Boxwood Blight webinar Jan 5

See the message below from Dr. Kelly Ivors at NC State: 

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 recently found on boxwood in North Carolina, Virginia, and Connecticut.

This webinar will be geared towards agents and boxwood growers in North Carolina and adjacent states, but I am also inviting interested parties from any other state, especially those that produce boxwood, to participate.

There is no limit on attendence, so anyone can watch the webinar LIVE!

This ELLUMINATE session will also be the re-start of our regional SE ornamental / floriculture IPM webinar series, which will continue on a monthly basis in 2012.

I will speak for 45 minues on this new boxwood disease in the U.S., followed by questions from the audience- that means the session could go until about

12:30 pm EST or later if there are a bunch of questions. I am hoping to have representatives from both VA and CT as well and give them time to make additional comments and address concerns in their states.

We will record the webinar during the live session; it will be made available for viewing at anytime after the webinar at the same URL pasted below.

Here's how to participate in the webinar:

Before the webinar, click on the link below.

http://go.ncsu.edu/box_blight_webinar

You will be able to enter the session starting at 10 am EST on the day it occurs (for trouble shooting if necessary), but the actual webinar will not start until 11 am EST.

All that you need is an up-to-date browser and internet connection. We will run the webinar off of NC State's ELLUMINATE site licence, so you don't need a copy of the program yourself. In order to 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.

http://collaborate.extension.org/wiki/Elluminate_Tips

Looking forward to the webinar, and getting the information out!

Thanks,

K

Boxwood Blight

Paul Bachi, plant disease diagnostician at the UK Research and Education Center in Princeton, has made available two of his most recent presentations.  Visiti UKREC's YouTube channel for Paul's videos on:

• Pinewood nematode & pine wilt disease
• Boxwood blight

Nov-Dec issue of Fruit Facts is online

The Nov.-Dec. issue of Fruit Facts is posted on our Horticulture Web site in the pdf format at:

http://www.ca.uky.edu/fruitfacts/ 

Please note the 2012 Kentucky Fruit and Vegetable
Conference program scheduled for Jan. 5-6 and the advanced registration deadline of Dec. 20.

Articles:

Fruit Crop News

Upcoming Meetings

Welcome to UK’s Newest Extension Plant Pathologist

2011 Fruit and Nut Crop Summary

Fruit Pesticide Residues

Crown Rot of Strawberry Transplants

KY Fruit and Vegetable Conference

Receiving Fruit Facts Electronically on the Internet

KY Landscape Industries Winter Conference Jan 26-27, 2012

Each year the Kentucky Nursery and Landscape Association, Kentucky Arborists’ Association, Kentuckiana Greenhouse Association and University of Kentucky Cooperative Extension Service jointly sponsor the Kentucky Landscape Industries Winter Conference. The workshops at this event are designed to assist the green industry in Kentucky with key information to assist businesses remain viable in this time of shrinking dollars. Join us for an outstanding program featuring two full days of education on January 26-27, 2012 at the Kentucky International Convention Center in downtown Louisville.

More information at http://knla.org/http://knla.org/

Imprelis Herbicide Damage

It seems that newly symptomatic Imprelis-damaged trees are still appearing in landscapes across the region. The UK Plant Disease Diagnostic Laboratory and plant pathologists alike receive many questions concerning diagnosis and treatment  of these weakened plants. 

While damage can sometimes be confused with disease symptoms, the herbicide must be detected by special analytical chemistry laboratories.  The UK Plant Disease Diagnostic Laboratory specializes in detection of plant pathogens such as fungi, bacteria, viruses, and nematodes, not chemicals or herbicides.

Michigan State University has one of the few facilities with the capability of detecting herbicide residues in soils (www.pestid.msu.edu). Private labs may be available, but as of this posting, they are unknown to our group.

Additional information is available from Purdue University (http://www.ppdl.purdue.edu/PPDL/pubs/briefs/ImprelisLCO.pdf or ) and Dupont (http://www.imprelis-facts.com/wp-content/uploads/2011/10/Guidelines-for-Removal-and-Replanting-093011.pdf and http://www.imprelis-facts.com/letter-to-lawn-care-professionals/ ) concerning Imprelis-related issues.

Kentucky Pest News newsletter

The latest issue of Kentucky Pest News is now online at http://www.ca.uky.edu/agcollege/plantpathology/extension/kpn/current.html.

Downy Mildew of Grape: An Overwintering Pathogen

Downy mildew (Plasmopara viticola) is a major disease of grape here in Kentucky. Infection by this pathogen can weaken plants, infect fruit and buds, and reduce photosynthesis.

Downy mildew disease symptoms develop in spring during warm, wet weather when temperatures range from 65 to 75 degrees. Fungal masses then begin to grow across plant surfaces, infecting tissue along the way. Symptoms usually subside when summer temperatures become hot and dry, but the disease quickly returns when temperatures begin to drop again in the fall.  

The pathogen, however, does not disappear in winter. It can survive mild winters in infected dormant canes and begin to grow again in spring (sporangia).
During this time of year, the pathogen also generates specialized overwintering spores (oospores). Leaf litter on the vineyard floor creates the ideal environment for winter survival of these spores.

It is a misconception that downy mildew is a late season disease. Very early in the spring, when temperatures begin to creep into the 50’s, the overwintering spores germinate on the ground, new spores (zoospores) splash up onto vines, and infection occurs. This infection can remain inactive until temperatures rise above 65 degrees, and the disease cycle begins once more.

 Control of downy mildew begins with removal of leaf litter. This helps eliminate early sources of the fungus. Fungicides can be applied after harvest to destroy spore-producing fungi, and dormant sprays can be used before bud break to help eliminate any pathogen that may have overwintered in canes.

 Understanding a pathogen’s life cycle is the first step in maintaining a disease-free vineyard. Control of downy mildew before it becomes a problem is the best way to manage the disease.

Crown Rot of Strawberry

Strawberry growers in KY have reported losses of up to 25% in new strawberry plantings this month due to crown rot issues.  Incidentally, last month a commercial strawberry supplier announced possible shipments of transplants and plugs infected with the pathogen that causes Phytophthora crown and root rot.   Several Kentucky strawberry growers submitted plant samples UK Plant Pathology Diagnostic Labs for diagnosis of this crown rot disease. Meanwhile, many growers applied the Phytophthora-specific fungicide Ridomil to their fields.  In spite of the assumptions, diagnosticians confirmed that all of the samples had Anthracnose crown rot. 

Various pathogens can cause rapid loss of new transplants, and as we saw in this example, the diseases may have very similar symptoms.  Correct diagnosis is critical for effective control.  Below are brief descriptions of some common diseases of strawberry transplants.

 

1.       Anthracnose Crown Rot – caused by the fungus Colletotrichum fragariae.  Dormant spores can remain on plant tissue until ideal conditions arise.  Warm, rainy/irrigated, humid conditions cause the fungus to begin growing again.  Upon reinfection of plants, the fungus produces new growth and sporulates.  These spores splash up and infect crowns, as well as petioles, leaves, and fruit.  As crowns are infected, plants wilt and die suddenly.  If crowns are cut lengthwise, crowns are firm, and red streaking or marbling is apparent.   Roots usually appear healthy.  Abound (azoxystrobin), Cabrio (pyraclostrobin), or Pristine (boscalid + pyraclostrobin) are effective fungicides.  Control of this pathogen is important to reduce disease incidence in spring.  Apply fungicides as foliar sprays, through drip irrigation, or as a transplant dip according to label instructions.

2.       Crown Rot, Phytophthora Crown Rot – caused by the water mold Phytophthora cactorum.  Warm wet conditions, as well as poorly drained soil encourage infection. This pathogen causes crown and collar rots, leaf blights, and fruit rots in strawberry and various other plants.  Symptoms begin in the upper part of the crown, with youngest leaves wilting first.  Above ground symptoms appear before roots are affected.  Upon splitting the crown, inner tissue is extensively soft, brown, and necrotic.   Ridomil (mefenoxam) may be applied as a drench application, while Aliette or ProPhyt (phosphite) can be applied as foliar spray or transplant dip according to label instructions. 

3.       Red Stele – caused by the water mold Phytophthora fagariae.  This water mold requires wet conditions to establish and infect.  Cool wet conditions are ideal for this pathogen, at which time it can extend throughout root systems quickly.  Water runoff and farm implements can spread the pathogen from plant to plant or from field to field.  Roots begin rotting from the ends, infecting upward toward the crown.  Cutting roots lengthwise reveals the red-colored stele.  Do not plant strawberry where Red Stele occurred in the past.  When conditions become hot and dry, this pathogen can produce survival structures that are heat and fungicide resistant.  Applying Ridomil (mefenoxam) to soil before planting can eliminate a significant amount of inoculum.  Alternatively, Ridomil can be applied through drip irrigation systems shortly after planting.  Phosphites such as Aliette or ProPhyt are effective as transplant dips or as preventative foliar applications only.  Follow label instructions for rates and other application regulations. 

Disease management begins with prevention.  Purchase disease-free transplants.  In the event of disease, consider field conditions and symptoms, then contact your county agent for advice.  Keep in mind that proper diagnosis is critical for disease control.  Your agent can assist with submission of plant samples to the UK Plant Disease Diagnostic Lab.  More information on strawberry disease control can be obtained from PPFS-FR-S-05 and ID-44.

Soybean Cyst Nematode in Nurseries

Nursery growers who ship plant material across state lines should be aware of regulations enforced by national plant protection standards.  In Kentucky, one such regulated pest is the soybean cyst nematode (SCN). 

So, what if your nursery doesn’t grow soybean? 

 SCN can infest weeds in nurseries, which subsequently can be transported in ball-and-burlapped materials.  Exports to states such as Pennsylvania may require State Phytosanitary Certificates (www.kystateent.org).

Publication ID-110 provides more information on management recommendations for nurseries and common weed hosts of SCN.    

Bacterial Leaf Scorch symptoms in urban trees

Noticed leaf-browning and scorch-like symptoms on oak this summer?  Bacterial leaf scorch may be the culprit.   The disease bacterial leaf scorch is caused by Xylella fastidiosa, a xylem-inhabiting bacterium that affects water and nutrient transport into leaves and shoots.  Oak, maple, hackberry, dogwood, elm, mulberry, and sycamore are among the long list of hosts.  Pierce’s disease of grape is caused by a different subspecies of the pathogen. 

During the infection process, bacteria are transported from host to host by leaf hoppers, spittle bugs, and sharp shooter insects.  Once infected, bacteria move down branches; details of this transport through vascular tissue are not fully understood.  Once bacteria reach xylem (vascular) vessels, they multiply and are carried throughout the plant fairly quickly. 

Symptom development occurs in urban trees during the summer and fall.  Leaves emerge and develop normally in spring.  However, during mid to late summer, when water or heat stress is highest, water-stressed leaves begin to turn brown at the margins.  Yellow or purple margins may be visible in some hosts, as opposed to typical browning.  Leaves become increasingly more necrotic and fall prematurely from trees as summer progresses.  Each season, symptoms worsen, and disease spreads to additional branches.  This gradual decline is a distinct symptom of bacterial leaf scorch.  Typically, it may be 5 to 10 years after symptoms are reported that trees must be removed.

There is no cure for bacterial leaf scorch, as bactericides and injection treatments have proven inconsistent and overall unreliable long-term solutions.  In landscapes, newly symptomatic branches can be pruned to remove bacterium-infected limbs.  This method may help extend tree life, but will not completely eradicate the disease or pathogen.  Additionally, watering and preventing tree stress, especially during hot dry seasons, may help prolong tree life.  As soon as bacterial leaf scorch is confirmed, replace trees with non-susceptible hosts such as ash, beech, or tulip poplar.  Plant new trees early, so they will have time to mature before diseased trees are removed.  Refer to publication PPFS-OR-W-12 for a list of resistant and susceptible trees and contact your local UK Extension agent for assistance.