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disease

Downy mildew

Pseudoperonospora cubensis · Peronospora belbahrii

Angular yellow spots on upper leaf surfaces with greyish-purple sporulation underneath. High economic impact in cucumber and basil.

  • Oomycete
  • Foliar
  • Wet leaves
  • Fast-moving

Signs Croptimus looks for

  • Angular yellow lesions bounded by leaf veins
  • Greyish-purple sporulation on the lower leaf surface
  • Lesions following nutrient deficiency patterns at first
  • Leaf necrosis once lesions coalesce
  • Whole-plant collapse in heavy infections within 7–10 days

Recommended action

Reduce leaf wetness duration, ventilate to clear morning condensation, and apply phosphorous-acid or mefenoxam-based protectants at first signal. Croptimus pinpoints which zones to target first.

Downy mildew can wipe out a cucumber or basil crop within 10 days of first lesion in warm humid conditions. The window for protectant spraying is narrow – once lesions are visible on a walk-through, you’ve already lost the early window.

Croptimus monitors the lower leaf surface (where sporulation actually happens) continuously, surfacing the disease before it becomes a sales problem.

Frequently asked

  • How does Croptimus distinguish downy mildew from nutrient deficiency?

    The model is trained on both classes separately and uses sporulation patterns visible on the lower leaf surface (not just the upper-surface colour) to disambiguate.

  • Is the model effective on basil?

    Yes – both cucurbit and basil downy mildew sub-models are deployed. Basil is the higher-priority crop for early detection because lesions render leaves unmarketable within 48 hours.

See Croptimus catch this live.

20-minute call. We run this exact class on a frame from your crop, send detections back within the week.

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