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Damping-Off

soil and cuttings

DAMPING-OFF, the rotting of 'seedlings and cuttings. in the seed-bed and the cutting bench, usually just above the surface of the soil. The immediate cause is a soil fungus (usually Artotragus or Pythium debaryanum, though other fungi may produce the same effect) which feeds upon decaying organic matter until it obtains a favorable opportunity for attacking a living host. This opportunity is generally af forded by a weakened condition of the seedlings or cuttings due to a more or less stagnated atmosphere highly charged with moisture and of rather high temperature. The fungus gains entrance to the weakened stems which soon turn brown or black. The foliage quickly becomes infested and sometimes in a single night a whole seedbed or bench full of cuttings may become a rotting mass with no healthy plants left. With careful management the trouble can be avoided. The propagating medium should be clean, sharp sand, which should be thoroughly drenched when the bed is watered, the excess water pass ing quickly away in perfect drainage. The bed

should never be allowed to become dry. In short, both seedlings and cuttings should be kept growing steadily and sturdily. The drench ing washes the spores of the fungus down through the sand. Should a bed become infested the healthy plants should at once be transferred singly and with as little soil as possible to fresh quarters. Neither nor drying the soil will kill the fungus, which can live for months when growth is impossible. Sterilizing the sand or soil with steam. is sometimes resorted to, the sand being heated for several hours. Less frequently plants in the open air are attacked. In the greenhouse and nursery experience in management will count for much.