Posts by Jean Williams-Woodward
May 9th, 2013 by Jean Williams-Woodward
- April 2013 Plant Disease Clinic Report
- A look ahead for what you might expect to see based upon samples we diagnosed a year ago in May 2012
And, updates on:
- Pseudomonas syringae leaf spot on watermelons
- Fusarium wilt of watermelon
- What’s the orange goo growing on tree stumps?
- Rose Rosette Virus
- Impatiens downy mildew
- Wet, cool weather has importance for early-season disease management (row crops)
- Wheat Diseases: Loose Smut, Sooty Mold, and Head Scab
- Turfgrass Diseases: Large Patch, Dollar Spot, and Spring Dead Spot
April 15th, 2013 by Jean Williams-Woodward
The April Update includes:
- March Plant Disease Clinic Report
- Table of plant disease samples diagnosed a year ago in April 2012
- Eastern red cedar rusts
- Bulb mites and spot anthracnose samples
- Watch out for downy mildews on ornamental plants
- Fungicide spray guide for Spring-planted peppers
- Wheat foliar disease update
- Turfgrass disease update
- Winter weather in March could affect row crop diseases
- Bacterial leaf scorch on blueberry research results
- Corrected contact information
See the entire report HERE
March 11th, 2013 by Jean Williams-Woodward
By Ansuya Jogi and Jean Williams‐Woodward
The tables in the link below consist of the commercial and homeowner samples submitted to the plant disease clinics in Athens and Tifton for February 2013 (Table 1) and one year ago in March 2012 (Table 2). Sample numbers were still low in February, but this will soon change! Much of the symptoms we saw on samples were due to environmental stress/injury. However, root and crown diseases caused by Phytophthora, Thielaviopsis basicola, and Rhizoctonia continue to be identified. Also, with the cooler, humid, wet weather, the fungus, Botrytis, will continue to cause problems in the field and in greenhouses, particularly on freeze damaged tissues. Looking ahead through March, based upon samples diagnosed a year ago, we will likely see an increase in turf samples and problems, as well as rust and Sclerotinia diseases starting to show up. I would suspect too that downy mildew diseases will also become prevalent on some crops, particularly on ornamentals in nurseries.
September 13th, 2012 by Jean Williams-Woodward
Jean Williams-Woodward, University of Georgia Extension Plant Pathologist, will present common winter annual flower diseases, what to watch for, and how to control them. This Webinar is free to all Landscape Contractors and Extension Professionals.
A complete schedule and archive of Landscape Professional webinars may be found at http://ugaurbanag.com/webinars
These webinars are easily viewed with a smart phone or iPad so you can be on the run.
June 15th, 2012 by Jean Williams-Woodward
Dr. Jean Williams-Woodward- University of Georgia Plant Pathologist
Downy mildew on impatiens identified in Georgia retail nursery and landscape
Downy mildew on impatiens (Impatiens walleriana), caused by Plasmopara obducens, has been confirmed from a commercial nursery and a home landscape sample this week. The commercial sample, submitted by the Georgia Department of Agriculture, originated from a retail nursery in the Atlanta area. The home landscape sample is interesting in that new impatiens plants were not transplanted into the landscape bed this year and that the impatiens are allowed to reseed each year. This could mean that the pathogen has survived within the landscape bed from infected plants in previous years. It is not known whether impatiens downy mildew can survive within seed. This bed is located in a shady area and is irrigated with spray emitters that wets the foliage regularly, which creates an ideal condition to spread the disease to adjacent plants. Furthermore, the cooler, wet weather that northern Georgia has seen over the past few weeks has likely contributed to disease development and spread. At this time, we don’t know how widespread impatiens downy mildew is within the state. It is also likely that hotter and drier weather patterns usually seen through the summer will stop or slow disease development.
Downy mildew symptoms on infected plants begins with leaf stippling, downward curling of leaves, leaf yellowing, and leaf drop and disintegration leaving the stems bare. The downy mildew pathogen sporulates profusely on the backside of the leaf, as well as from infected stems as they soften and collapse. If you suspect downy mildew on impatiens within Georgia, please submit a sample to confirm its presence to the UGA Department of Plant Pathology Plant Disease Clinic in Athens. The form and address can be found here:http://plantpath.caes.uga.edu/extension/documents/PlantDiseaseSubmissionFormApril2012.pdf
. For more information, contact Jean Williams-Woodward at email@example.com
June 4th, 2012 by Jean Williams-Woodward
” Bacterial spots and blights on ornamental plants “ will be presented by
Dr. Jean Williams-Woodward Warmer temperatures tends to increase bacterial
diseases on plants. Leaf spots, blights, and wilts are becoming more common
within nurseries and greenhouses. This webinar will cover what to look for
to identify and manage bacterial plant diseases.
Here’s how to participate in the webinar:
Before the webinar, click on the link below.
You will be able to enter the session starting at 10 am EDT on the day it
occurs (for trouble shooting if necessary), but the actual webinar will not
start until 11 am EDT.
All that you need is an up-to-date browser and internet connection (and no
firewalls!). We will run the webinar off of NC State’s ELLUMINATE site
license, so you don’t need a copy of the program yourself. In order to make
test that your system requirements are acceptable, visit the Configuration
Room linked on http://go.ncsu.edu/elluminate_config
In addition, Elluminate tips can be found at the link below.
February 11th, 2012 by Jean Williams-Woodward
Jean Williams-Woodward, UGA Extension Plant Pathologist
A relatively new downy mildew disease is infecting impatiens (Impatiens walleriana), a shade-tolerant, flowering annual plant that is a staple in landscapes. Downy mildew on impatiens caused by Plasmopara obducens was first seen in 2004 and it has shown up sporadically in the US since then, primarily in the northeastern US. However, this disease is currently devastating nursery crops and landscape plantings in central and southern Florida. Several factors may be the cause of the outbreak, including the movement of infected plants within the ornamental trade and the mild winter in Florida that has kept impatiens in the landscape longer than usual, which has provided an overwintering site for the pathogen. Infected plants often show downward curling leaves, small new growth, reduced flowering and a leaf stippling pattern that resembles spider mite feeding injury. This downy mildew is a prolific spore-producer. Sporangia can be seen on the leaf underside in cooler weather. Eventually, infected plants defoliate and may die. Oospores (survival spores) have been seen within the stems of infected plants in New England states that could allow the pathogen to survive within a landscape bed.
In response to this disease outbreak, it may be advisable for growers and landscapers to limit impatiens orders for spring sales and use begonias or New Guinea impatiens as replacement plants as these are not susceptible to infection. If plugs are coming from Florida growers, supplies of impatiens may be limited. We don’t know how the disease will progress during our hot, summer months; however, past experience with this disease in a few states suggests that the pathogen stops producing spores and infecting plants during hot weather. One of the main concerns for growers is that although they may be able to reduce infection and symptom development within their operation through preventive fungicide applications, once these plants go out into the landscape, the disease may cause severe losses for their customers in the spring and fall as fungicide use is often not continued in landscapes. Impatiens downy mildew infection can be reduced through fungicide drenches (28-day interval) or sprays (7-day interval) of Subdue MAXX (mefenoxam), Adorn (fluopicolide), Vital (potassium phosphite), Protect T/O (mancozeb), Pageant (pyraclostrobin + boscalid), Disarm (fluoxastrobin), Segway (cyazofamid), Stature SC (dimethomorph), FenStop (fenamidone) and Heritage (azoxystrobin) plus Capsil as a surfactant. Aliette (fosetyl-Al) has not provided control of this disease in several trials. Fungicide resistance development is a real concern for downy mildew diseases, so rotate fungicides making no more than two consecutive applications of the same fungicide or a fungicide with the same mode of action (with the same FRAC code).
Since most downy mildew diseases are blown northward from southern regions during storms, it may be only a matter of time before this disease shows up in Georgia and other southeastern states. If you have questions, please contact me at firstname.lastname@example.org.
December 26th, 2011 by Jean Williams-Woodward
On Thursday, January 5th at 11 am EST, NC State University will be hosting an ELLUMINATE LIVE webinar on Box Blight – a new disease to the US and recently found on boxwood in North Carolina, Virginia, and Connecticut. This webinar is intended for extension agents, interested parties and boxwood growers in North Carolina and surrounding states.
Dr. Ivors will speak for 45 minutes on this new boxwood disease in the U.S., followed by questions from the audience. Representatives from VA and CT also will make comments and address concerns in their states. The webinar will be recorded and made available for viewing at anytime after the webinar concludes at the same URL.
You can enter the session starting at 10 am EST. The webinar will begin at 11:00 am EST (and may last until 12:30 EST).
To test if your system is compatible with ELLUMINATE LIVE, visit the Configuration Room linked on http://go.ncsu.edu/elluminate_config