Plant and Insect Diagnostic Clinic Update - June 23, 2010

The following are highlights and updates about samples and questions recently received in the Clinic:


Soldier beetles have been common on flowering trees and plants this week.  Soldier beetles are predators, but also feed on pollen.  Soldier beetles will not feed on leaves or petals and are harmless.  For more information please see our IIIN.
Earwigs have been driving us all a bit crazy.  They seem to be everywhere - in homes, in the garden, on plants, under pots etc.  Earwigs are harmless indoors and considered accidental invaders.  Outside they can be a bit of a pest on plants feeding on leaves and petals.  For more information on earwigs please see this Yard & Garden Column.  
Horned oak galls have been showing up on oaks this spring. They are caused by a tiny wasp. The gall is woody tissue produced by the tree. Each gall has multiple wasp larva feeding inside. There are no practical controls for horned oak galls because the wasp larva is protected from any sprays inside the gall and systemic insecticides have not been found to be effective either.  Horned oak galls do not kill trees, but they can stunt branches and weight branches down. They can be pruned out of the tree, but usually they are very numerous on all the branches and pruning is not practical.


Phomopsis cane and leaf spot of grape caused by the fungus Phomopsis viticola is affecting grapes plants now. The disease can be managed by sanitation and fungicide applications.

Black rot of grape caused by the fungus Guignardia bidwelllii, the fungus survives the winter in overwintering leaves and in infected stems. Immature leaves are infected during wet periods throughout the growing season. Control of this disease can be achieved by using protective fungicides such as maneb, mancozeb or captan from bud break to bloom and 10 days after bloom. Removing overwintering mummified berries from the vine help reduce the amount of fungal inoculum. Species of Vitis and cultivars within species differ in their susceptibility to black rot.

Fire blight bacterium Erwinia amylovora is active now and showing symptoms on pear and also on apple. Removal of infected plant parts mainly in early winter when plant is still dormant will greatly reduced the amount of bacterial inoculums.  Resistant varieties should be considered whenever possible. 

Pine diseases, Dothistroma and Diplodia (or Sphaeropsis) needle blight is causing brown needles as every spring mainly in Austrian and ponderosa pines.  We are also processing Scots pine samples reported to have died in relatively short period of time, to evaluate for pine wilt  nematode infection.

 Soldier beetle.

A group of earwigs on top of a milkweed plant.


A horned oak gall.


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