Plants Grow Leggy shows Soil Too Fertile.
Heathers thrive in poor soil that forces them to develop deep, sturdy root systems. Too much nitrogen in the soil results in weak root systems and excessive vegetative growth. Do not fertilize heather plants!
Leaves Distorted, Yellowed, Stippled indicates Mites.
Mites may be yellow, green, red or brown. They have four pairs of legs, piercing-sucking mouthparts, and very compact bodies. They're only 1/50 inch long, barely visible to the unaided eye. Inspect the lowest leaves on heather for mites. They cause the upper surfaces of the leaves near the base of the heather shrub to be stippled with small yellow dots or red spots. Varieties of low growing heather that grow in rock gardens and as dense ground covers are particularly vulnerable. Leaves, stalks, and adjacent stems may be misshapen or swathed in fine webbing.
Start control measures as soon as the first stippling on the leaves is obvious. Spray the plants in the early morning with a forceful water spray to knock the mites off the leaf undersides. Repeat the water spray daily for three days. If that doesn't do the job, spray the mites with insecticidal soap combined with pyrethrum every 3 to 5 days for two weeks. Spray evergreen plants like heather with light horticultural, or "superior" oil, in the late winter or early spring to suffocate over wintering mites and their eggs.
For more information see file on Controlling Mites.
Leaves and Stems Covered With Small Bumps means Scale
Scale insects lurk under hard rounded shells. These shells, which may be white, yellow or brown to black, are only about 1/25 to 1/50 inch in diameter. They appear as bumps or blister-like outgrowths on heather stems and leaves. The first sign of a scale attack is often discoloration of upper leaf surfaces, followed by leaf drop, reduced growth, and stunted plants. Heavy infestations kill plants. Some species secrete honeydew, which coats foliage and encourages ants and sooty molds. Scale outbreaks can be triggered by pesticides used against other pests or by environmental stresses such as too much or too little water. Over fertilizing may encourage lush growth susceptible to scale attack.
Handle mild scale infestations by simply scraping the telltale bumps off plant surfaces with a fingernail, or cotton swab dipped in rubbing alcohol. Heavy infestations require spraying. Use a mixture of alcohol and insecticidal soap every 3 days for 2 weeks. Add 1 tablespoon of alcohol to a pint of the ready to use commercial soap spray. For stubborn infestations spray Sevin. Apply insecticides when the young larvae (or "crawlers") have hatched and before they start forming their new scales. A light horticultural oil sprayed on dormant plants in late winter or early spring will smother over wintering scale.
For more information see file on Controlling Scale.
Holes In Leaves And Flowers indicates Japanese Beetles.
Adult Japanese beetles are ½-inch long, with shiny metallic green and copper-brown wing covers. Beetle larvae (grubs) are greyish-white, with dark brown heads. Fully grown grubs are plump, 3/4 to 1 inch long, and lie in the soil in a distinctive arc-shaped resting posture. In the East, Japanese beetles sometimes converge in droves and destroy heather leaves and flowers. Grubs sometimes attack plant roots. Where possible, handpick the beetles from the heather plants and knock them into a pail of soapy water. Handpick stragglers not caught by the trap.
Poor Growth; Leaves Yellow & Drop tells us it is Root Rot.
Root rot is a fungus that attacks the roots of heather and other shrubs. It is more common in the northwestern region of the United States. Plants, singly or in groups, begin to look peaked, their foliage fails to develop well, yellows, dies and drops. Sometimes this happens gradually, other times fairly quickly. The entire plant may turn brown and die in the middle of the summer. When its roots are exposed to view, half of them may be gone. This fungus appears as white fans or veined sheets of plaque covering the major roots. It produces rhizomorphs, brownish-blackish growths that grow along the tops of roots, surfacing through the soil. The fungus produces mushrooms in the fall, rising from the rhizomorphs or decayed roots that are still in the soil. Dig up any plant infected with this fungus. Throw it and the soil around its roots in the trash. Do not plant heather in this spot again for several years.
For more information see file on Controlling Fungal Disease.
Orange Powdery Spots On Leaves means Rust.
A rust disease caused by a fungus occasionally attacks heather. It causes pale areas to appear on upper leaf surfaces, with powdery pustules directly beneath. Remove infected leaves as soon as possible. Remove and destroy diseased plants and all debris before growth starts in the spring. Rust can be prevented by periodic sprays of wettable sulfur on leaves and stems, begun several weeks before rust normally appears. Space plants widely apart for good ventilation, and avoid wetting foliage when watering.
For more information see file on Controlling Fungal Disease.
Leaves Covered With White Powder Powdery expect Mildew.
Powdery mildews are caused by fungi that live on the surface of plant cells, not inside them. Infected leaves are covered with a white or ash-gray powdery mold. Badly infected heather leaves become discolored and distorted, then drop off. Powdery mildews thrive in both very humid or very dry weather. Spray affected plants thoroughly with wettable sulfur once or twice at weekly intervals starting as soon as the whitish coating of the fungus is visible. Allow ample spacing between plants and collect and discard all aboveground refuse in the fall.
For more information see file on Controlling Fungal Disease.
