Thrips Management in Flowers

Thrips Management in Flowers.

Introduction:

Thrips are tiny slender insects with fringed wings. They feed by puncturing their host plant thus feeding on cell sap.

Thrips belong to order Thysanoptera. Western flower thrips (Frankliniella occidentalis) is the most commonly marked species in green house rose plants and summer flowers.

LIFE CYCLE AND DAMAGE:

Thrip life cycle include egg, two actively feeding laval and nympal stages, non-feeding prepupal and pupal stages and adult.

Females insert tiny eggs into flower buds. Eggs hatch into larva which start feeding thus causing damage to the bud. Larva eventually develops into pupa which drops into the soil or leaf litter (dry leaves). Pupa develops into adult stage which goes back to the plant for feeding and egg laying.

Egg→1^st Instar  →2^nd Instar→Propupa→Pupa→Adult→

Under optimal conditions, full cycle usually lasts two weeks.

Affected flower buds may become deformed and fail to open. Petals are covered by brown steaks and black spots. Tiny scars especially on young leaves are exhibited, with most of the affected leaves rolling back. Heavy infestation can cause stunted growth.

CONDITIONS FAVOURABLE:

• Thrips are favored by hot, dusty, windy and dry weather conditions.
• Poor sanity – sanitation in terms of dry fallen leaves, weeds, open flowers and failure to knock out infested flower buds. Some plants act as alternate host.
• Poor sanity around green house – in terms of weeds and flowering shrubs / trees which act as secondary host plant.

MANAGEMENT AND CONTROL

Monitoring:

Monitoring is very crucial to ensure detection of any entry of adults from outside. This is achieved by hanging sticky traps and well guided scouting system. Any detection of single adult calls for prompt intervention of chemical spray before egg laying

Cultural practices:

This entails;

• Removal of fallen plant debris / leaves where pupation takes place.
• Knocking of any open flower buds which might attract adults from outside or from the ground.
• Weeds removal, which act as alternate hosts.
• Incase of mild infestation, knocking of infested buds to eradicate eggs, laval and adult stages.

NB: In order to avoid cross contamination, removal of affected plant buds and plant parts should carefully be placed into bags and disposed in designated points.

• Procedural knocking of the buds in the morning and stem cut in the evening should be emphasized.
• Showering to lower temperatures.

Chemical control:

Chemical control must be applied during first sign of damage or during favorable weather conditions. In this case careful selection and mixing of chemical is a prerequisite. Controlled showering before chemical application is ideal to enhance effectiveness of the same just like for any other contact insecticide.

In case of high infestation, chemical application on soil / tuff is advised to kill pupal stage. However, the media must be well moistened to allow the chemical sieve through.

GREENLIFE PROGRAMME:

Target Sites Summary