Powdery Mildew on Monarda

METHODS OF PREVENTING POWDERY MILDEW ON MONARDA

            Monarda is a valuable plant in my gardens and have grown it for most of my adult life in many different places in B.C., from the wet southern coastal region to here in dry Kamloops.  I enjoy & appreciate many aspects of this plant: the shape and colours of the flowers, the scent of both the leaves and flowers, it attracts pollinating bees, butterflies and hummingbirds, the leaves can be used to make tea, the flowers are deliciously edible, and its overall striking beauty.  Monarda has a lot of value to me, and it makes me smile.

            There are a few problems that can be associated with growing Monarda: powdery mildew (Erysiphe cichoracearum fungus), rust, invasiveness, and crown die-out. Here in Kamloops our dry climate helps eliminate most of these.  Powdery mildew is the most common issue, which I am addressing here.  It starts early in the growing season.  White fungal threads produce spores, which germinate, penetrate the leaves, and absorb nutrients.  The grayish-white fungal patches develop on the upper surfaces of the leaves; eventually the leaves will yellow and die.  It can be most severe in late summer and fall.  The fungus can overwinter on plant debris and in buds, releasing spores the next spring to continue the cycle.  The solutions are not complicated.  With proper care and attention, and simple adjustments, the grower can continue to grow and enjoy it with greater success.  There are also disease resistant varieties to choose from.

            What factors can cause or exacerbate powdery mildew? 

A) Poor ventilation (plants are too close or too thick).

            Spacing the plant is a priority, allowing space for air to move around and through it.  Don’t have any other plants too close, and if necessary, thin the stems growing from the crown to increase air circulation.           

B) Water on the leaves caused by overhead watering.

            Eliminate overhead watering.  Install drip irrigation if possible.  If hand watering, use a wand extension to get water directly onto the soil and water early in the day so any water on the leaves can dry quickly.  Watering late in the day promotes the problem, as the temperature drop at night increases the humidity, which increases spore development.

C) Heat stress and high relative humidity.

            They are not tolerant of dry soils or shade.  Protect it from hot winds, and ensure it is near an adequate water supply and not out of reach of the watering system.  Plant it where it will get at least 6-8 hours of sun a day.  There is higher relative humidity in the shade, partly due to lower temperatures, both during the day and at night.  The lack of sunshine also doesn’t allow moisture on the leaves to dry quickly.

D) Diseased parts (leaves, stems, flowers) remaining on or near the plants.

            Proper hygiene is imperative.  Inspect the plant frequently – early diagnosis is key.  Promptly remove all diseased or dead parts and dispose of in the garbage.  Never compost!  Also sterilize any tools used, to prevent transferring the spores.

            There is an option for spraying affected areas with fungicide.  Personally, I will not use chemical fungicides.  Other options are to spray with a baking soda mix (1.5 tablespoons baking soda per gallon of water) weekly, or a weak milk solution (1 cup milk to 9 cups of water) every 2 weeks.  Some people will use a horticultural oil (3 tablespoons per gallon of water), spraying every 2 weeks.  I have never used any sprays.

            In conclusion, knowing Monarda’s ideal growing conditions and creating a healthy environment has made healthy plants which are resistant to disease.  I have already addressed the stresses that can affect this plant, put best practices into use, and have eliminated powdery mildew from my Monarda.

This article also appears on the Laughing Swan Website @ www.laughingswanfarm.com

Mothers blanket

Mother nature showed up with a blanket last night. She gently tucked in her little green people so they would be warm for the cold air she about to bring in to the interior region.
It is amazing to me that snow nearly always comes before cold. If it doesn't then plants will die and things are not as they should be. If you have zone 5 plants the limit they can tolerate is around -24C, and this only for a limited amount of time. The zone system is only a guide, so don't think in absolute terms.
This is something Brian Minter(http://www.gardeningbc.com/page/minter.html ) also stresses so just figure that if you have a zone 5 plant it's going to be OK in Kamloops if you live at river bottom. Further up the hill it goes into zone 4, and in places like Juniper, zone 3, all just rough guides to your plants survivability rates. Even gardeners on the lower mainland can have zones 3 and 4 if they are in the path of outflow winds that begin this time of year.
With lows going down to -20C on Wednesday we will be taking care of some of our borderline plants by making sure they either have enough snow cover or have a frost blanket placed over them.
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Who put the win in winter.

Another strangely beautiful January day. Tonite the temp is supposed to dip down to -10 or more, so don't put the parka away just yet.
The little green people out in the field must have some communication skills that humans either lost or never had. They just hang out, grow buds if it's warm, stand like sticks if it's cold, I never hear a word of complaint, only silent expiry in the spring. We humans could and do learn so much from our silent friends, without them there would be no us, but we have either forgotten that or have yet to learn it.
So, carry on, enjoy this crazy weather and let's hope for an early spring and lots of summer.
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Breaking snooze

We are going to open to the public this year. YIPPEE     Hold tight for more dates on that. Previously we only allowed people to come as a part of a garden club or special invitation, but we felt that so many people wanted to come and see/buy our plants that why not open for one day a week. Anyway it's a lovely drive and a pleasant way to spend a Sunday afternoon.
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Winter post