Damping off is a disease affecting different crops seedlings. Among the plants affected include Amaranth, Brassica, carrot, tomato, cucumber, melon amongst others. The disease can affect the leaves, roots, seeds, stem and whole plant part depending on the crop type. In cabbages the plant can manifest itself during the heading stage, post harvest, pre – emergence and seedling stage .The fungi cause the seedlings to damp off or collapse and decay. The disease may manifest itself either during pre or post emergence of the seedlings. If the infestation is pre emergence the seedlings will not germinate while in the case of post emergence the seedlings collapse, often submerged in a mass of fungal growth.
Many fungi are associated with damping off disease but the most common are those in the pythium spp. Infestation is favored by low soil p H, poor aeration, heavy seeding/ high plant population, excess soil moisture, low light penetration and presence of weeds. The fungus thrives on the plant exudates. The fungi can survive in the soil for long time in the following ways
- As mycelium in the soil
- As resting spores
- As sclerotic (tiny brown resting fungal bodies).
SYMPTOMS OF DAMPING OFF.
Based on the plant part affected the following signs are likely to be observed in a damping off infestation.
- Leaves: the leaves may show lesions/ abnormal colors and wilting.
- Roots may have lesions.
- Seeds may rot or develop discolorations.
- Stems may develop cankers,
- The whole plant may dieback; damping off.
A CASE OF DAMPING OFF IN CABBAGE
- In cabbage the following symptoms are likely to be observed.
- WIRE STEM. The stem above the soil line shrivels and darkens; the outer tissues come off leaving a dark wirely and woody inner stem. The plant will have stunted appearance.
- BOTTOM ROT, the lower leaves wilt, decays and turnsblack.
- Cabbage head rot: HEAD ROT, slimy dark decay at the base of outer leaves develops foliage leaves die and drop off.
DAMPING OFF CONTROL
Certified seeds which are known to be disease free should be used, nursery beds should also be raised to reduce water logging and excess moisture. Soil PH should be raised to between slightly acidic and neutral. This can be achieved by applying HUMIPOWER. This is a unique soil conditioner from Greenlife Crop Protection Africa Ltd which is capable of regulating the soil Ph. It is applied mixed with fertilizers or organic manures at the rate of 1kg per 50kg bag fertilizer or 1kg humipower for 4tones of organic manure
The product PYRAMID 700WP and GEARLOCK TURBO 250WP from Greenlife Crop Protection Africa Ltd are also effective in controlling damping off. PYRAMID 700WP can be applied by drenching at a rate of 100gm/ 20l or foliar application at a rate of 50gms/20l. GEARLOCK TURBO is applied at the rate of 30gms/20l.