DiseasePowdery mildew control

Bicarbonate & plant extracts against powdery mildew control

The effectiveness, measured

68 /100

Time horizon: Immediate

Why it works

Potassium bicarbonate is effective against powdery mildew, allowing you to cut and rotate with sulfur.

What to measure for this pairing

Powdery-mildew severitySulfur replaced

Why this problem matters

Powdery mildew (Erysiphe necator) thrives in warmth and moderate humidity, without needing rain. Under organic rules it is fought mainly with sulfur, complemented by bicarbonates, extracts and biocontrol agents.

Efficacy depends on timing and coverage: start early, in the sensitive post-budburst phase, and hold protection to veraison. An open canopy and close monitoring cut the number of applications needed.

Problem indicators

Sulfur applications per seasonLeaf and cluster severitySpray canopy coverage

Certification & rules: Decisive for organic harvest quality; sulfur is an authorised input.

How to apply the means

  1. 1Fit them into the programme as reinforcement and rotation.
  2. 2Apply preventively, with good coverage.
  3. 3Reapply frequently (short persistence).
  4. 4Log them as part of the phytosanitary programme.

Frequently asked

Does bicarbonate replace sulfur?

Not entirely — it is mostly a complement and alternative in specific windows, helping to reduce and rotate with sulfur.

Are all extracts allowed in organic?

No. Only those on the authorised-input lists — which is why logging by active substance is essential.

Same means, other problems

Same problem, other meansPowdery mildew

Related reading →Copper in organic viticulture: the limits, the maths and how to stay under them

How GrapeFlow helps

The proof organic certification demands — logged by plot and date.

Phytosanitary register with authorised inputs

Every treatment logged with product, rate and active substance, flagging what is allowed under organic rules — an audit-ready history.

Downy & powdery mildew risk models

Per-plot disease risk from local weather, to treat at the right moment and spend less copper and sulfur.

Electronic field notebook

All operations — weeding, green manure, biocontrol — logged by plot and date, ready for organic certification.