Ask the Experts from ISU

Lily of the Valley
Lily of the Valley can be difficult to confine in the home landscape.

Got gardening questions? For more gardening information, visit us at Yard and Garden Online.

Are there any cacti that are native to Iowa?

Three species of prickly pear are the only cacti native to Iowa. All three species are quite rare in Iowa. The prickly pear (Opuntia macrorhiza), little prickly pear (O. fragilis) and eastern prickly pear (O. humifusa) are typically found in sandy prairie sites or rocky locations. 

How can I kill lily-of-the-valley in a perennial bed?

Lily-of-the-valley is a perennial that does well in partial to full shade. It spreads rapidly, forming a thick, dense groundcover. Unfortunately, lily-of-the-valley also can become invasive. 

Lily-of-the-valley is often difficult to control in the home landscape. Plants can be destroyed by thorough, repeated digging and removal of their underground stems or rhizomes. Any pieces of rhizome that are left will sprout out and develop into plants. It often takes two or three attempts to completely destroy lily-of-the-valley by digging. The herbicide glyphosate (Roundup) is another control option. Glyphosate is a non-selective, systematic herbicide that destroys virtually all plants onto which it is applied. However, lily-of-the-valley is a very tough plant. Two or more applications of glyphosate may be necessary to completely destroy lily-of-the-valley.

Should we remove the suckers or sideshoots that form on sweet corn?

Some gardeners remove the suckers believing that the sideshoots reduce sweet corn yields by diverting energy from the main stalk and developing ear. Their removal, however, is not necessary and may actually reduce yields. Suckers develop on plants that are spaced too far apart. Space rows 2-1/2 to 3 feet apart with an 8- to 12-inch spacing within the row. High nitrogen and abundant moisture will also promote sucker formation.

What are the orange spots on my ash tree leaves?

Ash rust is a common fungal disease of all species of ash trees.  Infected leaves, petioles and small twigs swell and may become twisted and distorted.  Yellow to orange pustules develop and produce powdery spores.

Although it is unsightly, ash rust is not a serious threat to the health of the tree.  Because of this, control measures are not usually necessary.  A heavy infection may stress a young tree and make it more susceptible to winter injury.  Cultural practices that reduce stress, such as watering during dry periods or mulching, can help to improve tree vigor.

What is the scary looking insect with pinchers in my house?

It may be an earwig!  Earwigs are relatively easy to identify by the prominent pincers or forceps on the end of the abdomen.  These pincers are used as both offensive and defensive weapons.  Though they may try to pinch if captured and handled, they do not harm people.  The common earwig is about 5/8 inch long and dark brown with a reddish head and pale yellow-brown legs.  Earwigs are common in gardens, but usually they go completely unnoticed.  They will also occasionally wander into homes.  

Many people are disturbed by earwigs because they look very ferocious with large pinchers at the end of their abdomens.  They use the pinchers to intimidate, but it is definitely a case of the bark being worse than the bite.  They cannot pinch hard enough to even break skin.  Earwigs prefer to live in moist areas under logs or leaf litter.  Any earwigs found indoors can be swept or are returned to you garden.  Also, despite their name, rest assured that there is no truth to tales that earwigs like to climb into our ears.

Contacts :
Cynthia Haynes, Horticulture, (515) 294-4006,
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033,

Three high-resolution photos suitable for publication are available for use with this column:
Lily of the Valley, lotv.jpg, [1.4MB]
Side shoots on sweet corn, cornshoots.jpg, [800K]
Ash rust, ashrust.jpg, [1.3MB]