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Ask the ISU Experts

White Pine Tree

Note to media editors: Got gardening questions? Call the Hortline at (515) 294-3108, Monday-Friday from 10 a.m. to noon and 1 to 4:30 p.m., or e-mail us at hortline@iastate.edu. For more gardening information, visit us at Yard and Garden Online, http://www.yardandgarden.extension.iastate.edu


I have noticed that the inner needles of several pines have turned yellow and begun dropping to the ground.  Is this a problem? 

The loss of needles is probably due to seasonal needle drop. Deciduous trees, such as maple and ash, drop all of their leaves in fall. Though it largely goes unnoticed, evergreens also lose a portion of their foliage (needles) on a yearly basis. Seasonal needle drop on most evergreens occurs in late summer or early fall. Needle loss is most noticeable on white pines. As many as one-half of the needles on white pines may drop in late summer/early fall. Seasonal needle loss is less noticeable on spruces, firs and other pines as they retain a higher percentage of their needles. Seasonal needle drop is uniformly distributed throughout the inner part of the evergreen. The oldest needles are shed. The needles turn uniformly yellow or brown and drop to the ground. 


I would like to save some of my geraniums. How do I go about taking cuttings? 

Using a sharp knife, take 3 to 4 inch stem cuttings from the terminal ends of the shoots. Pinch off the lower leaves, then dip the base of each cutting in a rooting hormone. (Rooting hormones are available in liquid or powder form and can be purchased at garden centers and mail-order nurseries.) Stick the cuttings in a rooting medium of coarse sand or a mixture of coarse sand and sphagnum peat moss.


Clay or plastic pots with drainage holes in the bottom are suitable rooting containers. Insert the cuttings into the medium just far enough to be self-supporting. After all the cuttings are inserted, water the cuttings and medium thoroughly.


After the medium is allowed to drain, place a clear plastic bag over the cuttings and container to prevent wilting of the cuttings. Then place the cuttings in bright light, but not direct sunlight. The cuttings should root in six to eight weeks. When the cuttings have good root systems, remove them from the rooting medium and plant each rooted cutting in its own pot. Place the potted cuttings in a sunny window or under artificial lighting. 


When can I stop mowing the lawn in the fall? 

Continue to mow the lawn until the grass stops growing in the fall. The foliage of cool-season grasses, such as Kentucky bluegrass, stops growing when daytime high temperatures are consistently below 50 degrees F. In central Iowa, bluegrass usually stops growing in early to mid-November. Once the foliage stops growing, the lawn mower can be put away for the winter. 


What is that tiny bug with the painful bite?

During the late summer, small, black and white insect known as the minute pirate bug makes its presence known in a very convincing manner by biting with an impact that is out of proportion with its size. Minute pirate bugs are present all summer in fields, woodlands, gardens and landscapes where they feed on small insects and insect eggs.


They quietly go about their business without anyone taking notice until late in the summer when they migrate from fields and woodlands and begin the disagreeable behavior of biting humans. Their bite is surprisingly painful for such a small insect as they probe their short blunt beak into the skin. They do not feed on blood or inject a venom or saliva. People differ in their response to pirate bug bites. Bites on some swell up like a mosquito bite, some turn red and for others there is no reaction at all.

Wearing dark clothing on very warm days when pirate bugs are abundant may help reduce your attractiveness to the bugs. Repellents are generally not effective, though you may want to try them to see for yourself if they work or not for you.


Contacts :

Richard Jauron, Horticulture, (515) 294-1871, rjauron@iastate.edu

Jean McGuire, Continuing Education and Communication Services, (515) 294-7033, jmcguire@iastate.edu

White Pine Tree