Monday, April 21, 2014

The Naked Truth: Trees

Happy Spring! It’s been a month since the spring equinox and it’s finally starting to warm up and, more importantly, green up. Crocuses, snowdrops, daffodils (and early-season weeds) are blooming and the pussy willow is in full flower.

Tree buds are fully swollen and many of the maples are in bloom. While we’re waiting for trees to leaf out, this is the perfect time to examine trees “in the buff.” We can check for damage to limbs and branches that will become hidden once the leaves cover the tree.

Here are two examples of common twig problems from a recent walk:

OAK TWIG GALLS



The balls decorating the twigs of this mature oak tree are galls caused by a variety of parasitic wasps. There are a number of types of galls, caused by an even greater number of species of tiny wasps. The two most common twigs galls in our area are horned oak galls and gouty oak galls.

Galls are tumor-like structures and they’re formed of tree tissue. Tiny, non-stinging wasps induce the tree to form galls which act as protection for the wasp eggs and developing larvae. While they may not be aesthetically pleasing, they usually aren’t harmful to healthy, well-established trees. The galls can be pruned out of the tree, though that quickly becomes impractical as the tree grows. The general recommendation for oaks infested with galls is to maintain good tree health through watering during dry periods, fertilizing when necessary, and responding quickly to other insect or pathogen problems.


WITCH'S BROOM



This picture shows the crown of a majestic sycamore tree. The arrows indicate portions of branches where a proliferation of slender, closely-spaced twigs arise. These bunches of twigs are known as witch's brooms. They are caused by a fungal disease known as anthracnose. Anthracnose is a very common disease and can affect a wide variety of plants, though it doesn’t always cause witch's broom in other hosts. In sycamores, anthracnose can also cause lesions on leaves and cankers on branches.

The twigs in witch's brooms tend to be thin and poorly-spaced; as a result, they don’t leaf out well and tend to break easily. Much like the oak galls, witch's brooms usually won’t cause too much injury to a healthy, mature tree. Management includes sanitation, or the removal of infected plant tissue (in this case, raking and bagging or mowing leaves and twigs affected with anthracnose), and maintaining good tree health.


OTHER ISSUES

This is also a good time to look for limbs damaged by wind or ice over the winter. Dead or damaged limbs, branches that are crossing and rubbing against another branch or the trunk, or ones that attach to the tree at a small angle, need to be pruned out of the tree to ensure good tree health. Make sure to prune correctly, leaving the collar around the branch intact to allow for proper wound healing. 

Sunday, April 20, 2014

New blogger

Hi plant lovers! My name is Diane, and I'll be taking over blogging duties for the next few months. I just wanted to take a moment to introduce myself:

I'm a Horticulture Educator with the University of Illinois Extension, serving Champaign, Ford, Iroquois, and Vermilion counties. I grew up in central IL and received a bachelor's of science in Crop Sciences from the University of Illinois, and a master's of science in Plant Pathology from the Ohio State University. I worked at the University of Illinois Plant Clinic as an undergrad and after completing my MS. I'm spending several days a week at the Plant Clinic this summer as the acting diagnostician. My passions in life include plant pathogens and my two pet rabbits (who, when they go outside, quickly become plant pests).

I love spending time outdoors. Nature is a complex and beautiful thing and every day can be an adventure. Regardless of if we're spending time in a forest or walking to our cars, nature is all around us.

Friday, February 21, 2014

The Most Popular U of I Plant Clinic Blog Posts

The University of Illinois Plant Clinic has been blogging since 2011 and provided 87 blog posts.  By posting blogs to the U of I Facebook page and Twitter, we are able to provide timely information about topics of interest.  It is always interesting to analyze our blog's stats and see what topics have been the most popular.  Here are the 10 most popular blog posts to date.  Click on each title to read each blog - Enjoy!

 

1.)  How We Identify Corn Leaf Diseases at the U of I Plant Clinic

 

2.)  Will the Oak Galls Kill my Tree?

 

3.)  A Few Tomato Diseases Seen at the U of I Plant Clinic

 

4.)  Spruce and Pine Damage - (Herbicide or Environmental Factors)

 

5.)  The Difference Between Bacterial and Fungal Plant Pathogens

6.)  Downy Mildew on Impatiens in Illinois

 

7.)  So, You Want to Grow Grapes......

 

8.)  Eastern White Pine + Drought = Problems

 

9.)  App Attack:  Mobile Device Apps that can Aid IPM and Plant Identification

 

10.)  Everyone is Talking about Corn that has Turned White.....

Monday, February 10, 2014

Top 10 Problematic Trees of Illinois in 2013

Based on Plant Clinic sample submissions and questions, the following trees were considered to be the most problematic in 2013:



*The chart above does not include nematode sample data







(Links below provide further information on disease, insect, as well as abiotic threats discovered on each tree in 2013.)


#10. Crabapple
 Cedar apple rust:  http://hyg.ipm.illinois.edu/article.php?id=482
 Apple scab:  http://urbanext.illinois.edu/focus/applescab.cfm

#9.  Juniper
 Phytophthora Alert:  http://universityofillinoisplantclinic.blogspot.com/2013/06/phytophthora-root-and-crown-rot-alert.html

#8.   Arborvitae (Cedar)
Phytophthora Alert:  http://universityofillinoisplantclinic.blogspot.com/2013/06/phytophthora-root-and-crown-rot-alert.html

Browning of Evergreens:  http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/agdex4144
Conifer Dieback:  http://www.ppdl.purdue.edu/ppdl/pubs/briefs/conifer-dieback.pdf

#7.  Ash (excluding Emerald Ash Borer issues)
EAB:   http://hyg.ipm.illinois.edu/article.php?id=464
Ash Anthracnose:   http://hyg.ipm.illinois.edu/article.php?id=470

#6.  Ornamental Pear
Pear blights:  http://hyg.ipm.illinois.edu/article.php?id=490

#5.  Elm 
Verticillium wilt:  http://hyg.ipm.illinois.edu/article.php?id=518

#4. Pine
Eastern White pine + Drought = Problems
http://universityofillinoisplantclinic.blogspot.com/2013/03/eastern-white-pinte-drought-problems.html

#3.  Maple
Maple leaf blights:  http://hyg.ipm.illinois.edu/article.php?id=473
Taphrina diseases:  http://hyg.ipm.illinois.edu/article.php?id=478
Maple early fall color:  http://www.dnr.state.mn.us/fid/august97/08259704.html

#2.  Spruce
U of I Plant Clinic Report on Spruce Problems:  http://web.extension.illinois.edu/plantclinic/downloads/Plant%20Clinic%20Report%20Spruce.pdf

and the number one problematic tree of 2013:

#1.  Oak
Taphrina diseases:  http://hyg.ipm.illinois.edu/article.php?id=478
Oak wilt:  http://hyg.ipm.illinois.edu/article.php?id=506
Bacterial leaf scorch (BLS):  http://hyg.ipm.illinois.edu/article.php?id=513
Bur Oak Blight (BOB):  http://hyg.ipm.illinois.edu/article.php?id=537
NEW U of I Plant Clinic Report on Oak Problems:  http://web.extension.illinois.edu/plantclinic/downloads/Plant%20Clinic%20Report%20Oak%20LO.pdf