Tuesday, January 8, 2013

Significant Invasive Plant Disease and Insect Events and Noteworthy News from 2012.

First Finds & First Submissions, New Leadership & New Sites
A Look Back at Notable Events of 2012
(Taken from NPDN Newsletter:  Volume 7 Issue 11, December 2012)

Rachel McCarthy, Department of Plant
Pathology and Plant Microbe-Biology,
Cornell University
Last year ended with the announcement of some rather significant news. APHIS confirmed that boxwood blight, caused by the pathogen, Cylindrocladium pseudonaviculatum, was present in North Carolina, Connecticut and Virginia. This news created a stir in several of our labs and a buzz throughout the network, because it was the first time it had been confirmed in the United States. 

As 2012 draws to a close, let’s take a moment to reflect on some other significant events and noteworthy news from the year. In January 2012, Maryna Serdani, Department of Botany and Plant Pathology, Oregon State University (OSU), reported butternut to be a new host for thousand cankers disease and the walnut twig beetle. Suspect black walnut branch samples with signs of the disease and the beetle vector were dropped off at the OSU Plant Clinic. Scientists confirmed that the branches were those from a butternut, Juglans cinerea, and not a black walnut, Juglans nigra. The Oregon Department of Agriculture confirmed the beetles to be Pityophthorus juglandis and the OSU Plant Clinic recovered Geosmithia morbida, from the canker margins. This was the first time G. morbida and P. juglandis were detected on butternut in North America. 

On January 13, the Texas Department of Agriculture and USDA-APHIS confirmed the first detection of citrus greening in Texas. The disease was discovered in a tree in a commercial orange grove in San Juan. Texas is the second-leading state in grapefruit production and ranks third in orange production with approximately 28,295 acres in commercial citrus production in the Rio Grande Valley.

In February, APHIS announced that eight new plants – Ilex cornuta, Illicium parviflorum, Larix kaempferi, Magnolia denudate, Mahonia nervosa, Molinadendron sinaloense, Trachelospermum jasminoides, and Veronica spicata syn. Pseudolysimachion spicatum would be added to the list of Phytophthora ramorum regulated articles as of March 1, 2012. Inaddition, APHIS moved Cinnamomum camphora species from the associated host list to the proven and restricted host list based on new information received from the state regulatory agency in California. These changes brought the total regulated hosts for P. ramorum to 137.

In early March, APHIS, in cooperation with the California Department of Food and Agriculture, expanded the regulated area for the Asian citrus psyllid (ACP) in California. The detection of ACP in San Clemente, California, resulted in expansion of the ACP regulated area to include the Camp Pendleton area of San Diego County. APHIS applied restrictions on the interstate movement of regulated articles from the expanded regulated area that are parallel to the intrastate quarantine that had been previously imposed by CDFA. ACP is considered to be present only in some areas in California and subject to official control via parallel State and Federal quarantines. 

On March 16, APHIS announced a revised Federal Order to expand the regulated area in Florida for Guignardia citricarpa, the causal agent of citrus black spot (CBS). Due to additional detections of CBS during ongoing surveys by APHIS and the Florida Department of Agriculture and Consumer Services, Division of Plant Industry, the regulated area was expanded by eight sections in Collier County and 31 sections in Hendry County. 

APHIS launched the new Hungry Pests website in April and announced that the month will be dedicated to sharing information about the threat invasive plant pests, diseases and harmful weeds pose to America’s fruits, vegetables, trees and other plants — and how the public can help prevent their spread.
On May 24, Agriculture Secretary Tom Vilsack announced that the U.S. Department of Agriculture will support 321 projects in all 50 states, plus American Samoa and Guam. The 2012 Farm Bill submissions aim to prevent the introduction or spread of plant pests and diseases threatening U.S. agriculture and the environment.
On June 15, APHIS announced the first detection of South American palm weevil (SAPW), Rhynchophorus palmarum, in the state of Texas. APHIS previously confirmed the detection in Alamo, Texas on May 3. This detection was the result of a multi-state delimitation survey initiated in response to detections of SAPW in California in 2011. 

On May 11, 2012, a second SAPW was detected in the same general geographic area of Alamo, Texas. Both detections were found within 5 miles of the U.S.–Mexico border. In July, regional access to data within the National Repository was opened up to several users across the NPDN network. This level of access provides users the ability to view reports, maps and charts for their entire region. One of the greatest benefits of regional access is the daily first submission by state e-mail report. This e-mail report represents pest/pathogens by state that have been uploaded to the National Repository as confirmed for the first time.

On August 6, Dr. Jeff Jones, SPDN Director and Professor of Plant Pathology at the University of Florida,assumed the role of NPDN Executive Director and on September 1, Dr. Marc Fuchs, Associate Professor of Plant Pathology and Plant Microbe-Biology at Cornell University officially replacedDr. George Hudler as the NEPDN Director.

In October, the British environmental secretary announced a ban on the importation of all ash into the U.K. as reports of trees showing symptoms of ash dieback disease caused by the fungus Chalara fraxinea have popped up across the country. Ash dieback disease has been moving across mainland Europe with countries like Denmark reporting losses of up to 90% of their ash trees. In February 2012, ash dieback disease was found in British nursery tree stocks, but the new reports in October represented the first occurrence of the disease in a natural area in the UK.

Monday, January 7, 2013

Spruce Windbreak Problems

Norway Spruce, Richard Webb, Self-employed horticulturist, Bugwood.org
Every year, I receive many questions on spruce windbreaks.  These windbreaks appear to be declining either due to disease, spider mites, environmental issues, cultural issues, or all of the above.  First of all, we always suggest that you submit a sample of the affected branches to our Plant Clinic for an analysis.  For more information, you can go to the U of I Plant Clinic website:  http://web.extension.illinois.edu/plantclinic/  If you have questions about your problem or the sample process, you are always welcome to call (217) 333-0519.

Spruces are generally native to cooler regions and are adapted to cold conditions. They prefer full-sun locations with acidic and well-drained soils. Improper planting techniques as well as plantings in inadequate sites can be detrimental to spruce health. When exposed to unfavorable cultural or environmental conditions, spruce can become stressed and more susceptible to diseases and pests. 

Recently, we released a U of I Plant Clinic Report on Spruce Problems (Pest and Cultural Issues). 

It includes pictures and brief descriptions of spruce cultural issues as well as the most common disease, insect, and spider mite problems that affect spruce each year in Illinois.  It can be found at the following link:  http://web.extension.illinois.edu/plantclinic/downloads/Plant%20Clinic%20Report%20Spruce.pdf

Next, if you continue to have problems with windbreaks, please go to the Illinois Windbreak Manual, which can be found at the following link:  http://web.extension.illinois.edu/forestry/iwm_complete.pdf 
This manual is a great resource.  Some of the helpful information that I often pass on to others from this manual:
  • Most Illinois windbreaks will only last 40 to 50 years.  Once they mature, they can decline and lower branches can die.
  • Thinning a closely spaced windbreak needs to be done to promote individual tree formation and to discourage death of lower branches.
  • It is not good to plant entire windbreak to one species.  Monocultures can encounter serious problems with disease and insects pests and lack of variety of texture.
  • Same species should be planted in the same row - minimize shading problems for trees that don't grow as quick as neighboring trees in adjoining rows.
  • Remember to maintain, care, and protect your windbreak!
-Control competing vegetation
-Control disease and insect
-Protect from grazing livestock
-Correct Pruning
-Replant or renovating windbreak when necessary

Thursday, January 3, 2013

Emerald Ash Borer - Illinois First Detector Tree Pest Program


 The Emerald Ash Borer (Agrilus planipennis), or EAB, has been gradually making its way across the continental US since 2002. This beetle has killed millions of ash trees to date and poses a threat to all communities where ash grows. Originating from Asia, these small, green jewel beetles pose a serious threat to ash trees across the states. EAB has been reported in Canada as well as Michigan, Illinois, Indiana, Iowa, Kentucky, Maryland, Minnesota, Missouri, New York, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia, and Wisconsin. The EAB has a 1-2 year lifecycle. Adult females lay eggs on the tree and within 1-2 weeks the larvae emerge and bore through the bark and into the cambium. This is the nutrient-rich area just under the bark. Larvae feed laterally around the tree, girdling it and preventing nutrients from travelling up through the tree. Signs of infestation start with thinning of the upper canopy. Up to half of the canopy may be destroyed after a few years of infestation and the tree may be killed after about six years. Epicormic shoots will appear in the branch collars of the tree and around the base. EAB prefer to attack stressed or damaged trees, but will also infest healthy trees. Due to the severity of the problem, much is being done to prevent the spread of EAB. There are many public ad campaigns discouraging people from moving wood out of the county of its origin to reduce the spread of this and other borers. Federal and State agencies as well as Universities are working with the public to prevent the spread of the Emerald Ash Borer.
 (Rachel Kirchoefer and Phil Nixon)

Early detection and response is key to managing invasive pests. The Illinois First Detector Workshops are aimed at improving first-detector training and invasive species awareness. Plan to attend these workshops focusing on current and emerging invasive forest pests in Illinois. Each location will have sessions devoted to the emerald ash borer, thousand cankers disease, and invasive plants. In-depth training sessions will highlight identification, symptoms, management, and much more!

Registration for this program will be handled by various University of Illinois Extension host sites.  You can easily register via the Extension links and contacts listed below. 

February 12 – Springfield, IL –Springfield Extension Office
Hosted by University of Illinois Extension Logan-Menard-Sangamon Unit
(Registration will be open until February 5th.)
Contact:  Jennifer Fishburn- fishburn@illinois.edu

February 26 – Moline, IL -Deere-Wiman Carriage House
Hosted by University of Illinois Extension Henry-Mercer-Rock Island-Stark Unit
(Registration will be open until February 26th.)
Contact:  Martha Smith -smithma@illinois.edu or Tracy Mulliken- tmully@illinois.edu

March 7 – Mt. Vernon, IL –Jefferson County Extension Office
Hosted by University of Illinois Extension Bond-Clinton-Jefferson-Marion-Washington Unit
(Registration will be open January 22nd until February 28th.)
Contact:  Chelsie Keene- ckeene@illinois.edu

March 14 – Collinsville, IL – Collinsville Extension office
Hosted by University of Illinois Extension Madison-Monroe-St. Clair Unit
(Registration will be open January 7th until March 8th and cash, check, and charge accepted.)
Contact:  Sarah Ruth- ruth1@illinois.edu

March 21 – Champaign, IL – Champaign Extension Office
Hosted by University of Illinois Extension Champaign-Ford-Iroquois-Vermilion Unit
(Registration due by March 18th. No refunds after March 20th.)
Contact:  Sandy Mason- slmason@illinois.edu

March 26 – Lemont, IL- Midwest Golf House (*FULL)
Hosted by University of Illinois Extension Cook County
(Registration will be open December 1st until March 17th.)
Contact:  Greg Stack -gstack@illinois.edu

April 4 – Lemont, IL- Midwest Golf House
Hosted by University of Illinois Extension Cook County
(Registration will be open until March 26th.)
Contact:  Greg Stack -gstack@illinois.edu

A $25 registration fee covers on-site lunch and training materials. No registration at the door. If you do not cancel prior to the workshop, and do not attend, there is no refund.
All workshops 9:00 AM - 3:00 PM

*Each Workshop is worth
4.0 Continuing Forestry Education Credits
4.25 Continuing Education Credits (CEU’s) for IAA Certified Arborists

Questions:  Contact Stephanie Porter at satterle@illinois.edu

Wednesday, January 2, 2013

Honeylocust knot or galls - Call for more research

Question: "I was wondering if you know of any treatment for Honey Locust Knot? Or what is your suggestion to deal with that problem. I have a client that has 7 Honey Locust tree's that are clearly infected with this Knot" -Arborist from Maryland

Picture of a honeylocust sample received at the U of I Plant Clinic with galls on branches.

Picture of a honeylocust sample received at the U of I Plant Clinic with galls on branches.

You recently emailed Nancy Pataky with a question about honeylocust knot.  She is now retired and she has forwarded your email to me.  Honeylocust knot can be tricky, as to my knowledge, the cause has not been proven by research.  In my recent investigation on this topic, I have found that there could be many different causes for “knots or galls” in honeylocust.  You first need to rule out chemical/herbicide use near these trees.  For example, the herbicide, Imprelis (no longer sold), has been found by Midwest plant diagnosticians to cause knots in honeylocust.  Insects and bacteria are also some other causes for honeylocust galls.

We rarely see these honeylocust galls in Illinois, but when we did, we did not find any evidence of chemical or insects in the galls; therefore, Nancy Pataky suspected a bacterial cause.  She wrote about this topic in the U of I Home, Yard, and Garden newsletter:  http://hyg.ipm.illinois.edu/pastpest/200805a.html . Nancy Pataky’s theory of bacterial (Pseudomonas savastanoi) formed galls was based on research from the Ohio State:  http://ohioline.osu.edu/sc189/sc189_55.html . If you read this bulletin from the Ohio State, they had reports of this disease mainly in the Midwest, but also in Maryland.  The spread of the bacterium was thought to be caused by the lack of sanitation during hand pruning and the trees eventually died.  In this newsletter article, Nancy Pataky mentions that a plant pathology student at the Ohio State was beginning a new project on this problem; however, we have since learned that the funding was lost. 

We have an Agdia plant diagnostic listserve, a great resource for plant diagnosticians across the US to discuss problem plant samples. Here are some recent posts about honeylocust galls:

“Several years ago (2003ish) while working in Maryland, we found galls on honeylocust.  I'm surprised that this link is still active, but you can look at some images:  http://www.mda.state.md.us/sc/plants-pests/plant_protection_weed_mgmt/new_pest_detections_md_nurseries_-s2.php .  We called it honeylocust gall or knot.  The problem was on Shademaster and Skyline honeylocust and we found it both in the landscape and at a nursery.  It was present on the landscape trees for multiple years and eventually killed many of the trees.  At that time, I did some research and there was an article on the internet that suggested that Pseudomonas savastanoi was the cause.  I sent samples to Ohio State.  I do not know if they ever confirmed if this was the cause or what the status of the research is at this time.”

Another plant diagnostician that had a honeylocust sample with galls reported the following on the diagnostic listserve: “We had a similar case and could not rule out gall midge.  An entomologist thought it might be Neolasioptera brevis, but we had no direct evidence.” 

Since the release of Nancy Pataky’s article, I have received inquiries and reports about galls on honeylocust.  For example, a Canadian plant diagnostician has reported, “We had one honey locust sample came in the middle of July showing exactly the same gall symptoms. After one month's moist chamber incubation, some Lepidopteran larvae (Family Pyralidae,snout moths) came out from the galls. I have seen reports on locust twig borer (Ecdytolopha insiticiana) but our entomologist insisted that what we got were not the same.”

Therefore, if we are not sure of the cause, we can’t be sure of a treatment.  I would suggest that you send a sample to your local Plant Clinic.

I would also suggest that you rule out chemical/herbicide issues.  Next, I would try to cut into a gall and check for signs of insects.  If you suspect that this is a bacterial induced gall problem, please be sure to sanitize your pruners after each cut.   I am sorry, but, unfortunately, I have no other management suggestions besides keeping the tree in good health by fertilization and watering during times of drought.   

Please let me know if you know of any recent research done on honeylocust knot or gall. 

Stephanie Porter