maizestalkboreris lessthan
1%ofallthemaizeplanted.
“We’vefoundthat
Bttechnologycontinually
demonstratesanoutstanding
levelofeffectivecontrolof
B.fusca, thespottedstalk
borer(Chilopartellus) andthe
fall armyworm (Spodoptera
frugiperda), and growers [are
satisfied] in the majority of the
maize-growing regions.”
tackling Bt resistance
GrantPringle,a product
agronomistatPannarSeed,which
breedsandmarketsBtmaize
as part of its product range,
says that to prevent resistance
from spreading from southern
KwaZulu-Natal to other maize
production areas, all Bt maize
farmers need to follow specific
procedures and protocols as
part of their conventional insect
resistance management plans.
One such step is to carry out
full-width,pre-seasontillage
ofanylandplantedpreviously
toBtmaize where there was a
resistant stalk borer population,
and which is due to be planted
again to Bt maize. This will help
to kill many of the maize stalk
borer pupae in the maize root
balls and stalks left over from
the previous season. For no-till
farmers who prefer not to disturb
the soil, Pringle suggests soil
corrections such as liming.
Du Toit adds that, where
it is legal to do so, a further
option is to burn the stalks of
harvested MON89034 Bt maize
to kill the larval and pupal
stages of the Bt-resistant pests.
A second step, and one that
is a legal requirement for all
Fast Facts
- the extent of damage caused by maize
stalkborertosomeBtmaizecropsin
southernKwaZulu-Natalwaswholly
unexpectedbyBayersouthernafrica. - Encouraging Bt-resistant pests to
mate with their non-Bt-resistant
counterparts dilutes Bt resistance
in populationsofthesepests. - Bt maize farmers need to scout
their crops frequently for insect
damage and report any infestation
to their seed sales representatives.
OPPOSITE PAGE:
Maize farmers must
adhere to stringent
legal requirements
for refuge crops
aimed at preventing
thedevelopmentof
Bt-resistantpests.
BayerSouthernafrica
RIGHT:
Bt-resistant
maize stalk borer
(Busseola fusca)
has been identified
in some southern
KwaZulu-Natal
Btmaizecrops.
Paul-andrecalatayud
BELOW:
Any volunteer
Bt maize crop
seen growing in
a subsequent
rotation crop
should be uprooted
immediately or
destroyedwith
herbicide.
GettyimaGeSGRAnTPRInGLElloyd PhilliPSMAGdAduTOITSuPPlied23 August 2019 farmer’sweekly 37