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The Dog Days and Powdery Mildew
July 19, 2010

Air that you wear is still better than shoveling don't you think?

The Dog Days of Summer are here.

Personally, I think they came early.

Yes, another hot week and other than a small cloud burst on Sunday, the rain totally missed us.

Plants continue to grow like there is no tomorrow and blooms, bloom out way to fast.

Are you noticing a lack of bird songs now?

I mean the before sun up and after sundown singing as well as all day long.

Here in the north country, most birds are done romancing.

Indeed, the last wave of migratory bird fledglings are making themselves present.

Though there always seems to be a least one late batch of robins or what have you.

At least one pair of Northern Cardinals (non migratory) will have a late batch around here.

I do continue to hear Gray catbirds and House wrens singing love songs, however.

Late nesters like Cedar waxwings and Barn swallows are starting to fledge as well.

Still to come are American goldfinches, at least up here where seed crops aren't quite there yet.

Have you noticed the lack of female goldies at your feeders?

They are busy nesting and caring for babies.

Sometime next month our yards will be filled with the joyful sound of young goldfinches begging to be fed.

Please keep fresh water in your Bird Baths.

I make sure to fill my baths daily with fresh water.

Even then, algae can pop up over night.

I suggest a section of copper pipe to keep algae down.

Pre 1982 pennies work also, but you need several of them.

For me, a section of pipe works well and is easy to deal with.

No pennies to pick up or worry about hosing all over the place.

The deer family visible from my deck, also likes to visit my yard at night.

After a few munched plants, some measures have been taken to slow the critters down.

A day at the zoo with my mentoring child in dreadful humidity.

An afternoon at Lake Michigan with Karen, now that was nice.

A wedding on Friday in a church without AC. The reception was done up right.

Those were the big three for the week.

Not to mention all the other stuff that needs to be done all the time.

Life never slows down, or so it seems in the spring and summer months.

Maybe that is why they seem to fly by so fast.

The sounds of Cicadas fill the air on my evening walks.

As kids, they were known as heat bugs.

You too?

Fireflies, still put on a nightly show.

Thankfully, Japanese beetles have been minimal so far.

One thing that the Dog Days of Summer bring us are an abundance of fungal activity to our flower and vegetable gardens

Lawns aren't immune either.

Fungi are always there, they simply need the right recipe to grow and the Dog Days offer the right formula for most fungi.

(Monarda Snow White)

Heat, humidity, and other ingredients form the ideal situations for fungi and so often, you and I help it along.

Powdery Mildew is a very common fungus, and for the next two weeks, Powdery mildew will be the main topic of this newsletter.

You may already know how to handle this, but most of you haven't a clue on what to do or how to deter this from happening to your gardens.

Stick around, hopefully we can come up with an answer.

The mildew pictures are not mine, but that doesn't mean they couldn't be as I have experienced many of these issues my self.

The other pictures are from here.


When the dog days of summer arrive, you can almost guarantee the onslaught of fungus activity in your gardens and lawns.

There are many, many different kinds of fungus we must deal with, and Powdery Mildew a major player in our landscapes.

A fungus that warrants a 2 part series.

Actually,2 parts makes it more manageable for you and me.


Powdery Mildew, as the name implies, looks like powdery splotches of white or gray, on the leaves and stems of plants and in some cases, fruits are damaged too.

Powdery mildew is one of the most common and easily recognized plant diseases.

There are numerous fungi that fall under this general description.

Almost no type of plant is immune, however some are more susceptible than others, but lilac, phlox, zinnia, monarda, some rose varieties, cucumbers, squash, lawn grass and several other species of plants seem to be infected most frequently as well as some fruit trees.

In many cases, resistant strains of plants are being cultivated.

Powdery mildew fungi are host specific, meaning the different powdery mildew fungi infect different plants.

The powdery mildew on your lilacs will not spread to your grapes or your roses.

However all powdery mildews favor the same conditions.

They will be treated together here since most of these have similar habits and similar management practices.

There are numerous plants that may be infected in any year, and the actual injury to the plant varies greatly with the species and even the variety attacked.

For instance, lilacs are typically infected late in the growing season and this typically doesn't cause serious injury to the plants.

Lilacs are able to survive year after year in spite of the disease because growth and leaf maturity have taken place and most food for next year has been stored already.

On the other hand, begonia may be seriously injured by even a mild infection.

The tissue under the fungal growth dies soon after infection resulting in leaf drop and poor plant growth.

Thorough management practices and routines must be implemented in this case.

Among roses there are varieties that are more seriously affected than others.

If powdery mildew has been a problem in the past, choose a variety that has some resistance to the disease.


Powdery mildew appears as a dusty white to gray coating over leaf surfaces or other plant parts, often starting out as tiny dots.

Before you know it, your plants may be covered with the stuff.

In most cases this fungal growth can be partially removed by rubbing the leaves.

It might be identified incorrectly as dust that has accumulated on the leaves.

Powdery mildew, however, will begin as discrete, usually circular, powdery white spots.

As these spots expand they will coalesce, producing a continuous matt of mildew.

A plant pathologist using a microscope can determine whether a fungus is present anytime the whitish patches are present.

Symptoms usually appear mid to late in the growing season on outdoor crops and flowers.

The fungus is favored by periods of high relative humidity or site conditions that promote a more humid environment, such as close spacing of plants, densely growing plants, or shade.

Indoors, symptoms may occur at any time of year, but the rate of spread and development will be affected by the relative humidity and temperature.

Injury due to powdery mildews includes stunting and distortion of leaves, buds, growing tips, and fruit.

The fungus may cause death of invaded tissue (tender begonia, for example).

Yellowing of leaves and death of tissue may result in distorted leaves and premature leaf drop.

Nutrients are removed from the plant by the fungus during infection and may result in a general decline in the growth and vigor of the plant.

The seriousness of the disease will depend on the extent of the various types of injury.

Disease Cycle:

The fungi which cause powdery mildew are spread by spores produced in the white patches.

These spores are blown in the wind, splashed by water and even spread by your contact, to other parts of the plant or to other plants during the growing season.

Generally each species of fungus will be limited in the number of plant species that can be attacked.

For example the species of fungus infecting lilacs will not cause powdery mildew on roses.

During the winter the fungus survives on infected plant parts and in debris such as fallen leaves.

It may produce resting structures known as cleistothecia, which resist harsh winter conditions.

These will appear as small black dots within the white powdery patches.

The next spring, male and female spores (ascospores) are released from the cleistothecia, shot up into the air, and carried by air currents to leaves of plants where they make baby mildews and a new infections will begin.

During the growing season, the fungus produces asexual spores (conidia) that help the fungus to spread and infection to build.

This is the general cycle for most powdery mildews of outdoor plants.

Management Strategies

There are several effective fungicides available for different sites and plants, but use on plants varies with each product, and not all fungicides registered for use to treat powdery mildew may be used on all plants.

Be certain the product you purchase is labeled for the intended use(s), and follow directions on that label.

Regulations may vary from state to state and Canadian provinces.

For outdoor ornamental plants, gather up fallen leaves in autumn and destroy them.

Where powdery mildew is a problem, resistant varieties (if available) should be grown.

If needed during the growing season, begin fungicide applications when the first white patches are noticed.

Better yet, start treatment before you ever see any signs of a fungus.

Repeat as indicated on the product label or home made remedy during cool humid weather or after a rain.

Some products with a broad range of applications for outdoor ornamentals include products containing:

Copper, bacillus subtilis, neem oil, potassium bicarbonate, sulfur or lime sulfur.

Some of these products may also be used to treat powdery mildew infections in the vegetable garden (I use Copper).

Other products may also be available, so refer to the appropriate pest management guidelines or contact your local Cooperative Extension Office for more information.

Homemade remedies work well too.

More on Powdery Mildew next week.

How to deter, prevent, attack and a few more bits of information you just have to know on powdery mildew.

Well, it's time to fly for now.

Before I go, here is your positive thought for the week.

If you're never scared or embarrassed or hurt, it means you never take any chances.

Julia Sorel

What a sad way to live.

Living in your self made cocoon.

Never stepping out of your little comfort zone.

Life is meant to be exciting and to share with others.

Stumbles, falls and failures are some of our greatest teachers.

To conquer a fear is a giant leap of faith.

Embarrassment will last as long as you allow it too.

Life is grand.

God gave you so many excellent skills to use, but you must step out of your box and discover all that you are capable of being and doing.

Don't allow a few man taught fears keep you down.

Takes chances (not stupid choices).

Start each day with a promise to yourself and ask for our 'Creator's' help.

You will be amazed.

Before you know it, you will be jumping out of your little comfort zone.

You will be smiling and sharing your gifts with others.

And that is what it is all about.

Remember to share your smiles this week.

A smile is one of God's simple yet more profound gifts that we are to share.

Until next time.

9 You whom I have taken from the ends of the earth, And called from its remotest parts And said to you, 'You are My servant, I have chosen you and not rejected you.

10 'Do not fear, for I am with you; Do not anxiously look about you, for I am your God. I will strengthen you, surely I will help you, Surely I will uphold you with My righteous right hand.'

11 "Behold, all those who are angered at you will be shamed and dishonored ; Those who contend with you will be as nothing and will perish.

12 "You will seek those who quarrel with you, but will not find them, Those who war with you will be as nothing and non-existent.

13 "For I am the LORD your God, who upholds your right hand, Who says to you, 'Do not

fear, I will help you.'

Isaiah 41: 9-13

"Treat the earth well:

It was not given to you by your parents,

It was loaned to you by your children.

We do not inherit the Earth from our

Ancestors, we borrow it from our Children."

Ancient Indian Proverb

Your friend indeed,

Ron Patterson

PS. If you enjoy these letters, please forward them to friends, family and co-workers.

Better yet, have them sign up so they can receive their own letters.

Gardening For Wildlife.

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