Frequently Asked Plant Questions
Why is the black walnut tree toxic to tomatoes?
Black walnut trees are toxic to tomatoes and many other plants including: asparagus, cabbage, pepper, potato, apple, blueberry, blackberry, azalea, yew, columbine, lily, and petunia.
The black walnut tree releases a toxin called juglone from its roots, leaves, nuts, and branches. The soil directly beneath the tree canopy has the highest concentration of joglone, while the area surrounding the tree has a smaller concentration, but still enough to affect the plant. Plants affected by the black walnut toxin will show yellow foliage, wilting, and eventually death.
For more information, be sure to check out this publication from Purdue University on black walnut toxicity.
What can I do if I suspect that my ash tree has become infested with Emerald Ash Borer?
Depending on how much damage the emerald ash borer has done will determine what you should do once you notice something is wrong with your ash tree(s). If the tree is still healthy (less than 50% of the canopy has been lost) you can probably still save the tree using insecticides; however, if more than 50% of the canopy has been lost, you may not be able to save the tree.
Indiana, in cooperation with 12 other state agencies, Ontario, and Quebec, have put together a wonderful website called Emerald Ash Borer University. This website provides the latest information on Emerald Ash Borer including: what the emerald ash borer is, where it is found, methods to protect your ash trees, and much more.
When is the best time to plant my vegetables?
Purdue University has a great publication on when to plant your vegetables in your garden. DeKalb County's last freeze date in the spring is usually May 6-15 (zone D)and the first freeze date in the fall is between October 6-15 (zone F). You will want to follow the recommendations for each of the vegetables you want to plant based on these freeze dates (when you can first start to plant them to the last planting date to make sure you get a harvest before the first killing frost).
What do I do if my flowers aren't growing?
The first thing I would suggest would be to get a soil sample done in your gardens. Usually labs will run a test for around $20 and give you feedback on what is in your garden and what type of fertilizer to use. Purdue University has a great publication to show you the steps of taking a soil sample.
Next step would be to make sure there are no black walnut trees around because they can leach toxins into the ground that are poisonous to several plants (Black Walnut Toxicty publication). If there is a black walnut tree nearby, there are still several plant options that you can use.
There are many more possibilities behind why your flowers are not growing, but those are the first two things I would check when trying to figure out the problem.
Is this plant poison ivy?
Photo source: Sherrie Lowe and Patricia Grace, University of Florida
These leaves do belong to a poison ivy plant. Poison ivy can grow as a shrub or vine in Indiana. It's distinguishing characteristic is the set of tri-foliate leaves (three-clustered). For more information on poison ivy and other plants that can cause skin irritation, check out this publication from Purdue University's Weed Science Department on the "Don't Touch Me Plants".
What is an invasive plant and what invasive plants are in DeKalb County?
Invasive plants are plants that grow quickly and agressively, displace other plants as they spread, and are not native to North America. As of the last survey taken in Indiana in 2007, there are 60+ species of woody and non-woody plants that are invasive; at least 28 of those invasive species are found in DeKalb County.
For more information on all of the invasive plant species found in DeKalb County and Indiana, and how to get rid of them, you can visit Indiana's "Most Unwanted" Invasive Plant Pests website or the Indiana Department of Natural Resources Invasive Species website.