When susceptible crop plantings follow at close intervals i.e. within 12 months or less, beet cyst nematode builds up in the soil to damaging population concentrations. High populations may reduce the yield by 20-40%. The beet cyst nematode was found in vegetable lands around cities such as Johannesburg, Pretoria, Cape Town and Durban, Pinetown, Port Elizabeth and Pietermaritzburg. Populations in the soil are usually low, but monocrop farming styles can create a soil environment conducive to exponential growth.
Crops that are affected are: cabbages, Chinese cabbages, cauliflowers, Brussels sprouts, broccoli, turnip, radish and swed, beet root, rhubarb and spinach.
if the nematode is present, seedlings will be most affected while older more mature plants are more tolerant and tend to survive better.
To control Beet Cyst Nematode a proper crop rotation system must be implemented. If high infestations are suspected the soil must be treated with a fumigant nematicide before the next crop is grown. There is no other effective control method than proper crop rotation. Chemical control must be the last resort but it is much cheaper and economical to implement good crop rotation systems. A tolerant beetroot and cabbage variety is not available in South Africa (as far as I know), but there are in the UK.
The nematode can survive adverse conditions in the soil for years inside a cyst. Once conditions are favourable they start multiplying.
Since the nematode is soil borne, it is easily spread via boots, wheels, machinery, crates, tools and animals. It does not spread easily since it is so small.
Nematodes feed on plant roots. The first signs show plants that do not get enough water although the soil can be wet. Some plants will be stunted. They usually are found in one section of the land at first. If the plants are pulled out of the soil, the roots will show a bearded growth pattern. This is an indication of the plant trying to combat the damage the nematodes are doing. Some nematodes cause swelling of the roots and they look very misformed. Upon close inspection of the roots, small white round bodies can be seen. As they get older they turn harder and brown. The brown body is the dead female protecting the dormant eggs. When conditions are favourable they are released into the soil.
Optimum temperature for growth and reproduction is 21-27°C.
Beetroot cyst nematode can also be confused with Rhizomania disease. The wilting symptoms can also be cause by other nematodes so its not unique to this nematode. Leaf symptoms can also be confused with those caused by poor soil structure or magnesium deficiency. So check your soil first and compare how other crops that are not sensitive to the nematode performed.
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