Thrips can be a problem for the greenhouse grower all the way to the field or garden grower. To control thrips we need to understand what a thrip is and its habits and habitats. After we learn what the thrip is, we can better understand how the thrip acts, habitats, and how to GET RID OF THEM. Thrips contribute to a huge amount of headaches from the professional and commercial grower, greenhouse grower, down to the gardener. Thrips can make a healthy plant look like it’s on its last leg, in a matter of a day or two depending on the infestation.
Lifecycle and Information
As you can see above thripes if left untreated can cause some serious damage to your produce! Thrips damage plants by feeding on leaf and flower tissue, leaving a silvery appearance. They also lay eggs in leaves and flower tissue in young developing fruit (such as cucumbers). This damages leaves and flower petals and causes distorted and damaged yields. Thrips can also transfer disease such as the Tomato Spotted Wilt Virus so it is very important to keep these pests out of your grow!
- Nymphs and adult thrips are very small, straw colored, long insects that are a little less than 1mm long.
- Adults have narrow, fringed wings; nymphs are wingless
- Thrips can move FAST and prefer to hide in folds of leaves and fruit
- Females lay eggs in plant tissue and each female lays between 6-10 eggs per day over her lifespan of 4-5 weeks. Eggs hatch in 5 days with 72F weather.
- Nymphs feed on plant tissue for 8-10 days, then drop to the ground to complete development in protected sites on the ground or greenhouse floor.
- Thrips have an immobile stage, the pupal stage, which takes 7-10 days
- When adults emerge they fly to upper parts of plants and begin laying eggs after a day or two.
- Use yellow or blue sticky cards at a rate of 1 trap per 500-1000 square feet. Place traps at tops of the plants, around the canopy.
- Count the number of thrips on traps weekly; replace traps every 3-4 weeks as the glue dries out
- Use a 1-15x lens to examine leaves for presence of thrips or signs of feeding damage.
Control Thrips With Diatomaceous Earth
Earthworks Health LLC offers a bundle package that combines our awesome applicators to help you apply and a whole 50lb bag of the diatomaceous earth itself. Feel free to click here to be directed to the information page of this product bundle! As with any pest, a combination of monitoring and an effective product like diatomaceous earth to kill them is going to be the most effective way to rid them. Please see below for steps on how to use diatomaceous earth to kill a thrip infestation on your plants.
Steps on Applying DE to Kill Thrips
- Clean up any dead plant material on or around plants to prevent other varieties of insects that may cause harm to your plant. In my experience bugs that eat my plants are drawn to the dead plant material. So if you are greenhousing it this year, get your room cleaned and disinfected before you start really growing.
- Apply Diatomaceous earth, in a visible fashion, to the entire plant and be sure to focus on tight areas or areas where plant foliage may be folded. Be sure to get the underside of the leaves
- Apply a 1 inch think layer of DE on the grounds from the center stem out a few inches past the drip line of the plant. This step is super important to be sure we get any of the dormant nymphs that come to the ground to develop into adults. This action prevents the nymph from becoming an adult, where adults fly to the canopy and lay eggs.
- As a prevention you may do this action every 2 weeks in your grow. But during an infestion its best to keep up on the application on a weekly basis.
- Be sure to reapply after every rain or watering as DE will get washed away. Just be sure its visible, very important
- Repeat steps 1-6 as needed throughout the growing season