Pictorial Guide to Identifying & Treating Chilli ThripsPosted on : May 14, 2014
If you can see them – it’s probably not chilli thrips. Usually mistaken for gnats when flying in swarms
Target plants with new growth. Then move from plant group to plant group as food supplies dwindle and new growth appears on something else.
Misdiagnosed-even by experts as chemical burn, herbicide damage, spider mites & rose rosette disease.
Damage starts at the top of the plant and works its way down. Chilli thrips rarely feed on mature plant material.
Intervention is critical to plant survival – especially plants like Indian Hawthorne that only produce new growth once a year.
Damage is done by feeding and reproduction (eggs are laid inside plant tissue). Examples of feeding damage:
Mottled color changes from red to green.
Rapid stem/bud development as plant tries to grow out of the damage.
Asparagus-like stems are common with heavy feeding damage
Eggs are laid inside plant tissue – usually in cracks/crevices where young will be protected. Hatching causes lesions and distorted plant development.
Tissue interruption at bud eyes causes rapid cane/bud development with lack of foliage or feather-like foliage.
When leaves fully change to green, they are puckered, distorted, with silvering or bronzing where feeding occurred.
Blooms look like daisies (this is the hybrid tea rose, St. Patrick)
Abnormal lateral branching with lack of normal foliage.
Lesions/scars left from eggs hatching and eruption of young.
Slick stems topped with a lion’s mane of foliage (usually very small and feathery)
- Cut off all damaged parts of the plants. Bag and dispose of damaged plant material to reduce breeding populations. Do not compost infected plant material.
- Start chemical treatment with products rated for chilli thrips (e.g. Spinosad, Dinotefuran, Abamectin). Nursery professional also report Monterrey Horticultural Oil is effective as a suffocant. Only a few pesticides work on chilli thrips. Spray when pests are not swarming (best times are 10:00am and 2:00pm).
- Biological controls are important in chilli thrips management. Some are Beauveria bassiana (pathogenic fungus on insects), Amblyseius swirskii (predatory mite), and Orius insidiosus (insidious flower bug).
- Continue Treatment until symptoms disappear.
- Chilli thrips are problematic in Houston from May to September.
If you suspect that chilli thrips are in your garden:
- Cut samples of leaves, buds, and stems from symptomatic plants.
- Put the samples in a gallon zip lock bag with a folded piece of dry paper towel.
- Seal the bag.
- Label the bag with (1) your name, (2) your contact information, (3) the city, county, state where the sample was taken, (4) date the sample was taken, and (5) specie of the host plant (e.g. rose, hybiscus, basil, etc.).
- Complete the attached sample submission form and send the sample by overnight delivery to:
Horticulture Extension Specialist
Texas AgriLife Extension Service
1710 FM 3053 North
Overton, Texas 75684
Schedule the delivery to that samples arrive Monday through Thursday.
Written by Gaye Hammond
Master Rosarian, Houston Rose Society – gayeh@LPM-triallaw.com