Last updated on October 23rd, 2023 at 08:49 pm
Controlling thrips effectively in your garden or on your plants can be challenging, but it’s essential to prevent these tiny, destructive pests from damaging your plants. Thrips are small, slender insects that feed on plant sap and can cause damage to leaves, flowers, and fruit. Here’s how to control thrips effectively:
- Identification: First, make sure you correctly identify thrips and confirm that they are the pests causing damage to your plants. Thrips are typically tiny (1-2 mm), slender, and often yellow, black, or pale in color. They feed by puncturing plant tissue and sucking out the cell contents.
- Cultural Practices:
- Prune Affected Plant Parts: Remove and dispose of heavily infested leaves, flowers, or buds to reduce the thrips population.
- Keep Your Garden Clean: Thoroughly clean up plant debris and fallen leaves to eliminate potential hiding spots for thrips.
- Biological Controls:
- Predatory Insects: Introduce natural predators such as ladybugs, lacewings, and minute pirate bugs, which feed on thrips. Encourage these beneficial insects to thrive in your garden.
- Nematodes: Beneficial nematodes, specifically Steinernema feltiae, can be applied to the soil to control thrips pupae.
- Insecticidal Soaps and Oils:
- Use insecticidal soaps or neem oil as a natural, non-toxic solution. These can be sprayed directly on the affected plants, smothering and killing thrips on contact.
- Sticky Traps:
- Yellow or blue sticky traps can be used to capture adult thrips flying near your plants. These traps are especially effective in greenhouses.
- Systemic Insecticides:
- If the infestation is severe, you may need to resort to systemic insecticides. These are absorbed by the plant and poison thrips when they feed on plant tissue. Always follow the label instructions and be cautious about their impact on non-target organisms.
- Rotate Crops: If you have recurring thrips problems, consider rotating crops to reduce the buildup of thrips in the soil.
- Companion Planting:
- Some companion plants, like marigolds and alliums (garlic, onions), are believed to repel thrips. Interplanting these with susceptible crops can be a preventive measure.
- Monitoring: Regularly inspect your plants for signs of thrips infestation, such as silver streaks, stippling, or distorted growth. Early detection can help you manage the problem before it becomes severe.
- Quarantine New Plants: If you introduce new plants into your garden, quarantine them for a period to ensure they are not carrying thrips or other pests that can spread to your established plants.
- Chemical Pesticides (As a Last Resort):
- Only use chemical pesticides as a last resort, and be sure to choose a product labeled for thrips control. Follow the manufacturer’s instructions carefully, and avoid using broad-spectrum pesticides that can harm beneficial insects.
- Repeat Applications: For persistent thrips infestations, be prepared to repeat your chosen control methods at regular intervals to target newly hatching thrips.
Integrated pest management (IPM) practices, which combine multiple methods, are often the most effective way to control thrips without relying solely on chemical pesticides. Regular monitoring, early intervention, and encouraging natural predators are key components of successful thrips control in your garden.
These insects belong to the family Thysanoptera, which is made up of about 3,000 species of thrips. However, the small fruit thrips (Frankliniella occidentalis) are among the best known. Very prolific, this long-limbed insect is very common in greenhouses, verandas and indoor plants. However, it can also be found outdoors when the environment is warm and the hygrometry is low. In general, populations explode from May to September. Difficult to discern with the naked eye, you will have to rely on the silver spots they leave on the plants or take a good magnifying glass to identify them under the leaves of infested plants.
What are the risks for plants in case of a thrips invasion?
They empty the contents of plant cells after piercing plant tissue. In doing so, the puncture releases toxic saliva. This then results in unsightly grayish spots and discolorations. Leaves begin to wither and young shoots become deformed, resulting in poor growth and even necrosis. The flowers suffer deformations in the petals. In most cases, the plant does not die. However, it becomes more exposed to cryptogamic and viral diseases (tomato bronzia, etc.). It can also reduce the harvest.
The plants most targeted by these small beasts:
These bugs like greenhouse crops and indoor plants. However, some plantations are more sensitive to them!
-Vegetables : broccoli, cabbage, cucurbits, beans, turnips, onions, leeks, radishes, tomatoes and radishes.
-Fruits: strawberry and raspberry plants
-Plants: azaleas, begonias, chrysanthemums, orchids, roses
-Fruit trees, olive trees and shrubs in the ornamental garden.
Prevention against thrips infestation
-Adopt crop rotation to break the reproductive cycle of this species.
-Limit proliferation by maintaining a moist, ventilated atmosphere. Spray water on the plants. If the plant is not too concerned about fungal diseases, spray the underside of the leaves with water. In fact, you can spray these pests with a strong stream of water from a garden hose or shower to dislodge these small plant-eating insects.
-Plant garlic, clover or flax at the foot of the plants they prefer for a protective repellent effect.
And what to do when thrips are established?
-Place blue sticky traps, if possible combined with pheromones. Thrips are attracted to this color and you are less likely to catch beneficial insects in the garden by mistake with these traps.
-Invite auxiliary insects that are their natural predators: mites (Amblyseius cucumeris), lacewings (Chrysopa carnea), nematodes, bugs…
-Use a decoction of garlic by macerating two cloves of garlic in a liter of water for 24 hours. Then add a tablespoon of dishwashing liquid or better, black soap and rapeseed oil. Then spray the infested areas. Repeat every 5 days for a month.
-You can also simply dilute 4 to 5 tablespoons of black soap in a liter of water.
-Sprinkle diatomaceous earth or dilute sweet orange essential oil to spray on attacked plants.
-After the treatment, repot your plants in a clean pot with new healthy soil.