Flower Thrips (WFTs - Frankliniella occidentalis) are often a problem
year after year in greenhouse production. They are tough to manage during all
crop growing stages, but even more so when crops are flowering. They can be
very difficult to control, particularly in flowers and buds due to their
preference for tight, dark places. WFTs prefer feeding on pollen, young foliage,
flowers and buds. Feeding can cause curled, distorted, puckered and chlorotic
foliage. Typically, irregular white spots form, and the leaf surface may appear
silvery or have a stippled appearance. New growth and flowers typically are
deformed and discolored with feeding scars. WFTs also have the ability to
transmit viruses such as impatiens necrotic spot virus (INSV) and tomato
spotted wilt virus (TSWV).
Western Flower Thrips
the chance of high populations of WFTs resulting in crop injury, start control
measures early and use an integrated approach. Listed below are basic thrips
new shipments of plants and remove or treat plants that contain thrips.
with a clean growing area. Old plant material and “pet” plants are a perfect
place for thrips to hide out between crops. Remove stock plants and leftover
plants from the growing area. These can serve as not only as hosts for thrips
but also as reservoirs for viruses spread by thrips. Be sure to control weeds
in and around the perimeter of the greenhouse.
(opening size < 200 microns) on doors and vents can help prevent thrips from
moving into the greenhouse from outside crops or weeds.
crops regularly for the presence of thrips and physical damage caused by their feeding.
Use sticky cards to monitor populations early in the crop cycle, before flowers
or buds are present. Include Thripline™
ams pheromone lure from Bioline™ pest
control products with your sticky cards to increase thrips movement, which will
provide an earlier and more accurate population assessment.
use of chemical controls:
o Begin spray rotations
when populations are low and before flowers or buds are present.
o First apply products
that are effective on adults and immature stages such as Avid® miticide/insecticide,
and then rotate to an insect growth regulator following an appropriate
rotational program such as Scimitar® GC
and Flagship® 25WG insecticide on
o Check spray coverage as
this is often the factor that can hinder control of pesticide applications. Using
water-sensitive spray paper will aid in the evaluation of proper spray
In addition to WFTs, whiteflies are also significant
pests for many flowers and nursery crops. The two most common whitefly species that
infest greenhouse and outdoor nursery crops are the greenhouse whitefly (Trialeurodes
vaporariorum) and the silverleaf whitefly (Bemisia tabaci). The
adults and immature stages have piercing/sucking mouthparts, which are inserted
in the phloem and extract plant sap. Injury is generally observed as chlorotic
plant tissue and black sooty mold growing on the honeydew-excretions of the
whiteflies. Large populations of whiteflies can cause stunting of plant growth
and senescence of leaves.
The best whitefly control strategies depend on life
stage, spray coverage and application timing. Using a neonicotinoid such as Flagship
25WG is the backbone of a
successful control strategy. Including Flagship in a rotational program is an
excellent tool for whitefly control, especially if used as a
drench!! Avid and Endeavor® insecticides
are also terrific materials to incorporate into a whitefly control program.
The key is to start control measures early and use an
integrated approach. Listed below are basic control measures that should be
weed-free production areas. Whiteflies feed on numerous hosts, so eliminate
potential sites of contamination.
new shipments of plants and remove or treat plants that are harboring
openings in greenhouses to help exclude populations because adults are mobile.
egg and nymph populations by checking the undersides of leaves with a hand
lens. If immature pests are present, Avid and Endeavor are appropriate
treatments. Check for adults with yellow sticky cards. Flagship is an
appropriate application for all feeding stages. Treatment threshold levels depend
on crop, product applied and the experience of the grower.
insecticides with different modes of action to manage resistance. Use the appropriate
water volume to cover the underside of plant leaves. In some cases, an adjuvant
may be needed. Systemic materials, such as Flagship, have longer residual
activity when used as a drench.
Rate /100 gal
4.5 - 8 oz/100 gal, 8 -17 oz/A
4.5 - 8 oz/100 gal, 8 - 17 oz/A
1 lure/1000 ft sq
periodical change in the spray or application pattern changes the spray angles
and allows improved spray coverage.
© 2012 Syngenta. Important: Always read and follow label
instructions before buying or using Syngenta products. The label contains
important conditions of sale, including limitations of warranty and remedy. All
products may not be registered for sale or use in all states. Please check
with your state or local extension service before buying or using Syngenta
products. Scimitar® GC is a Restricted Use Pesticide. Avid®,
Bioline™, Endeavor®, Flagship®, Scimitar®,
Thripline™ and the Syngenta logo are
trademarks of a Syngenta Group Company.