Planting spring bulbs, diagnosing tree decline

By John Fulton

[September 21, 2011]  Spring bulbs may be planted through October. When purchasing bulbs, the bigger the bulb, the more expense, but the greater the flower bloom size. Daffodil bulbs sometimes have two bulbs together. Double bulbs may be pulled apart before planting.

Spring-flowering bulbs generally need well-drained soil and do best under deciduous trees. They will be rather short-lived under evergreens.

Large bulbs, such as tulips and daffodils, should be planted 6 to 8 inches deep. Small bulbs are planted about 4 inches deep. The rule of thumb is to plant bulbs at a depth equal to two to three times the height of the bulb. Plant the bulb with the point up. It is a good idea to map the location, or place a colored golf tee above the bulb. Then mulch with 3 to 4 inches of mulch, and water thoroughly after planting.

Tree decline

When an entire tree looks like it is dying, the injury, disease or insect logically must be affecting the trunk or the roots. These areas would cut off the water supply to the entire tree. Look at the entire tree and compare it with nearby trees. Also consider when the problem started and what changed on the site about that same time. Healthy trees don't suddenly die because they are old.

Many below-ground reasons may cause tree decline. Drought, flooding, compaction of the root zone, poor soils, planting too deeply, inadequate space for roots and many other things could be involved. We have definitely had more than our share of stressful weather the past few years, with alternating flooding and drought.

Often, diagnosing such a problem is a process of elimination. One of the possibilities more difficult to eliminate is root rot. Most gardeners believe that they cannot possibly know the health of a mature tree's roots.

Cankers on the stems, stem tip dieback, off-color foliage, early fall color and early defoliation are clues that a tree may be stressed by underground causes.

To detect the wood rots and root rots, look for mushroom-like fungi growing at the base of the tree or shrub. In wood rot fungi, the conks (also called shelf fungi or fruiting bodies) may be found growing on the trunk or main branches. These are signs of the disease. The actual fungus is probably growing in or on the roots, or inside the wood.

One of the most common examples is Ganoderma root rot, which produces a shelf-type of fungal structure at the base of many trees, especially honeylocust. The structure is reddish-brown and appears to have been varnished. Its presence indicates invasion by a root rot. Other fungi may indicate wood rots.

Wet weather often triggers the formation of these structures. They could easily be confused with fungi growing on dead organic debris near a tree. If, however, they are growing from the tree itself, they are excellent signs of wood rot or root rot.

No chemicals help a tree in decline. Use approved cultural practices, such as proper watering and fertilizing to improve vitality. Cut out dead branches in the dormant season, fertilize in late fall or early spring, and keep traffic off the root system. For very old or large trees, fertilization and watering may have no benefit, but these practices sometimes help the tree survive for years.

[By JOHN FULTON, University of Illinois Extension]