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Horticulture and Home Pest News
Horticulture & Home Pest News is filled with articles on current horticulture, plant care, pest management, and common household pests written by Iowa State University Extension specialists in the Departments of Entomology, Horticulture and Plant Pathology.

Plant and Insect Diagnostic Clinic Update - May 2, 2012

This article was published originally on 5/2/2012

The following are highlights and updates about samples and questions recently received in the Plant & Insect Diagnostic Clinic:
 
Insects
 
We continue to get question about the abundance of fuzzy brown moths (FBM) this year.  We do not yet know if there will be more caterpillar activity than normal, but speaking of FBM offspring we did get a photographic sample of a variegated cutworm.
 
The variegated cutworm is different from most cutworms in that it is a climbing cutworm that feeds above ground on many different vegetables and ornamentals.  Favored plants include tomatoes, potatoes and hostas.  See photos below. 
 
We received a neat sample of eriophyid mite galls on a birch tree.  Like all leaf galls, they are harmless and there are no practical controls.  See below for pictures.
 
This has been a great year for the eastern tent caterpillars, the insect responsible for silken tents at the fork of the branches in apple, crabapple and Prunus trees. There are more tents in the landscape this year than we have seen in the past several. This might be a consequence of the mild winter, though it also indicates last summer was a good period for egg-laying by the adult moth.  Given enough time and caterpillars, the eastern tent caterpillar can defoliate a tree. This is stressful but not fatal. One control option is to scrape the tent down at night when the caterpillars are inside and discard in the trash or in a far-away part of the yard. Spraying the tree is an option but usually more trouble than it is worth.  See our Insect Notes for more information.
 
Diseases
 
Spring is here, plants are growing and so are the diseases.  We received a sample with iris leaf spot, one of the most common leaf disease or iris.
 
We have received a sample of bur oak blight, which we diagnosed from a branch, leaf symptoms will not be apparent until later in the summer.
 
Some coleus came in this week with downy mildew.
 
We continue to receive samples with freeze damage.
 
Variegated cutworms feeding on tomato foliage and fruits.Variegated cutworms feeding on tomato foliage and fruits.
 
Variegated cutworm feeding damage on hosta leaves.Variegated cutworm feeding damage on hosta leaves.
 
Eriophyid mite galls on a birch leaf.Eriophyid mite galls on a birch leaf.
 
Small orange eriophyid mite inside a cut open gall.
Tiny, orange eriophyid mite inside a cut open gall.
 
 
Silken tent made by the eastern tent caterpillars.  Note the defoliated trees surrounding the tents.Silken tent made by the eastern tent caterpillars. Note the defoliated trees surrounding the tents.