April 14, 1995

Still No Chemical Control for Earthworms

The activity of earthworms, especially night crawlers, often creates a rough lawn surface that can be both annoying and dangerous. The small castings left on the soil surface by earthworms are only one of many factors that contribute to lawn bumpiness, though they are often the most recognizable. Another "problem" associated with earthworms is the movement of large numbers to places where they are unwanted (for example, on sidewalks or patios, and in swimming pools).

Care of Spring-Flowering Bulbs

Iowans are currently enjoying the beauty of tulips, daffodils, and other spring-flowering bulbs. Proper care of these plants through the remainder of spring and early summer helps to insure repeat performances in succeeding years.

Remove the flower heads on tulips and daffodils as soon as the flower heads fade. This prevents the plants from expending large amounts of energy in fruit (pod) development. The weakened bulbs need the food manufactured by the plant foliage.


Petunias have been one of the most popular flowering annuals for years. Their popularity can be attributed to several desirable traits. Petunias are easy to grow, bloom reliably all summer, and are available in a wide range of colors, flower forms, and growth habits.

Petunia varieties can be divided into two main groups based on flower and growth habits. The two types are grandifloras and multifloras.

Rhizosphaera Needle Cast

Rhizosphaera needle cast on blue spruce, caused by the fungus Rhizosphaera kalkhoffii, has been the most common plant disease sample received in the Plant Disease Clinic this spring. This disease typically causes second-year needles to turn a purple-brown color and fall from the tree. Small black fruiting structures of the fungus can be seen in the small, pore-like openings of infected needles. These fruiting bodies appear in rows along the length of the needle. A hand lens or magnifying glass is helpful in viewing these structures.

Swiss Needle Cast

Swiss needle cast, caused by the fungus Phaeocryptopus gaeumannii, is a disease that we see on Douglas fir in Iowa. The symptoms are very similar to Rhizosphaera needle cast on blue spruce. Infected needles turn a yellow-brown color and fall from the tree. The undersides of the infected needles will show rows of small black fungal fruiting structures along the length of the needle. Symptoms typically begin on the lower branches.


Topiary is the art of fashioning living plants into ornamental shapes. The art of topiary has been practiced for centuries, dating back to the hanging gardens of Babylon. Topiaries were also very popular in English gardens. Many shapes in the English gardens were formal such as globes or pyramids. Today's topiaries take on a variety of shapes from formal to playful. Watering cans, teddy bears and many other fun forms join the more traditional shapes. A trip to Florida and Walt Disney World shows the level that the imagination can go with plant creations.