Plant and Insect Diagnostic Clinic Update - June 21, 2013

 The following are highlights and updates about samples and questions recently received in the Plant & Insect Diagnostic Clinic.  Visit the PIDC’s Facebook page to ask questions and for updates and more pictures.

With the warm weather things are really picking up here in the clinic. 


Abiotic problems

We have observed lots of tatters on oak and hackberry this year (see picture below). Research indicates that tatters are caused by exposure to very low levels of chloroacetanilide herbicides. If exposed to these herbicides when in vulnerable stages of leaf development we get tattered appearing leaves. Subsequent leaves are normal and there should be no long term health impacts on the trees.


We continue to receive a variety of woody ornamental plants and trees that are in decline. Particularly new plantings suffered from last year’s drought. Obviously there was not enough rain, but also high air and soil temperatures are a stress for trees.


We have also received samples of growth regulator herbicide damage on oaks, ash, and on a couple of tomato plants.



Anthracnose is showing up on several broadleaf trees including oak, ash, and sycamore. This fungal disease is generally harmless to the tree but it may cause early defoliation, especially on sycamore. For more information and pictures please read this article.


We haven’t seen any crabapple or apple trees dropping their leaves yet, but some of them are showing signs of a fungal disease called apple scab which can also cause early defoliation.  See also the article in this issue.



Vein pocket galls on pin oak caused by a small fly can lead to severely curled leaves, but there should be no long term harm to the tree. Please see picture below.


European elm flea beetle larval and adult damage has been observed. The larval mines cause the ends of leaves to brown and the adults leave small holes in the leaves. Please see this article and picture below.


Hawthorn leafminer has been causing damage. The damage to the tips of leaves is usually not noticed until the larvae are done feeding. Although it is not pretty, the damage is harmless to the tree.


Also see below a couple of fun insects I photographed in the past few weeks.


Tatters on the older oak leaves, newer leaves appear normal.


Vein pocket galls on a pine oak.  You can see the abnormal swelling along the leaf veins.



Larval and adult feeding damage on an elm.  The larvae mine in the leaves and cause the distortion on browning.  The adults leave the small holes in the leaves.


Beautiful colors on a fiery searcher beetle.  They are predators that feed primarily on caterpillars.


It is an adult glowworm!  It is a beetle with the forewings greatly reduced so you can see the membranous hindwings.  And aren't those antennae cool?


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