Tiny but mighty, these pests bedevil local gardener. More than 6,000 species of thrips roam the planet, yet only five are of real concern to local gardeners, attacking an array of backyard plants from fruits and vegetables, to ornamentals. Plant damage is a result of thrips feeding on developing plant parts, causing deformed or scarred leaves and flowers. They transmit various tospoviruses such as impatiens necrotic spot virus and tomato spotted wilt virus. One of the most reviled species of all is the western flower thrips, which quickly multiplies and ravages a wide range of plants, especially backyard perennials.
At a mere 1 millimeters long in adulthood, these tiny terrors inflict damage through feeding. "They have a super-specialized mouth that's like a big needle injected into a plant cell, sucking out all its sustenance. This causing the cell to collapse," says Ken Lain, owner of Watters Garden Center in Prescott, Arizona. "They don't discriminate. They pull it out and move to the next cell, scraping the tissue as they feed. They'll feed on any soft plant tissue, especially early spring flowers."
Once a thrip punctures and feeds on a plant cell, not only does it cause a visible mark on the plant, but it kills that cell. This is especially problematic when the pests feed on developing plants because "it causes all this messed up growth," Lain says, "and if that wasn't bad enough if a feeding thrip is carrying a tospovirus, the virus would be transmitted to the plant. Which is bad … I call it the kiss of death."
The televised microscope at Watters Garden Center has been busy magnifying this tiny creature appropriately nicknamed 'No-See-Ems.' Nearly transparent yellowish bodies with a large head and bright red eyes, these guys are small. You can spot them on your plants with a simple cell phone test. Tap a sample plant over the glass of your phone, and if you witness dust-sized insects jumping around, you have a problem.
From Egg to adult can happen in as little as 10 days, with adults eating on your plants up to 45 days. Because thrip reproduces so quickly, they can be tricky to control in the garden.
Scouting. Check anything and everything in the landscape. Assume they are always there; if they're not, they soon will be.
Monitor your gardens with yellow sticky traps placed right above the plants' canopy attracts flying adults. Again, the cell phone method helps identify infestations. "Also, the carbon dioxide when blowing on a flower agitates them into moving around. Try it; they like to handout inside flowers." Ken Lain says.
Prevention. Isolate and inspect your plants. "Don't move infested plants to other growing areas because thrip easily spread to neighboring plants. Thrips are "little hitchhikers" easily carried by wind and on your clothing. Use fans in a greenhouse the blows air out ridding the house of flying adults. Screen greenhouse vents and doors, and never leave the door open. Clean and weed-free are huge. Don't allow weeds to grow under your plants, they are the perfect breeding grounds for the pupate stage of this insect.
Control. "If an infestation occurs, we go all 'Marine' on them in a literal 'shock-and-awe' approach to controlling their spread," Lain says. In a greenhouse, it's easy to release ladybugs into the house. When contained, these little red ladies devour thrip until the problem is gone.
Lain says, 'We have tubs of ladybugs with hundreds of insects here at the garden center ready for garden use.”
Not only will the ladybugs help your garden, but utilizing them is a great opportunity to sneak in a science lesson!
Conventional chemistry in the gardens is practical and most likely to be required at some point. Organic 'Triple Action' we have here at Watters is impressive when used early in an infestation and less likely to harm other beneficial insects.
Plant Protector is the long term solution for this bug when used early in detection. The systemic liquid is poured over the root zone of plants and absorbed directly into the tissue of the plants, and far easier to apply on large trees and shrubs, than a spray.
Multi-Purpose Insect Spray is applied later in spring when this insect does a lot of damage. Administered through a hose-end sprayer until the infected plants are dripping wet. At this stage, the thrips are so plentiful we recommend a follow-up application 10 days later to prevent further infestations.
"You're not alone. Ask a professional for help." Lain says. "We don't want to spread this little plant devil, so bring a sealed plant sample to Watters Garden Center, and we'll put it under the microscope the see how bad things really are. Then we can offer the correct solution."
Watters Garden Center is a locally owned and operated garden center that specializes in providing avid gardeners and novices alike with the expertise and products to get things growing in the mountains of Arizona.