Since early spring, our office has been receiving numerous
inquiries about browning of eastern cedar trees in Connecticut. Symptoms
include distinctive off-color needles and tip diebacks. Upon close inspection
and examination, no primary causing organisms were found on affected trees.
This phenomenon was first observed in the state 2004 (seed the linked fact
sheet 2005 Update on the Eastern Red Cedar Problem) and has been recurring
since then. Weather conditions and climate changes are considered possible
contributors to eastern red cedar declines in the state, especially continuous summer
drought stress and mild/and extreme cold winter temperatures. For more information,
please see the fact sheet Browning, Dieback, and Decline of Eastern Red Cedar.
April 2018
Disease Alert: Volutella Blight of Pachysandra
Volutella Blight was the subject of our What's New update in the spring of 2016 and 2017, and it looks like we will be having another spring with conditions favorable for the growth and spread of this pathogen. It is typical for pachysandra to appear yellowish in color following the winter, but if your pachysandra beds are looking sparse you should examine the plants for signs of Volutella Blight. Brown spots on leaves and black shriveled stems are characteristic of this disease. If you notice any of these symptoms in your pachysandra, please feel free to
contact us and
summit samples for confirmation. Cultural control and fungicide applications can help manage this disease. For more information on this pathogen, please see our fact sheet;
Volutella Blight of Pachysandra (PDF* format).
New Fact Sheets
Volutella blight is a common fungal disease of boxwood. The disease affects leaves and stems, which can cause extensive browning of leaves and diebacks in nurseries and landscapes. The fungus is considered a weak and opportunistic pathogen. So, winter injury, excessive insect feeding, or poor root conditions can make plans more vulnerable to the disease. For more information of the disease, please read the linked fact sheet Volutella Blight of Boxwood (PDF format).
Red thread is a common foliar disease on cool-season turfgrass including fine fescue, tall fescue, perennial ryegrass, and Kentucky bluegrass. The disease more prevalent in the cool and humid spring and fall. The disease can reduce the density of turfgrass and result in an undesirable appearance. More detailed information of the disease can be found in the fact sheet Red Thread of Turfgarss (PDF format).
Two
needle cast diseases caused by
Rhizosphaera kalkhoffii and
Stigmina lautii, respectively, are commonly found on spruce trees in Connecticut. Infection of fungal needle cast diseases can cause early defoliation and significantly reduce the aesthetic values of the trees in landscape plantings and Christmas tree plantations. Linked fact sheet,
Needle Cast Diseases of Spruce (PDF format), briefly describes these diseases and stratifies for their control.
August 2017
Disease Alert: Downy Mildew of Impatiens
Above: Lower surface of impatiens leaf with sporulation of the downy mildew pathogen.
The destructive disease impatiens downy mildew has been confirmed on residential plants in CT this summer. The disease is caused by
Plasmopara obducens, a fungus-like organism (also called a water mold or oomycete). All cultivars of the common garden impatiens,
Impatiens walleriana, are susceptible. However, New Guinea impatiens appear to be tolerant to downy mildew. The downy mildew pathogen is spread by infected plants, water/rain, and wind. Early symptoms of downy mildew begin as light-green yellowing, mottling, or stippling and often go unnoticed. Advanced symptoms include stunting of whole plants, leaves, and flower buds, downward curling of leaves, wilting, plant collapse, and severe defoliation that results in bare, leafless stems. Plants suspected of having this disease should be sent or brought to the PDIO for analysis. If downy mildew is diagnosed on your plants, all infected plants should be dug up (roots included) and placed into municipal trash, when acceptable. Infected plants should not be composted. For more information, please see our fact sheet
Downy Mildew of Impatiens (PDF* format) by Dr. Yonghao Li.
Disease Alert: Late Blight
Reported in MA- Scout for Late Blight of Tomato and Potato
Late Blight has been confirmed in Hampshire County, MA on cherry tomatoes. It is very important for commercial growers and home gardeners to be on the lookout for late blight of tomato and potato in their fields and community or backyard gardens. The recent weather has been very favorable for the development of this disease, so it is important examine plants for symptoms. Information on this important disease can be found in the fact sheet Late Blight of Tomato and Potato in Connecticut--2012 (PDF* format) by Dr. Sharon Douglas.
Any suspicious tomato or potato samples should be sent or brought to The Plant Disease Information Offfice for examination and diagnosis as soon as possible.
April 2017
Disease Alert: Cedar-Apple Rust
Cedar-Apple Rust was the subject of our What's New update in May 2016 and with all the rainy weather we've been having lately, you may be noticing the interesting orange galls adorning your Juniperus trees and shrubs again. The photo below on the left shows a cedar-apple rust gall on a cedar tree producing spores. These spores may be carried by the wind and infect apple and crabapple trees, which are just beginning to leaf out. Now is the time to begin treating apple and crabapple trees with fungicides to protect them from cedar-apple rust leaf spots (photo below right) and defoliation on heavily infected trees. For more information on this pathogen, please see our fact sheet; Cedar-Apple Rust (PDF* format) by Dr. Sharon Douglas.
Disease Alert: Volutella Blight of Pachysandra
Volutella Blight was the subject of our What's New update in March 2016 and it looks like we will be having another spring with conditions favorable for the growth and spread of this pathogen. It is typical for pachysandra to appear yellowish in color following the winter, but if your beds are looking sparse you should examine the plants for signs of Volutella Blight. Brown spots on leaves and black shriveled stems are characteristic of this disease. If you notice any of these symptoms in your pachysandra, please feel free to contact us for confirmation. Cultural control and fungicide applications can help manage this disease. For more information on this pathogen, please see our fact sheet; Volutella Blight of Pachysandra (PDF* format) by Dr. Sharon Douglas.
January 2017
Disease Alert: Oak Wilt
Oak wilt is an aggressive fungal disease which kills thousands of trees annually in the Midwest and Eastern United States. The disease is transmitted to healthy trees by nitidulid beetles which carry the fungal spores on them from infected trees. The disease can also be transmitted from a sick tree to a healthy tree via root systems that have grafted together. So far, oak wilt has not been detected in Connecticut, but the neighboring state of New York has found infected trees in four counties. Here is a link to the Department of Environmental Conservation's article on the recent findings: Deadly Oak Wilt Disease Found in Brooklyn and Several Towns in Suffolk County. The symptoms of oak wilt are most noticeable during the summer when leaf discoloration begins to occur. In red oaks, leaf death and defoliation occur rapidly whereas white oaks tend to die branch by branch over a longer period of time. For more information on this disease and what symptoms to look for, please read the USDA Forest Service brochure: How to Identify, Prevent, and Control Oak Wilt. If oak wilt is suspected on a tree here in Connecticut, branch samples with leaves displaying wilt can be submitted to the PDIO for analysis.
November 2016
Disease Alert: Winter Injury
The recent drought conditions in Connecticut have left many plants stressed and more susceptible to winter injury this year. As winter approaches, it is important to make sure the root zone of ornamental plants have adequate moisture before the ground freezes. A deep watering and a layer of mulch around the base are recommended. Physical protection from burlap or anti-desiccant sprays can help protect plants from water loss and burn caused by the wind. Winter injury may not always be apparent until the following spring or summer when plants are actively growing. Branches and twigs weakened by winter damage are also more susceptible to disease, so it is important to prune out any unhealthy branches. For more information, please see our fact sheet; Winter Injury on Woody Ornamentals(*PDF format) by Dr. Sharon Douglas.
July 2016
New Fact Sheets
Apple Scab, Black Spot of Rose, and Running Bamboo
(Phyllostachys spp.) in Connecticut (Updated)
Apple scab, caused by the fungal pathogen Venturia inaequalis, is a common disease of apple and crabapple trees. Lesions on leaves can lead to early defoliation of infected trees. Fruit infection occurs later in the season leading to cracked and deformed fruit as well as lesions on the apple.
Black spot is a fungal disease of roses which occurs on plants all around the world. The first symptoms appear as small brown spots on leaves, which grow larger and darker in color. Leaves may turn yellow and fall off the plant. Canes can also become infected and the fungus will overwinter there and be spread to the leaves again the following season. This disease can reduce flower yield and lead to less tolerance of winter injury.
Running bamboo (Phyllostachys spp.) spreads vigorously through underground rhizomes which leads to problems in controlling the plant from expanding into unwanted areas. Public Acts
13-82 and 14-100 address the issue by prohibiting the planting of running bamboo within 40 feet of a property line and ensuring that retail sellers and installers provide customers with warnings about the spread and methods of root containment (underground barriers).
Disease Alert: Bacterial Diseases of Tomato and Pepper
Bacterial diseases have been prevalent on tomato and pepper plants this season. Symptoms start out as small necrotic spots on leaves, stems, and fruit which expand as the disease develops. The lesions often have a yellow halo surrounding them, as you can see in the image below on pepper (photo taken by Dr. Yonghao Li). These spots get larger and coalesce as the disease progresses, eventually causing leaves to become dry and die. To prevent this disease, starting with pathogen free plants is important. The bacteria can persist in infected plant tissue, so sanitation is key if you find this disease in your field or garden. Avoid overhead irrigation. A fungicide spray program should be initiated before the beginning of disease development. For more information about bacterial diseases on tomato and pepper, please see our fact sheets; Selected Bacterial Diseases of Vegetables (PDF* Format) by Dr. Sharon Douglas and Bacterial Spot of Pepper (PDF* Format) by Dr. Yonghao Li.
June 2016
Disease Alert: White Pine Decline
We have been receiving many inquiries about declining white pine trees from arborists and worried citizens. Symptoms include yellow/brown needles, needle drop, and dieback throughout the affected trees. Although these symptoms may suggest a fungal needlecast disease, it appears that the cause of the problem may be related to recent environmental conditions. The CT Tree Protective Association (CTPA) recently posted an article on their website which describes the situation (clink here for a link to the article). The CTPA references a recently published paper by Dr. Nicholas Brazee at the University of Massachusetts, which mentions that there are four fungi commonly found on blighted white pine needles but the increase in infection may be due to stress from recent climate fluctuations. At this time, there is not a simple answer as to the best way to manage declining white pine, as many of the samples we received in the PDIO did not have any fungal pathogens present. But we will continue to provide updates on the situation as it develops. Dramatic needle browning and canopy dieback of eastern white
pine (Pinus strobus) in southern New England (PDF* format) by Dr. Nicholas Brazee of UMass Amherst.
May 2016
Disease Alert: Cedar-Apple Rust
With all of the rainy weather, fungal growth is thriving on many different plants. One of the most noticeable is the cedar-apple rust gall which can be found on Juniperus hosts, mainly Eastern red cedar. When conditions are favorable, these galls produce telial horns, which are made up of gelatinous orange spores. Once these spores germinate, they are carried by wind and rain to crabapple and apple trees where they infect the leaves. This disease is not usually considered to be a serious threat to either host tree, but the crabapple or apple host can be treated to prevent leaf spot and defoliation when significant damage occurs. For more information on this pathogen, please see our fact sheet; Cedar-Apple Rust (PDF* format) by Dr. Sharon Douglas. Photo above taken by Dr. Yonghao Li.
April 2016
New Fact Sheets
Downy Mildew of Cucurbits and Botryosphaeria Canker of Woody Ornamentals
Cucurbit downy mildew affects the foliage of
cucumbers, melons, squash, pumpkins, and watermelon and can cause serious damage when infections begin early in the season. Symptoms include leaf spots which begin as a light yellow or green color and merge together as the disease progresses to form large brown spots and leaf death.
Botryosphaeria canker affects many woody ornamentals in nurseries, landscapes, and in the forest. The first noticeable symptom is dieback and wilting in the canopy of affected trees and shrubs. Upon closer inspection, canker areas may be visible including reddish-brown sunken lesions, bark splitting, and black fungal fruiting structures.
March 2016
Disease Alert: Volutella Blight of Pachysandra
Recently in the PDIO we have been receiving many samples of pachysandra which are infected with Volutella Blight. The first symptoms of this disease which you may notice are brown spots on the leaves. Stems may also shrivel and die, leading to patches of dieback. If you notice any of these symptoms in your pachysandra, please feel free to contact us for confirmation. Cultural control and fungicide options can help treat this condition. For more information on this pathogen, please see our fact sheet; Volutella Blight of Pachysandra (PDF* format) by Dr. Sharon Douglas.
February 2016
New Fact Sheets
Grape Downy Mildew and Grape Anthracnose
Many diseases affect grapevines grown in Connecticut. Downy mildew, which is caused by a water mold, infects leaves, young stems, flowers, and developing fruit. Patches of growth can often be found on the underside of infected leaves. Anthracnose, a fungal disease of grapes, can cause lesions on leaves, stems, and fruit. These two new fact sheets provide information about these pathogens as well as management options.
Grape Downy Mildew (PDF* format)
Grape Anthracnose (PDF* format) by Dr. Francis Ferrandino.
January 2016
New Fact Sheet
Grape Powdery Mildew
Grape powdery mildew is a major problem on grapevines (
Vitis spp.) grown in Connecticut. This fungal disease can infect young stems, flowers, leaves, and developing fruit which can lead to a major reduction in yield. This fact sheet provides information about the disease cycle of the grape powdery mildew pathogen
Erysiphe necator as well as methods for management.
Grape Powdery Mildew (PDF* format) by Dr. Francis Ferrandino.
December 2015
PDIO Image Gallery
The PDIO image gallery is now up and running with photos of common plant disease problems found in Connecticut. Below most photos is a link to a fact sheet on the disease which provides useful information and management options.
PDIO Image GalleryNovember 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 MB, 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.
Archived Posts
July 2013
-Begin to Scout for Impatiens Downy Mildew-
Last year impatiens downy mildew was confirmed in many residential and commercial landscapes throughout Connecticut. This disease is caused by Plasmopara obducens, a fungus-like organism (also called a water mold or oomycete). All cultivars of the common garden impatiens, Impatiens walleriana, are susceptible. However, New Guinea impatiens appear to be tolerant to downy mildew. This pathogen does not infect cucumbers or squash (or any vegetable) or any other common bedding plants. The downy mildew pathogen is spread by infected plants, water/rain, and wind. It can splash from plant-to-plant within a landscape bed or can be airborne and travel over much longer distances. Early symptoms of downy mildew begin as light-green yellowing, mottling, or stippling and often go unnoticed. These symptoms are often mistaken for nutrient imbalances or spider mite infestations. Advanced symptoms include stunting of whole plants, leaves, and flower buds, downward curling of leaves, wilting, plant collapse, and severe defoliation that results in bare, leafless stems.
Downy mildew is particularly destructive under moist conditions and cool nights--just the weather we have recently been having throughout the state.
Impatiens downy mildew--note stunted plants with distorted leaves.
Subtle chlorosis and twisting of leaves of impatiens with downy mildew.
Any suspicious impatiens samples should be sent or brought to The Plant Disease Information Offfice for examination and diagnosis as soon as possible.
IF downy mildew is diagnosed on your plants, all infected plants should be dug (roots included) and placed into municipal trash, when acceptable. Infected plants should not be composted.
If you have any concerns or want more information about this destructive disease, please call The Plant Disease Information Offfice at 203.974.8601.
July 2013
-Late Blight Reported in MA-
-Scout for Late Blight of Tomato and Potato-
Late blight was confirmed in Franklin County, MA on tomato on 11 July 2013 and in Erie County, NY on tomato on 10 July 2013. The recent weather has been very favorite for this disease of tomato and potato, so it is important to scout for this destructive disease. It is very important for commercial growers and home gardeners to be on the lookout for late blight in their fields and community or backyard gardens. Information on this important disease can be found in the fact sheet Late Blight of Tomato and Potato in Connecticut--2012 (820 kb, 7 pages, PDF format*).
Any suspicious tomato or potato samples should be sent or brought to The Plant Disease Information Offfice for examination and diagnosis as soon as possible.
