Prévention et Solutions de Replantation

Apple powdery mildew, caused by the fungus Podosphaera leucotricha , is a common problem in French orchards. Its impact, ranging from leaf deformation to loss of fruit quality, presents a challenge for professional growers. This article explores ways to detect, prevent, and treat this disease, while proposing solutions to compensate for losses by replanting suitable fruit trees.

Symptoms of apple powdery mildew

On the leaves

• White, floury coating: A powdery coating appears on the upper surface of the leaves, a typical sign of infection.
• Deformation and rigidity: Affected leaves curl up, lose their flexibility and functionality.
• Increased fragility: These leaves become vulnerable to external aggression, particularly insect attacks.

On the buds

• Ruffled appearance: Infected buds swell irregularly.
• Insufficient development: Shoots are weak and unable to support optimal fruiting.

On fruits

• Discoloration: Fruits lose their natural shine and appear dull.
• Corky texture: A roughness develops, affecting their marketability.

Factors that promote the development of powdery mildew

Weather conditions

• Moderate temperatures: Between 10 and 25°C, the fungus proliferates rapidly.
• High relative humidity: Unlike other fungal diseases, powdery mildew does not require rain to establish itself, but it thrives in a humid environment.

Inadequate orchard management

• Lack of ventilation: Dense plantings create microclimates favorable to the fungus.
• Presence of infected debris: Infected buds and leaves, left in place, become sources of contamination.

Prevention of powdery mildew in apple trees

Choice of resistant varieties

Varieties such as Akane have a natural resistance to powdery mildew. However, varieties such as Reine des Reinettes require increased vigilance. Adapting plant selection to the region's sensitivity is essential to limit risks.

Cultural practices

• Size and ventilation: Maintaining optimal air circulation reduces humid microclimates.
• Winter cleanup: Remove infected branches and buds to limit the initial inoculum.
• Proper spacing: Spaced planting prevents moisture buildup.

Use of suitable rootstocks

Robust rootstocks like M9 T337 NAKB can enhance the tree's overall resistance to powdery mildew and other stresses.

Biological treatments against powdery mildew

Natural products

• Sulfur: Known for its effectiveness, it acts by preventing the germination of spores.
• Potassium bicarbonate: Makes the environment unfavorable to the fungus by modifying the acidity of the surfaces.
• Horsetail manure: This natural fungicide stimulates the trees' defenses.
• Milk or whey: These products create a protective film against infection.

Biological innovations

• Bacillus subtilis : This probiotic competes with pathogens, limiting their progression.
• BNA (Old-Fashioned Natural Whitewash): Applied to the trunks, it constitutes a protective barrier.

Conventional control of powdery mildew

Specific fungicides

• Wettable sulfur: Versatile, it works against powdery mildew and scab, but must be applied at moderate temperatures.
• Systemic fungicides: Offering both preventative and curative protection, they require strict management to avoid resistance.

Precautions for use

• Alternating products: To limit resistance, vary the modes of action.
• Treatment schedule: Apply treatments at the first symptoms, respecting the recommended intervals.

Replanting after a loss: Our professional solutions

When faced with losses caused by powdery mildew, it's crucial to react quickly to maintain your farm's profitability. At Arboriverse, we offer a complete range of plants suitable for rebuilding your orchards:

• Grafted fruit trees at producer prices: Take advantage of competitive prices directly from our specialist nurseries.
• Varieties adapted to your region: We help you select the varieties most resistant to powdery mildew and other local constraints.
• Fast and reliable delivery: Directly to your plot, we ensure an efficient logistics chain.

FAQs

• What are the best organic treatments for powdery mildew? Sulfur, horsetail manure, and Bacillus subtilis are particularly effective in organic treatments.
• Can powdery mildew be completely prevented? Complete prevention is difficult, but resistant varieties and appropriate cultural practices significantly reduce the risks.
• How long does it take to obtain a harvest after replanting? Depending on the type of plant (scion, half-stem, high-stem), it takes between 2 and 4 years for a first significant production.
• Do you offer advice on replanting? Yes, our experts will guide you every step of the way, from choosing the plants to planting them in your orchard.
• Are rain tarps useful against powdery mildew? They limit direct moisture, but can promote humid microclimates if not properly installed.
• What types of plants do you offer? We offer a wide range including cattail, tall, half-stem, bare-root, and potted plants.

Conclusion

Apple powdery mildew remains a serious threat to orchards, but proactive management and tailored solutions can limit its impact. In the event of losses, Arboriverse is your preferred partner for replanting with professional-quality fruit trees tailored to your needs and region. Contact us today to ensure the sustainability of your production.