U of I Tree Disease and Pest Update: June 1, 2013

Monthly Summary

(Courtesy of Kelly Estes, State Survey Coordinator)

Average Temperature and Precipitation

Modified Growing Degree Days (Base 50⁰ F,  March 1 through May 30)

Station Location	Actual Temperature	Historical Average   (11 year)	One-Week Projection	Two-Week Projection
Freeport	465	447	556	675
St. Charles	484	425	568	679
DeKalb	489	492	587	711
Monmouth	537	546	639	767
Peoria	570	583	675	807
Champaign	614	597	725	863
Springfield	652	666	770	913
Brownstown	666	727	789	937
Belleville	705	760	830	971
Rend Lake	774	821	907	1063
Carbondale	763	777	890	1038
Dixon Springs	773	836	904	1056

GDD of Landscape Pests

GDD of Conifer Pests

 

Update from the U of I Plant Clinic 

 (Courtesy of Stephanie Porter, Diagnostician and Outreach Coordinator and 

Travis Cleveland, Pesticide Safety Education Specialist)

U of I Plant Clinic Website:  http://web.extension.illinois.edu/plantclinic/

U of I Plant Clinic Facebook Page:  https://www.facebook.com/UofIPlantClinic

Follow Stephanie Porter on Twitter @skporter

Similarly to previous springs, we are seeing many different issues with various species of spruce.  The problems that we often see at the U of I Plant Clinic are outlined in our Spruce Problems Fact sheet:  http://web.extension.illinois.edu/plantclinic/downloads/Plant%20Clinic%20Report%20Spruce.pdf

Unfortunately, we can commonly able find several diseases, spider mite, or abiotic issues on a single branch sample.  Thus far, we have had only one sample that was diagnosed with SNEED or Sudden Needle Drop (Setomelanomma holmii).  This sample was declining from other problems.  I fear that last summers drought stress, in addition to the recent above average, wet weather will be the perfect recipe for an infection of SNEED.  Field diagnosis of SNEED is not recomended. This disease should be confimed by a diagnostic laboratory. There are many other spruce problems (disease, spider mite, environmental, and cultural) that cause symptoms that may lead to confusion.  In addition, we often find many other black, fungal saprophytes on spruce branches that can be easily confused with the fungal structures of SNEED.  I have not heard of any new SNEED research, but the latest information on disease management is being reported from the Missouri Department of Conservation:  http://na.fs.fed.us/fhp/fhw/csfhw/nov03/sneeddetail.pdf

SNEED – Sudden Needle Drop (Setomelanomma holmii) found on Spruce

Stigmina needle blight is often found on spruce needles and can be easily confused with that of Rhizosphaera needle cast.  We do not yet know whether Stigmina is a pathogen on spruce. We do know that this Stigmina is associated with needle blight symptoms on stressed spruce.  It appears that North Dakota has been doing some preliminary research of Stigmina needle cast.  In their fact sheet, http://www.ag.ndsu.edu/cpr/forestry/needle-cast-diseases-of-spruce-diagnosis-and-treatment, they recommend the following:  "Timing of treatment for Stigmina needle cast is similar to Rhizosphaera, except preliminary data suggest that the trees should be treated indefinitely, with at least two properly timed fungicide applications per year."

We have recently diagnosed Verticillium wilt on elm.  Hundreds of plant species, including trees, shrubs, groundcovers, vines, vegetables, fruits, herbaceous ornamentals, and flowers may become infected. Some trees that are frequently infected by this disease are maple, ash, and elm. Symptoms can be seen throughout the growing season and include wilt, branch death, and quick decline of plants. Peel off some of the bark on a symptomatic branch and look for staining of the wood in distinct streaks of brown, dark green, or yellow-green wood. Verticillium-infected ash trees do not always show staining. There is no cure for Verticillium wilt. Still, there are many cultural and preventive strategies to manage the disease and help infected trees live with the fungus. Because the fungus remains in the soil even after removal of an infected plant, replanting with resistant varieties is a desirable control option.  Always start with healthy plants and avoid susceptible species. Supply balanced fertilization and provide adequate irrigation to improve the health of stressed plants.  If you have any questions on sampling or sample submission, please contact the U of I Plant Clinic at 217-333-0519.

Verticillium sp. isolated from an elm sample on PDA agar at the U of I Plant Clinic

As many of you already know, there has been an epidemic of fungal leaf blight diseases on many trees across the state, thanks to the conducive, weather conditions.   The majority of the leaf blight reports have been on maple.  For more information on the U of I Plant Clinic diagnosis of leaf blights of maple, you can refer to the recent Home, Yard, and Garden article, Maple Blight Mania:  http://hyg.ipm.illinois.edu/article.php?id=473

Invasive Species News from the Illinois Cooperative Agriculture Pest Survey (CAPS) Program

Monthly Summary (Courtesy of Kelly Estes, State Survey Coordinator) 

Storm Damage? Friendly Reminder about Moving Firewood 

The recent storms that have swept across the state have left destruction in their wake – including downed trees and limbs. I’m sure there will be lots of activity in across much of the state in the coming days. But, don’t forget the dangers associated with invasive species and moving this debris. There are many invasive insects and diseases that are found in firewood-gypsy moth, emerald ash borer, Asian Longhorned beetle, and thousand cankers disease are just a few. While they may not move far on their own, when people move firewood and debris, they can move hundreds of miles. This aided movement can spread these pests to areas where they were not present before.  If you are cleaning up fallen ash trees, please keep in mind there are federal and state regulations limiting the movement of ash and ash products in Illinois. Don’t forget to take a look for signs and symptoms of the emerald ash borer. Adults generally begin emerging from ash trees at the end of May. EAB activity will soon begin in many areas of the state; degree day accumulations indicate that emergence should be beginning.  Visit the Illinois CAPS blog for all the latest news on invasive pests in Illinois or contact Kelly Estes (kcook8@illinois.edu) with any questions.