Instructions for preventing dwarfism or crazy disease

Dwarf curl disease is caused by a virus. There is no cure once the tree is infected. Instructions on how to distinguish leaf mosaic, dwarf curl, micronutrient deficiency and how to prevent it with disease-free seeds, sterilize tools, and control aphids.

Summary: Dwarf curl disease, also known as mad pepper disease, is dangerous in that the tree does not die immediately but has a long-term decrease in productivity. The heavy tree produces many small buds close to the base, thick and brittle leaves, short internodes, and sparse fruit clusters. Because the disease is caused by a virus, there is no "cure" for it. The correct way is to recognize early, eliminate the source of the disease and control the aphids that transmit the disease.

Applies to: Pepper orchards with basic construction and business in the Central Highlands and Southeast, especially self-propagating orchards or buying varieties from unknown sources.
Duration: Prevention from seed selection stage, year-round monitoring. When diseased plants are detected: treat within 7 days.
Difficulty level: Medium. The most difficult thing is to distinguish from micronutrient deficiency and not to spare sick plants.
Estimated additional costs: 1-3 million VND per hectare per year for inspection, cleaning tools and broker bed bug prevention.

What is torsion of dwarfism

Dwarf curl disease or crazy pepper disease on pepper is often related to viruses such as *Cucumber Mosaic Virus* (CMV) and *Piper Yellow Mottle Virus* (PYMoV). The virus invades the plant, causing growth disorders in leaves, buds and stem internodes.

Points to remember:

There is no cure for a virus-infected tree.
Sick trees can still live for many years but have low productivity.
Sick plants are a source of infection for healthy plants.
Most transmitted through cuttings, pruning tools and sucking insects.

Therefore, the way to prevent this disease is different from fungal disease. You don't have to see a disease and then spray treatment and that's it.

Three common types of symptoms

Light leaf mosaic

This form is easily overlooked:

The leaves have dark green — light green mosaic streaks.
The leaves do not deform much.
The tree still grows and can produce fruit.
Symptoms look like micronutrient deficiency.

If the orchard only has a few odd trees showing leaf mosaic, it needs to be marked for monitoring. Don't rush to get seedlings from these plants.

Deformed leaf mosaic

This form is clearer:

The edges of the leaves are curled and wavy.
The leaves are long and narrow, the tip curves down like a spear.
The leaves are thick, brittle, and the surface is wrinkled.
The leaves have yellow or white streaks along the main veins.
Short, small branches, few flowers, sparse fruit clusters.

The tree can still produce fruit but the yield and quality are clearly reduced.

Curly, short, crazy

This is a severe form:

Leaves are small, deformed, rough.
The internodes are short, the tree is very low.
The pepper tops get smaller but produce a lot of buds, forming a tuft.
The buds grow tangled close to the base or close to the stem.
The basic construction tree is slow to climb and difficult to create a canopy.

This form is often called "crazy pepper" because the plant produces buds haphazardly but does not develop into strong vines.

Distinguished from malnutrition

Lack of zinc, boron, magnesium or nutritional imbalance also causes small leaves and curled leaf edges. But there are a few other points:

Sign	Nutrition	Dwarf/crazy
Distribution	There are often many trees in the same lot	Usually individual plants, then gradually spread
Leaf	Yellow or deformed but less clearly encrusted	Mosaic, thick, brittle, wrinkled leaves
Bud	Weak tree, few buds	The buds are many, the internodes are short and tangled
Reaction to micronutrient fertilization/spray	There is improvement after 2-4 weeks	No clear improvement

If you have added the correct nutrients but the plant is still curled up, you need to think about a virus.

Path of spread

Infected cuttings

This is the most dangerous transmission route. Just take cuttings from a mother plant that has been infected with the virus, the seedlings will almost always carry the disease from the beginning.

Do not take the same from:

The orchard has crazy pepper trees.
The mother tree has mosaic leaves even though it is still green.
The orchard has an unknown pest history.
The pepper vines are weakening, the branches are short, the buds are distorted.

Pruning tools

Wire cutters and pruning knives can carry diseases from diseased plants to healthy plants. The risk is highest when:

Cut the diseased tree and then cut the healthy tree immediately.
Batch shaping without sterilizing scissors.
Propagated from multiple mother plants but using the same knife.

Broker

Some sucking aphids can transmit viruses between diseased and healthy plants. orchards with many aphids, mealybugs, and companion ants often have a higher risk of spreading diseases.

Preventive measures

Choose disease-free varieties

Buy seedlings from a reputable facility.
Choose a mother plant that grows well, has even leaves, and is not mosaic.
Do not take seedlings from plants with suspicious symptoms.
Prioritize seed orchards that are periodically monitored for pests and diseases.

With pepper, making a mistake from the same seed is a mistake lasting 10-15 years. Don't save a few thousand dong per seedling and then lose the whole orchard.

Disinfect tools

When pruning or taking cuttings:

Use scissors specifically for diseased plants, if any.
Disinfect scissors with 70 percent alcohol or suitable disinfectant solution.
Disinfect after cutting suspected disease plants.
Don't let the cutlery stick to tree sap and then use it again and again.

This operation takes a little time but greatly reduces the risk of spreading the virus.

Controlling aphids

Monitor aphids and mealybugs on buds, young leaves and flower buds.
Keep the orchard well-ventilated, do not fertilize too much nitrogen, this will cause the buds to grow continuously.
Protect ladybugs, parasitic wasps, and aphid-eating flies.
When aphids appear in large numbers, locally spray the bedbug nest with the drug allowed to use according to the label.
Ant control because ants help aphids spread.

crop-protection products should not be sprayed throughout the orchard according to a rigid schedule. Spraying at the wrong time will cause natural enemies to disappear and aphids may flare up again faster.

Treating diseased trees

The new tree is suspicious

Mark the tree with colored string.
Do not take seeds from this tree.
Check again in 2-4 weeks.
Supplement micronutrients once if nutritional deficiency is suspected, then monitor response.

If the plant does not recover and the mosaic/curling symptoms become more obvious, move on to treating the diseased plant.

The tree is clearly sick

Dig out the entire tree, including the base.
Take it out of the orchard for destruction.
Do not cut diseased vines to make cuttings.
Disinfect tools after handling.
Watch for neighboring trees within a radius of 5-10 meters.

Don't regret one disease and then spread it to the entire pepper row.

Monitor periodically

[ ] Check young leaves and small leaves every month.
[ ] Mark plants with mosaic leaves, curly leaves, and short internodes.
[ ] Record plants supplemented with micronutrients and results after 2-4 weeks.
[ ] Watch for aphids, mealybugs and ants in the orchard.
[ ] Disinfect tools when pruning, cutting, and taking cuttings.

Seed orchards need to be inspected more closely than production orchards, because a diseased mother plant can spread to thousands of seedlings.

Common mistakes

Spraying with fungicide to treat viruses: no effect. Viruses are not fungi.

Confused with micronutrient deficiency and keeping diseased plants for too long: plants become a source of infection.

Taking seeds from trees that "still bear fruit" but have mosaic leaves: seedlings carry the virus from the beginning.

Mass pruning without sterilizing scissors: causes disease to spread very quickly.

Only kill diseased plants, ignore aphids: the source of infection continues to move.

Take notes

Date of discovery of suspected disease plants.
Symptoms: mosaic leaves, curled leaves, short internodes, tufted buds.
Treated trees: monitored, added micronutrients, dug up.
Aphid condition in the lot.
Original seed source of each batch.

Recording the seed source helps trace back if a batch has many diseased plants at the same time.

References

*Pepper pests and prevention measures* — Vietnam Academy of Agricultural Sciences, National Agricultural Extension Center.
*Instructions for preventing dwarfism or dysentery* — Hainong technical document.
*Sustainable Pepper Technical Handbook* — Vietnam Pepper Association.