The root knot nematode disease also known as
eelworms or “mandolo” reduces yield and quality of tobacco.
Root knot nematodes are found and stay for
long periods in the soil. Distribution of nematodes in the soil is irregular or
patchy. Nematodes affect tobacco in the nursery and field causing roots to be
swollen or have knots, and even rot. Other symptoms include yellowing, wilting,
and stunting of plants. Root knots are caused by nematodes. Nematodes cause disease in
tobacco plants through injuring roots resulting in reduced intake of water and
minerals from soil. Nematodes are spread
by dirty irrigation water, through contaminated implements during ploughing,
and planting tobacco in infested soil.
The best approach to manage root knot nematodes is
through Integrated Pest Management (IPM) in the nursery and field as described
a 4 year rotation, for example Tobacco-Maize-Groundnuts-Tobacco and
include fallow in the rotation
the following resistant / tolerant varieties: Burley BRK4 /Flue cured AFH1, AFH2, AFH3 and AFH4
and burn all tobacco leftover seedlings and stalks soon after completing
the Nursery: broadcast Dazomet
pesticide such as Basamid at 1.5kg for each bed of 30m2. Mix the
chemical with soil by cultivating the bed using a new hoe across and along
the bed 14 days before sowing. Cover with a black plastic paper.
Alternatively you can use Metham sodium such as Herbifume should be
drenched on the seedbed at the rate of 3 litres in 30 litres of water for
a bed of 30 m2. Drench the chemical 14 days before sowing.
Cover with a black plastic paper for 14 days, after which you remove the
black paper and cultivate the soil to allow air in.
When using a pesticide, always wear protective clothing and follow the instructions on the product label, such as dosage, timing of application, and pre-harvest interval.