Saturday, June 20, 2009

Chilli Thrips Invade East Texas

Earlier this month I received plants from an East Texas wholesale nursery with damage that the grower thought was possibly herbicide damage. As soon as I put the sample under the microscope my worst fears came true. The damage was not the results of a preemergent herbicide. Rather, the damage was from chilli thrips. I went out to the nursery and walked the entire facility with the grower to determine what plants were impacted. We estimated that approximately 20% of the nursery was infested with chilli thrips. The good news is that we have the tools to develop a management program that should be able to clean up the nursery. Unfortunately, we were unable to determine where the thrips came from. I would suggest that all ornamental crop producers and landscapers in the state be on the lookout for unusual plant damage.

. Chilli thrips are extremely small and difficult to distinguish from other thrips species
without the aid of a good hand lens or compound microscope. Adults are pale with dark wings and less than 1 mm in length. Immature chilli thrips are also pale in color and resemble the immature stages of many other thrips species.

Feeding Damage. Chilli thrips infestations are usually first detected by their distinctive feeding damage. Unlike flower thrips, which feed primarily on pollen, chilli thrips feed on various plant tissues. Feeding causes bronzing (tissues turning bronze in color) of leaves, buds, and fruit. Damaged leaves may curl upward and appear distorted. Infested plants become stunted or dwarfed and leaves may detach from the stem at the petioles in some plant species. Feeding may also cause buds to become brittle and drop. Young leaves, buds and fruits are preferred, although all above-ground parts of host plants may be attacked. Damage can be easily confused with herbicide damage, broad mites, or even a foliar pathogen.

Chilli thrips damage on pomegranate

Chilli thrips damage on Japanese maple

Host range.
Chilli thrips have a very broad host range and may feed on many of the common plants. All broadleafed plants should be considered potential hosts for this thrips. Some of the more common plants attacked are roses (all types), Indian hawthorn, cleyera, begonias, plumbago, blueberry, schefllera, duranta, sweet viburnum, verbena, oaks, live oak, red maple, Japanese maple, grape, Japanese maple, English ivy, viburnum, and ornamental peppers.

Chilli thrips damage on shrub roses

Chilli thrips damage on Indian hawthorn

Plant Monitoring and Identification. Plants with the symptoms described above should be examined closely for the presence of thrips. Thrips collected from the leaves or buds of plants with suspected damage should be collected and properly identified. If you wish to participate in efforts to monitor the distribution of this pest in Texas, place samples of thrips or suspected thrips-infested plant parts into a Ziploc bag, add a dry piece of paper towel or napkin to avoid excessive moisture, and seal the bag. Label the bag with collection information including locality (city or town and county), date, species of host plant, and your name and contact information. Send samples via express mail (next-day delivery) to assure good sample quality. Please send samples to: Chilli Thrips Lab, Texas AgriLife Extension Service, P.O. Box 38, Overton, TX 75684