Sep 2020

No silver bullet as the problem continues…..


One of the most frustrating, if not the most frustrating, part of my growing and advising career has been arch enemy number 1 whitefly. 

Last week as I was looking at a crop of tomatoes it struck me how bad the whitefly numbers are.  Concerning for this relatively early stage crop was the lack of penetration from the tools in our tool box.  It would appear that whitefly may be showing resistance to what has been the aces up our sleeves. 

This has meant a slight change of tactic, using alternatives I try keep to a minimum.  There is now a need to increase the natural, softer approach in regards to the products I advise.  Personally, I think anything you spray on a plant effects the plant’s growth/transpiration in some form.  Soaps or oils are not something I like to apply more than once every two to three weeks but needs must.

I can talk until the cows come home in regards to beneficials, biologicals, chemical treatment and physical barriers such as sticky traps – but none of these have been a silver bullet.  I have been in this industry since 1993 and NO one has the answer to definitively help eradicate this pest.  I like everyone else made it through every season with the (limited) tools we have at our disposal.  However, I could only speculate nationally what the lost earnings, due to reduced production may be, not to mention the associated cost to control whitefly including the products and labour requirements (probably amounts to the price to buy a small country).

The greenhouse industry is constantly discussing how we can improve and automate systems to reduce labour.  Renewable energy is also a hot topic and will continue to evolve in the next few years.   I am an advocate for both of the above but possibly in regards to whitefly I may have added this to my ‘give up- it’s in the too hard basket’. 

This week is a reminder to me that actually no we need to keep working for other integrated solutions.  The silver bullet may be a far-off fantasy but it still deserves the attention and should be high on the agenda.


Get your sprayers calibrated and serviced

Final reminder please make sure your sprayers are working correctly.  The importance of contacting the target is key.


Other related articles this week:  see link below


Image above taken this week.  There is a few dead Whitefly (if you look closely) which is great but they should not have been there in the first place. The other issue is there were still many adults alive that had either hatched out since the last application or have built resistance.

Using sticky bug roll by greenhouse entrances and on your high trolleys are great for monitoring Whitefly numbers.


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


Article Written and compiled by Stefan Vogrincic, Consultant, Grower2Grower

Article Edited by Marie Vogrincic, Editor, Grower2Grower


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