UNDERSTANDING THE DIFFERENT TYPES OF TREE DISEASES CAUSED BY FUNGI AND BACTERIA TOGETHER

UNDERSTANDING THE DIFFERENT TYPES OF TREE DISEASES CAUSED BY FUNGI AND BACTERIA TOGETHER

Most plant diseases – around 85% – are caused by fungal or fungal-like organisms. However, other serious diseases of food and feed crops are caused by viral and bacterial organisms. Certain nematodes also cause plant disease. Some plant diseases are classified as “abiotic,” or diseases that are non-infectious and include damage from air pollution, nutritional deficiencies or toxicities, and grow under less than optimal conditions. For now, we’ll look at diseases caused by the three main pathogenic microbes: fungus, bacteria and virus. If plant disease is suspected, careful attention to plant appearance can give a good clue regarding the type of pathogen involved.

A sign of plant disease is physical evidence of the pathogen. For example, fungal fruiting bodies are a sign of disease. When you look at powdery mildew on a lilac leaf, you’re actually looking at the parasitic fungal disease organism itself (Microsphaera alni). Bacterial canker of stone fruits causes gummosis, a bacterial exudate emerging from the cankers. The thick, liquid exudate is primarily composed of bacteria and is a sign of the disease, although the canker itself is composed of plant tissue and is a symptom.

A symptom of plant disease is a visible effect of disease on the plant. Symptoms may include a detectable change in color, shape or function of the plant as it responds to the pathogen. Leaf wilting is a typical symptom of verticilium wilt, caused by the fungal plant pathogens Verticillium albo-atrum and V. dahliae. Common bacterial blight symptoms include brown, necrotic lesions surrounded by a bright yellow halo at the leaf margin or interior of the leaf on bean plants. You are not actually seeing the disease pathogen, but rather a symptom that is being caused by the pathogen.

Here are a few examples of common signs and symptoms of fungal, bacterial and viral plant diseases:

Fungal disease signs:

Fungal disease symptoms:

Bacterial disease signs (difficult to observe, but can include):

Bacterial disease symptoms:

 

Causes & Classifications Of Tree Diseases

A tree disease suggests any deviation or malfunctioning due to a persistent agent. There exist about a hundred diseases for each of thousands of plant species, with different triggers.

Causes

There are abiotic and biotic inducers (non-living and living). Biotic diseases are further grouped according to the pathogen type (bacteria, fungi, viruses, phytoplasmas, nematodes, etc.).

Here it should be noted that in most cases, pathogens are parasites. However, not each pathogen is a parasite, and not each parasite is a pathogen. Thus, some parasites cause no harm to plants and, correspondingly, don’t provoke any diseases. On the contrary, parasites may be beneficial. Also, some earth-dwelling bacteria don’t parasite on plants but produce harmful toxins that trigger tree root diseases.

Classifications

The most common classifications base on the following parameters:

Tree disease identification takes into account signs and symptoms. Signs are changes produced by pathogen tissues (e.g., white rust). Symptoms are how plants suffer from infections (e.g., defoliation, crown thinning, decay, wilt, etc.). Using change detection technology, foresters can understand when woods are stressed.

Tree Leaves Disease

As the name suggests, these affect foliage. The main culprits of foliar infections are fungi. However, signs and symptoms can be similar to chemical injury of insect infestations, which complicates tree leaf disease identification and the choice of corresponding management. The problem eradication strongly depends on the reasonability of treatment costs and is not always possible due to favorable weather conditions for fungi development. In this regard, the most typical method of foliar tree disease treatment is removing and destroying the leaves in the fall. It prevents pathogen overwintering and relapse in spring.

Tree leaf diseases affect both conifers and hardwoods and differ by the degree of severity. While some cause little harm, the rest are rather dangerous and can cause mortality.

Pine Needle Diseases

Conifer foliage infections are typical but rarely represent a serious threat. Thus, in most cases, they don’t require treatment unless merchantability is in question. This refers to ornamental and Christmas trees, and spraying is the common method to defeat the pathogen colonization. In large forests, it is rarely implemented though due to a lack of feasibility and necessity. Generally, there are three types of pine needle diseases: needle rusts, casts, and blights.

Needle Rusts

Needle rust covers the needles and refers to the least dangerous coniferous tree diseases.

Needle Casts

Needle cast fungi grow inside the needles forming long hysterothecia and typically cause defoliation (or casts, hence, the name derives). Depending on the pathogens, there distinguished lophodermium, elytroderma, rhabdocline casts, and many more. About forty pathogenic genera cause this tree disease in the US.

Needle Blights

Needle blight is also an infection inside the needle that causes its partial death. The most common types of tree diseases in this category include snow, brown felt, brown spot, and red band needle blights.

Sooty Mold

It is a soot-like substance on the leaves due to insects’ honeydew secretion. This condition is not a disease since fungi dwell in honeydew without penetrating the plant, yet the black sooty covering severely reduces Christmas tree merchantability. It is typical for the northeastern regions of the USA and affects different pine species.

Hardwood Leaf Diseases

Most infections of hardwood species are also caused by fungi, with no specific tree diseases treatment. Common management suggests removing and destroying contaminated leaves.

Anthracnose

The anthracnose infection reveals leaf necrosis of irregular shapes and burnt foliage that may also affect stems. This is a fungal pathology that may cause severe damage, yet it is difficult to tackle, especially in wet spring weather favorable for fungi development.

Leaf Rusts

Leaf rusts are among common tree diseases and are typically non-dangerous unless they cause early leaf sheds and, thus, negatively impact growth. Rusts are yellowish spots with powdery spores on the upper leaf part. Typically, rusts cover hosts in the second part of August and affect maple, birch, poplar, ash, plum, willow, and cottonwood.

Leaf Spots

These tree diseases are infections in the form of spots, most of the brownish color. They are caused by some fungi species (like Actinopelte, Septoria, Mycoshaerella, Phyllosticta) and parasitic algae. Cool wet springs are particularly favorable for the infection spread. Poplar hybrids are especially prone to leaf spot infestations.

Tar Spot

This tree leaves disease is usually caused by the Rhytisma fungi colonizing the maple family (maple proper and sycamore). The symptoms start as yellow-green or light green spots in late spring-early summer with added tar-like formations by the late summer. Even though they don’t kill the trees, they cause leaves sheds, which may affect the plant development. The infection is common in the northeastern part of the USA. If the fallen contaminated leaves are not removed in the fall, a new cycle will start next season.

Powdery Mildew

The signs of this tree leaf disease look exactly like white talcum powder. It should be distinguished from dust or bird droppings. It spreads in spots or patches and is mainly induced by the Microsphaera fungi. Unlike other fungi infections, it particularly persists in hot dry weather and colonizes succulent plants. The most common treatment is chemical control.

Leaf Blister

In this case, leaves are infected by the Taphrina genus that causes additional growth of the contaminated area (blisters, curling, expansion, puckering). The pathology starts with light green spots that acquire a white coating and eventually become brown. This tree disease is frequently found in the oak family, peaches, female catkins, and alder. It develops under cool wet weather conditions at the stage of leaf expansion. Leaf blisters do not result in defoliation and do not produce a serious impact on the suffering plant.

Tree Bark Disease

Stem pathologies are typically induced by fungi like leaf ones. However, these are more serious, depending on what part is affected. Tree branch diseases have less severe consequences for the plant since the infected branch can be removed. Little can be done with tree trunk diseases though when fungi reach the vascular system, the host dies.

Rusts

Rust is among the most common evergreen tree diseases, in Arkansas pines in particular. It is especially dangerous and can be lethal for young samples due to trunk galls. Mature plants can live with that as long as only branches are infected, and the disease does not destroy the central stem.

Black Knots

The black knot is a fungal pathology typical for the genus of Prunus, fruit and ornamental cherries, and plums in particular. This tree bark skin disease is caused by Apiosporina morbosa that may dwell on the host plant for several years. Black knots start as greenish-brown and brown formations (swellings) during the first year that grow into black hard galls during the second one. After two or three years, mature galls usually die and turn whitish or pinkish due to fungi colonization. Such galls can be numerous on a tree, and this is a danger.

The fungi spores spread to new branches in wet mild weather. The treatment includes chemical or mechanical control (fungicide spraying or pruning, correspondingly). The removed branches must be instantly destroyed because the spores continue to release up to four months. This tree branch disease becomes lethal when it reaches vital stem parts.

Cankers

Canker is a tree bark disease with necrotic areas. It occurs due to pathogenic fungi (e.g., Botryosphaeria, Hypoxylon, Phytophthora, Botryosphaeria, Cytospora) that penetrate through bark cracks or mechanical and natural injures (e.g., man-made wounds, frost cracks, fire burns, sunscalds). Healthy plants cope with the infestation, yet weakened ones cannot resist it.

The consequences may be different. In some cases, cankers only weaken the infected hosts. In others, multiple cankers kill them. Chemical treatment is not effective in this case. Pruning is the common method when infected branches have to be removed. However, the whole tree is cut if there are cankers on the stem.

Decays

This tree disease diagnosis is pretty simple – typically, it is identified through mushrooms (aka conks) covering the tree and discolored bark. The conks develop for many years before they can be noticed. They penetrate the plant through wounds and are located deep inside. For this reason, simple conk removal won’t solve the problem. Instead, the host can combat the conks itself thanks to compartmentalization. It is a natural process to release chemical compounds to get rid of the fungi as well as to plug the vascular tissue and generate callus. The success depends on the fungi’ ability to adjust to the change and the host’s health. Decays are not lethal, but they do weaken the plant and spoil the timber salability. In severe cases, such trees are omitted during timber harvesting operations, as they lose their economic value.

Wilts

Wilt is a lethal tree trunk disease that is diagnosed through burnt leaves with no defoliation. The plant dies due to fungi inside its vessels that hinder crown water saturation. Susceptible species include mimosa, oak, Dutch elm, and more.

Tree Root Disease

Tree root diseases affect the root and lower stem of both evergreen and hardwood species. Compared to leaf and bark infections, they have the highest tree mortality rates since they prevent water and nutrient absorption by the plant. Also, as it develops in the unseen tree part, it remains undetected until the damage becomes visible. Thus, it is more difficult to diagnose tree root diseases.

Pine Root Diseases

The most common root infections in conifers are annosum root rot, loblolly pine decline, and littleleaf disease.

Annosum Root Rot

This pathology is typical for Arkansas pines and widely spreads on sandy soils. It occurs due to the fungus Heterobasion annosum that generates sponge-resembling formations (hence the other disease name – root sponge). It gets into the host through fresh cuts and wounds and then attacks the roots.

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THE SCIENCE BEHIND HOW TREES IMPROVE SOIL ORGANIC MATTER DECOMPOSITION

THE SCIENCE BEHIND HOW TREES IMPROVE SOIL ORGANIC MATTER DECOMPOSITION

Trees play a crucial role in improving soil organic matter decomposition through various scientific mechanisms. Here are some key ways in which trees contribute to this process:

  1. Leaf Litter and Organic Inputs: Trees shed leaves and other organic materials, which contribute to the organic matter content of the soil. These organic inputs, known as leaf litter, contain carbon compounds that serve as a food source for decomposer organisms in the soil.
  2. Rhizodeposition: Trees release organic compounds, such as sugars, amino acids, and organic acids, through their roots. This process, known as rhizodeposition, provides a source of energy and nutrients for soil microorganisms involved in decomposition.
  3. Root Exudates: Tree roots release exudates, including enzymes, organic acids, and other compounds. These exudates facilitate the breakdown of organic matter in the soil, enhancing decomposition processes.
  4. Microbial Activity: Trees support a diverse and active microbial community in the soil. Soil microorganisms, such as bacteria, fungi, and archaea, play a crucial role in decomposing organic matter by secreting enzymes that break down complex organic compounds into simpler forms that can be absorbed by plants.
  5. Soil Aggregation: Trees contribute to the formation of soil aggregates, which are small clusters of soil particles bound together. Soil aggregates create pore spaces that allow for better water infiltration, gas exchange, and movement of decomposer organisms. This facilitates the decomposition process by providing a favorable environment for microbial activity.
  6. Soil Moisture and Temperature Regulation: Trees provide shade and transpire water, creating a more favorable microclimate in the soil. Moderate soil moisture and temperature conditions support optimal microbial activity and decomposition rates.
  7. Mycorrhizal Associations: Many tree species form mutualistic relationships with mycorrhizal fungi. These fungi form a symbiotic association with tree roots, extending the root system and enhancing nutrient uptake. Mycorrhizal fungi also contribute to organic matter decomposition through their enzymatic activities.
  8. Earthworm Activity: Trees, especially those with dense leaf litter, can attract earthworms to the soil. Earthworms feed on decaying organic matter, facilitating its breakdown and nutrient cycling.

By promoting the decomposition of organic matter, trees contribute to the nutrient cycling and fertility of the soil. The organic matter decomposition process releases essential nutrients that become available to plants, supporting their growth and overall ecosystem productivity.

It’s important to note that the specific mechanisms and rates of organic matter decomposition can vary depending on tree species, soil conditions, climate, and other environmental factors. However, the overall contribution of trees to soil organic matter decomposition is well-established and underscores their importance in maintaining healthy and productive ecosystems.

Besides soil erosion, soil quality is another issue facing agriculture in India today. For example, according to Rattan Lal, President of the International Union of Soil Science, the carbon content of top soil in Punjab, Haryana and Uttar Pradesh — the granary of the country – is a mere 0.05%. Healthy soil is expected to have 2% carbon content.

Forests contribute in soil formation through physical, biological and chemical weathering of the parent rock materials and also through the addition of foliage and its subsequent decomposition. It is well-known that trees help improve soil fertility. Studies show that compared to farms in which only crops are cultivated, when trees are also grown, crop production increased to 200% or more in two-thirds of cases. Increasing the soil’s organic content also increases the amount of water that soil can hold. For every 1% increase in the soil organic content, the soil can hold an additional 60,000 liters per acre.

Science knows very little about soil. Centuries ago, Leornado Da Vinci is supposed to have said: “We know more about the movement of celestial bodies than about the soil underfoot.” That still holds true today. According to the Atlantic: “There can be 10,000 to 50,000 species in less than a teaspoon of soil. In that same teaspoon of soil, there are more microbes than there are people on the earth. In a handful of healthy soil, there is more biodiversity in just the bacterial community than you will find in all the animals of the Amazon basin.”

What little we know about soil and its interaction with trees and the rest of the ecosystem is just the tip of the iceberg. We know for instance that some species of trees provide habitat for bacteria and fungi in their root structure. These organisms perform nitrogen fixation, which is a significant factor in soil fertility.

Trees also recycle nutrients by pulling them up from deeper layers of the ground and bringing them up to the surface through the decomposition of leaf and plant litter to form soil organic matter. Tree canopies also trap some amounts of nutrient from the atmosphere, a source of free fertilizer which is washed from the leaves to the soil by rain.

No Ploughing Recommendation: No-till agriculture, where seeds are directly inserted into the soil, is considered to be supportive to soil biodiversity. No-till results in more organic matter in soil and less erosion, which means more fertility, less fertilizer, and higher yields.

Ploughing reduces a farm’s long-term productivity by exposing the organic-matter-rich topsoil to the surface. This creates fluctuations in soil moisture and temperature, which many soil organisms cannot handle. Tilling also reduces the pores in soil, which would otherwise have allowed water to infiltrate the soil and recharge groundwater.

For example, the number of earthworms per square meter varied between 119 in ploughed land and 160 in no-till land. Earthworms are an important component of the sub-surface soil ecosystem and play an important role in adding nutrient to soil. Tilling also affects certain fungi in the soil that form beneficial symbiotic relationships with plants – receiving sugars from plants and supplying them with nutrients such as phosphorus and nitrogen.

WHY IS MULCH IMPORTANT TO YOUR PLANTS AND SOIL

When you have plants of flowers, vegetables, shrubs, and trees a lot of beginners to gardening do not realize how crucial the use of mulch is to the survival of the plants. No matter what type of garden you have whether it is a container, vegetable, flower gardens or shrubs and trees it is a must to have mulch and it will help in several ways.

  1. Lowering the use of water. To save water and keep the plant’s roots with sufficient water – use mulch. Concerning water, just a thin layer of nature’s blanket (mulch) will cut down on moisture leaving the soil surface. Denser mulches may cut water usage by as much as 50%.
  2. Controlling the weeds. By having mulch down this will prevent or at least slow down the growth of weeds. Even if a few eventually pop through they will be easy to see and pull out of the ground.
  3. Protecting against the cold. Placing mulch in your garden will protect against freezes that will usually kill many plants. People living even in zones 10 sometimes get a freeze and this would prevent a loss of their plants.
  4. Keeping the soil from drying. A good layer of ing will ensure that the soil will retain moisture a lot longer time.
  5. Improving soil. This means that you need to use organic mulches that decompose to contribute organic matter to the soil.

Many sorts of mulch add another layer of good looks and quality to your garden beds too. On the market now nurseries have safe colored mulch that will enhance the looks of your garden. For the benefit of the plants though try to use mulch that is made from local items shredded up like wood from trees and bushes growing in your area.

There is an ample assortment of materials which can be used for mulching your garden.

  1. Some very good organic materials are wood chips, shavings or bark from trees growing in your area shredded, the smaller the better. Because wood is an organic material, it will slow decomposition and be blended into your garden soil, leaving more vitamins and nutrients for many years to come.
  2. Grass clippings or dried leaves from your trees each autumn are also outstanding natural items to use for mulching your plants and flowers. Some believe straw and hay is the best to use especially alfalfa. As these are organic materials, they’ll add to the general richness and be producing abundantly and be sustaining vigorous and luxuriant growth in your soil as they decompose.
  3. A lot of people like to use mulch materials that can last for many years at a time like some popular ones that are plastic and rubber material made from recycled tires. These frequently come in the form of circular rings for placing under trees and bushes with ease. Some even use small chunks of rubber.
  4. Rocks, stones, and pebbles can work as a mulch also since dressing the plain soil around your flowers and plants with pebbles or rocks functions the same purpose of holding moisture and forbidding weed growth. Remember though these items can heat up faster and higher than other types.
  5. Snow is one the best mulches of them all, as it can let you grow plants that would not last through the winter in areas without snow farther south

Though traditionally, most mulches were made to both shield from danger the plants and flowers while feeding and improving the soil. Mulching permits you to rehash nature’s products to better your garden, really nothing is wasted, and in the action, your garden will appear greener and more healthy.

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