Aphids may be green, black, brown, red, pink, or some other color. These pear-shaped insects are slow moving and range in size from 1/16 to 1/8 inch long. They have conspicuous slender antennae and near the rear end of the abdomen there are two tubes called cornicles. Some may have transparent wings.
Habit
Dense colonies of aphids may be found along stems or on the underside of a leaf. They are drawn to succulent new growth. Several generations may occur and populations can build up quickly.
Damage
Aphids are sucking insects which draw great quantities of sap, causing leaves and stems to become distorted. This distorted growth is often mistaken as herbicide injury. Some plant sap is excreted as honeydew, which makes the plant sticky. Sidewalks, cars, and patio furniture may become wet with honeydew. Care should be given in plant selection as to avoid the mess caused by this honeydew. A sooty mold often grows in the honeydew and blackens stems, leaves and any other surface.
Control
One non chemical control is to wash off aphids with a steady stream of water. Avoid heavy applications of nitrogen fertilizer which can encourage succulent plant growth. Natural predators such as lady beetles and aphis lions feed on aphids but may not always provide adequate control
Aphids may be green, black, brown, red, pink, or some other color. These pear-shaped insects are slow moving and range in size from 1/16 to 1/8 inch long. They have conspicuous slender antennae and near the rear end of the abdomen there are two tubes called cornicles. Some may have transparent wings. Dense colonies of aphids may be found along stems or on the underside of a leaf. They are drawn to succulent new growth. Several generations may occur and populations can build up quickly.
Aphids are sucking insects which draw great quantities of sap, causing leaves and stems to become distorted. This distorted growth is often mistaken as herbicide injury. Some plant sap is excreted as honeydew, which makes the plant sticky. Sidewalks, cars, and patio furniture may become wet with honeydew. Care should be given in plant selection as to avoid the mess caused by this honeydew. A sooty mold often grows in the honeydew and blackens stems, leaves and any other surface. One non chemical control is to wash off aphids with a steady stream of water. Avoid heavy applications of nitrogen fertilizer which can encourage succulent plant growth. Natural predators such as lady beetles and aphis lions feed on aphids but may not always provide adequate control
Plants infected by Verticillium Wilt develop in response to water stress. Symptoms range from sudden wilt of individual branches to basic leaf scorch, stunted leaves, and branch die-back that occurs over a period of years. In many instances, symptoms develop only on one side of an infected tree. Larger infected branches, and occasionally small ones, exhibit brown, black or greenish streaks in the sap wood.
The fungus is an excellent soil inhabitant an can survive in the soil for many years. The fungus enters plants through the root system and colonizes the water conducting tissue (xylem) of susceptible hosts. Water transport becomes blocked by the fungal growth as well as gums created as defense mechanisms of the host plant itself. Some of the most highly affected species will fail within the first year of infection while the majority of species will show die-back over a period of years.
The fungus will remain in the soil even it the infected tree is removed. As far as a cure goes, there isn’t one. The progression of the infection may be slowed by maintaining the tree vigor through regular maintenance. (pruning, watering, and fertilization) In fact this may help delay the eventual death of the tree for several years. If a tree is found to have succumbed to the fungus, remove the tree and replant with a variety that is resistant to Verticillium Wilt. The wood debris for the failed tree should not be used as mulch unless it is composted properly.
Trees and shrubs susceptible to Verticillium
- Ash
- Dogwood*
- Plum
- Azalea
- Elder
- Redbud
- Barberry, Japanese
- Elm
- Rose
- Boxwood, Korean
- Honeysuckle
- Russian olive
- Buckeye, Ohio
- Lilac
- Serviceberry*
- Catalpa
- Linden*
- Smoke tree
- Cherry, other stone fruits
- Locust, black
- Spirea
- Coffee tree, Kentucky
- Magnolia
- Sumac
- Cork tree
- Maple
- Viburnum
- Currant and gooseberry
- Oak, pin and red (rare)
- Wigela
Trees and shrubs resistant or immune to Verticillium
- Apple
- Hawthorn
- Oak, white and bur
- Arborvitae
- Hickory
- Pear
- Beech
- Honeylocust
- Pine
- Birch
- Hophornbeam
- Poplar
- Butternut
- Juniper
- Serviceberry*
- Dogwood*
- Larch
- Spruce
- Fir
- Linden*
- Sycamore
- Ginkgo
- Mountain ash
- Walnut
- Hackberry
- Mulberry
- Willow
Trees and shrubs susceptible to Verticillium
Ash
Dogwood*
Plum
Azalea
Elder
Redbud
Barberry, Japanese
Elm
Rose
Boxwood, Korean
Honeysuckle
Russian olive
Buckeye, Ohio
Lilac
Serviceberry*
Catalpa
Linden*
Smoke tree
Cherry, other stone fruits
Locust, black
Spirea
Coffee tree, Kentucky
Magnolia
Sumac
Cork tree
Maple
Viburnum
Currant and gooseberry
Oak, pin and red (rare)
Wigela
Trees and shrubs resistant or immune to Verticillium
Apple
Hawthorn
Oak, white and bur
Arborvitae
Hickory
Pear
Beech
Honeylocust
Pine
Birch
Hophornbeam
Poplar
Butternut
Juniper
Serviceberry*
Dogwood*
Larch
Spruce
Fir
Linden*
Sycamore
Ginkgo
Mountain ash
Walnut
Hackberry
Mulberry
Willow
*Some plant species are listed in both tables (linden, dogwood).
The resistance or susceptibility will depend on the cultivar and the strain of Verticillium present in the soils.
*Some plant species are listed in both lists (linden, dogwood).
The resistance or susceptibility will depend on the cultivar and the strain of Verticillium present in the soils.
There are upwards of 300 species of fungi known to cause powdery mildew over a wide range of host plants. Most species of woody shrubs and trees can be infected. Some species of powdery mildew fungi infect only a few closely related hosts, whereas others have a broad host range.
Powdery mildews are first visible on leaves as a white or dusty grey patches. Flowers and fruit can also be infected. Symptoms appear about midsummer and progress to completely cover the leaves by fall. The overall affect of the powdery mildew can be superficial as is the case in Lilac. There are cases where it can become quite severe distorting, dwarfing and discoloring leaves. Oak can become heavily affected. Early leaf loss can occur as a result of the infection.
Powdery mildew fungi survive the winter on plant tissue and mycelium. Spores are released from the fruiting bodies in the wet spring weather and migrate to unaffected tissue via water or wind. Cycles of infection continue as the days remain warm and dry and the nights are cool and damp.
Most powdery mildew do not have much of an affect on tree health, there are times where some intervention is needed, especially after a plant has had repeated infections. Control can generally be handled culturally. Proper placement of the plants can make a difference. Dense, shady or damp areas favor disease development. Removal of dead leaves around the plants in the fall can really help further inoculation of the plant. . Be sure to avoid excessive fertilization which encourages new growth which tends to be more susceptible to infection. Planting disease resistant varieties is perhaps the best control method out there.
Fungicides can be use to prevent infection, however they must be applied at the first signs of infection otherwise it is just too late.
Culprit: Armillaria mellea (A generic catch all for many varieties of Armillaria)
Armillaria is a common soil inhabiting fungus, commonly affecting Quercus, Prunus, Malus, Acer and Pinus. (Not limiting lists there are other genus’s also affected).
Common occurrence of Armillaria can be found throughout hardwood and coniferous forests. It spreads by a series of brownish – black string like rhizomorphs, which can actually travel quite a distance from the host plant. Evidence of infection is similar to other root troubles; loss of vigor, premature fall leaf coloration, dieback and even complete failure.
White mycelial fans grow below the bark in the cambial zone at the base of the trunk and in the larger roots, the fruiting body of Armillaria is a tanish, honey colored mushroom growing in colonies on decayed wood as well as live trees.
Due to its wide spreading nature and profusion in the landscape young trees planted in an area know to have hosted Armillaria will most likely be a candidate to host this fungal party. There is no chemical control for Armillaria therefore control is limited. By removing all wood in the landscape affected by the fungus, including roots and stumps, as well a selecting varieties of ornamental trees and shrubs that show resistance to the fungus will help in limiting the spread of this fungus to other plants.
Armillaria mellea – Mycelial Fan
Armillaria mellea – Rhizomorphs
