Can You Put Diseased Plants Into the Compost?

The compost heap provides the gardener’s gold: humus. But what to do with diseased or pest-infested plants? Compost them or better dispose of them elsewhere?

Can You Put Diseased Plants Into the Compost?

Attention: Permanent spores of harmful fungi.

In general, plants that have disease or pest infestations in the root or stem area are not suitable for composting.
Certain harmful fungi that often trigger these diseases, such as aster wilt, cabbage hernia, fusarium or sclerotinia wilt on cucumber and tomato, root rot on strawberry plants, and cylindrocladium shoot dieback on boxwood, produce resistant permanent spores that spread further through the compost if sufficiently high temperatures of 60 to 70 degrees are not reached during composting.
Similarly, pests that live or persist in the soil, such as nematodes or vegetable flies.

No problem with mildew and aphids

It is also better for gardeners to avoid composting seed-bearing weeds and root weeds, such as couch grass and goutweed, since a possible later carryover with the compost cannot be ruled out with them either.
In the case of disease or pest infestation on leaves and fruits, such as scab, powdery mildew, leaf spot disease or aphid infestation, composting is possible, however, if the diseased parts of the plant are then immediately covered with soil or other dense material, such as grass clippings. Existing spores and pests are thus prevented from spreading. Survival of these pests in the compost is then no longer to be expected with proper composting as a result of the rotting processes.