Amy Papineau, Landscape and Greenhouse Horticulture Field Specialist, Jonathan Ebba, Landscape and Greenhouse Horticulture Field Specialist
  • man pruning ornamental tree

What do you do when you encounter a plant problem such as disease or abnormal growth in the landscape?  You or a client may find a problem occurring with a single plant or you may find a swath of plants in decline. When you suspect a plant disease is causing damage in the landscape, UNH Extension and its UNH Plant Diagnostic Lab can help you by providing accurate disease identification and management recommendations. 

With an accurate diagnosis, the specialists at the Plant Diagnostic Lab can help you develop a management strategy and help you answer questions such as:

  • Will pruning out damaged parts of the plant stop the disease from doing further damage?
  • Will removing affected plants stop the spread in the landscape?
  • Are my watering, pruning, or other care practices contributing to the development of this problem?
  • Is this damage actually caused by disease, or is there something else going on here?
  • Is the plant likely to recover? 
  • Is this likely to happen again next year?
  • Can the problem be remedied with a fungicide application?

Plant disease diagnosis and management recommendations are provided to growers, landscapers, gardeners, and others through UNH Cooperative Extension’s Plant Diagnostic Lab. Whether in a production setting or in the landscape, plant diseases can have devastating impacts. Quick and accurate identification of the disease or other factor that is causing plant decline or damage is an important first step in successful management of the problem.  Accurately identifying the cause of disease can help you avoid spread or recurrence of the problem and will provide you with the information you need to select effective controls.

When you send plant material to the UNH Plant Diagnostic Lab, plant health specialists will examine and test the samples to determine causes of poor growth, damage, abnormalities, or other symptoms.  By examining the samples under a microscope and performing other diagnostic procedures (including testing with advanced molecular approaches), the specialist can accurately identify fugal, bacterial, and viral infections, and will provide you with management recommendations based on the disease-causing organism(s) identified.

The UNH Plant Diagnostic Lab recently moved to a new location on the campus of UNH in Durham and is now located in fully renovated lab space in Barton Hall. Along with this move to a new space, the lab has new staff who are integrating modern diagnostic capabilities into the lab services.  With the addition of molecular diagnostic tests introduced by the lab director and plant health specialist Dr. Bo Liu, ultra-rapid identification of many diseases will be possible.  Dr. Liu, along with plant diagnostician Madie Hassett, provide services grounded in speed, accuracy, and value to the client. 

To make use of the services provided by the UNH Plant Diagnostic Lab, mail or deliver (Monday to Friday, 8am-5pm) samples of affected plants or plant parts to the lab along with a completed submission form and sample fee to: UNH Plant Diagnostic Lab, Barton Hall Room 206, 34 Sage Way, Durham, NH 03824.  This video provides instruction for packaging and sending samples to ensure they arrive in the best condition for diagnosis.  

Some diseases may be accurately identified through emailed images. Sending clear images to the lab ( before you send your sample or at the time of submitting your sample can aid in quick diagnosis and development of recommendations. Some plant diseases can be identified quickly when the lab receives them, while some diagnostic procedures take up to two weeks to complete.  The lab will contact you by email when your report is ready.

If you are experiencing a plant growth problem, consider calling your local Extension Field Specialist as well. Extension specialists in each NH county are available to work with farms and green industry businesses to diagnose plant problems and to provide recommendations for control or management. Specialists work hand-in-hand with the Plant Diagnostic Lab.

Plant health specialists at the UNH Plant Diagnostic Lab can be reached at (603) 862-3043 or


Landscape and Greenhouse Horticulture Field Specialist
Extension Field Specialist, Landscape Horticulture
Phone: (603) 862-1601
Office: Cooperative Extension, Taylor Hall, Durham, NH 03824

Landscape & Greenhouse Field Specialist
Extension Field Specialist, Landscape & Greenhouse
Office: Coop Extension, Taylor Hall, Durham, NH 03824