Root-knot and lesion nematodes (Meloidogyne and Pratylenchus spp respectively) are the most important nematodes faced by grain farmers in South Africa. Increases in soil temperature and the presence of moisture lead to a resumption of activity after winter dormancy. This is especially the case at present, following the abundant rain in most local crop production areas in summer.
In their infective stages, these microscopic organisms use their reserve energy to move through the soil by means of the water layers surrounding soil particles in search for the roots of possible hosts. They infect and feed on the roots of grains and weeds, and can cause serious crop damage.
Weeds should therefore be removed from grain lands to prevent infestation, as nematodes can survive in their roots. Live root-knot nematode females have been found in the middle of winter in the Free State on ragwort bushes. These abundant, yellow-flowered weeds create the ideal habitat for the nematodes, which start reproducing as soon as the soil temperature rises.
RAPID REPRODUCTION
Two of the most prevalent rootknot nematodes in South Africa, M. incognita and M. javanica, can develop at fairly low base temperatures of 9,8°C and 10,6°C respectively.
A single female root-knot nematode can produce up to 1 800 eggs (reported in a susceptible soya bean cultivar) within 20 to 30 days of infecting the root of a host plant at a soil temperature of 26°C. This means that a single female, which can live for an average of three months, has the potential to produce approximately 5 400 eggs in one season.
Should the soil temperature increase, however, the nematode could reproduce within a shorter time, which is why farmers should keep their grain lands free of weeds.
This story is from the September 25, 2020 edition of Farmer's Weekly.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 8,500+ magazines and newspapers.
Already a subscriber ? Sign In
This story is from the September 25, 2020 edition of Farmer's Weekly.
Start your 7-day Magzter GOLD free trial to access thousands of curated premium stories, and 8,500+ magazines and newspapers.
Already a subscriber? Sign In
R17m donation of tractors, bulls and infrastructure
Small-scale farmers in KwaZulu-Natal have been given an opportunity to grow into sustainable commercial businesses through a holistic integrated programme that will provide mechanisation, infrastructure and sector expertise.
Top dairy products revealed
Lactalis South Africa has won the South African Dairy Product of the Year Award for six of the past eight years. This year it won with a 10-month-old Gouda made especially for Woolworths.
Poor waste management highlighted on Earth Day
Most of South Africa’s waste ends up in dumps, if not strewn across open spaces or littering streams and oceans.
Kenya hosts soil health summit
The health of African soil was discussed at length by gathering of experts, writes Jeff Kapembwa.
Report shows the impact that heat has on agricultural workers
The UN’s International Labour Organisation (ILO) recently released a report showing the impact of climate change on the health of workers.
Factors to bear in mind when dipping livestock
It is important to consider the intervals at which you dip livestock in relation to the specific season in which ticks become more or less, writes Shane Brody.
Good outlook for pome fruit
Varieties of fruit could be the key in growing the pome fruit sector, writes Glenneis Kriel.
Building a sustainable agriculture sector in the Western Cape
Technology, research, financial mentorship and more will be required, writes Marinda Louw Coetzee.
PwC research shows food crisis impact
A new report details how the looming food crisis will affect Africa, writes Jyothi Laldas.
Braaied meat and soft-boiled egg Thai salad
This salad with maize, peanuts and eggs will turn leftover braai meat into a completely different meal. Recipe and photo: South African Poultry Association.
