Oh dear! It’s Oedema.

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Oedema on the young leaves in this begonia basket.

Oedema, that physiological disorder that appears during periods of low light and high humidity.  There’s been quite a bit of it reported in Ontario greenhouses this spring, and unfortunately it’s related to the long rainy (or snowy!) spring we’ve been having.  If you’ve noticed salt-like crystals, odd tumour-like growths or water-soaked spots on either side of your plant leaves this disorder might be the culprit.

The disorder affects a wide variety of greenhouse ornamentals.  It’s usually noticed in spring crops like sweet potato vine (ipomea), geranium, begonia and/or petunia. Continue reading “Oh dear! It’s Oedema.”

It’s “B” Season! Watch for Botrytis, Broad Mite and Burn.

Honeybee 2Although native bees and honeybees may just be starting to gather strength and are beginning to fly outside, other “B’s” have been of growing concern in the greenhouse for some time now.

These include common spring bedding crop problems like Botrytis cinera (aka grey mold), Broad mites, and leaf burn (from a variety of causes).

Keep reading for tips on how to manage these issues during this time of year.

Continue reading “It’s “B” Season! Watch for Botrytis, Broad Mite and Burn.”

Botrytis Bumming You Out?

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Botrytis spots on Primula petals.

With the intense period of rain we just had, and with MORE rain coming on Friday, it’s time to think about Botrytis control and prevention.  One of the most common and destructive diseases of greenhouse crops, outbreaks usually follow periods of cool, damp, cloudy weather.  Unfortunately, I can’t order up more sun for you, but I CAN suggest some management tactics.

 

Continue reading “Botrytis Bumming You Out?”

Improperly ventilated heaters & ethylene damage

Spring is on its way, and with cold nights and warmer days we are seeing a common spring problem – poor air quality damage on spring bedding crops.  Symptoms, solutions and preventative measures are included in this 2017 update to a previous post.

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.

Typically symptoms from ethylene damage and sulfur dioxide damage can been seen fairly quickly after exposure.

Figure 1. Signs of ethylene damage include leaf curling and epinasty, seen here in A) New Guinea Impatiens and B) lettuce seedlings.

In the short term (a few hours to a few days), ethylene damage results in leaf curling, epinasty (leaves bending downwards from the petiole) and flower drop.  If the stress continues over a Continue reading “Improperly ventilated heaters & ethylene damage”

‘Tis the Season for Powdery Mildew; Here’s what Ontario’s Flower Growers can do .

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Powdery mildew on roses.

All through the night while the growers were sleeping, spores of Erysiphe, Leveillula, Microsphaera and Sphaerotheca were teeming.

Caused by one of these many pathogenic fungi, Powdery Mildew is often white and felt-like to the eye.

OMAFRA’s Greenhouse Elves are on the case, giving chemical, biological and cultural controls that curb this pest’s pace.*

*(No need to be worried or terse – the rest of this post won’t be in verse!).

Continue reading “‘Tis the Season for Powdery Mildew; Here’s what Ontario’s Flower Growers can do .”

4 Ways You’re Accidentally Killing Your Predatory Mites!

PowerPoint PresentationNote: This is a re-post because it now comes with an awesome new video of how to monitor you mite sachets!

Recently, I had an interaction with a grower where their long-standing biocontrol program for thrips suddenly seemed to be failing. After a (too long) investigation by  myself, the grower, and consultants, we found out the horrible truth: their predatory mite were being MURDERED (Duh dun DUHNNN!)… By improper storage.

This post focuses on whether YOU might also be guilty of mite murder.

(And yes, I’ve stooped to the level of click-bait titles).

Continue reading “4 Ways You’re Accidentally Killing Your Predatory Mites!”