Damping off is the single term used to describe



underground, soil line, or crown rots of seedlings due to

unknown causes. The term actually covers several soil borne

diseases of plants and seed borne fungi. The fungi which

cause root rot are species of Phyium, Phytophthora,

Rhizoctonia and Fusarium.

There are two types of damping off: pre-emergence and post-

emergence. In pre-emergence damping-off, seeds may rot and

seedlings may decay before they emerge. In post-emergence

damping off the seedlings emerge then may pale, curl, wilt,

and collapse from a rot at the soil line and below. The

base of the stem is generally water-soaked at first then

turns gray to brown or black then rots.

Vegetable seedlings often do not grow well under humid

conditions, particularly if the soil is cold and wet.

Damping off fungi flourish in moist, unhygienic conditions.

The disease often starts at one end of a seed tray, and

quickly spreads to the other end. A fluffy fungal growth

may also appear on the soil surface as well as on the dead

seedlings.

When preparing to plant be sure that flats, tools, plant

containers, and benches are clean. Damping off pathogens

can live in these containers. The easiest way to disinfect

them is to dip them in a bleach solution for 10 seconds.

Use 1 part bleach to 4 parts water. Or use 70 percent

rubbing alcohol.

Plant in a light, well drained fertile seedbed. Preferably

use sterile soils that have been pasteurized with heat

before planting. Maintain a soil pH at the low end of the

average scale. A soil of 6.4 pH is less susceptible to root

rot than a pH of 7.5. As plants are watered the pH

gradually increases. Test often and continue to maintain a

lower pH while the plants are still germinating. If

necessary use one tablespoon of vinegar to 1 gallon of water

to lower a rising pH level.

Plant seeds no deeper than 4 times their own thickness.

Keep the seedbed soil on the dry side after planting and

allow plenty of bright light but not direct sunlight.

Use plant containers with drainage holes, water from the

bottom only, and avoid excess watering. Do not allow pots

to stand in water as excess water cannot drain and the roots

will be starved for oxygen which will stop all growth of

seedlings. Never water late in the day.

Avoid overcrowding and overfeeding of plants. Do not

overfertilize, especially with nitrogen.