December
2007

 

 

 

By
B. Rosie Lerner
 
Purdue
Extension
Consumer Horticulturist

 

 

 

 

 

12-06-07

Questions & Answers

Q. This winter, I was cutting down some trees that had poison ivy growing on them during the summer. I broke out in a rash, even though the poison ivy leaves were gone. Does poison ivy stay poisonous even after the leaves die? How do I remove the plants, even though they are already dead, without becoming contaminated? I am terribly sensitive to poison ivy and thought that I would be safe by waiting until winter.

A. The cause of poison ivy blisters, a compound called urushiol, is contained in the plant sap and can remain active even after the foliage dies back. The stems, trunks and roots will also contain urushiol, which can remain active for five years or longer. So even dormant and dead plants can contain irritating sap. Of course, covering the skin with gloves, clothing, etc., provides reasonable protection, but you can pick up contact with the sap from protective clothing and tools!

Though there are many tales and testimonials of various home remedies and products, according to the FDA, there is no proven, consistent way to inactivate the urushiol. For more information regarding poison ivy rash and prevention, see http://www.fda.gov/fdac/features/796_ivy.html. You might also consult an allergist for other advice on how to prevent/treat. 

Q. I have had a Norfolk Island pine for decades. It has always been healthy except periodically it has dropped off the bottom row of branches when it produces a new row of branches at the top. It is over four feet high, and I really don't want to lose it after all these years.

The tree had new growth at all of the tips of the branches and had a new row of branches at the top about six inches long already. A few weeks ago, I noticed that there was a mushroom growing at the base of the tree. I have never seen this occur before. I removed the mushroom and about a week later the tree looked slightly droopy. Another week later, the tips of the branches were drying out and the new branches were also looking dry. Three weeks after the mushroom appeared, the tree is definitely dying. I have tried plant food spikes, watering, misting, but nothing has worked. I am afraid I am too late to save this tree. Is there anything I can do to save it?

A. Mushrooms growing at the base of outdoor trees are commonly seen, but are not so common on houseplants. Mushrooms typically grow on decaying organic matter, so when they are seen growing on the trunk of a tree, it is an indicator of decaying plant tissue. Some fungi will enter an otherwise healthy tree through a wound or pruning cut and cause internal decay. Based on your description, your best bet to save the tree is to take a cutting and discard the old decaying trunk. Norfolk Island pine cuttings can only be taken from the top of the central leader stem; cuttings from the lateral branches will not form a new leader. You'll find more information about how to take cuttings at http://www.hort.purdue.edu/ext/HO-37web.html. More information on wood decay fungi is available at http://www.ppdl.purdue.edu/PPDL/weeklypics/8-29-05.html.

     

Writer: B. Rosie Lerner
Editor: Olivia Maddox,