“Sticking” it to high populations of thrips in greenhouse crops.

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Can patterned tapes significantly improve thrips catches?

You’ve likely noticed by now that thrips populations are especially high because of the hot, dry summer. Many growers are noticing their usual biocontrol programs can’t keep up, and further defenses are needed this year.

The use of mass trapping strategies may be the key to getting an edge over thrips. This post discusses the latest research on mass trapping of thrips in ornamentals, including patterned sticky tapes and the use of pheromones.  

Continue reading ““Sticking” it to high populations of thrips in greenhouse crops.”

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Ramping up thrips biocontrol BEFORE they get out of control!

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Western flower thrips adult on an open Mandevilla flower.  Photo credit: Caitlin MacDonald, USEL student.

Now that the warm weather is finally upon us, it’s time to start worrying about thrips control.

What we’ve learned over the years is that pesticides just don’t cut it – the only reliable chemical for western flower thrips in Ontario is DDVP, which requires constant application.  This means biological control is your best bet.  Here’s a summary of the most effective tools, tricks, and timing, to ensure your biocontrol dollars are well spent.

Continue reading “Ramping up thrips biocontrol BEFORE they get out of control!”

Can you safely mix nematodes and pesticides?

Entomopathogenic nematodes – used to control fungus gnats, shoreflies and thrips – are often a “gateway bio” into biocontrol use in greenhouses.  This is because not only are they effective and easy to use, but they’re generally compatible with insecticide use.   Readily applied with regular spray equipment or through drip lines, nematodes can even be tanked mixed with pesticides to save on labour costs.

In this post, I’ll share some of my research at NC State, looking at which commonly used pesticides in Canadian and U.S. greenhouses are safe to use with nematodes.

Continue reading “Can you safely mix nematodes and pesticides?”

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

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.

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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.

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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.

 

 

 

Two new fungicide registrations!

That’s right!  As of today, flower growers have 2 new weapons against fungal diseases at their disposal. Heritage MAXX (azoxystrobin) and Medallion (fludioxonil) are now registered for use in outdoor and greenhouse ornamentals.

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Impatiens showing signs of nutritional deficiency due to Pythium root rot infection.  Heritage MAXX is now available for Pythium control in greenhouse ornamentals.

Heritage (a Group 11 fungicide) is a systemic fungicide, and is appropriate for control of Pythium, Grey mould (aka Botrytis blight) and Rhizoctonia.  It can also be used for foliar diseases such as Powdery Mildew, Downy mildew, Rust, Anthracnose and Alternaria  Leaf Spots.  You can find the new label here: HeritageLABEL2016.

Medallion (a Group 12 fungicide) is a contact fungicide, and is appropriate for control of root rots such as Fusarium, Rhizoctonia, and Black Root Rot (Thielaviopsis) when applied as a drench.  It can be applied foliarly for Grey Mould, Anthracnose Leaf Spot and Rhizoctonia Stem Rot.  MedallionLABEL2016.

Alternaria on impatiens

Medallion fungicide is now available to Canadian ornamental growers to help control diseases like Alternaria leaf spot (shown here on impatiens).

Both are broad-spectrum fungicides that can be used curatively or prophylactically.

As with any chemical control product, make sure to read and follow the label carefully prior to use.

(Also, 1000 points each to the team that helped push these label expansions forward:Cary Gates, Flowers Canada; Jim Chaput, OMAFRA; Jennifer Llewellyn, OMAFRA and Graeme Murphy, formerly of OMAFRA).