Garden diseases

A fungal disease, devastating in a wet summer, that destroys foliage and then tubers in a few days.

A fungus forming a white, powdery felt on the surface of the leaves, which end up drying out.

A fungal disease forming orange to brown pustules on the leaves, which yellow then dry out.

A soil disease that causes swellings on the roots of Brassicaceae, condemning the plant. Persists a very long time in the soil.

Viral diseases transmitted by piercing insects (aphids above all) or by tools. No remedy once the plant is infected.

A leaf fungus of the nightshade family: on the leaves it draws brown spots ringed with concentric circles, shaped like a target, which climb from the lower leaves upwards and gradually weaken the plant in warm, humid weather.

A very polyphagous grey mould: in humid, stagnant conditions a downy grey felt invades flowers, fruit, leaves and stems, and rots them.

A classic fungal disease of orchards: in a wet spring, a fungus marks leaves and fruit with velvety olive-brown spots, then cracks and 'corks' the fruit.

A springtime fungal disease that blisters, puckers, thickens and reddens the young leaves of the peach, making them dry up and fall, which weakens the tree.

A fungal orchard disease that rots the fruit until it mummifies, and can dry out flowers and twigs in a wet spring.

A complex of soil fungi that makes young seedlings collapse, the stem pinched and thinned right at the surface of the substrate, often within a day or two of emergence.

A physiological disorder (not a disease or a pest, and not contagious): the bottom of the fruit browns and dries out because calcium does not reach its tip steadily, most often because of erratic watering.

A bacterial disease of pome fruit (apple, pear, quince) and of several ornamental and hedging shrubs (hawthorn, cotoneaster, pyracantha, rowan): flowers and shoots turn brown and dry out as if scorched, the tips of the shoots bend into a shepherd's crook. In the European Union it has been a regulated non-quarantine pest (RNQP) since 2020: no more compulsory reporting or control for gardeners, but rules remain for the movement of plants, and it is still a quarantine pest in a few protected zones (in France, Corsica).

A soil fungus that invades the conducting vessels: wilting on one side of the plant, leaves that yellow then dry out while keeping their shape, brown vessels visible when the stem is cut. Its microsclerotia persist for years in the ground.