Tuesday, September 18, 2012

Diseases that affect Trees and Shrubs

Plum Trees

Plum Bladder (or pocket) Brown Rot Fruit Fungus

Turns fruit into a dried-up reddish-brown pepper-shaped fruit. It creates a moldy surface with a grey powdery surface. Along with damaged fruit, distinct discoloration (red, yellow, orange and brown) can show up on the leaves causing them to drop prematurely.  Both diseases can be on the same tree.

Treatment

Diseased fruit should be removed from the tree and collected from the ground as soon as possible.  Rake up fallen, diseased-looking leaves on a regular basis.  Discard all plant material directly into the trash. Treatments start in middle to late April the following year by spraying dormant lime sulfur fungicide on the entire tree, followed up with a three-part spray treatment of copper fungicide spaced about every 10 days starting at the time of bud (usually late May) and continuing into June. Never spray within 24 hours of any rainfall.

Fruit Trees (such as Cherry, Plum and/or Apricot)

Bark Damage – Systemic Disease

Thin barked fruit trees are susceptible to lawnmower and weed-eater bark damage. The damage caused by these every day tools create openings near the ground for a group of fungus diseases that move through the tree in the conducting cells that transport sap, called systemic disease. Letucostmoa and Cytospora are the most common of these diseases. They cause splitting of the trunks and main branches which can extend all over the tree, causing a slow death of the infected parts of the tree. Apple, pear and crab trees area also affected by this disease. Sometimes these diseases cause dark, gum-like fluids to ooze out of the small linear silts in the bark of the lower parts of the trunk.

Treatment

There are no fungicidal treatments available for systemic woody plant diseases. Keep the grass from growing up the base of the tree and be very careful when working around the tree.

Rose, Apple, Crab, Pear, Mountain Ash, Hawthorn, Cotoneaster Spirea and Ninebark

Fire Blight

This is a bacterial disease that shows up in a few locations on the tree, usually unnoticed in early to late June. It is typically spread by bees and wasps when they are gathering flower nectar. Either the flowers or the early immature fruit or both will show the signs of the disease along with a few nearby leaves. The flowers look crushed and are brown in colour. The immature fruit is usually black-brown and moldy. The nearby leaves are a distinct chestnut-coloured brown and wrinkled in apples and pears. As the disease progresses through the summer, the terminal twig near the infections turns a dark colour, often quite black and with a distinct curl. Resembling a long, thin burnt match stick.

Cotoneaster hedge shrubs – Their leaves turn yellow, orange, or red-black and fall from the plant. The infection often occurs in separate, distinctive patches in the hedge characterized by dead twigs and stems. The disease if spread by contaminated hedge shears.

Treatment

If it’s advanced – fire blight is very difficult to control. The tree or shrub needs to be removed as soon as it is noticed. In all other cases – remove infected portions with sterilized tools at least 30 centimeters into good branch wood. Make the cut at a branch or twig junction. Sterilize the tool with diluted bleach, denatured alcohol or methyl hydrate after each cut (otherwise the disease can be transmitted to a new location). Treat removed twig/branch areas with copper spray fungicide immediately.

Spruce trees

Cytospora canker (white blister) and Sirococcus tip blight

The presence of both of these diseases weakens the trees and makes them susceptible to the spruce spider mites (the pest responsible for needle loss). New white blister infections will show up on branches as amber fluid weeping out of slits in the bark on branches, stems and exposed roots that have popped out of the grass. Older blisters turn resinous white and eventually different dark shades of brown and finally black. This disease will suddenly cause the death of an entire branch. Tip blight appears on the ends of the twigs and result in a slight to prominent curl in the twig with a gradual loss of all the needles. Spruce needle cast can also shop up on the needles growing in the damp shade of other branches. The needles become distinctly grey green and by using a hand lens look for black spots. The spots are a fungus stage of this disease.

Treatment

Treating the many diseases and pests of spruce trees is very complicated and requires a treatment program that needs to be acted on for at least the next two years. Contact your local garden centre for complete instructions on the treatment.

Please Note

It is never a good idea to plant a tree or shrub in the exact same spot that you have removed a diseased tree from.

Posted by Perfect Landscaping at 11:58 AM 0 Comments