Recognizing and treating fungus problems on your plants.

She asked, “What’s wrong with my plants? Should I spray them with liquid Sevin?”  We walked out to look at the leaves on the viburnum Davidii that lined one of the planting beds.

fungus damage on viburnum leaf

fungus damage on viburnum leaf

I said, “Liquid Sevin won’t help you here because it is an insecticide. The problem with these plants is not insect related but is fungus related instead.” I pointed to the holes in the leaves. “These are a sign of a fungus disease that is called ‘shot holes.’ The problem starts as a spot on the leaf and then grows outward in concentric circles. As the spot on the leaf kills the plant cells, it ends up looking like a hole that has been eaten by a worm or an insect. The dark brown end of the other leaf in the picture is a sign of another kind of fungus.”

We started walking around and looking at other plants. Some of the leaves on the dragon wing begonias were looking funny. The spots are fungus related as are the curly leaves. You will also notice a browning on the margins of the leaves.

fungus problem on dragon wing begonia leaf

fungus problem on dragon wing begonia leaf

The hosta plants are showing a lot of fungal damage. Some of this damage may be from getting too much sun, or the abundance of sun and the fungus are working together. The fungus attacks any weak spot in the leaf.

fungus damage on hosta leaf

fungus damage on hosta leaf

I frequently see the damage pictured below in acuba. Again, I think some of it is light related, but it seems to be mostly a fungus infection.

Fungus on acuba will eventually spread and kill the plant

Fungus on acuba will eventually spread and kill the plant

Here is fungus damage on a Knockout rose. Note the holes in the leaves and the damage on the leaf margins.

fungus damage on knockout rose leaf

fungus damage on knockout rose leaf

Paige and I discussed the fact that when something goes wrong with a plant, our first reaction is to water it more. Since fungus problems are moisture related diseases, this is the totally wrong thing to do. The begonia pictured below is a prime example of a plant that has been over watered. The leaves drop off or become spotted. The leaf margins die back, and there may be some kind or other of a powdery mildew that will attack the flowers.

indications of fungus disease on a begonia plant

indications of fungus disease on a begonia plant

Below is a plant that is probably beyond repair. One of the types of fungus is called ‘stem rot’ and is soil borne. This picture shows over- watering in its extremity.

advanced damage on plants from fungus

advanced damage on plants from fungus

I don’t know enough about the different names or kinds of fungi to be able to go into the subject and I don’t really think it is necessary. The main point is to be able to recognize a problem as fungus related instead of insect or otherwise related. The concept is the important thing.

Paige asked, “So how do I tell fungus damage from insect damage?” I replied, “If you just start looking at the problems you will see the difference. I have given you the concept and I define a concept as a collection of questions that I have never asked before.”

You can treat fungus problems on your plants. There are a number of fungicides on the market that will work. I am currently using Daconyl which gives me very good results. I think that one should have two different fungicides and alternate them. Sometimes one fungicide will kill a type of predatory fungus that works against another kind of fungus.

Daconyl, a very effective fungicide purchased at Home Depot

Daconyl, a very effective fungicide purchased at Home Depot

Your favorite nurseryman should have several kinds of fungicides to choose from. One of the best fungicides that I have found is Cleary’s 3336. This fungicide is systemic and helps control all sorts of fungus diseases, even going through the plant to reach the roots. You may find it at BT Grower’s supply online.

One of the things I like about Paige is that she asks well thought out questions—lots of them. When I told her that the fungus treatment would not get rid of the damage that had already occurred, but would prevent the damage from becoming worse, she asked, “Should one wait until the damage shows up, or should one spray to prevent the damage?”

I replied, “It is best to be proactive, but later is better than not at all.”

occasional treatment of plants with fungicide will enhance their growth and beauty

occasional treatment of plants with fungicide will enhance their growth and beauty

In the nurseries and greenhouses that produce our ornamental plants, the grower will maintain a strict fungicide program. I think that in your yard, it is satisfactory to be able to recognize the problem when it shows up. I also believe that if one were to spray the ornamentals about once a month with a fungicide, the quality of growth would improve greatly.

Remember:

Insecticide kills insects

Fungicide kills fungus.

You can decrease plant fungus problems by watering in the morning instead of at night.

And a Word from Our Sponsor:

Thanks for visiting Johntheplantman. These articles are sponsored by my book

As usual, I would just love for you click here to go to Amazon and purchase the ebook edition of my wonderful book, Requiem for a Redneck to go on your Kindle. I have also noticed that Amazon now has a free Kindle app for iphones and tablets. Is that cool or what?

If you want a consultation in your yard in N.W. Georgia, send me an email at wherdepony@bellsouth.net

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4 Comments (+add yours?)

  1. Dekie Hicks
    Jul 29, 2012 @ 17:50:28

    I’ve been wondering what was going on with those begonias. Thanks for the information.

    Reply

  2. ponygirl
    Jul 29, 2012 @ 17:56:23

    hello

    Reply

  3. Trackback: Plants that perform well in a shade garden—adding texture and color. « johntheplantman's Landscaping Ideas from a Veteran Gardener
  4. Margaret
    Aug 05, 2012 @ 14:55:16

    Now I know why my acuba bushes have black spots on their leaves. Thanks Johntheplantman. Mawi

    Reply

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