Spruce Diagnostic Workshop

Thanks to the Illinois IPM Grant, I was able to develop a Spruce Diagnostic Workshop.  The first spruce diagnostic workshops were held at the Gardeners' Big Day at Dixon Mounds, Lewistown, Illinois.

The workshop was designed to bring awareness to home gardeners that over the last several years, we have been seeing many spruce issues in Illinois at the U of I Plant Clinic.  This is largely due to the fact that spruce are not a native to our area.  They prefer moist, well drained sites (sandy soils, hilly, or mountainous terrain) and NOT poorly drained or clay soils!  Spruces do not do well in hot and dry conditions.  Sometimes spruce problems do not start to develop until roots outgrow the area, grow into poor soil, or until weather stress aggravates the situation. Without adequate growing conditions or a proper site, spruce trees can become more susceptible to pests!  The Colorado Spruce (known to most as the "blue spruce") seems to have the most problems!

I also wanted to make participants aware that a single spruce tree could be diagnosed with many problems.

In my diagnostic workshop, everyone was given a factsheet with pictures and descriptions of the following spruce problems:  site issues, climate problems, herbicide injury, nutrient stress, Rhizosphaera needle cast, Stigmina needle blight, root and butt rot, Cytospora canker, SNEED (Sudden needle Drop), Spruce adelgid galls, Spruce spider mite, and Bagworms.

Next, I set up 8 spruce diagnostic stations with examples of Illinois spruce problems listed on the factsheet.

Each participant was given a spruce diagnostic activity sheet. By working in groups, they were told to visit each of the 8 spruce diagnostic stations and answer the questions on the spruce diagnostic activity sheet by using the spruce fact sheet as a guide.

This Diagnostic workshop help the participants to learn the following:

• The diagnostic and management differences between Rhizosphaera needle cast and Stigmina needle blight
• How to scout and identify spruce spider mites as well as identify the correct time to treat for these pests
• The diagnostic signs of Cytospora canker and how to properly manage this disease
• How to identify bagworms and adelgid galls as well as how to properly manage these pests
• The symptoms and sources of spruce nutrient problems
• How to properly check for spruce site problems
• How to recognize SNEED symptoms as well as knowing that SNEED has not been proven to be a disease and it can only be diagnosed by a trained diagnostician by properly identifying their ascospores
• How to recognize herbicide injury symptoms on spruce and to be very, careful when handling herbicide complaints.  We need to remember to rule out all other possible causes for similar symptoms as well as have the proper resources to help determine if herbicide is to blame.

Question: Do you recommend a one time fungicide injection treatment for apple scab?

Answer:  We first want to promote basic IPM and recommend using resistant crabapple varieties.  Here is a link to "Recommended Crabapples for Illinois Landscapes" : http://extension.illinois.edu/IPLANT/plant_select/trees/Selecting_Crabapples.pdf

If the ornamental, crabapple is highly, susceptible to apple scab, you may even consider replacing the tree.

Raking up leaves will help a bit, but most of the time, if the tree is susceptible, it may not be able to escape apple scab infection.

When we give apple scab recommendations, we always give recommendations from the University of Illinois Home, Yard, and Garden Pest Guide as well as the University of Illinois Commercial Landscape and Turfgrass Pest Management Handbook.  Various protectant fungicides are listed and applications should begin when leaves to emerge from buds (1/4 inches green) and continue at labeled intervals until 2 weeks after petal fall.

I found a paper where they did some research on injections to prevent apple scab:
http://onlinelibrary.wiley.com/doi/10.1111/j.1744-7348.2005.00019.x/pdf
They had good results with the fungicides applied in this research; however, none of these fungicides are registered in Illinois.  With injections, we worry about repeated injury to the tree and the possibility of other plant pathogens being able to enter through these wounds.  In this research, they found that the trees healed or callused fairly quickly, which is good to avoid problems.  But, this may not always be the case.  Also, what are the long term effects to trees from injections?

At this time, the only injectable fungicide registered in Illinois for ornamental crabapple for leaf diseases is Alamo (Propiconazole) and it is applied by macro injection.  This is not an option for apple tree or food crops.  The University may recommend this type of systemic fungicide application for crabapples infected with apple scab in "sensitive areas" or areas where fungicide drift could be an issue in the environment.  For example, a sensitive area may be crabapple trees near a pond with fish.  But, most of the time, if basic pesticide safety is practiced or fungicide applications are made during reduced wind speeds, drift should not be an issue.

Therefore, in most instances, injections to prevent apple scab or leaf disease is not recommended.
(Stephanie Porter and Travis Cleveland)

Boxwood Blight Information (Not found in Illinois)

This blog is in response to all the questions that I have been receiving about a newly discovered disease in the US called Boxwood Blight (Cylindrocladium pseudonaviculatum).  This disease has not been found in Illinois, but has been found in other locations in the US:

Date Confirmed  in  US          Location___

10/26/2011                 Surry County, North Carolina

10/26/2011                 Middlesex, Fairfield, Hartford,  
                                    New London Counties,  
                                    Connecticut

11/01/2011                 Carroll County, Virginia

12/13/2011                 Providence County, Rhode Island

12/14/2011                 Prince Georges County, Maryland

12/19/2011                 Barnstable County, Massachusetts

12/20/2011                 Washington County, Oregon

12/23/2011                 Westchester County, New York

1/24/2012                   Lancaster County, Pennsylvania
3/26/2012                   Lake County, Ohio

 Detection:  http://www.nh.gov/agric/divisions/plant_industry/boxwood-blight.htm

Survey Status of Boxwood Blight; Leaf and Stem Blight

 http://pest.ceris.purdue.edu/map.php?code=FBBJCXR

Boxwood Blight (Cylindrocladium pseudonaviculatum) 

History:

•This disease was 1st described in UK –mid 1990’s

•2002 found in New Zealand and disease was named in UK

•Since 2002, this disease was reported throughout Europe

Host: Buxus species

1). Initial Symptoms dark to light brown spots/lesions on leaves.  Leaves turn brown/straw colored and defoliation occurs quickly

2). Also infects stems with distinctive dark brown to black lesions (leads to plant death)

3.)  Does not appear to affect roots

CONSIDERED A SERIOUS DISEASE

Key: DETECTION and DESTROY
Fungicides do not appear promising, but research is ongoing

If you suspect this disease on boxwood, please send a sample to a NPDN Plant Diagnostic Lab near you.

For additional information and pictures of Boxwood Blight, here is a list of informational websites:

Boxwood Blight -A New Disease for Connecticut and the US

 NPDN Pest Alert A Boxwood Blight New to the US, Cylindrocladium pseudonaviculatum 

Boxwood Blight - A New Disease of Boxwoods  

NC Pest Alert - "The Box Blight" 

A Boxwood Blight - New to US 

The "Box blight" pathogen 

Boxwood Blight 

Boxwood Blight Alert 

A Double Coconut Palm Problem in Illinois?

No, it is not very, often that we receive a palm sample at the U of I Plant Clinic.  We are used to seeing corn and soybeans, as well as spruce, pine, oak, maple, and other tree problems. But, recently, we received a sample of a double coconut palm from a conservatory.

This palm has been declining since at least July (These pictures were taken in July 2011), but recently symptoms have appeared to be serious. This client submitted leaf and root samples to the University of Illinois Plant Clinic.  The double coconut sample submitted to the U of I Plant Clinic was examined for the presence of disease pathogens as well as signs of insects and none were found on the sample submitted.  The root sample that was submitted did not appear to be rotted.  The problem was concluded to be abiotic (no disease). 

I am very, fortunate to have received help from University of Florida– IFAS,  Fort Lauderdale Research and Education Center experts such as Monica L. Elliott, Ph.D. and Timothy Broschat, Ph.D.  After receiving pictures as well as soil/tissue nutrient analysis, they provided the U of I Plant Clinic with the following information:

"The leaf that has already expanded has physiological issues.  In photo “A”, there is a yellow clear line across the entire expanse of leaf about half way down from the leaflet tips – that is an indication of a one time stress during the leaf development – could be cold, could be very mild boron deficiency – hard to say exactly the problem.  These palms are very, very slow growing.  I don’t remember how many leaves they produce a year, but it isn’t very many, so a leaf is in development for months, not days.  The necrotic leaflets on the one side of the expanded leaf are physiological, not pathogenic – but it is difficult to know exactly what caused the damage.  Same for most of the necrotic leaflet tips on the younger, expanded leaf.

Picture A- showing "yellow clear line across the entire expanse of leaf about half way down from the leaflet tips"

The leaf that is emerging in photo “B”:  those spots could very well be pathogenic in origin.  Usually, when I see a halo around a lesion, I suspect pathogen and not physiological.  But, as shown, I can draw a diagonal line through those “spots”, which again is more likely to be indicative of physiological than pathogenic cause.  And, you can observe necrotic leaflet tips, which would be physiological and not pathological." -Monica L. Elliott, Ph.D.

Photo B- "showing a diagonal line of “spots”

"I had responded earlier about the soil and leaf analyses not suggesting anything nutritional, but after seeing these photos, I agree with Monica that this looks physiological.  This is not typical of phytotoxicities, which tend to result in marginal or tip necrosis on all, but the youngest leaf or if systemic, distortion, or tip necrosis of the spear leaf.  This suggests to me a possible temperature problem though it is not typical chilling injury, which affects older leaves more than the newly emerging leaf.  Perhaps cold irrigation water?  These symptoms are similar to something that was common on Dracaena marginata back in the early 1980s, but after years of working on it, we were never able to pinpoint its cause.  We were able to rule out nutritional deficiencies such as boron and calcium, which would be the most likely candidates." - Timothy Broschat, Ph.D.