someone else to help you. Regardless, though, on what you do, act fast.
Aside from seeking the thrips themselves, or looking for the disease symptoms they can cause, feeding damage may also be revealing. Silvery striations along the leaves are indicative of feeding. They feed on leaves somewhat like the way a person would mow a lawn: back and forth, or round and round, forming a pattern. The silvery patches are actually groups of individual, spent plant cells. Other symptoms of feeding may include deformed leaves, buds and flowers. Some vegetable, such as peppers and cucumbers, and some fruits, may suffer abortion. The last sign is the presence of fecal matter. The feces show themselves as tiny black specks. Please bear in mind, if you see these signs of feeding damage, you have a great deal of these nasty pests — at least locally on the plant(s) on which the symptoms appear. If it is found on a single specimen, which, coincidently, happens to be next to the door, get rid of the plant. Keeping it may spell trouble; and the plant is probably not worth it. Be alert, act preventively, play it smart. One of the biggest threats to thrips is the analytical, logical human brain — use yours. [Intro]
Some Solutions
When thrips, like the ever-popular western flower thrips, become established in your crop their foothold can be tenacious. It is, therefore, very important to locally spray at the very first sign of them — assuming they aren’t actually already resistant to whatever you’re using and you can actually get the spray to them in the first place. However, if you’re using biocontrols, which I feel is the very best way to go (did I really say spray before?), your actions should be preventive and aggressive. It doesn’t have to cost very much money, but it must be preventive and aggressive for the best results! There are several biocontrol agents which are very effective against thrips. Some kill the larval stages, some the prepupal and pupal stages, others the adults. You may want to use them all. Two in particular, Neoseiulus cucumeris (for the larvae) and H. miles (as previously mentioned, for the in-ground pupal stages), when used in concert, preventively and aggressively, have proven themselves repeatedly — in interiorscapes and greenhouses.
Want something more? Here’s a new tip that you may find useful in your war with thrips.
Need thrips controls? Try looking at Neoseiulus cucumeris, Hypoaspis miles, Iphiseius degenerans, Orius insidiosus, and Amblyseius swirskii. Also check out some biorational sprays, our soap and oil, and maybe some garlic spray, and others. [Intro]
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