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Galls on Hawthorn leaf

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  • rh_chelt
    Hello I have attached 3 images of a Hawthorn leaf found today here in Cheltenham. There are a number of lighthouse or nail galls on the upperside of the
    Message 1 of 3 , 6 Sep 08:26
    Hello

    I have attached 3 images of a Hawthorn leaf found today here in Cheltenham.  There are a number of "lighthouse" or "nail" galls on the upperside of the leaf, with 1 or 2 of a similar morphology on the underside.  Some of  the features on the upperside are complemented by a shallow underside depression, as shown in the third picture.
    I cannot fit the galls into the key for Crataegus, but I must be missing something.

    Regards

    Robert Homan



  • Brian Wurzell
    Dear Robert, If I saw numerous upperside structures like these associated with a group of hawthorn leaves bunched and clustered at the tip of a long
    Message 2 of 3 , 6 Sep 17:03
      Dear Robert,

      If I saw numerous upperside structures like these associated with a group of hawthorn leaves bunched and clustered at the tip of a long hedgerow stem, I would be inclined to attribute them to larvae of the midge Dasineura crataegi.

      Your examples look more sparsely scattered on a leaf not otherwise deformed and it is not clear which part of the stem it occupied or whether the host is of tree or shrub stature. But these galls might still be caused by an immature D. crataegi or two feeding more casually or surviving for a shorter period of time.

      I cannot find another organism in the English or French literature which comes any closer, so I offer this as a suggestion only, hoping it may be helpful. Thank you for an interesting observation.

      Best wishes,

      Brian.


       



      On Wednesday, 6 September 2017, 16:26, "theapiary@... [british_galls]" <british_galls@...> wrote:


       
      [Attachment(s) from theapiary@... [british_galls] included below]
      Hello

      I have attached 3 images of a Hawthorn leaf found today here in Cheltenham.  There are a number of "lighthouse" or "nail" galls on the upperside of the leaf, with 1 or 2 of a similar morphology on the underside.  Some of  the features on the upperside are complemented by a shallow underside depression, as shown in the third picture.
      I cannot fit the galls into the key for Crataegus, but I must be missing something.

      Regards

      Robert Homan






      Virus-free. www.avast.com
    • R Homan
      Thank you Brian The leaf was from a stem about 15 cm in length, one of several trimmed from a garden hedge, Some of the stems were topped by D crataegi galls
      Message 3 of 3 , 8 Sep 00:32

        Thank you Brian


        The leaf was from a stem about 15 cm in length, one of several trimmed from a garden hedge,  Some of the stems were topped by D crataegi galls with the same type of "growths" evident, largely on the underside of the leaves around the galled tip.  I think the leaf I queried must have been from a position somewhat lower along a stem, as suggested by the presence of the large, vacated Stigmella mine.  Therefore, the conclusion must be, as you suggest, that my leaf had slightly unusual D crataegi mini-galls present.


        Regards


        Robert 


        From: british_galls@... <british_galls@...> on behalf of Brian Wurzell brian_wurzell@... [british_galls] <british_galls@...>
        Sent: 07 September 2017 00:03
        To: british_galls@...
        Subject: Re: [british_galls] Galls on Hawthorn leaf
         
         

        Dear Robert,

        If I saw numerous upperside structures like these associated with a group of hawthorn leaves bunched and clustered at the tip of a long hedgerow stem, I would be inclined to attribute them to larvae of the midge Dasineura crataegi.

        Your examples look more sparsely scattered on a leaf not otherwise deformed and it is not clear which part of the stem it occupied or whether the host is of tree or shrub stature. But these galls might still be caused by an immature D. crataegi or two feeding more casually or surviving for a shorter period of time.

        I cannot find another organism in the English or French literature which comes any closer, so I offer this as a suggestion only, hoping it may be helpful. Thank you for an interesting observation.

        Best wishes,

        Brian.


         



        On Wednesday, 6 September 2017, 16:26, "theapiary@... [british_galls]" <british_galls@...> wrote:


         
        [Attachment(s) from theapiary@... [british_galls] included below]
        Hello

        I have attached 3 images of a Hawthorn leaf found today here in Cheltenham.  There are a number of "lighthouse" or "nail" galls on the upperside of the leaf, with 1 or 2 of a similar morphology on the underside.  Some of  the features on the upperside are complemented by a shallow underside depression, as shown in the third picture.
        I cannot fit the galls into the key for Crataegus, but I must be missing something.

        Regards

        Robert Homan






        Virus-free. www.avast.com

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