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December 2017
Growth stage 3 (GS3)
The final stage of development begins when
flowering is completed and ends at physi-
ological maturity. During GS3, seed size or
weight per seed is determined. As physi-
ological maturity approaches, sunflower is
able to utilise progressively lower tempera-
tures for seed growth, while also becoming
increasingly tolerant for drought.
Stress during GS3 can reduce yield, but
usually not to the extent of the reduction
during GS2, since seed weight is relatively a
smaller contributor to yield than seed num-
ber under most conditions.
Unfortunately, moisture is usually the most
yield limiting factor. It is also difficult to pre-
dict when and how much precipitation will
be received.
Graph 1
illustrates long term
seasonal averages. It should, however, be
stated that such data and yield are most of-
ten unrelated.
Even moderate amounts of rainfall received
at critical stages of growth, such as the first
phase of GS2, can stimulate yield potential
far beyond what a monthly total will in-
duce. The trend evident in the precipitation
averages, however, would suggest that
delayed planting further removes crop de-
velopment from the months when rainfall is
most expected.
Another factor, which affects sunflower
stand, is poor germination due to excessive
heat at the time of planting. Because sun-
flowers sometimes have to be planted in
January, or even into early February, tem-
peratures during this period often reach
up to 32°C to 35°C. Temperatures in this
range are not ideal for sunflower seed
germination.
Even when seeds germinate, high tempera-
tures may cause them to wither and die. An-
other risk factor is that top soil tends to dry
out fast in the heat and therefore a producer
is forced to plant the seeds a bit deeper
where the soil moisture content is higher.
Although this can be a solution, it is, unfor-
tunately, a risky practise as one hard shower
of rain after planting will cause a thick crust
to form and the seedlings will be unlikely to
emerge. Sunflowers can be a most reward-
ing crop and the market is reliable, but it is
important to choose the planting time care-
fully and ensure a good plant population.
Planting dates
ARC-Grain Crops in Potchefstroom has
been conducting research on planting dates
since 2007 and have demonstrated pro-
found effects upon sunflower growth and
development. This summary of findings at
ARC-Grain Crops illustrates the importance
of planting date in producing maximum
yields of sunflower.
For the past ten cropping seasons, seed
yield from 38 national sunflower cultivar
trials planted at Potchefstroom were evalu-
ated under three different planting dates
(1 to 30 November, 1 to 30 December and
1 to 30 January).
The results indicated that sunflower seed
yield declined as planting dates were de-
layed (
Graph 2
). Seed yield was reduced by
approximately 0,21 t/ha for each 30 days de-
lay in planting date after November.
The yield probability percentages for differ-
ent planting dates were subsequently cal-
culated at different yield threshold ranges
(0,5 t/ha to 3 t/ha). Results showed that the
probability of getting higher yield under a
specific yield threshold (>1,2 t/ha) was low-
er at late planting dates in comparison with
November and December planting dates
(
Graph 3
).
It means that sunflower planted later in the
season will have a lower yield potential. It
can be concluded that a higher yield might
be achieved by planting during November
and December rather than with a late plant-
ing, especially during January.
Producers who are looking to planting sun-
flower as a main and not as catch crop,
should consider planting the crop dur-
ing November and no later than end of
December in order to reach
the target yield of more
than 2 t/ha.
Presisie-beginsels én presiese produsente
Rygerigte bespuiting is nog ‘n manier om die koste te beheer.
Indien die spuit met twee rye spuitpunte, wat afsonderlik deur twee
tenks voorsien word, toegerus is, kan sekere onkruiddoders net op
bepaalde plekke toegedien word.
Hierdie stap kan die hoeveelheid onkruid of plaagdoder gebruik,
beduidend verminder en kan tot voordeel van die gewas wees daar
waar die opbrengste verhoog sou kon word. Dink net aan die effek
as Roundup nie binne die plante se blaredak gespuit word nie,
maar wel in die bane waar dit die onkruid behoorlik kan dood.
Meer aandag kan aan die spesifieke gebruike van spuitpunte gegee
word. Deesdae is daar ‘n groot aantal spuitpuntsoorte beskikbaar.
Maak daarom seker dat die regte punt vir die regte taak aangewend
word. Die nuwe spuitpunte wat binne en onder die gewasse
se blaredak, 360˚ kan spuit, is iets wat na my mening ‘n besliste
tree in die regte rigting is.
Werktuie
Trekkers is ‘n geweldige kapitale uitgawe vir enige boerdery. Deur
die effektiwiteit van hierdie belegging te verhoog, sal die koste per
eenheid verseker verlaag word. In dié geval is die toerusting op
die trekker wat die bestuurder se effektiwiteit, doeltreffendheid en
presiesheid kan verhoog, van kardinale belang.
Auto Steer is ‘n manier om die trekker se effektiwiteit en doel-
treffendheid te verhoog. Die trekker sal altyd op die regte plek ry
om dubbele werk of banke te voorkom – wat ‘n wesenlike besparing
meebring.
As aanvaar word dat ‘n trekker ‘n 6 m-implement kan trek en dat
hy effektief net 5,5 m wyd werk, gebruik so ‘n trekker 40 liter
diesel meer om 100 ha te bewerk. Die koste behoort ongeveer
R12/ha hoër te wees. Dit klink seker nie beduidend nie, maar dit is
die klein jakkalsies wat die wingerd verniel.
Presisieboerdery speel ook ‘n belangrike rol in die stroper se wer-
king. Die stropertafel verdien besondere aandag. Dit help nie jy
produseer die meeste mielies per hektaar, maar dit land nie in
die wa nie.
Maak seker dat die stroper die koppe inkry en die pitte in die tenk
kry sonder om te mors. Een kop op die grond is geld uit jou sak en
net jy sal daarvoor betaal. Die stroper moet ook oor die vermoë
beskik om die nodige opbrengsdata akkuraat te versamel en vir
verdere verwerking beskikbaar te stel.
Arbeiders
Ten einde presisieboerdery te laat werk, moet jy as produsent dit
ook aanvaar. Jy moet jou personeel ook hierby laat inkoop en seker
maak hulle bring hul kant. Dit beteken dat jy en hulle meer aandag
aan groot en klein dingetjies moet gee.
Dit help nie jy het al hierdie tegnologie op die werktuie en toerus-
ting, gewassatellietmonitorkaarte, stroperkaarte en wie weet wat
nog alles en jy doen niks met die data nie. Jy moet hierdie inligting
in jou beplanning inspan, jouself teen die kaarte meet, foute soek en
aktief oplossings vir die uitdagings identifiseer. Hierdie inligting sal
‘n bydrae lewer dat daar meer sente in jou sak klingel.
Vir meer inligting, kontak Pietman Botha by 082 759 2991.