Plant and Insect Diagnostic Clinic Update - August 25, 2010

News Article

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


DISEASES


Thousand cankers disease of walnut is an insect-disease complex that has been causing mortality of black walnut in the western U.S. We had hoped the insect and disease were not in the native range of black walnut, but an infestation was confirmed in Tennessee last month in the heart of the native range of black walnut.  For more information on this disease please see this informational website from Tennessee. 


Bur oak blight (B.O.B.) has been prevalent on bur oaks this year. B.O.B. is caused by a species of Tubakia fungus. This is a newly recognized disease and research is still ongoing. We do not know how much this disease affects the overall health of the tree, nor do we have any treatment recommendations yet other than minimizing other stresses (such as by watering during especially dry periods). For more information on this disease, please see this HHPN article.


The lack of rainfall the past few weeks (definitely a good thing) has led to sooty molds becoming more obvious on plants.  Sooty molds are a group of dark colored fungi that grow on the surface of leaves.  They grow on honeydew form sap feeding insects like aphids, soft scales.  Sooty molds become more noticible when rainfall does not wash the honeydew from the plant leaves.


INSECTS


Springtails have been popping up in basements. Springtails use a spring-like apparatus to jump. They are often confused with fleas as they are about the same size. Springtails are harmless and feed on decaying organic matter in wet areas. They do not harm furnishings or infest food. They usually do not reproduce indoors, but if there is water in your basement it is possible. Reducing moisture with dehumidifiers can help. Usually they are coming in form the outside so sealing cracks and reducing moisture around the foundations can help.  For more information please see our IIIN.


Bumble flower beetle is not one we talk about often in Iowa.  This medium-sized scarab feeds on nectar, pollen and overripe, cracked, and rotting fruits and vegetables.  Clients this summer have been reporting damage to tomatoes on the vine.  Sanitation is the best emedy this late in the season.  Pick tomatoes slightly ahead of ripe, and do not leave any ripe or damaged produce in the garden. Garden insecticide sprays such as Sevin or permethrin will be moderately effective, though spraying during harvest is undesirable.


Sooty mold on maple leaf.  Sample from Allamakee County IA.  Note cottony maple scales on the leaf, the source of the honeydew that lead to the sooty mold.


Sooty mold on maple leaf. Sample from Allamakee County IA. Note cottony maple scales on the leaf, the source of the honeydew that lead to the sooty mold.


The bumble flower beetle, a scarab beetle, is a scavenger that can attack ripe and cracked vegetables.


The bumble flower beetle, a scarab beetle, is a scavenger that can attack ripe and cracked vegetables.

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