By Willem Boshoff and Francois du Toit
Intensive seedling tests
undertaken recently showed that
Pannar has a wheat
cultivar – PAN 3144 – with resistance to both the old and
new Russian wheat aphid biotypes.
Seed of PAN 3144 should
already be commercially available by the 2008 planting
season.
The identification of a new
Russian wheat aphid biotype in the eastern Free State by
researchers from the ARC Small Grains Institute this past
season, and the impact of this new biotype on resistance
sources that have been successfully employed in South Africa
over the past decade, could have far-reaching implications
for wheat production, especially in the eastern Free State.
Producers in this important
wheat production area have been placed under pressure over
the past few seasons due to higher winter temperatures and
associated droughts, as well as the appearance of stripe
rust on once resistant cultivars.
Producers should note that
the wheat cultivars PAN 3364, PAN 3235, Caledon and Gariep,
which are sold by Pannar and which were resistant to Russian
wheat aphid in the past, are susceptible to the new biotype.
Considering all reports on
the occurrence of Russian wheat aphid on previously
resistant wheat cultivars over the past season, the
expectation is that the new biotype has most likely already
spread over a wide area and that producers can expect
further problems on the once resistant cultivars in the
coming season. Wheat producers should therefore seriously
consider the use of preventative treatments such as the use
of seed treatments for the upcoming season.
The good news is that Dr
Francois du Toit began work on alternative sources of
resistance to Russian wheat aphid back in the 1990s. Pannar
currently has material at an advanced stage of development
with different sources of resistance which are effective
against the old as well as the new biotypes.
In addition to PAN 3144,
five second-year Elite lines with resistance to both
biotypes have been sent in for provisional classification.
These lines all possess good adaptability, high yield
potential as well as resistance to most of the prevailing
rust races. The urgency of the situation and the shortage of
wheat cultivars with sufficient resistance to the new
Russian wheat aphid biotype should provide sufficient
backing for the speedy classification of these lines.
Acknowledgement: Ms Vicki
Tolmay of the ARC Small Grains Institute is hereby
acknowledged for providing samples of the new biotype of the
Russian wheat aphid to Pannar’s research division.
Pannar kultivar bied weerstand teen nuwe Russiese koringluis
Deur Willem Boshoff and
Francois du Toit
 |
|
Links is saailinge
van PAN 3144 wat weerstand bied teen die ou sowel as
nuwe Russiese koringluis-biotipes en regs is
saailinge van die cultivar Gariep wat duidelik
vatbaar is vir die nuwe biotipe. |
Intensiewe saailingtoetse
wat onlangs gedoen is, het getoon dat Pannar reeds beskik
oor ‘n koringkultivar, PAN 3144, wat weerstand bied teen
beide die ou en nuwe Russiese koringluis-biotipes.
Saad van PAN 3144 behoort reeds teen die 2008 plantseisoen
kommersieel beskikbaar te wees.
Die identifisering van ‘n
nuwe Russiese koringluis-biotipe die afgelope seisoen in die
Oos-Vrystaat deur navorsers van die LNR-Kleingraaninstituut,
en die impak van die nuwe biotipe op weerstandsbronne wat
suksesvol oor die afgelope dekade in Suid-Afrika ontplooi
is, kan verreikende gevolge vir koringverbouing in veral die
Oos-Vrystaat inhou.
Produsente in hierdie
belangrike koringverbouingsgebied is die afgelope paar
seisoene onder druk geplaas weens hoër wintertemperature en
gepaardgaande droogtes asook die voorkoms van streeproes op
eens weerstandbiedende kultivars. Produsente moet daarop let
dat die koringkultivars PAN 3364, PAN 3235, Caledon en
Gariep wat deur Pannar bemark word en wat in die verlede
bestand was teen Russiese koringluis, vatbaar is vir die
nuwe biotipe.
Na aanleiding van navrae
oor die voorkoms van Russiese koringluis op voorheen
weerstandbiedende koringkultivars die afgelope seisoen, word
verwag dat die nuwe biotipe heelwaarskynlik reeds oor ‘n wye
gebied mag voorkom en dat produsente die komende seisoen
meer probleme op die eens bestande kultivars kan verwag.
Voorkomende maatreëls soos die gebruik van saadbehandeling
kan dus ‘n belangrike oorweging wees deur koringprodusente
vir die komende plantseisoen.
Die goeie nuus is dat Dr.
Francois du Toit reeds in die middel-negentigs begin werk
het aan alternatiewe weerstandsbronne teen Russiese
koringluis. Huidiglik beskik Pannar oor gevorderde materiaal
met verskillende bronne van weerstand wat effektief is teen
sowel die ou as nuwe biotipe.
Benewens PAN 3144 is vyf
tweedejaars Elite-lyne, wat beskik oor weerstand teen beide
biotipes, ingestuur vir voorlopige klassifikasie. Hierdie
lyne beskik almal oor goeie aanpassing, hoë
opbrengspotensiaal asook weerstand teen meeste van die
heersende roesrasse.
Die dringendheid van die
situasie en die tekort aan koringkultivars met voldoende
weerstand teen die nuwe Russiese koringluis-biotipe behoort
ondersteunend te wees tot die klassifikasie van hierdie
lyne.
Erkenning: Erkenning word
hiermee verleen aan Me Vicki Tolmay van die
LNR-Kleingraaninstituut vir die verskaffing van Russiese
luis van die nuwe biotipe aan Pannar.
