Prevention of citrus ulcer disease and scar disease

Citrus canker and citrus scar disease both cause rough spots on leaves, young branches and fruit, reduce appearance and are spread through wind and rain. Instructions on distinguishing symptoms, preventing from disease-free seedlings, pruning canopy, wind protection, controlling leafminer and spraying at the right time.

Summary: Citrus ulcer disease and scar disease both cause bad fruit, making it difficult to sell beautifully, but the causes and ways of development are different. Ulcers are a bacterial disease, spread through rain, wind and wounds; Scar disease is a fungal disease that often damages young buds and young fruit when moist. This article provides instructions on distinguishing between the two diseases, preventing them according to the bud — flower — young fruit stages and reducing disease sources in the orchard.

Applies to: Saffron oranges, V2 oranges, diamond oranges, tangerines and some citrus trees in Ha Giang, Hoa Binh, Nghe An, Mekong Delta.
Duration: Room all year round, focus on when young buds appear, after rain and wind and young fruit stage.
Difficulty level: Medium. It is necessary to properly distinguish between ulcers and scars to choose treatment methods.
Estimated additional costs: 3-8 million VND per hectare per year depending on the number of seasons, rain and disease pressure.

Distinguishing between ulcers and scars

Criteria	Citrus ulcer disease	Scar disease
Agent	Bacteria	Mushroom
Stains on leaves/fruit	Round, rough, with yellow edges, sometimes cracked in the middle	Rough, rough, deformed young tissue
Spread	Wind, rain, tools, seedlings, wounds	Splashing water, prolonged humidity, disease source on old leaves/fruit
Sensitive period	Young locs, young fruit, after leafminer	Young buds, flowers, young fruits
Consequences	Leaf loss, fruit loss, reduced appearance	Rough, distorted, reduced fruit

Two diseases can appear in the same orchard. It is necessary to look closely at the disease, the time of appearance and the rainy and humid conditions.

Why do leafminers make ulcers worse

The leafminer creates tunnels in young leaves. These wounds are very convenient entrances for ulcer bacteria:

Young deer infected with leafminer often have more severe ulcers.
Young leaves curl, tear, and have difficulty drying after rain.
Bacteria follow rainwater and penetrate through the wound.

Therefore, ulcer prevention cannot be separated from leafminer management in lucky seasons.

Severe disease conditions

Rain with strong wind.
The orchard has a dense canopy, it takes a long time to dry after rain.
The tree produces many young buds continuously.
Using disease-free seedlings.
Unsanitary pruning tools.
The orchard has many diseased leaves, branches, and fruits from the previous crop.

Cancer disease is especially easily transmitted through planting materials and tools. A diseased seedling can carry the disease into the new orchard.

Room from seedlings and orchard design

Choose disease-free seedlings with clear sources.
Do not take grafts/grafts from trees with ulcer symptoms.
Plant at moderate density, with airy canopy.
There are windbreaks in strong wind areas.
Avoid spraying water on the canopy if the orchard is diseased.

For new orchards, disease-free seedlings are the cheapest solution. Treating diseases after they have entered the orchard is always more expensive.

Staged Room

After harvest

Remove diseased branches and severely diseased leaves.
Collect diseased and fallen fruits.
Prune for airiness.
Disinfect pruning tools when transferring diseased plants to healthy plants.

When the tree produces young buds

Monitoring the spell-painting worm.
Prevent insect pests from crossing the threshold, prioritize measures that are less harmful to natural enemies.
Spray to prevent disease before or immediately after prolonged rains if the orchard has a history of disease.

Flower and young fruit stage

Protect young fruits in the first 1-2 months because this is the stage where scars can easily form.
Do not spray heavy crop-protection products/chemicals when flowers are blooming unless necessary.
After rain and wind, check the young fruit for new bumps or ulcers.

Treatment when the orchard has disease

Mild illness

Remove severely diseased branches/leaves.
Spray locally if necessary.
Control spell worms on the next lucky wave.
Track after the rain.

The disease spread

Clean the entire orchard.
Apply copper-based spray or appropriate product according to local recommendations and product label.
Alternate methods, avoid spraying the same type too much.
Increase canopy pruning and reduce humidity in the orchard.

Don't expect old wounds to disappear. The goal is to protect new fortune and fruit.

Common mistakes

Confusing scars with ulcers: treatment is not focused properly, especially when ignoring leafminers.

Using seedlings from unknown sources: brings disease into the orchard from the beginning.

Not cleaning the pruning shears: the disease is transmitted through pruning operations.

Canopy too dense: leaves and fruits stay wet for a long time, disease breaks out after rain.

Only spray when the fruit is severely rough: the stains on the fruit will not recover, only to prevent a new wave.

Monitor and record

[ ] Which lucky batch is the most seriously ill?
[ ] Proportion of young leaves with leafminers.
[ ] Percentage of young fruits with ulcers/scars.
[ ] Strong rainy and windy day before the disease appeared.
[ ] The measures have been taken and are effective in the next lucky draw.

Recording each wave of fortune will help know whether the disease comes from the weather, leafminers or disease sources still in the orchard.