Powdery Mildew Being a Pain? Effective Products for PM Relief.

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Powdery mildew on cut roses in Ontario.

With May’s weather continuing to be up and down, humidity control is a problem in the greenhouse, meaning Powdery Mildew (PM) is too.  This pest is rearing it’s ugly head in crops like Kalanchoe and Dahlia.

We won’t cover the basics of PM here:  biology, spread and prevention were covered in a previous post.  Instead, we’ll focus on monitoring, and which control products to use once you’ve found an infection.

This post was written with help from Plant Pathologist Ann Zemke of the Chase Research Group.

Continue reading “Powdery Mildew Being a Pain? Effective Products for PM Relief.”

‘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 .”

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).