![]() The fungi are indiscriminate in the species or varieties of plants attacked, so you can’t control the problem by trying to find resistant cultivars. Spores may be numerous and are typically black and shiny, but they are rarely discernible without the aid of a microscope. The spores may persist in the soil in a dormant stage for years if plant material is not available as a food source. The fungi are members of several genera of fungi, including Pythium, Fusarium and Rhizoctonia. The spores can also be introduced into the potting medium on the surfaces of tools or pots or trays. The problem is caused by the spores of fungi that are already present in the potting soil. Seedlings may die within 18-24 hours after colonization by the pathogens. The thread-like, constricted stems are unable to support the tops of the seedlings and they fall over. Immature stem tissues have a sunken, water-soaked appearance with discolored brown to gray lesions at the soil line. (Hardening off is the process of moving plants outdoors for part of the day to gradually acclimate them to the direct sunlight, dry air and cold nights.) Young stems may be attacked just after emerging from the soil because they haven’t yet had a chance to harden off. When the failed seeds are dug up and examined, tissues inside the seed coat are rotted and lack recognizable roots or seed leaves. The fungi, attracted by fluids excreted by the plant, enter the tender young cells and dissolve their cell walls. Seeds may be attacked in the soil by the fungi right after they germinate. The death of young plants is caused by a group of soil-borne fungi, and the disease is referred to as “damping off.” Unfortunately, these situations are fairly common in the field or in the greenhouse under certain conditions. Photo: Clemson University - USDA Cooperative Extension Slide Series, Bugwood.By Steven Jakobi, Master Gardener Volunteer, Cornell Cooperative Extension of Allegany CountyĪfter a winter of planning, preparation and expense, few things are more disappointing for the gardener than the failure of seeds to send shoots up from the soil, or watching seedlings emerge, but then suddenly wilt and die. Covering the seeds with compost or Sphagnum Moss (instead of sowing mix) may also help. Sulfur powder, or a tea of Seaweed, Garlic or Chamomile has been used to treat small areas of infection and prevent it spreading. ![]() Damping Off fungi need high humidity, so thin your seedlings promptly to prevent overcrowding, avoid overwatering (especially on cool sunless days when water doesn’t evaporate quickly) and make sure there is good ventilation and air circulation. However, if your climate dictates that you start your seedlings inside then you have a potential problem. Growing your seedlings in a well ventilated, cool greenhouse will produce far fewer problems with Damping Off. Damping Off is mostly a disease of indoor seed raising. ![]() You may lose a few plants occasionally, but so what. It shouldn’t be a big problem if you take the precautions outlined below. ![]() The best defense against Damping Off is to avoid giving it the growing conditions it needs. Fortunately such techniques aren’t really necessary for the home grower. Almost all soil contains the spores of Damping Off so commercial growers often avoid soil in their mixes, or sterilize it with heat or chemicals. Other kinds of Damping Off kill the seed before it germinates, or rot the roots, causing the tops to turn yellow and die. This type of Damping Off mainly affects very small seedlings and becomes is less of a problem as they get older and their stems get tougher. These develop shrunken black stems and eventually fall over and die, though the stem may remain upright for a while afterward. The best known type of Damping Off first manifests itself as a fuzzy whitish mold on the surface of the soil and then goes on to girdle the succulent stems of newly germinated plants. This fungus disease can be the bane of the inexperienced seed starter and comes in several guises. ![]()
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