Jun 2019
Winter Whitefly

Populations are slowly coming under control

With mild temperatures in May the level of whitefly has been irritatingly persistent. Winter is now upon us, so growers should be on top of the whitefly in order to get effective control from beneficial insects (Encarsia) and bug roll to reduce the need for biological and chemical spraying for the next three months.  

I always liked using the bug roll on my high wire trolleys so when the staff are performing any job from layering, arching, clipping, twisting or dropping there is a better chance of catching the pests.  Whitefly, when disturbed, are much more likely to fly and land on the yellow, sticky trap.   You have a much better chance of catching adult whitefly if your roll is constantly refreshed (every two or three hours).  The yellow sticky trap works well if you have minimal numbers of whitefly per plant.   Over the years I have witnessed bug roll in the top of the canopy running the length of each individual row.    Apart from the additional cost of labour, of this exercise there is a large financial capital investment needed to purchase this product.  Depending on the width of the roll it is another plant shading obstacle.  For the first week it might work well but personally I don’t believe it is a long-term solution for the sustainable control of whitefly.

Using sticky traps is advised at the entry/exit doors in greenhouses.   This is generally where the highest population of whitefly is present.  Reducing whitefly at doors will go a long way to reducing the establishment of whitefly populations.

Contact your local Horticentre branch for a Winter deal on Bug Scan Rolls

For now, if you are on top of the whitefly populations  I would consider a combination of beneficial insects and the strategic use of bug roll throughout the winter months.   If you can reduce your spraying by half, through use of this product, it is a real benefit to plant health.  However, if you still have whitefly, you can spray with products which are less harmful to adult Encarsia.  No spray is totally safe, for Encarsia, as even plain water could be harmful.  Talk to your local supplier about the options available. 


Check out this video.


This (dead) whitefly on the fruit was next to the main door of a crop I recently visited.  The populations of whitefly, at this particular property, were 90-95% less than last year due to targeted and effective control methods.  However, by the door there was still a huge population.  This is why it is so important to keep your doors shut as much as possible, and use liberal amounts of bug roll in these hot spots.


Cover photo taken South of Auckland in early June 2019


Monitoring insect pests using blue and yellow sticky cards is a great for flower and vegetable growers to identify potential new threats.


I appreciate your comments.  Please feel free to comment below or on the grower2grower Facebook page:


Article Written by Stefan Vogrincic, Consultant, Grower2Grower

Article Edited by Marie Vogrincic, Editor, Grower2Grower


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