Insect Management
Cotton Insect Management
Thrips - Several Species
Description
Thrips are very small insects that may be seen if the plant is shaken onto a
white cloth.
Biology
Thrips feed on the tender plant foliage of cotton. The eggs are laid on
plant tissue or may be inserted into slits. Eggs, nymphs, and adults are found
together throughout the summer. Average time to complete life cycle is two
weeks. This results in several generations per year.
Damage
Adult and larvae feed on leaves, terminals, and other tender plant parts.
Ragged crinkled leaves with a silvery appearance are typical symptoms of thrips
damage to young cotton. Leaves usually curl upward and appear burned along edges
as a result of feeding in the terminals. Thrips damage is usually on young
cotton and severe damage may stunt cotton growth and reduce yields.
Scouting
When scouting, thrips should be counted after shaking or beating 20 plants
onto a cloth or into a box. In addition, damage should be observed and
classified according to the following criteria:
None - If no thrips or damage.
Light - If newest unfolding leaves show only a slight brownish
tinge along the edges with no silvering on the underside of these
or older leaves, and you see a few thrips.
Medium - If newest leaves show considerable browning along the
edges and some silvering on the underside of most leaves and you
find 1 to 5 thrips per plant.
Heavy - If you readily notice silvering of leaves, deformed
terminal buds, and the plant is generally ragged looking, the
thrips are numerous.
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