{The Plant Disease Information Office}

The Plant Disease Information Office (PDIO) is part of the Department of Plant Pathology and Ecology of The Connecticut Agricultural Experiment Station. The PDIO is a full-service plant disease diagnostic laboratory that assists all Connecticut stakeholders, including homeowners and professionals.  Plant samples are diagnosed utilizing molecular, serological, biochemical, and traditional diagnostic methods. The PDIO also assists with inquiries about plants, plant identification, and plant health.

Inquiries and samples can be submitted via phone, email, mail, and in person. The contact information for the PDIO is listed below:

Dr. Yonghao Li, Plant Pathologist, (
Ms. Lindsay Patrick, Technician (

The PDIO is open 8:30 a.m. to 4:30 p.m. Monday - Friday

PDIO Hours of Operation and Holiday List

PDIO Phone: (203) 974-8601;  Toll Free in CT 1-877-855-2237

PDIO Mailing Address:
Plant Disease Information Office
Connecticut Agricultural Experiment Station
P.O. Box 1106
New Haven, CT 06504

Office Location Address (use this address for UPS and FedEx, as well as to visit):
Plant Disease Information Office
Jenkins-Waggoner Laboratory
Connecticut Agricultural Experiment Station
123 Huntington Street
New Haven, CT 06511

The Experiment Station's PDIO is a member of the National Plant Diagnostics Network (NPDN)



{Boxwood blight leaf spots}

November 2015
-Newly Expanded and Revised-
Disease Management Guide for Connecticut Arborists 2015-2016

A newly revised and expanded disease management guide by Dr. Sharon M. Douglas, Emeritus Plant Pathologist, is now available.  It can be downloaded to print hard copies or can used in electronic form with links.  The Table of Contents includes: Host Genus and Disease Index, Host Common Name and Disease Index, Introduction to Use of the Disease Management Guide, An Introduction to Tree Health Problems, Common Tree Health Problems, Disease Management Guide, Disease Management Calendar, Fact Sheets, Disease Diagnosis, and Selected References. The Guide includes fact sheets with full color photos. Disease Management  Guide for Connecticut Arborists 2015-2016 (PDF* format, 23,100 KB, 486 pages). 

August 2015

New Fact Sheet

Browning, Dieback, and Decline of Eastern Red Cedar

First observed in 2004, Eastern Red cedar (Juniperus virginiana) in many areas of the state have exhibited a recurring range of symptoms, including needle browning and premature drop, branch and twig death, and general tree decline.  This new fact sheet titled Browning, Dieback, and Decline of Eastern Red Cedar (PDF* format) by Dr. Sharon M. Douglas reviews what we know and don't know about this problem. 

July 2015
New Fact Sheet
Using Mineral Nutrition to Suppress Plant Diseases

This new fact sheet reviews one of the fundamental strategies for maintaining plant health and suppressing plant diseases by managing nutrition.  Proper nutrition can often influence the fine line between host susceptibility and resistance.  Examples of specific diseases and elements are covered in the fact sheet on Using Mineral Nutrition to Suppress Plant Diseases (PDF*format) by Dr. Wade Elmer.

June 2015
New Fact Sheet
Fire Blight Management During Bloom

Fire blight, caused by the bacterial pathogen Erwinia amylovora, is an important and potentially devastating disease of apple and pear.  Bloom time is a very important stage for fire blight infection because the natural openings in the flowers provide the fire blight bacteria an easy entry into the tree. This fact sheets discusses how to understand management of this disease from the standpoint of disease biology.  This new fact sheet on Fire Blight Management During Bloom (PDF*format) by Dr. Quan Zeng is now available.

May 2015

New Fact Sheet

Rhododendron Tissue Proliferation

Rhododendron tissue proliferation is a condition that causes tumor-like growths and shoots to form at the base of many cultivars of rhododendron.  Early symptoms are often confused with crown gall, a disease caused by the bacterium Agrobacterium tumefaciens. A new fact sheet on Rhododendron Tissue Proliferation (PDF*format) by Dr. Lindsay R. Triplett is now available that describes how to handle this condition.

April 2015
Updated and Revised Fact Sheets Available
Downy Mildew of Basil

Last year many gardeners were disappointed with their basil crops--plants collapsed early in the season, often before they could be harvested.  Widespread outbreaks of downy mildew of basil was the likely culprit.  A new fact sheet on Downy Mildew of Basil (PDF*format) by Dr. Yonghao Li is now available that discussed how to recognize and manage this destructive disease.

Dooks Needle Blight (Formerly Canavirgella Needlecast) of White Pine

Many white pine throughout the region have been showing a yellow and brown discoloration of current-season needles.  Although several needlecasts have been associated with this damage, Canvirgella needlecast was reported as a key component.  Recently, however, the identity of Canavirgella banfieldii has been questioned, since there is evidence that it is really Lophophacidium dooksii, the fungus associated with Dooks needle blight—the two names are thought to be synonyms for the same fungal species Dooks Needle Blight (Formerly Canavirgella Needlecast) of White Pine  (PDF format*) by Dr. Sharon M. Douglas is now available. 

Excess Water Problems on Woody Ornamentals

As the snow is melting, localized flooding may occur. Excess water and poorly drained soils can  present serious problems for many woody ornamentals that may result in plant decline and death as well as uprooting of trees and large shrubs.  Learn how to recognize and manage water issues in the newly updated fact sheet Excess Water Problems of Woody Ornamentals (PDF format*) by Dr. Sharon M. Douglas.

Pruning- An Introduction to Why, How, and When

Pruning is probably one of the least understood and most daunting landscape maintenance practices for most homeowners.  Many people aren't sure what to do or when to do it.  This updated fact sheet reviews the basics of pruning for shrubs and small ornamental trees.  Learn more about pruning with Pruning: An Introduction to Why, How, and When  (PDF format*) by Dr. Sharon M. Douglas.

  --For Children--

Coloring and Activity Books

The Experiment Station's Coloring and Activity Books for Kids are now available online in the Publications section of this PDIO website.  These books highlight many topics of plants and agriculture in Connecticut and the activities of Station scientists.  The newest edition, Coloring and Activity Book for Kids III (2011) (PDF format*), is now available.  It was edited and prepared by Dr. Sharon M. Douglas.


--Archived Disease Alerts--

Disease Alert- Begin to Scout for Downy Mildew of Impatiens (July 2013)

Disease Alert- Late Blight Reported in MA: Scout for Late Blight of Tomato and Potato (July 2013)

Disease Alert- Downy Mildew of Impatiens (August 2012)

Disease Alert- Late Blight of Tomato and Potato (June 2012)



Newly revised and updated presentation by Sandy Anagnostakis titled Growing Chestnuts in the Northeast (PDF format*).

Some previously posted presentations from meetings are archived and can be accessed by clicking here.


13 August 2015 (updated)

*NOTE: Some of these documents are provided in Adobe® Acrobat™ (.pdf) format. If you do not have Adobe® Acrobat™ Reader to view and/or  print your these documents,  you will need to download the Adobe® Acrobat™ Reader. To get a free copy of the software, click the "Get Acrobat" image. 
{Adobe Acrobat Reader}



Content Last Modified on 11/12/2015 12:23:29 PM