Tips on how to use this section
The symptoms of the most common problems are in the left column of the chart. In the right column are the probably causes of those symptoms. For those problems for which there is detailed information in a different part of Yardener’s Helper, the name of the problem is linked to a detailed file. For those problems for which there are no additional files, the discussion is found in the paragraphs below the chart.
|Problems of Andromeda|
|Leaves Yellowed; Veins Green||Iron Chlorosis|
|Leaf Edges Browned||Winter Windburn|
|Leaf Undersides Speckled||Andromeda Lacebugs|
|Branches Wilted; Holes In Stems||Borers|
|Plant Parts Skeletonized||Asiatic Garden Beetle|
|Leaves Turn Yellow And Collapse||Wilt|
|Leaves Covered With White Powder||Powdery Mildew|
If Parts Of Your Shrub Just Disappear Over Night, You Have A Deer Problem
For information see the file Controlling Deer
Leaves Yellowed, Veins Green means Iron Chlorosis
If the pH (acidity/alkalinity) of your soil is greater than 6.5 Andromedas may develop an iron deficiency. The higher the soil pH, the less able the shrub is to utilize the iron available in the soil. Iron chlorosis affects the lower leaves first, turning them yellow but leaving the veins green. The leaves may also be smaller than normal. A quality pH meter can be used to determine the approximate pH of your soil. If the soil tests higher than pH 6.0, add some powdered sulfur, peat moss or used coffee grounds to make it more acid. Chlorosis tends to be more of a problem for andromedas grown in the sun. For more information see the file for Dealing With Acidic Soils
Leaf Edges Browned shows Winter Windburn
Because andromeda foliage is evergreen, leaves lose moisture all winter long, even when the ground is frozen solid and the roots cannot take up water. Exposure to harsh winter winds and bright sun may injure andromeda leaf tips and burn leaf edges. Erect a burlap windscreen near those shrubs located in exposed sites. Do not wrap the shrubs so that they are deprived of air circulation. Spray an anti-transpirant on the leaves while the temperature is still above 40°F. in the fall to prevent loss of leaf moisture and browning of the leaves. For more information see the file on Dealing With Winter Injury To Trees and Shrubs
Leaf Undersides Speckled indicates Andromeda Lace bugs
Andromeda lace bug nymphs are 1/8 inch long when they hatch in late spring. They resemble dark specks and cover the undersides of leaves with brown droplets of excrement. Their damage is also apparent on leaf surfaces. They suck cell sap, which stipples the leaves with creamy-white or grayish dots. Adults are small square-shaped bugs, 3/16 inch long or less, with elaborately reticulated wings resembling lacework. The eggs hatch in May in Virginia and early June farther north. Insect damage becomes apparent. These lace bugs are major pests of broadleaf evergreens throughout the East, occurring from western North Carolina to Maine. They attack shrubs that are stressed, especially those that receive too much sun.
It is important to identify and treat this problem early, because lace bugs have several generations over the growing season. The damage they do to andromeda foliage remains visible, even after the pests have been eliminated. Spray affected foliage, top of leaves and undersides, with a pyrethroid insecticide. The encapsulated pyrethrum product is particularly effective against lace bugs. Use all insecticides according to label directions. For more information see file on Dealing with Lace Bugs.
Plant Parts Skeletonized indicates the Asiatic Garden Beetle
Larvae of these beetles (grubs) feed on new andromeda leaves, roots and the bases of young stems. They're grayish, 3/4 inch long, and bent in a C-shape like Japanese beetle grubs. Adult beetles feed at night, skeletonizing foliage and flowers. They're velvety chestnut-brown, nearly 1/2 inch long, resembling Japanese beetles. They lay their eggs in the soil at the base of the plants. Handpick visible beetles for immediate control. For long-term control consider introducing predatory nematodes or milky spore disease (Bacillus popiliae) into the soil. They attack the grubs. In the spring, carefully cultivate the soil around the shrubs, without hurting the roots, to expose the eggs, larvae and pupae to the weather and to predator birds. For more information see file on Dealing with Asiatic Garden Beetle.
Leaves Turn Yellow And Collapse is caused byWilt
A wilt disease caused by a soil-dwelling fungus attacks andromeda growing in waterlogged soil. The fungus enters their roots and spreads to the crown, where the roots meet the base of the shrub. Young leaves become yellowish and wilt. Wilting is most obvious on a cloudy morning. Over watering only kills the roots and encourages the fungus. Wilt is more likely to attack plants recently transplanted. Keep soil temperatures low by mulching, and increase soil acidity by adding peat moss or sulfur. Improve soil drainage and aeration before replanting in the same spot.