The best remedy is a course of pre-emptive foliar treatments — targeted to the specific pathogen(s) the tree is susceptible to – which will reduce the level of infection of treated leaves. Timely action is important: these anti-fungal or anti-bacterial applications must begin early in the season to be successful.
Once a disease is identified, arborists can prescribe the appropriate treatment. This may involve pruning away infected branches, applying fungicides or antibiotics, or implementing cultural practices like adjusting watering or mulching to mitigate disease progression.
Even if a tree is diseased or infested, there is the option to treat it with liquid fungicides and other formulas. However, treatments need to be ongoing, which adds time and cost to your yard maintenance. If you notice splits in the tree trunk, this can be fixed by pinning the opening together with rods.
It is recommended to apply glyphosate herbicide to trees at the time of tree removal or test adjoining trees to detect latent infections early. Herbicide application can also help kill roots of infected trees so that they can no longer infect new roots via root grafting.
Diseased Trees
An infected tree can spread disease to other trees and plants in the area, causing significant damage. If you notice signs of disease, such as dead branches, discolored leaves, or fungus growing on the trunk, it's time to remove the tree before it causes any more damage.
Treating a Sick Tree
Once you've determined that your tree is sick, you'll need to take steps to help it recover. Depending on the cause of the illness, this may involve pruning, fertilizing, applying fungicides or insecticides, removing dead or damaged limbs, or providing additional resources like water and light.
If a tree is dying, you may need to plant it in a different location. Most California trees need plenty of room and sunlight to reach their full potential. Keep them out of shady areas and away from power lines to keep them in optimal condition. You also want to make sure the tree isn't planted too deep into the soil.
Another one of those great home remedies for plant diseases is apple cider vinegar. To make a natural fungicide out of this, take one tablespoon of vinegar and mix it with a gallon of water. Shake it well and add to a spray bottle.
Fire Blight
It is incredibly destructive and spreads rapidly, especially in hot weather and during bloom. The pathogen often invades in spring, taking advantage of openings presently by flower blossoms or branch tips. Wounds ooze bacteria that insects, rain, or wind carry to other trees.
Wound recovery rates vary widely for different tree species. The speed of recuperation is greatly affected by developmental environmental conditions, vigor and health of the tree. Some trees may never completely close their wounds due to their genetic capacity or perhaps inadequate resources to keep the tree vigorous.
While it is possible to revive sick or dying trees, bringing dead trees back to life is typically not feasible. There are several reasons to remove a dead tree — but how exactly can one tell if a tree is dead, sick, or healthy?
Be patient: If you treat your tree well, the tree should recover from shock and establish itself. It can take up to 3 years for a tree with transplant shock to fully recover.
Peeling or loose bark or cracks in the tree around the tree's root collar. Swelling, soft or decaying wood, or small holes in the tree trunk. Dead, dying, or drooping branches in the canopy. Wilting, discolored, or damaged leaves.
Leaves are shed in an effort to save energy in the fall– this is what is known as a dormant stage. While in a dormant state, your trees are not dead — although growth is halted for the season. Generally, when a tree dies, the leaves will turn brown, but they do not fall to the surface below.
Injury commonly seen on infected plants includes stunting and distortion of leaves, buds, growing tips, and fruit. The presence of white to gray fungal growth over leaf surfaces is the most common sign of the disease. Powdery mildew begins as circular, powdery white spots and expands to coat the entire leaf surface.
Once a wound occurs, decay-causing fungi can enter the heartwood and the decay process begins. Trees have a unique defense. The wood around the wound begins to produce special compounds in the wood cells that set up a wall or barrier to isolate the infected area. This is called compartmentalization.
Apply Fertilizer in The Right Place. The root zone area, the space beneath the canopy of the shrub or tree, contains most of the plant's fine or “feeder” roots that absorb water and nutrients. It extends from he trunk (outside of the buttress or structural roots at the root flare) to the outermost branches (Fig. 3).
However, if caught early, many trees can recover from disease, pest infestations, or environmental stress with proper care. In summary, while it's possible to save a dying tree, the likelihood depends on the root cause and how quickly you act.
Sometimes the best treatment is to simply leave the tree alone. Other times it involves spraying or injecting the tree with low-impact chemicals, pruning out affected branches, or even removing the tree altogether.
The best fungicides for tree fungus prevention and treatment are liquid copper fungicide, potassium bicarbonate, and chlorothalonil. Liquid copper is a broad-spectrum fungicide that can kill off fungi quickly, while the other two help reduce infection levels.