WHAT
IS THE RUSSIAN WHEAT APHID?
The aphid originally came from Russia, and was first recorded
in Kenya in 1 995. It is a serious pest of wheat, barley
and triticale. Farmers have reported 20-1 00% losses caused
by aphid infestation. The pale green aphid feeds inside
the rolled leaves of cereals. The Russian wheat - Ch
aphid is found in all wheat - or barley producing areas
of Nakuru, East & West Mau Escarpment, Ngorengore, Eldoret,
Kitale, Nyandarua, Timau and Maralal.
Above: A healthy wheat crop
Below: A damaged wheat crop
HOW
CAN YOU TELL WHEN INFESTATION IS STARTING?
- You
can easily detect an attack by the Russian wheat aphid on
the crop by scouting for damage signs.
- First
noticeable sign is slight to moderate yellowing of small
areas of crop within the field.
- The
crop appears to be under drought stress, even if there is
no drought.
- Bright
purple discolouration develops with moderate to severe leaf
rolling.
- The
aphid causes the leaves to curl up tightly. The aphid lives
inside the tightly rolled leaves. Look for aphids inside
the tightly rolled new leaves of the plant.
- Plants
become stunted. Later the flag leaf becomes twisted and
the ear is bent.
- Dry
weather favours rapid increase of the aphid.
WHAT
CROP PROTECTION MEASURES ARE RECOMMENDED
CHEMICAL
CONTROL
- Chemical
control of the aphid is the only option for many farmers
because our commercial wheat varieties are susceptible to
the aphid.
- Chemical
control can be achieved when systemic insecticides are applied
to the seed at planting, or when foliar systemic insecticides
are applied. Tightly rolled leaves protect the aphid from
contact insecticides which are not recommended.
- Foliar
insecticides can be applied when damage signs are noticed.
One spray is recommended but you can repeat if necessary.
Chemicals
applied with seed at planting
| Chemical |
Rate
per 100 kg of
seed |
| Gaucho
350 FS |
200
ml |
| Carbofuran
350 ST |
740
ml |
These
insecticides protect against the aphid for about 6 to 8
weeks. After this period a foliar spray with systemic insecticides
may also be required.
Chemical
applied as foliar insecticides
| Chemical |
Rate/ha
+ 200
litres of water |
Rate
per
20 litres sprayer |
| Azorcord
|
750
ml |
75
ml |
| Metasystox
|
500
ml |
50
ml |
| Dimecron
|
800
ml |
80
ml |
CULTURAL
CONTROL
- Use
the correct seed rate to ensure good plant density, as low
plant densities are susceptible to heavy attack by the aphid.
- Plant
as early as possible for your area.
- Use
recommended fertilizer rates A well-fertilized crop that
is not stressed is more tolerant to aphid attack.
- Remove
volunteer plants and grasses because they act as the aphid's
hosts even before the main crop has been planted.
CAUTION
Insecticides
are dangerous to humans and animals. Read and follow the
manufacturer's instructions. Always wear protective clothing,
gumboots, mask, plastic gloves (or Polythene bags) and a
waterproof raincoat.
Compiled by
M Macharia
KARI Headquarters Library
resource.center@kari.org
KARI/NJORO PO NJORO
|
