Diagnosing Plant Damage & Identifying Insects

8 May 2007

Virginia Cooperative Extension, Charlottesville/Albemarle County Office
460 Stagecoach Road, Charlottesville, Virginia 22902
phone: 434.872.4580   fax: 434.872.4578

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Along with the flush of spring growth many gardeners may also start noticing problems with the plants in their landscapes and insects all around. Some of these problems or insects are easy to diagnose but many times it helps to have someone to consult with to solve the problems or identify the insects. There are many resources for this help in our communities including your local Extension Office.

If you want to bring a sample of your troubled plant or mysterious insect or send us a digital image of something too large to carry the following tips should help you make the most of your efforts to find help.

The accurate diagnosis of plant disease or insect damage depends upon receiving a fresh sample or a high resolution photo. All specimens should be fresh when collected and brought to us as soon as possible. When specimens arrive dried, wilted, crushed, or in advanced stages of decay, accurate diagnosis is usually impossible. If the sample is in good condition, the disease or insect will be diagnosed and acknowledged within a few days. If culturing for plant pathogens is required, this will extend the time for results to be returned.

Collecting Plant Specimens

1. Where possible, collect the whole diseased plant, including roots and at least one pint of moist soil. Dig (do not pull) plants with a shovel or trowel.
2. Collect more than one plant if various stages of decline are evident. Dead or dry plant material is of no value to the diagnostician. When possible, include healthy plants or plant parts for comparison.

Packaging Plant Specimens

1. Immediately after digging small plants, place the moist root ball in a plastic bag and tie the bag around the stem just above the soil line. This will prevent the soil from drying during transit. Enclose the tops of the plants in a ventilated plastic bag. Do not wet the plants before packaging.
2. When distinct spots on the leaves are the only symptoms, include several twigs with leaves still attached. Place them between dry strips of cardboard or in a thin magazine and then place the sample in a closed plastic bag.

Collecting and Packaging Insect Specimens

1. More than one specimen is always helpful for the proper identification of a species.
2. Representatives of several stages of each species are always desirable.
3. Live specimens are preferred but if this is not possible it is best to preserve specimens in rubbing alcohol.
4. Specimens preserved dry should be placed in pill boxes, jars, or similar containers so specimens will not be crushed
5. If insects are on plant material they should be placed in a plastic bag to prevent excess drying.
6. The following are helpful: exact location where found, date of collection, and food plant or other host association if known.

In addition to the help you can find at local Extension offices, most counties have Master Gardener Help Desks set up at local farmers markets and some at public libraries. Check with your local Extension office to see what options are available in your community.

For example, in Albemarle County you can find Master Gardener Help Desks at the City Market, Crozet Market, and coming soon, the Scottsville Market and the Meade Park Market.

The Nelson County Master Gardeners in addition to their farmers market will be presenting a workshop called "Problems and Solutions in the Garden" on Saturday, May 26 from 9-12:00 am. This seminar will be a garden tour of three gardens in the Stoney Creek area of Nellysford. For questions and directions, call Jeanette Gatje at 434-361-1309.

Please join the Piedmont Master Gardeners for "How to Grow Beautiful Roses". This workshop will be given by Al Minutolo, local Master Gardener. The event will take place at Jefferson Madison Regional Library Central Branch in the Madison Room, 201 East Market Street, May 15 from 7:00-8:30 pm. The event is free and open to the public. Validation for parking in Main Street Garage is available. For more information go to www.piedmontmastergardeners.org or call 434-872-4580.

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For more information about this and other landscape topics contact your local Virginia Cooperative Extension office. The local Virginia Cooperative Extension office numbers are Albemarle 872-4580, Fluvanna 591-1950, Greene 985-5236, Louisa 540-967-3422, and Nelson 263-4035.

If you can identify the insect in the photo send me a note (peter@vt.edu) with your snail mail address and I will draw a winner at random from the correct entries for a prize.