What’s New
--Updates, Alerts, and News from the PDIO--
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 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).
These fact sheets provide information about the topics above as well as control options. All of these fact sheets and many more can be found in our Publications section. Apple Scab, Black Spot of Rose by Dr. Yonghao Li, and Running Bamboo (Phyllostachys spp.) in Connecticut by Dr. Jeffrey Ward.
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 by Dr. Sharon Douglas and Bacterial Spot of Pepper 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 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 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.
These two new fact sheets provide information about the pathogens and their associated control techniques. Cucurbit Downy Mildew and Botryosphaeria Canker of Woody Ornamentals by Dr. Yonghao Li.
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 Pachysandraby 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, Grape Anthracnose 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 by Dr. Francis Ferrandino.