identifying disease on apple/pear trees: please help

chefdarka(z5 Chicago/USA)May 31, 2010

I inherited a small orchard up in Twin Lakes, WI. We have a total of approximately 30-35 trees (predominanetly apple and pear). I sprayed with dormant oil this spring followed by a fruit tree spray last month.

However, in recent weeks, I've noticed brown spots on the leaves of my pear trees. The apple trees, on the other hand, have leaves that are curling up and brown. They almost look burnt.

I'm at a loss to how to proceed. Is there any particular insectiside that I use? I am nervous that if I don't attempt to remedy this quickly, I will have a disaster on my hands. PLEASE HELP AND HELP SOON. Thank you in advance.

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jean001(z8aPortland, OR)

any chance of pictures?

    Bookmark   May 31, 2010 at 10:55PM
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chefdarka(z5 Chicago/USA)

Yes, I have several pictures but I don't know how to download them to this site.

    Bookmark   June 1, 2010 at 7:12AM
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chefdarka(z5 Chicago/USA)

I believe these photos will accurately depict the problems I am facing.
I am in desperate need to determine which spray (s) to use to try to remedy this situation.

    Bookmark   June 3, 2010 at 11:15AM
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chefdarka(z5 Chicago/USA)

I went to a company called CONSERVE up in Wauconda, IL. This company supplies a lot of commercial sprays, etc. When showing my photos, the disease on the pear tree (photo 2) was said to be BLACK SPOT. On closer examination, I was also told that this pear tree has BLACK KNOT.
The apple tree disease was left as an unknown. However, I was told that a concoction of "Pentrabark"(sp) + "Agrafos" (sp) applied to the bark of the trees may considerably lessen the spread of this unknown disease.
That's where I am now with this problem.

    Bookmark   June 4, 2010 at 8:41PM
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alan haigh

I would not trust a diagnosis that didn't involve investigation under a microscope by a competent pathologist if it was an uncommon problem. Once I know what a disease is I think first of what is making the trees vulnerable. If it is a rare disease there is a good chance that it is the result of environmental stress.

I've never heard of pears getting black knot and the disease is rampant in many orchards I manage.

    Bookmark   June 5, 2010 at 6:42AM
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chefdarka(z5 Chicago/USA)

I absolutely agree with you. I am planning on contacting the extention up in Wisconsin. However, being a newbie, I also think that it is wise to take advantage of having someone in the business come out and actually see the entire orchard. I believe an actual walk through, by someone besides myself, may provide more of a macro snapshot of the orchard and possibly uncover potential issues/problems that I am not even recognizing and thus not addressing.

When I returned from the orchard yesterday, I started looking through the forum threads. I did read the discussions you had with others regarding black knot and your experiences with plum trees. Interestingly enough, I have recently purchased 2 stanley plum trees, so of course, I was most interested in the threads.

Regarding environmental issues, we have one major issue and that is rain. We have had an unusually rainy spring coupled with above average temps. This may be contributing to some of the issues.

This may have contributed to our trouble last year. 7 counties in WI suffered through tomato blight last summer/fall. We were one of the victims. My vegetable gardens were hit badly. We lost in upwards of 120 tomato plants in roughly 1 week.

On a completely different note, I would like to inquire about cherry trees. One: can I graft a sour cherry tree onto a regular cherry tree? and Two: How much pruning do sour cherry trees require?

    Bookmark   June 5, 2010 at 8:03AM
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Is it windy at your site?

    Bookmark   June 5, 2010 at 8:40AM
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chefdarka(z5 Chicago/USA)

I would say predominantly no. Although there have been occassions where the winds were strong enough that I dared not burn any piles; but that premise is applicable to just about everywhere.
I can say that the bulk of the orchard sits in a lower lying area in comparison to the surrounding land. Therefore, the venue of the orchard sometimes contributes to the "winds". Why do you ask?

    Bookmark   June 5, 2010 at 9:09AM
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chefdarka(z5 Chicago/USA)

Here are additional photos I took yesterday of the pear tree.

    Bookmark   June 5, 2010 at 9:58AM
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alan haigh

Forget about pesticide burn. That looks pretty serious.

I agree that a visit from a paid consultant would be a good investment if the consultant is legit.

    Bookmark   June 5, 2010 at 10:09AM
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I think your apples could have leafhopper damage (I just sprayed mine today for the same issue). Seems they especially like young tender trees that they can hop onto from the ground. Check out the pictures in the link. Also, my pears get those dark spots,usually in tops of trees, but seems more of a nuisance than really damaging, but I would guess it's a fungal/bacterial thing that perhaps myclobutanil (Immunox) might help.

Here is a link that might be useful: leafhopper damage pictures

    Bookmark   June 5, 2010 at 11:39PM
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Beeone(4 N. Wyo.)

Your apple trees look like they could have wind or frost damage.

    Bookmark   June 6, 2010 at 2:48AM
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See link on pear scab (aka blackspot). As I mentioned earlier, immunox should take care of it, although as the article says, it's not as severe or devastating as apple scab. Regarding your apples, I posit leafhopper b/c the upper leaves of your apples are curled, a result of the leafhoppers sucking the sap out of them. If you can kill the leafhopper nymphs (often seen on underside of leaves) it will be easier to control damage in future. Insecticidal soap, pyrethrins, and imidacloprid are all apparently effective, esp. the last as it's systemic in leaves -ie suck the sap, and bang your dead:).Honestly, you could probably ignore all of it and be OK, as they're not devastating issues.

Here is a link that might be useful: blackspot

    Bookmark   June 6, 2010 at 8:19AM
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alan haigh

It doesn't look like scab to me but I don't see much of it on pears here, mostly I see fab. in concert with psyla.

The thing is what the apple has is definately not scab so I believe it may not be a disease issue at all but some kind of burn. If I apply oil when it's slightly raining I can almost duplicate the leaf damage, just haven't done quite as much.

Immunox is affective on apple scab but not pear at all. Mancozeb is the only thing fairly inexpensive that deals with it well, but not reactively.

    Bookmark   June 6, 2010 at 9:34AM
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I'm no expert, but to me that looks like the very early stages of fireblight, on both kinds of trees

    Bookmark   June 7, 2010 at 11:27PM
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Scott F Smith(6B/7A MD)

My vote is burn from the fruit tree spray you did. Maybe it was very hot when you did it and it was very cool and cloudy in the days before. Its not fireblight.


    Bookmark   June 8, 2010 at 10:55AM
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I am in Marietta, Ohio and my pear trees look exactly like yours. I have 2 that are 3 yrs old. I did not spray mine with pesticides, so I doubt they are burnt from that. My guess is that it's from an insect or blackspot, as mentioned above.
It is definitely not fireblight. We did have 2 late freezes this spring, so it could be frost damage also.

Please post again if you do find out exactly what it is.

    Bookmark   July 28, 2010 at 12:46AM
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robarba(z5 Chicago)

I am in Chicago, IL and my pear tree looks just like that picture. I also have not sprayed anything. I also think it is blackspot. I will have to look into what to do; what to spray on and when. Of course, suggestions are welcome!! Thanks.

    Bookmark   August 10, 2010 at 11:03PM
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alan haigh

Rust mites and psyla can cause scorched leaves. You can usually find psyla with a good magnifying glass but rust mites will require a microscope and something like 20X mag.

The rust mites may already be gone by the time you see symptoms.

I did a little research when I saw a lot of this on Bosc this season at several sites.

    Bookmark   August 11, 2010 at 5:37AM
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It is really a dilemma or us amateurs who care for few trees. I have a pear tree and an Apple tree. I sprayed with dormant oil spray. Then weekly with Bonide then switched to Sven. What I have now
An apple tree with dark green leaves and look very healthy but all the apple dropped down with black spot on it. I still have One lonely apple on the entire tree.
The pear tree lost most of its leaves, they turn yellow and fall. Some pear fruit fell down but I still have lots on the tree but with parley any leaves on the tree. Are the Fruits will survive without leaves I don't know. I read somewhere that you need 35 leaves to survive one fruit.
The two sprays I used said it kills 100 kind of bugs. I must have bug no 101.

    Bookmark   August 12, 2010 at 2:02AM
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