Plant & Insect Diagnostic Clinic Update - May 6, 2009

The clinic has received the following samples in the past two weeks:


We received our first sample of clover mites of the season.  Clover mites are a harmless mite that feed outdoors on grass and clover.  Clover mites are not damaging to plants, but in the spring and fall clover mites can wander into homes in large numbers.  They are tiny (1/64th inch), rusty brown to dark red and have very long front legs that extend forward as they crawl.When crushed clover mites leave a permanent purple stain.  Please see our IIIN for more information.

Ticks  People are outdoors enjoying the spring weather and doing some morel hunting.  (Feel free to e-mail with directions to good mushrooming spots in the Ames area!) With all the outdoor activity we are encountering ticks.  It is important to remove ticks as soon as possible with a good yank.  Ticks have to be attached for over 24 hours before any disease transmission becomes likely.  Do not burn ticks, douse in alcohol and then burn, or do anything that will upset the tick.  A clean pull is the best way to remove a tick with the least risk of disease transmission.  For great information on Iowa ticks, the disease they can carry, and how to avoid or remove them please see Ticks and Tick-borne Diseases in Iowa.


Rose spot anthracnose caused by fungus Sphaceloma rosarum

Stress related purple needles on blue spruce. 

Phomopsis and Kabatina tip blight on junipers

Phytophthora root rot on lilac.

Colletotrichum leaf spot on ivy. 

What we believe to be winter injury on boxwood (and other evergreens) has been very common, widespread and abundant this spring. See photo below.  This past winter was tough on the plants and many look terrible.  At this time the extent of damage is unknown.  It's unclear if the damage is limited to just the foliage or if the branches are also dead.  Wait until late May or June before taking any action.  The boxwoods should begin to develop new growth in the next few weeks.  Prune out those areas that remain brown in late May.  Plants that are largely dead will probably need to be replaced.  For more information on boxwood problems please see May, 2009 ISU Extension Yard & Garden column.


Winter injury on boxwood.  Photo by Donald Lewis
Winter injury on boxwood. Photo by Donald Lewis



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