The tree diseases are known as a pathogen, fungi, and bacterial diseases. They affect any type of tree irrespective of its type, structure, or age. Tree diseases have the potential to cause serious damage to your trees; therefore, it is necessary to identify them early before they cause any more damage. A brief discussion of each of the diseases is presented in the following paragraphs.
The first type of tree disease is known as fungal. Tree diseases caused by fungi include needle blight, needle rhizomes, wilt (lateral or central), and root-knot. Needle blight is caused by a fungus named Saprolegnia, which is found in warm environments such as damp, rainy climates. It thrives on dead leaves and other plant parts; hence, you can easily spot it by discoloring the needle-like leaves and white powdery substance that accumulates on the affected areas. To determine if your tree is infected, examine the underside of young needles for signs of fungal growth.
The second type of tree disease is caused by bacterial diseases. These include the pathogens known as Staphylococcus aureus, Streptococcus salivarius, and Bacillus cereus. They generally thrive in humid, moist surroundings, especially in trees that are growing in floodplains, near fountains, and along rivers. Symptoms of bacterial tree diseases include white spots (called plaques) on the trunk and twigs, and dark, water-soaked lesions on the trunk, branches, or leaves. To determine if your tree is infected, look at the bottom of wet leaves for Staphylococcus or check for Streptococcus antigens on a culture of healthy skin.
The third type of pathogen is the arborist’s mites, also known as wood-destroying arthropods. They are most commonly found on deciduous trees. The symptoms of an arborist’s mites include distorted needle edges on the leaf surfaces, soft, disintegrated, shredding material on the leaf surface, and small white cysts on branch veins. To look for these organisms, scrape the underside of diseased needles to check for Staphylococcus or check for Streptococcus antigens on a culture of healthy skin. To cure these pathogen-infected leaves, pinch off infected needles and wash branches with insecticide.
Fungi caused by fungi are also unsightly and can cause major damage to a tree’s bark, leaves, and fruit. They are most commonly found on evergreens. In addition, they can be found on other deciduous trees, but they tend to proliferate more quickly on evergreen trees than on conifers. Some of the types of fungi involved in tree diseases include black rot, Botrytis, ringworm, silver frost, and needle blight. To diagnose these pathogens, scrape the underside of infected leaves and fruit and look for Streptococcus or Staphylococcus antigens on a culture of healthy skin.
Tree diseases, also called necropathy, affect the whole tree system, affecting both the leaves and roots. They can affect all parts of a tree, including twigs, flowers, fruits, and roots. Tree diseases that affect the entire root system, causing the death of the entire plant, are most serious and fatal. Tree diseases can be caused by fungi (or their subtypes) as well as bacteria, viruses, protozoa, and other organisms.
Many of the fungi and protozoa are harmless, while bacteria and viruses are detrimental to the health of a tree. Tree diseases that are caused by fungi are usually distinguishable by their characteristic features, such as wilt or leaf discoloration; leaf patches or baldness; yellowing of foliage; and the presence of fungi growing on the affected portions of the tree. Tree diseases caused by bacteria on the other hand cause similar symptoms (such as wilted foliage, brown spots on the foliage, and so on), but lack the characteristic feature of fungi growth. Other types of tree diseases include wood decay (penter), scale insects (scale lice), insect pests, and fungal infection (cysts, candida, yeasts).
Bark diseases are common in oaks and other conifers, and generally affect the whole bark of the tree. The most common is needle disease, which is caused by mycorrhizae fungi. Many other diseases, such as “blue bark” and “hank,” are rare and specific infections, caused by particular species of fungi. Bark diseases are highly contagious and can spread rapidly between trees.