Western Flower Thrips
Beginner
This pest affects:
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Scientific Name
Frankliniella occidentalis
Identification
Larvae
- Nymphs resemble adults in shape and colouring.
Adults
- Yellow-brown, long and narrow, threadlike
- Less than 2 mm long
- Fringe of hairs on their wings (visible with microscope)
Damage
- Feeding from bloom through shuck causes scars on the fruit surface that enlarge as the fruit grows, and may cause fruit deformity
Often Confused With
Spray burn – injury most apparent on the outer side of fruit
Period of Activity
Pink through shuck fall.
Scouting Notes
Begin monitoring as individual blocks begin to bloom. Monitor for thrips by examining blossoms from trees by slapping a shoot with five to ten blossoms against a yellow card or look for the immature stages within the blossoms. Often nymphs are not dislodged by the slapping method so also dissect individual flowers and examine them with a hand lens for nymphs. First instar nymphs are white in color and often difficult to see, so be sure to check carefully. Check a minimum of 50 trees per orchard for nymphs. In warm springs, adults will often migrate in and out of a block without being detected so it is important to always sample for nymphs.
Threshold
If two or more adult thrips are present or if any nymphs are found, a treatment is warranted. If a treatment is applied, make it before the calyx becomes tight around the developing ovary.
Advanced
This pest affects:
|
Scientific Name
Frankliniella occidentalis
Identification
Larvae
- Nymphs resemble adults in shape and colouring.
Adults
- Yellow-brown, long and narrow, threadlike
- Less than 2 mm long
- Fringe of hairs on their wings (visible with microscope)
Damage
- Feeding from bloom through shuck causes scars on the fruit surface that enlarge as the fruit grows, and may cause fruit deformity
Often Confused With
Spray burn – injury most apparent on the outer side of fruit
Biology
WFT has an extremely wide host range including weeds, floricultural crops, field crops, and tree crops. Nectarine is more susceptible than peach to thrips damage.
The WFT population built up on weeds, especially clover, in and around orchards throughout the season. Adult thrips may move from the cover crop or other nearby crops into nectarines and deposit eggs as soon as blossoms appear. Upon hatching, nymphs begin feeding at the base of the pistil (developing fruit) and continue to feed until the calyx or shuck drops. The entire life cycle is several weeks long and there are numerous generations per year. Thrips feeding on fruit from bloom to shuck stage results in scarred fruit which lowers the market quality.
Period of Activity
Pink through shuck fall.
Scouting Notes
Begin monitoring as individual blocks begin to bloom. Monitor for thrips by examining blossoms from trees by slapping a shoot with five to ten blossoms against a yellow card or look for the immature stages within the blossoms. Often nymphs are not dislodged by the slapping method so also dissect individual flowers and examine them with a hand lens for nymphs. First instar nymphs are white in color and often difficult to see, so be sure to check carefully. Check a minimum of 50 trees per orchard for nymphs. In warm springs, adults will often migrate in and out of a block without being detected so it is important to always sample for nymphs.
Threshold
If two or more adult thrips are present or if any nymphs are found, a treatment is warranted. If a treatment is applied, make it before the calyx becomes tight around the developing ovary.
Management Notes
Do not mow blooming ground cover from 1 week before bloom until after petal-fall to reduce driving thrips up into nectarine trees.
Some information included above excerpted from;
