As beautiful as roses are, they are often plagued by pests that can cause damage to the plant and leave gardener/rosarians feeling frustrated. One such pest is the Western flower thrips, which is a common problem in Arizona gardens. Along with mites, thrips have been the bane of rosarians for years, causing unsightly damage to their cherished roses. However, what’s worse than the damage caused by thrips is often the actions of unknowing gardeners who may exacerbate the problem without realizing it.
Have you ever noticed your white or pale pink roses turning an unappealing brown color? It could be due to this pesky little insect. These tiny creatures scrape the surfaces of flower petals and consume the exposed nutrients, causing discoloration in light-colored flowers. Interestingly, they seem to prefer white and pink roses over their red counterparts. Flower petals, pollen, and newly unfolding leaves attract thrips because of their tender tissue.
I’m not saying we should start a “Save the Thrips” movement, but it might benefit us to step back and consider how we are going about controlling their numbers in our garden.
The western flower thrips may seem like a tiny insect, but it can cause significant damage to our roses. These pests prefer to feed on rapidly growing tissue, but they don’t stop there. They also target developing flowers, buds, and foliage of the plant. Their feeding behavior involves puncturing leaves and sucking the plant sap, which results in silvery appearance on the leaves that eventually turn into brown scarring. which can be confused with windburn or blown sand damage. As gardeners and rose enthusiasts, it’s essential to understand how these pests operate and take necessary steps to control their infestation for a healthy and thriving garden.
It’s not always easy to spot the tiny pests that are causing damage to your flowers. These insects tend to hide deep within the layers and folds of flower buds, making them difficult to detect. When it comes to identifying thrips infestation in plants, a thorough examination of the plant parts is crucial. It’s important to inspect not only the visible areas but also the folds in leaf tissue near the base of the plant where thrips tend to hide. Look out for feeding scars and other signs of damage caused by these pests. While thrips are a common culprit for this type of damage, it’s essential to look for the insects themselves as lace bugs and other plant bugs can also leave behind similar black specks.
If you gently blow onto the bloom, you’ll see some tiny tan specks hurry about on the petals. If you find three to five thrips on a small plant, it’s highly likely that there are many more hidden within the folds of leaves or that have already dispersed from the plant. It’s important to act quickly, and take appropriate measures, to control and prevent further infestation by these pests.
This is especially true when it comes to pest control. This is a frustrating situation for gardeners. Not only is it possible they are wasting resources on ineffective treatments, but they’re also unintentionally killing off important predators that could have helped keep these pests in check.
it’s important to remember that these tiny pests have natural enemies that may already be working to control their populations. In fact, by the time you notice visible damage, it’s likely that natural predators such as predaceous mites, minute pirate bugs, wasps, lacewings, ladybugs, and even beneficial nematodes are all feeding on thrips. However, these natural enemies are very susceptible to insecticide sprays and may not be present in fields where insecticides have been used.
For this reason, it’s crucial to exercise caution when considering pesticide use. Applying chemicals too early can disrupt the delicate balance of beneficial insects and potentially do more harm than good.
Thrips are one of the most challenging pests a gardener faces. Despite the use of various pesticides, no single product can provide complete control over thrips due to their unique characteristics. Their small size, high mobility, and hidden feeding behavior make them difficult to detect and manage effectively. Additionally, their protected egg and pupal stages make it even more challenging to control their population. It’s important to understand that no pesticide provides complete control of thrips, which is why an integrated pest management approach is necessary for effective management.
Instead, home gardeners should consider monitoring thrip populations closely and only applying pesticides when serious damage is occurring, and other control methods have been exhausted. By doing so, you can protect your roses while also supporting a healthy ecosystem in your garden.
Managing thrips doesn’t have to come at the cost of harming non-target species or the environment. Supreme oil sprays and insecticidal soaps are effective solutions that are also eco-friendly. These products work by suffocating thrips and their eggs, preventing them from causing further damage. Unlike traditional pesticides, they do not leave harmful residues on plants or in the soil. Plus, they are safe for beneficial insects like bees and ladybugs.
Using supreme oil sprays and insecticidal soaps in fall, winter, and early spring can help prevent thrip populations from getting out of control before the growing season begins. However, these products can harm plant tissue when temperatures are above 90 to 95 degrees Fahrenheit. Neem insecticides are minimally effective in controlling thrips during the spring – and discouraged in the summer. Spraying plants off with water to dislodge them is somewhat effective. Reflective mulches have also shown some promise. Aluminum foil placed under the plants are said to confuse/disorient the insect.
The Arizona heat seems to agree with the thrips and mites. The recommendation for controlling the two is essentially the same. Spray down your roses and knock them off your blooms, buds, and leaves (thrips aren’t good fliers). You aren’t going to eliminate them, but you can reduce the amount of damage they cause. Careful pruning helps remove any damaged or diseased parts of the plant, promoting healthy growth and preventing further damage. Removing infested terminals also prevents the spread of pests to other parts of the plant or nearby plants in the landscape.
Resources:
Jeff Schalau, “Recognizing and Controlling Thrips,” (May 2001) https://cals.arizona.edu/yavapai/anr/hort/byg/archive/thrips.html
E.T. Natwick (emeritus), “Western Flower Thrips,” (April 2017) https://ipm.ucanr.edu/agriculture/lettuce/western-flower-thrips/
Photo by Jack Kelly Clark, UC IPM Program, “Western Flower Thrip – Frankliniella occidentalis” UC Statewide IPM Project, © 2000 Regents, University of California
