Diagnostics

Why Proper Diagnosis Matters

Mistaking the cause of a problem isn't just a waste of time. Incorrect actions can make the situation worse: for instance, treating with a fungicide when there's a nutrient deficiency will be ineffective, and attempting to "feed" a tree suffering from root rot can accelerate its demise.

As authors of a fruit-growing guide note, plants under stress often display similar external signs, whether it's a pest attack, disease, or nutritional imbalance (Buckingham, 2010). Therefore, it's unwise to rush to a diagnosis and, especially, to immediately resort to chemical plant protection products.

Examination Sequence

If you suspect something is wrong, the tree inspection should follow a specific algorithm, moving from the general to the specific.

Step 1. Assess the Overall Condition and Growing Site

Before examining individual leaves or branches, evaluate the big picture:

• How does the tree look compared to neighboring trees of the same variety and age?
• Are there any signs of general decline: weak growth, small and pale leaves, premature autumn coloring, or early leaf drop?
• What are the growing conditions like: is there water stagnation at the roots, is the soil drying out, is the tree shaded by other plants?

It's important to remember that many problems start at the roots, and you can only see them through the condition of the entire above-ground part. For example, when the root system is affected by Phytophthora, the tree may wilt and dry up without visible causes on the leaves and branches (Krivko, 2014).

Step 2. Inspect Individual Tree Organs

The diagnosis should be systematic, examining all parts of the plant:

• Leaves. The most informative organ. Pay attention to color, spots, coatings, deformations, and signs of feeding damage.
• Shoots and branches. Assess the condition of the bark, presence of growths, cracks, gumosis, as well as the nature and length of annual growth.
• Flowers and fruits. Examine for wilting, rot, deformation, and spotting.
• Trunk and root collar. A very important area where fungal and bacterial diseases often manifest. Look for cracks, bark peeling, gumosis, tumors, and signs of pest activity.

Step 3. Gather History and Account for Contributing Factors

A correct diagnosis is impossible without analyzing the growing conditions in the current and previous seasons:

• Weather conditions. Were there frosts during flowering (which can destroy flowers but the cause would be non-infectious), strong winds, hail, or, conversely, prolonged drought?
• Agrotechnics. Were watering and fertilizing carried out, when and in what amounts? What is the soil management system in the root zone? For example, excessive nitrogen fertilization can make tissues looser and more susceptible to diseases, while potassium or magnesium deficiency may manifest with characteristic symptoms on leaves (Buckingham, 2010).
• Tree age. Older trees suffer more from nutrient deficiencies and have a weakened immune system (Hessayon, 1993).

Step 4. Determine the Nature of the Damage: Localized or Systemic

This is a key point that helps distinguish disease from nutritional imbalances or weather effects:

• In diseases and pests, damage often spreads from the center to the periphery. For example, in moniliosis, individual branches dry out first, and then the disease covers the entire tree.
• In nutritional imbalances, symptoms usually appear scattered throughout the tree or on shoots of one type (e.g., chlorosis on young leaves due to iron deficiency or on old leaves due to magnesium deficiency) (Srivastava, 2020). As a rule, these changes are not strictly tied to one specific location on the tree.
• In the case of frost or sunburn, damage is localized on the south or southwest side of the trunk, as well as on the most protruding parts of the crown (Krivko, 2014).

Tools and Materials for Diagnosis

For a quality inspection, you will need:

• A magnifying glass to spot small pests like mites and aphids, as well as to study fungal spores on coatings.
• A garden knife or pruner for removing bark or cutting branches to see the condition of the wood (e.g., the presence of dark rings in verticillium wilt) (Seethapathy et al., 2023).
• A paper bag or envelope for collecting leaf or branch samples with suspicious symptoms, which can be shown to a specialist or used for further study.
• A notebook for recording all observations, dates, and measures taken.

Main Rules of Diagnosis

1. Don't panic. Upon discovering a problem, don't rush to grab the sprayer. First, conduct a thorough inspection and try to understand the root cause.

2. Look for patterns. Are the symptoms widespread across the tree or only on certain branches? Are only young leaves affected or all of them? This information is critically important for differential diagnosis.

3. Remember the interaction of factors. Often problems arise from a combination of tree weakening (e.g., by drought) and subsequent activation of secondary infections. For instance, weakened trees are more often attacked by bark beetles and parasitic fungi (Trunov, 2012).

4. Use an integrated approach. Observe the tree over time. How are the symptoms changing? Is the condition worsening, remaining stable, or improving? This will help assess the severity of the situation and the effectiveness of the measures taken.

Only such a systematic approach will allow you to correctly determine what exactly is bothering the plum—disease, pest, or improper care—and choose effective solutions. In the next chapter, we will analyze in detail how signs of trouble appear on different organs of the tree, from roots to fruits.

Leaves

Leaves are the most sensitive indicator of a tree's condition. They are the first to react to nutrient deficiencies, pest attacks, and fungal infections. When inspecting, pay attention to:

• Color changes. Yellowing can be caused by nitrogen, magnesium, or iron deficiency, as well as viral infections. A reddish or purple tint, especially along the edges, often indicates phosphorus deficiency (Buckingham, 2010).
• Spots and necrosis. Small brown spots with clear boundaries are a typical sign of fungal diseases, such as clasterosporium (shot hole disease). Here, the affected tissue falls out, leaving holes in the leaf (Seethapathy et al., 2023). Oily, water-soaked spots, especially on young leaves, indicate bacterial blight or bacterial spot.
• Deformations. Leaves curling downward or upward, crinkling, dwarfing—possible consequences of aphid infestation, which sucks sap, or virus activity. Leaf curl in plums is less common than in peaches but can be caused by fungal infections (Seethapathy et al., 2023).
• Coatings. A white or grayish powdery coating is a sign of powdery mildew. A black, sooty coating on leaves and shoots appears on the sticky secretions of aphids or psyllids (Buckingham, 2010).
• Chlorosis. Yellowing of the leaf while veins remain green indicates iron deficiency (lime-induced chlorosis on alkaline soils) or magnesium deficiency. Unlike infections, chlorosis manifests systemically, not in spots, and often starts on the upper or, conversely, lower leaves depending on the mobility of the element (Srivastava, 2020).

Shoots and Branches

The condition of the shoots allows you to assess the tree's growth vigor and the presence of serious vascular infections.

• Tip dieback. If the tips of young shoots turn black and dry up, but the leaves don't fall off, they remain hanging—this is a classic symptom of monilial blight (moniliosis). The disease affects flowers and then spreads to branches (Mandal et al., 2021).
• Necrosis and bark cracks. The appearance of sunken, dying areas of bark on branches is a sign of canker diseases (cytosporosis, bacterial canker). Gum often exudes around such areas.
• Growths. Hard, black, rough swellings on branches up to several centimeters in diameter—this is black knot, a disease characteristic of plums in warm and humid climates (Seethapathy et al., 2023).
• Annual growth. The length of new shoots is a health indicator. If the growth is less than 25–30 cm, it signals the tree is weakened due to poor nutrition, crop overload, or root damage (Tarasov, 1981).

Bark

Bark is the protective barrier. Any damage to it opens the door for infections.

• Cracks and frost cracks. Vertical cracks on the south or southwest side of the trunk result from sharp temperature fluctuations in winter and sunscald. Such wounds require sanitary treatment as they become entry points for rot pathogens (Krivko, 2014).
• Gumosis. Transparent or brownish resinous droplets on the bark—the tree's defensive reaction to damage. Gum can be exuded due to bacterial canker, bark beetle damage, and cytosporosis. Heavy gumosis on the south side of the trunk often indicates sunscald (Trunov, 2012).
• Bark peeling. If the bark easily separates from the wood and you see brown or black streaks underneath, this strongly indicates verticillium wilt or another vascular disease (Seethapathy et al., 2023).

Flowers

Plum flowers bloom early, so they are often damaged by late spring frosts.

• Browning and drying. Flowers suddenly turn brown, wilt, and don't fall off, remaining on the branches—this is moniliosis (brown rot). A gray fluffy coating (fungal spores) appears on them (Buckingham, 2010).
• Complete ovary drop. If flowers fall off without forming ovaries, and the tree looks healthy, the cause is often a lack of pollinators, bad weather during flowering, or physiological drop. In strong winds or rain, pollen cannot reach the stigma, and ovaries don't form (Mandal et al., 2021).

Fruits

Affected fruits are the most visible and painful problem for a gardener.

• Brown, rapidly expanding rot spots. If the spot becomes covered with grayish or cream-colored cushions (sporulation), this is brown rot (moniliosis). Fruits mummify and often hang on the tree until spring, serving as a source of infection (Seethapathy et al., 2023).
• Small dark spots with a sunken center. This could be clasterosporium (fruit spot) or puncture marks from fruit fly.
• Deformation and "pockets". Fruits lacking stones become empty, elongated, resembling a pod—this is "witches' broom," caused by the fungus Taphrina pruni (Seethapathy et al., 2023). The fruit becomes inedible.
• Skin damage. Marks in the form of small punctures or gnawed tunnels inside are the result of the activity of codling moth or sawfly. If a fruit falls prematurely, you can cut it open and find the larva.

Roots

Assessing the root system's condition without excavation is difficult, but there are indirect signs indicating problems underground.

• General wilting. If leaves lose turgor, droop, and watering doesn't help, and there are no typical drought symptoms (yellowing edges), root rot should be suspected (Seethapathy et al., 2023).
• Appearance of bracket fungi. If bracket fungi have grown at the base of the trunk, it's a sure sign that the wood inside the trunk and roots is actively being destroyed (Buckingham, 2010).
• Poor growth. Dwarfism of the tree, small leaves, and lack of flowering with good care may indicate root damage by nematodes or prolonged waterlogging.

Localizing the problem to a specific organ is only the first step. Next, you need to analyze the specific symptoms to narrow down the possible causes. The next chapter is dedicated to this.

Color Changes

Changes in the color of leaves, shoots, or fruits are one of the first signals of trouble.

• Yellowing (chlorosis). If leaves turn yellow but the veins remain green, it almost always indicates an iron deficiency (lime-induced chlorosis) or magnesium deficiency. Iron is necessary for chlorophyll synthesis, and its availability drops sharply on alkaline or over-limed soils (Buckingham, 2010). If the edges of old leaves turn yellow and dry out, and necrotic spots appear on young ones, it more likely indicates potassium deficiency. In nitrogen deficiency, all leaves, especially the lower ones, turn yellow and become smaller, and overall growth decreases (Srivastava, 2020).
• Reddening or purple tint. Leaves acquire a reddish hue, especially along the edges or between veins, often in phosphorus deficiency (especially in cold weather). This can also be related to root chilling early in spring (Mandal et al., 2021).
• Browning. Brown tissue color is a sign of necrosis (dying). If leaf edges turn brown and dry up, it could be a burn from excessive fertilization or potassium deficiency. Brown, oily spots on leaves and fruits are a symptom of bacterial blight or moniliosis.
• Bronzing. Leaves become bronze or grayish, dull, then dry up. This is most often the result of spider mite infestation, which sucks sap from the underside of the leaf. In severe infestations, a fine web appears on the leaves (Buckingham, 2010).

Spotting

Spots are the most characteristic sign of fungal and bacterial infections. Their shape, color, and location help make a diagnosis.

• Small brown spots with a dark red border. If the spots eventually fall out, leaving "holes," this is clasterosporium (shot hole disease). Spots appear not only on leaves but also on fruits and branches (Seethapathy et al., 2023).
• Large spreading brown spots. On leaves—could be a sign of Phytophthora or other rots. On fruits, a rapidly enlarging brown spot with zones (concentric rings) is brown rot (moniliosis). If the spot is covered with a grayish fluffy coating, it's gray mold (botrytis) (Buckingham, 2010).
• Water-soaked (oily) spots. Translucent when held up to light, often with a yellow halo, characteristic of bacterial spot (Xanthomonas arboricola pv. pruni). The affected tissue dries out, crumbles, and the leaves acquire a torn appearance (Seethapathy et al., 2023).
• Orange-red raised spots (pustules). Appear on the underside of leaves. This is rust—a fungal disease especially active in wet years (Buckingham, 2010).

Coatings

A coating on the surface of organs results from the development of mycelium or pest secretions.

• Powdery coating. White, initially easily wiped off, then grayish or brownish coating on leaves, young shoots, and fruits—powdery mildew. Causes deformation and growth retardation (Seethapathy et al., 2023).
• Sooty coating. A black, smoky film on leaves and shoots—this is sooty mold, which develops on the sugary secretions (honeydew) of aphids or psyllids. The mold itself is not parasitic, but it impairs photosynthesis and reduces aesthetics (Buckingham, 2010).
• Gray fluffy coating. On flowers, ovaries, and fruits (on rot spots)—sporulation of the fungus Botrytis (gray mold) or Monilinia (moniliosis) (Buckingham, 2010).
• Olive-brown velvety coating. On leaves and fruits—scab (fungus Venturia). Scab is less common on plums than on apples, but under favorable conditions it affects fruits, making them unsuitable for storage (Seethapathy et al., 2023).

Deformations

Changes in the shape of leaves, shoots, and fruits are a serious symptom often indicating viruses, systemic infections, or chronic disorders.

• Leaf curling. Leaves curl downward or upward. This is a classic sign of aphid infestation, which feeds on the underside of the leaf. Less commonly, curling is caused by viruses or hormonal disorders (Mandal et al., 2021).
• Small leaves and rosetting. Shoots are shortened, leaves small, deformed, clustered in rosettes. A typical sign of zinc deficiency or phytoplasma infection ("witches' brooms") (Buckingham, 2010).
• Shoot distortion. Shoots grow zigzag, distort—often the result of bacterial blight (bacteriosis), which affects the vascular system.
• Fruit "pockets". Fruits grow hollow, without a stone, elongated, resembling a pod. This is caused by the fungus Taphrina pruni—witches' broom, or more precisely, the "plum pocket" disease (Seethapathy et al., 2023). The fruits completely lose their food value.

Dieback

Dieback of individual parts or the entire plant is the most alarming symptom.

• Dieback of shoot tips and flowers. Sudden wilting and blackening of young shoots and flowers (they don't fall off) is monilial blight. In spring, the infection spreads very quickly (Buckingham, 2010).
• Branch dieback. If sunken areas (wounds) appear on the bark, the tissue underneath turns brown, and the branch dies—these are canker diseases (cytosporosis, nectria canker). Gum may appear at the base of the trunk. The process is slow, year by year, and eventually the tree dies (Seethapathy et al., 2023).
• Complete wilting. If the tree wilts entirely, starting from the top, and leaves dry up remaining on branches, this often indicates verticillium wilt (fungus Verticillium), which clogs the vessels. Or root damage by Phytophthora (Seethapathy et al., 2023).
• "Bleaching" and drying of bark. During sunscald or frost cracks, the bark on the trunk peels and dries out. This is non-infectious dieback, but it creates entry points for secondary infections (Trunov, 2012).

Gumosis

Gum (viscous, transparent or brownish resin) exudes from cracks or wounds on the bark. This is a defensive reaction indicating deep tissue damage. Gumosis is not a disease itself, but a symptom.

• In bacterial canker. Gum exudes from sunken spots on the bark, which later peel off. The smell of the gum is sour (Seethapathy et al., 2023).
• In cytosporosis. The bark becomes bumpy, gum exudes abundantly, then the bark dies off.
• In trunk damage. From frost cracks, sunscald, mechanical damage (e.g., from a lawnmower). In these cases, gumosis is the least harmful cause, but the wound still requires treatment.
• In trunk pest damage (bark beetles). At the sites of pest tunnels, the gum is mixed with boring dust.

Damage

Damage is the trace of external impact: insects, animals, birds, humans.

• Eaten leaves. The edges or the entire leaf blade are eaten. This is the work of caterpillars (codling moth, leafroller), sawflies, or leaf beetles. If leaves are eaten from the edge to the middle—likely beetles or older caterpillars; if the leaf is skeletonized (only veins remain)—the work of small caterpillars or sawflies (Buckingham, 2010).
• Tunnels and gnawed holes. Inside fruits, you can see tunnels with excrement—that's the codling moth. On the bark—sinuous tunnels with dark inclusions (boring dust)—these are bark beetles or wood borers.
• Bark damage (girdling). If the bark is eaten in a circle at the base of the trunk, and teeth marks are visible under the bark—the work of hares or voles. This is very dangerous as it disrupts nutrient transport (Tarasov, 1981).
• Mechanical damage (wounds). Chips, cracks, broken branches from wind or careless pruning. They are dangerous as entry points for infections.

Having studied the symptoms and their localization, you can move to the next stage—systematizing the possible causes. Understanding what exactly causes the observed complex of signs is the key to choosing the right treatment strategy. The next chapter is dedicated to this.

Diseases

Pests

Pests cause direct damage by sucking sap, boring tunnels, or damaging fruits.

• Aphids. Small insects whose colonies accumulate on the underside of leaves, shoots, and sometimes fruits. They suck sap, causing curling and deformation of leaves. They secrete sugary honeydew on which sooty mold develops. Several species occur on plums: plum aphid, black cherry aphid, etc. (Buckingham, 2010).
• Codling moth. Caterpillars eat tunnels inside fruits, leaving excrement. Affected fruits fall prematurely. Moths lay eggs on fruits during their ripening period. The oriental fruit moth is especially dangerous (Mandal et al., 2021).
• Plum sawfly. Larvae bore tunnels in young fruits, damaging the stone. Affected fruits fall off. Adults lay eggs in flowers or young ovaries (Buckingham, 2010).
• Plum weevil (blossom weevil). Beetles eat buds and flowers, reducing yield. Larvae develop inside fallen fruits. Noticeable by characteristic "pinches" on fruits (Seethapathy et al., 2023).
• Bark beetles and wood borers. Larvae bore tunnels under the bark, disrupting sap flow. Small holes with boring dust appear on the bark. The tree gradually weakens and dies. They attack weakened specimens (Seethapathy et al., 2023).
• Spider mite. A microscopic pest that feeds on leaf sap. Manifests as bronzing and drying of leaves, especially in dry and hot weather. In severe infestations, a fine web is visible (Buckingham, 2010).
• Fruit fly. Larvae bore tunnels in fruits, causing them to rot. Punctures remain on the fruit skin, from which juice exudes. The problem is characteristic of southern regions (Seethapathy et al., 2023).
• Birds and rodents. Starlings, thrushes, and other birds peck buds and fruits. Hares and voles eat the bark at the base of the trunk, which can lead to girdling and death of the tree (Buckingham, 2010).

Nutritional Imbalances

Deficiency or imbalance of nutrients leads to metabolic disorders and manifests with characteristic symptoms (Srivastava, 2020; Milosevic & Milosevic, 2020).

• Nitrogen deficiency. General growth weakening, pale yellow leaves (especially on old shoots), small fruits. The tree looks stunted. Nitrogen is necessary for protein and chlorophyll synthesis (Buckingham, 2010).
• Phosphorus deficiency. Small leaves, dark green with a purple or bronze tint, especially along the edges. Flowering and fruiting decrease. Poor shoot maturation, reduced winter hardiness (Mandal et al., 2021).
• Potassium deficiency. Leaf edges turn brown, dry out, curl ("marginal burn"). Fruits become smaller. Potassium is responsible for water balance and sugar transport (Buckingham, 2010).
• Calcium deficiency. Young leaves deform, edges die off. Sunken brown spots (bitter pit) may appear on fruits. Calcium is involved in building cell walls and regulating water balance (Srivastava, 2020).
• Magnesium deficiency. Chlorosis—yellowing of leaves between veins, starting with the old lower leaves. In severe deficiency, leaves turn brown and fall off. Magnesium is a component of chlorophyll (Buckingham, 2010).
• Iron deficiency (lime-induced chlorosis). Characteristic yellowing of young leaves with green veins. On alkaline or over-limed soils, iron becomes unavailable to the plant. This is one of the most common causes of chlorosis in plums (Buckingham, 2010).
• Zinc deficiency. Small leaves (little leaf, narrow, deformed), rosetting (shortened shoots with clusters of small leaves). Fruiting decreases (Buckingham, 2010).
• Boron deficiency. Dieback of terminal buds, shoot distortion, corking of fruits. Boron is involved in cell division and pollination (Mandal et al., 2021).
• Fertilizer excess. Excessive application, especially of nitrogen fertilizers, leads to rapid growth of green mass but reduces winter hardiness and can cause root burn. Excess potassium hinders the absorption of calcium and magnesium (Trunov, 2012).

Adverse Weather Conditions

• Frosts. Damage flowers and ovaries. Buds turn brown and fall off. Late spring frosts are especially dangerous. Winter frosts can cause frost cracks—cracks in the bark, especially on the south side (Krivko, 2014).
• Sunscald. Sharp heating of the bark on the south side in late winter—early spring leads to burns. The bark cracks, peels, deep wounds appear that are difficult to heal (Tarasov, 1981).
• Drought. Lack of water causes wilting, curling, and yellowing of leaves, premature fruit drop. Young trees suffer especially severely (Krivko, 2014).
• Waterlogging. Excess moisture in the soil leads to oxygen starvation of roots, development of root rots. Leaves become pale yellow, the tree wilts.
• Hail and strong wind. Mechanical damage to branches, fruits, and leaves. These are entry points for infections and a source of stress for the tree.

Care Mistakes

• Improper planting. Burying the root collar, planting in heavy or too acidic/alkaline soil, wrong site selection (air stagnation, high water table)—all weaken the tree from day one (Buckingham, 2010).
• Irrigation regime violations. Irregular watering (alternating drought and flooding) is especially dangerous: it causes fruit cracking and weakens the immune system (Krivko, 2014).
• Improper pruning. Excessive pruning weakens the tree, opens wounds for infections. Ignoring pruning leads to crown thickening, reduced light and ventilation, and hence disease development (Trunov, 2012).
• Untimely or incorrect fertilization. Excessive nitrogen or its late application (second half of summer) stimulates shoot growth that doesn't mature by winter and freezes. Lack of potassium-phosphorus fertilizers weakens the tree before winter (Mandal et al., 2021).
• Ignoring sanitary measures. Leaving mummified fruits, fallen leaves, infected branches—maintaining a source of infection. Birds and rodents—a consequence of lack of protection (Buckingham, 2010).

Having understood the diversity of causes, it's important to learn to distinguish situations that can be corrected with planned measures from those requiring immediate action. The final chapter is dedicated to this.

How to Assess Urgency: The Key Principle

The main criterion for determining the need for urgent intervention is the rate of symptom spread and their scale. If the problem affects vital organs (trunk, root collar, main scaffold branches) or is progressing rapidly, act immediately.

Situations Requiring Emergency Measures

Algorithm of Actions in an Emergency

If you detect one of the listed signs:

1. Do not delay. Time is the main enemy in such cases.

2. Identify the problem. Compare the symptoms with the descriptions of diseases and pests. If unsure, photograph the damage and show it to a specialist.

3. Carry out urgent sanitary measures. Remove all affected branches, fruits, leaves. When pruning, be sure to cut 10–15 cm into healthy tissue. Disinfect tools after each cut (with alcohol or a 10% bleach solution) to prevent spreading the infection (Buckingham, 2010).

4. Treat the wounds. Clean wounds on the bark down to healthy wood, disinfect (e.g., with a copper sulfate solution), and cover with grafting wax or a special paste.

5. Apply protective agents. If the problem is related to disease, treat with an appropriate fungicide (strictly according to instructions). If pests—with an insecticide.

6. Assess the possibility of rescue. If the tree is severely affected (more than 50% of the crown or girdling damage to the trunk), weigh the risks. You may have to remove it to prevent the infection from spreading to neighboring trees.

7. Take care of the tree after the crisis. Water abundantly, apply fertilizer (potassium-phosphorus), mulch the root zone. This will help the tree recover.

When Haste Is Not Needed

Not all problems require immediate action. Sometimes fears are unfounded, and excessive intervention is harmful (Buckingham, 2010).

When you can take your time:

• Natural ovary drop ("June drop"). If the tree drops some small ovaries in early summer, it's a normal physiological process. The tree regulates its crop load. No intervention is needed.
• Autumn leaf yellowing. This is a natural process if it starts in the second half of August—early September.
• Single spots on leaves. If spots are not spreading massively and don't lead to leaf drop, you can limit yourself to routine prevention.
• Single bark damage. If a small area is damaged without signs of infection (no gum, no rot, no pests), the wound will heal on its own if favorable conditions (moisture, nutrition) are created.
• Some visual changes without worsening the general condition. If the tree continues to grow actively and yield fruit, and symptoms are mild, you can conduct a planned examination and care adjustment (e.g., soil analysis for pH and nutrients).

Summary: How to Make a Decision

The final decision-making scheme when detecting problems with a plum tree:

1. Dynamics assessment. Symptoms progress within days → URGENT. Symptoms develop slowly (weeks-months) → PLANNED.

2. Scale of damage. More than 1/3 of the crown or the trunk is affected → URGENT. Isolated branches or leaves → PLANNED.

3. Organ importance. Root collar, trunk, main scaffold branches affected → URGENT. Peripheral branches, leaves, fruits → PLANNED.

4. Presence of secondary signs. Fruiting bodies of fungi appeared, heavy gumosis, brown wood, signs of rot → URGENT. Uniform coating, spots, deformation without rot → PLANNED.

In this article, we have systematically examined how to determine the cause of problems with a plum tree by inspecting the tree, analyzing the location and nature of symptoms, evaluating possible causes, and identifying situations requiring urgent intervention. This systematic approach allows the gardener to act consciously and effectively, increasing the chances of preserving the health and longevity of fruit trees.