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🌼Problem guide

Marigolds diseases and pests

The database lists 3 problems recorded on this crop. 2 of them can cost the whole harvest, and 1 survive in soil or debris into next season — those are the ones that decide your rotation. The largest number are active in June.

Pressure through the year

The number of problems listed as active in each month. Pick a month to see what to sow, plant and harvest then.

Start from what you can see

What actually prevents them

  • Water at the base of the plant in the morning, never over the leaves. Splashing soil onto foliage is the delivery route for every problem listed here, and morning watering lets anything that does land dry before nightfall.

    Applies to: Gray Mold (Botrytis)

  • Mulch the soil surface. A physical barrier between last season's spores and this season's lowest leaves removes the first infection of the year, which is the one that seeds all the others.

    Applies to: Gray Mold (Botrytis)

  • Give the plants their full spacing 20×30 cm and keep the centre of each one open. Air moving through the planting dries the leaves faster, and leaf wetness duration is what turns a spore landing into an infection.

    Applies to: Gray Mold (Botrytis), Slugs & Snails

  • Rotate this bed and everything else in the same family on at least a three-year cycle. 1 of the problems below survive in soil or crop debris between seasons, so returning the same crop to the same ground hands them the host they were waiting for.

    Applies to: Gray Mold (Botrytis)

  • Clear and remove the spent crop at the end of the season rather than digging it in. Debris left on the surface is where the persistent problems overwinter, and next spring they start from your own bed rather than from somewhere else.

    Applies to: Gray Mold (Botrytis)

  • Keep affected material out of the compost heap — 1 of these survive a garden heap and come back with the finished compost. Bag it for municipal green waste, which is composted at temperatures a garden heap does not reach.

    Applies to: Gray Mold (Botrytis)

Every listed problem

Ordered by how much they can cost you.

Fungal diseases(1)

  • Fuzzy grey-brown mould on flowers, fruit and stems; soft watery rot; tan spots with concentric zoning on leaves. Spores puff out in clouds when disturbed.

    How it spreads
    Rain and irrigation splash
    Compost
    Keep out of the compost
    Conditions
    5–22°C · humidity ≥90% · wet leaves / rain
    First move
    Treat, then re-check in 5–7 days

    Also at risk: Grapes, Strawberries, Raspberries, Blackberries, Redcurrants, Gooseberries

Pests(2)

  • Fine pale stippling or bronzing of leaves, delicate webbing on undersides and growing tips, and leaf drop in heavy infestations; tiny moving dots visible with a lens.

    How it spreads
    Carried by insects
    Compost
    Safe to compost
    Conditions
    27–40°C · dry air ≤55%
    First move
    Treat, then re-check in 5–7 days

    Also at risk: Aubergines

  • Irregular ragged holes with smooth edges in leaves and fruit, seedlings eaten to the ground overnight, and tell-tale silvery slime trails on soil and foliage.

    How it spreads
    Carried by insects
    Compost
    Safe to compost
    Conditions
    5–22°C · humidity ≥80% · wet leaves / rain
    First move
    Treat, then re-check in 5–7 days

    Also at risk: Lettuce, Peas, Celeriac, Swiss chard, Rhubarb, Strawberries

Why rotation matters here

1 of these overwinter in the soil or in crop debris rather than on the plant. Pulling the sick plant does not remove them: they wait for the same host to come back to the same ground.

Problems of other crops