Leafminer control in Ontario’s greenhouse crops -what’s working?


Fig. 1. Leaf mines on gerbera leaves.

As much as we all hate thrips, there are, frankly, worse problems to have.  And it’s name is Leafminer.  These flies cause just about the ugliest damage we see in floriculture (Fig. 1), and they have incredible pesticide-resistance capabilities. Outbreaks seem to go in cycles, and I’ve had quite a few gerbera and mum crops come across my desk with leafminer this past 2 weeks.

This post covers chemical options (BawHawHawHa!!! Oh… Sorry… I’ll get myself under control now) and non-chemical options for leafminer, as well as how their control fits into the big picture in greenhouse IPM programs.  

Continue reading

Supplemental Lighting Options for Bedding Plant Seedling Production

Happy spring!  With the season in full swing, we know that growers are busy this month.  I read an interesting article on the effects of supplemental LED lighting in bedding plants this week, and I’ve summarized it here with the key messages at the bottom of this post.  It seems like an appropriate article for the season, especially if you are starting to think ahead to how you might improve production for the 2017 spring season.

Much of the LED lighting research done in ornamental plants has focused on finding the best wavelengths for plant production.  This can vary based on the plant being grown, and the qualities desired.  Before we dive into the study, let’s review some of the reasons why you might consider LED lights from a plant production standpoint. Continue reading

A Burning Question: Ethylene and Sulfur Dioxide Damage in the Greenhouse

I’ve had a handful of calls in the past few weeks asking me to identify poor air quality damage on spring bedding crops.  Even if you have never had problems, the following is a good refresher on why proper maintenance of greenhouse heating systems is important.

 Natural gas and propane are popular choices when it comes to heating a greenhouse.  The products of burning fuel are carbon dioxide (CO2) and water (H20); both compounds we know are good for your plants.  However, combustion is often (if not always) incomplete, and impurities such as carbon monoxide (CO), sulfur dioxide (SO2) and ethylene (C2H4) are also released leading to poor air quality if your heater is not properly vented.

These impurities can leave your crop looking a bit down (Literally! It’s called epinasty, see more below), and it can happen in as little as 24 hoursContinue reading

Snack attack: how to help prevent your thrips bios from eating one another

Effective biocontrol programs for western flower thrips often use multiple natural enemies.  These include predatory mites like N. cucumeris or A. swirskii, but also  generalist predators like Atheta and Orius, which can feed on mite eggs and nymphs.

So, how can you make sure your generalist predators aren’t just eating all your predatory mites, instead of your thrips? Continue reading

Managing Million Bells

By Sarah Jandricic and Chevonne Carlow

It’s that time of year again, when baskets of Million Bells (Calibrachoa) are going up in the greenhouse.  Here’s how to deal with and prevent some of their most common issues.

Fe def calibrachoa

Iron deficiency in Calibrachoa.  The resulting yellowing can look similar to symptoms caused by black root rot or nitrogen deficiency.

From a nutritional standpoint, the best thing you can is keep the pH of your calibrachoa in its ideal range; between 5.5 and 6.0.  A pH higher than this can inhibit nutrient uptake, especially micronutrients such as iron. 


Iron deficiency can be difficult to distinguish from other issues (like Black Root Rot – see below), but typically leads to yellowing of new growth.  Leaves may only show chlorosis between the veins, or it may be spread throughout the leaf.  This is different from nitrogen deficiency where yellowing occurs in the oldest leaves. If iron deficiency occurs, adding a chelated form of iron is best for uptake.

Yellowed plant growth (yellow circle) and dead plugs (orange circle) on a plug tray of Callibrachoa.
Yellowed plant growth (yellow circle) and dead plugs (orange circle) on a plug tray of Callibrachoa from black root rot.

Million bells are also highly susceptible to Black Root Rot (Thielaviopsis) – I’ve seen this take out a good chunk of a crop.  Symptoms include:

  • Stunting of foliage and roots
  • Plants in a tray will have uneven heights
  • black areas on roots
  • yellowing of leaves

Prevention is worth a pound of cure with this disease, as it is difficult to eradicate once established.  Important steps to take include:

  • Proper Sanitation. To avoid an issue with Black Root Rot year after year, immediately dispose of  diseased plants, limit water splashing, and sanitize benches, floors and used pots/plug trays.  Always physically wash surfaces  with a cleaner to remove organic matter, then follow up with a  disinfectant such as KleenGrow (ammonium chloride compound).
  • Consider prophylactic applications of fungicides on plug trays.  Products include Senator (thiophanate-methyl) or Medallion (fludioxonil). Preventative applications are an especially good idea if you’ve issues in the past. Adding bio-fungicides containing Trichoderma harzianum (e.g. Rootshield, Trianum) may also help
  • Lowering your pH. This disease is significantly inhibited by a lower pH – between 5.0 and 5.5.
  • Manage fungus gnats and shoreflies, since these insects can spread Black Root Rot between plants. Treatments include nematodes, Hypoaspsis mites , or applications of Dimiln (diflubenzuron) or Citation (cyromazine).

If already established, rotated applications of Senator and Medallion may limit Black Root Rot, but are unlikely to cure it.


Aphids tend to be found on flowers and new growth of Calibrachoa.

Lastly, Million Bells are highly attractive to aphids.  With baskets hung up in the greenhouse, they can be “out of sight, out of mind”, but  regular monitoring is needed to prevent large aphid outbreaks.  Place sticky cards directly in baskets, and routinely check plant material for aphid cast skins and honeydew.

Once aphids are detected (and they will be!), applications of  Beleaf (flonicamid), Enstar (kinoprene) or Endeavor (pymetrozine) will usually take care of them.  However, be aware that all of these insecticides take around 4-5 days to start causing aphid death.




Guide to Weed Control in Ontario


Publication 75 covers herbicides for outdoor ornamentals and non-crop areas outside the greenhouse.

Ontario’s latest Guide to Weed Control is now available as a free PDF from OMAFRA.  Chapter 16 covers weed control in outdoor ornamentals, and includes effectiveness ratings for registered products.  This publication may also be useful for cleaning up weeds outside the greenhouse.

Note that the only herbicides currently registered for use INSIDE the greenhouse are EcoClear and Munger.  Both are acetic acid-based products appropriate for the control of broadleaf and grass weeds.

A hardcopy of the guide (Publication 75) can be ordered from OMAFRA here for a nominal fee.

IPM “Basics” Workshop on Feb 25th


Scouting plants for insect pests: an IPM basic!

Check out this flyer for details on my “Intro to IPM” workshop on Feb 25th.  The workshop will cover identification of common pests (insects AND diseases!), review of IPM basics, and optimizing IPM strategies in greenhouse floriculture crops.

This is a great workshop for new greenhouse employees, first year scouts, or as a refresher.

A more advanced workshop will be offered in the summer on integration of biocontrol and IPM for key pests (date and exact topic TBD, so check back!).

Met52 to be temporarily unavailable

After several months of uncertainty, Monsanto BioAg  will continue to offer Met 52 bioinsecticide.  However, as new sources of inputs are being pursued, the product will not be available between February and October 2016.

This affects both the EC and Granular formulations.


Met52 comes as a granular (pictured) or emulsifiable concentrate (EC) formula.  Both will be temporarily unavailable in Canada from Feb to Oct 2016.

Met 52 (which contains the beneficial fungus Metarhizium anisopliae) is one of three fungal-based bio-insecticides we have registered in Canada for greenhouse pests such as thrips and whitefly.

During this gap period, growers using Met 52 in their IPM programs may want to switch to products containing the fungus Beauveria bassiana (e.g. BotaniGard 22WP, BioCeres WP).  Beauveria also has activity against thrips and whitefly.  For more details on best use of Beauveria-based products, see this page on the GreehouseIPM.org website.



How are pesticides registered in Canada?


Cary Gates at Canada Blooms 2014. Cary is Pest Management Director for Flowers Canada Growers.

Ever wonder what, exactly, is involved in getting a pesticide registered for use in Canadian greenhouses – and why it seems to take so long?  This guest post by Cary Gates (Director of Pest Management, Flowers Canada) lifts the curtain on the process.

How are Pesticides Typically Registered?

When I speak to growers, one of the things I’m told they need most are new biological and/or conventional pesticide registrations.  But getting a new registration is no simple task. 

Brand new active ingredients take a significant amount of time and financial investment from pesticide manufacturers to bring to market.  And, often the return on this investment is not realized immediately, due to the relatively small market ornamental growers represent. 

To address this, grower associations like Flowers Canada work with registrants to submit a User Requested Minor Use Registration (URMUR) request to the Province. This lowers the cost of registration for pesticide manufacturers.  However, typical registration timelines still remain around 3-4 years

If a product is already registered on a different crop in Canada, we can pursue a label expansion (known as a User Requested Minor Use Label Expansion, or URMULE) .  URMULES typically take 9 months to process.  URMULES can take considerably more time if additional registration data is required (e.g. occupational exposure data). Some label expansions have taken multiple years to process.  

Flowers Canada submits approximately 8- 10 label expansion requests annually, which are often the result of grower requests.  A large percentage of these are approved.

If you would like to know more about the progress of any new registrations, feel free to contact me.

The Role of Canada’s Pest Management Centre (PMC):

Outside of label expansions and registrant submitted registrations, many pesticides are made available to floriculture farmers through Agriculture Canada’s Pest Management Centre.

The PMC is a division of AAFC that works to assist growers’ access new pest management tools (both biological and conventional pesticides). 

Delegates at the 2014 PMC's Priority Setting Meeting. Photo from http://www.agr.gc.ca.

Delegates at the 2014 PMC Priority Setting Meeting. Photo from http://www.agr.gc.ca.

The PMC hosts an annual priority-setting meeting where growers, researchers, industry grower associations and extension staff prioritize pests and diseases alongside researchers, pest management companies and regulators.  Sarah Jandricic and I will be attending this meeting in March. (For more information about the goals and format of the meeting, click here).

Each year, the group isolates only 10 priority insect-pest problems, 10 priority pathology problems and 10 priority weed problems out of all the possible pests affecting all crop groups in Canada. 

If a particular pest or disease is one of the few selected, then the PMC will help fill any data gaps that are preventing a pesticide from being registered to “solve” a priority problem.  They do this by assisting registrants in compiling data, conducting efficacy trials, sponsoring pesticide dissipation research, and coordinating discussions with Health Canada.  Because of the workload involved, this avenue of registration often takes longer than an URMUR or URMULE.

A researcher in a full spray suit applying pesticides to seedlings in the ground.

A pesticide residue trial being conducted by members of the Pest Management Centre (PMC). Photo from http://www.agr.gc.ca.

FCG has been very fortunate in being able to isolate multiple priorities annually – sometimes up to 5-6.  This has benefited growers tremendously, as many pesticides used in greenhouses today were registered with the PMC’s assistance

Quarantine Issues:

Although we have been fortunate enough not to have to deal with many invasive pests, they can occur from time-to-time and threaten the ability of farmers to move and export plants. 

In the past, growers have had to deal with issues like Chrysanthemum White Rust, Sudden Oak Death, Duponchelia and Japanese Beetle. All of these quarantinable pests required expedited pest management solutions. 

Submitting emergency use registrations remains a very high priority, with subsequent full registration requests being prepared thereafter. In fact, we just oversaw a new pesticide registration, Acelepryn (chlorantraniliprole) for those in JB regions who need to treat their crops during flight period.  Typically, an emergency use registration can be processed for grower use in under a month.

Grower Involvement is Key:

One of the activities I enjoy most about working for an industry association is visiting greenhouses and talking to growers directly.  This allows me to hear first-hand about issues affecting the sector.  Grower visits steer my focus on priority pests and diseases and help me find tools to control them.

If you would like to know more about the role that Flowers Canada FCG logoGrowers plays in pesticide registration, please visit our website (www.flowerscanadagrowers.com) or call/email me anytime (519.836.5495 X228, Cary@fco.ca)