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San Jose scale: what it is, how it originates, and how to eliminate it effectively.

St. Joseph'S Louse

Quadraspidiotus Perniciosus

Pathogen:

Insect

Type:

Risk to the plant:

HIGH

San Jose scale: what it is, how it originates, and how to eliminate it effectively.
San Jose scale on pear trees | idMicrobe

Don’t know which pest or disease your plant has?

Correctly identifying the problem is key to saving the plant.

 

A plant expert analyzes the photos and sends you a clear diagnosis within 24 hours, explaining the causes and the most effective solutions step by step.

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DESCRIPTION

WHO CAUSES IT?

Quadraspidiotus perniciosus, commonly known as the St. Joseph's Louse, is a hemipteran insect of the family Diaspididae. This pathogen is a pest that affects a wide variety of fruit trees, including pear trees. Adult females are circular in shape and grayish in color, while males are winged and smaller in size. The adult female can produce up to 400 eggs, which hatch into nymphs called "crawlers." These nymphs disperse and adhere to the bark, branches and fruits of the pear tree, where they begin to feed on the sap. In doing so, they secrete a protective waxy coating. Quadraspidiotus perniciosus goes through several nymphal stages before becoming an adult. This life cycle can repeat itself several times a year, especially in warm climates, contributing to its rapid spread and increased pest population.

SYMPTOMS

In the pear tree, the San José Louse causes significant damage to both the bark and the fruits. Feeding by nymphs and adults weakens the tree, reduces fruit production and can cause the death of branches and, in severe cases, the entire tree. Affected fruits develop red Taches around feeding sites, which decreases their quality and commercial value. Severe infestation can lead to defoliation and reduced resistance of the tree to other diseases and adverse environmental conditions.

- General weakening of the tree
- Reduction in fruit production
- Death of branches
- Red Taches on the fruits
- Defoliation
- Lower resistance to other diseases and adverse conditions

San Jose Scale: Symptoms and Damage in Pear Trees
Damage caused by the San Jose scale in Peral
San Jose scale in Peral: How to recognize and treat it effectively

Don’t know which pest or disease your plant has?

A plant expert reviews your photos and sends you a clear diagnosis within 24 hours, with step-by-step solutions.

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TEMPERATURE AND HUMIDITY

15-30°C

60-90%

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HOW IS IT SPREAD?

Direct contact between plants, Wind, Infected plant material, Contaminated tools, Insect vectors, Movement of infested plants

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HOW TO REMOVE IT?

Home remedies

BONE MEAL OR GROUND FISH SHELLS

RUSTY NAILS OR IRON SHAVINGS

BANANA PEELS

EPSOM SALTS (MAGNESIUM SULFATE)

SOLUTION WITH HOUSEHOLD BORAX

GROUND OR BOILED EGGSHELLS

COMPOST WITH ONION OR GARLIC SCRAPS

VEGETABLE COOKING WATER

WOOD ASH

WATER WITH VINEGAR OR LEMON (VERY DILUTED)

GARLIC INFUSION

USED COFFEE OR TEA

BANANA AND EGGSHELL INFUSION

POTATO OR LEGUME COOKING WATER

COMPOST FROM FRESH GREEN LEAVES

COMPOST OR WELL-AGED MANURE

DILUTED MILK (1:10)

BANANA TEA

LEAF COMPOST

NETTLE SLURRY

POTASSIUM SOAP AND NEEM OIL SOLUTION

POTASSIUM SOAP SOLUTION + NEEM OIL + DIATOMACEOUS EARTH

BAKING SODA AND NEUTRAL SOAP SOLUTION

GARLIC INFUSION WITH NEUTRAL SOAP

CHROMATIC OR ADHESIVE TRAPS

DILUTED MILK

HORSETAIL INFUSION

TRUNK WHITEWASHING

DIATOMACEOUS EARTH

WOOD ASH

NETTLE SLURRY

CUT THE AFFECTED BRANCHES AND APPLY CINNAMON

GARLIC AND CINNAMON INFUSION

INFUSION OF WORMWOOD, CHILI OR CHILLI

CLEAN THE AFFECTED AREA AND APPLY ASH PASTE WITH GARLIC OR CINNAMON

GARLIC AND MINT INFUSION

LIGHT TRAPS

APPLY CINNAMON POWDER

PITFALL TRAPS

CRUSHED EGG SHELLS

CLEAN AND SEAL THE WOUND WITH CLAY, CINNAMON AND GARLIC PASTE

GARLIC INFUSION

MATURE COMPOST

TRAPS WITH VINEGAR AND SOAP

SEAL HOLES WITH ASH PASTE AND CRUSHED GARLIC

VINEGAR AND BAKING SODA SOLUTION

ANT TRAP

TAPE TRAP

PHEROMONE TRAP

ALCOHOL TRAPS

FUNNEL TRAP

There are no home treatments

Chemical treatments

• RAPE OIL 1.53% [AL] P/V
• RAPE OIL 848.24 g/l [EC] P/V
• PARAFFIN OIL (CAS [8042-47-5]) 83% [EC] P/V
• PARAFFIN OIL (CAS [97862-82-3]) 40% [EW] P/V
• PARAFFIN OIL (CAS [97862-82-3]) 80% [EC] P/V
• DELTAMETHRIN 1.57% [SC] P/V
• DELTAMETHRIN 2.5% [EC] P/V
• DELTAMETHRIN 2.5% [EW] P/V
• PYRIPROXIFEN 10% [EC] P/V
• Quadraspidiotus perniciosus (Pheromone)
• POTASSIUM SALTS OF FATTY ACIDS C14-C20 48% [EW] P/V

Authorized treatments in organic farming

• RAPE OIL 1.53% [AL] P/V
• RAPE OIL 848.24 g/l [EC] P/V
• PARAFFIN OIL (CAS [8042-47-5]) 83% [EC] P/V
• PARAFFIN OIL (CAS [97862-82-3]) 40% [EW] P/V
• PARAFFIN OIL (CAS [97862-82-3]) 80% [EC] P/V
• Quadraspidiotus perniciosus (Pheromone)
• POTASSIUM SALTS OF FATTY ACIDS C14-C20 48% [EW] P/V

Insect allies

PREDATORY MITES

LADYBUGS

LACEWINGS

PARASITIC WASPS

HOVERFLIES OR PARASITIC FLIES

PREDATORY BUGS

There are no natural allies

Mycodiplosis oidii (predatory mosquito)

EFFECTIVE PRODUCTS TO ELIMINATE THIS DISEASE

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Fungus Fighter Plus | Fungicide for Plants

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Ultimate Bug Killer | Broad-Spectrum Insecticide

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Fast acting bug spray with up to 2 weeks protection, controls common garden pests

- Carry out regular inspections of the pear tree to detect early signs of infestation.
- Implement a biological control program using natural enemies of the louse, such as parasitoids and specific predators.
- Apply horticultural oils during the tree's dormant period to suffocate nymphs and adults.
- Use specific insecticides according to technical recommendations, ensuring product rotation to avoid resistance.
- Prune and destroy infested branches to reduce the pest population.
- Maintain good garden hygiene, eliminating plant debris and fallen fruits that may harbor the louse.
- Monitor the climate and adjust management practices according to the conditions that favor the development of the pest.
- Educate field personnel on the identification and management of the San José Louse to ensure effective detection and control.

Recommendations

Consulting on plant problems and diseases
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