Thrips

Two species of thrips are commonly found on protected crops: Western Flower Thrips (WFT), (Frankliniella occidentalis) and Onion or Tobacco Thrips (Thrips tabaci). 

Larvae and adults pierce the leaf surface and suck out cell contents causing extensive 'silvering'. 

WFT can also transmit Tomato Spotted Wilt Virus on chrysanthemums and many other crops. Other species of thrips are also being found, particularly on specimen plants. If in doubt send a sample to Fargro. 

There is a pheromone for monitoring of Western Flower Thrips (see pheromone traps).

Amblyline cu (Amblyseius cucumeris / Neoseiulus cucumeris)
Type: Predatory mite. 

How it works: Feeds on young thrips larvae, and in the absence of thrips, on pollen. 

Species controlled: Most thrips species. Also Tarsonemid mite (good control on cyclamen and strawberry) and broad mite. 

When to use: Always use preventatively on peppers, cucumbers, pot and bedding plants, strawberries and cyclamen. 

Rates of use:  Shaker bottle: 50 - 250 mites per m2Controlled Release System (CRS) / Gemini sachet: 1 sachets per 1 - 2 m2 or one sachet per plant. 

Type: Predatory bugs. 

How it works: Voracious predator of thrips and other soft bodied insects such as aphids. They often kill far more thrips than they need to reach maturity. 

Species controlled: Orius will attack all stages of thrips on plants.
O. laevigatus performs well on the majority of crops, particularly those with pollen producing flowers.  O. majusculus establishes better on cucumber. 

When to use: Ideal to control established thrips populations on a range of plants and can be used alongside other biologicals. 

Rates of use: 0.5 to 1 per m2 every 2 weeks until established.

Type: Predatory mite. 

How it works: Predates but can survive in the absence of prey feeding on pollen. 

Species controlled: Predates on whitefly (eggs and larvae), as well as thrips. It will not control established populations or where large numbers of adults are moving into the crop. Consumes more thrips per day than the standard A. cucumeris and unlike A. cucumeris will predate on second instar thrips. Populations have the potential to grow faster than A. cucumeris. 

When to use: Introduce early into the crop cycle to protect. Requires minimum temperatures of 15°C night and 20°C day. 

This predator is released under licence for use on a limited range of glasshouse grown crops, please contact Fargro for further details.

Type: Microscopic nematodes. 

How it works: A special formulation for foliar application by high volume spraying. The nematodes swim through a film of water and attack female thrips. 

Species controlled: Adult female Western Flower Thrips. Larvae are not always attacked but pupae frequently are. Also controls leafminer. 

When to use: At any time of the year, ideal at temperatures above 16°C. Do not use under strong lights or when the sprayed crop is likely to dry within 3 to 4 hours. A series of 4 or 5 weekly sprays is best to control a thrips population. Nemasys can be used alongside Conserve and several other pesticides for a wider range of activity. 

Rates of use (for foliar application):
  • Preventative: 50 million per 400 m2 or 250 million per 2000 m2.
  • Standard control: 50 million per 200 m2 or 250 million per 1000 m2

 
 
  
Amblyseiulus spp. (Photo: Holt Studios)Orius laevigatus feeding on a thrips lava
(Photo: Holt Studios)
Amblyseius montdorensis adults
(Photo: Holt Studios)