Scientific Name: Erysiphales spp.

Powdery mildew is one of the most recognisable fungal diseases in South African gardens. It presents as a dusty white or grey coating on leaves, stems, and flowers, quickly spreading across crops like cucumbers, pumpkins, peas, beans, and even chillies. Though it thrives in warm, dry conditions with high humidity and poor airflow, it doesn’t need free moisture to infect. It’s a regular nuisance in home gardens and tunnels. If ignored, this fungus stunts plant growth, reduces yields, and can severely damage flavour and marketability in food crops.

Organic gardeners know that once powdery mildew sets in, controlling it can be both time-consuming and expensive. Treatments often need to be reapplied, and even then, the damage can continue. That’s why the smartest approach is a preventative one. Avoiding the disease altogether through careful planning and early interventions is far more effective than reacting after visible signs appear.

To slow or stop infections, increase airflow between plants by proper spacing, trellising, or pruning dense foliage. Avoid overhead watering which raises humidity on leaf surfaces. Drip irrigation systems such as the Livingseeds Drip Irrigation System are ideal. Remove infected leaves promptly, and begin spraying before signs appear if conditions favour disease. The most effective prevention strategy starts with biologicals like Double Nickel and Pellos. 

• Biologicals

  • Double Nickel 55 
    A living bacterial fungicide containing Bacillus amyloliquefaciens. Use preventatively or at first sign of infection to suppress powdery mildew and boost plant defences. Do not use with copper sprays.

  • Péllos
    A biological fungicide with Ampelomyces quisqualis, a natural hyperparasite of powdery mildew fungi. Active for up to 21 days per application. Suitable for routine use on most vegetables and ornamental plants.

• Organics

  • Copper Soap
    An organic fungicide that combines fatty acids with soluble copper. Apply preventatively. Not compatible with beneficial microbes like Péllos or Double Nickel 55.

Note: Avoid mixing Copper Soap with microbial products to preserve the viability of beneficial organisms.