Farmer’s Weekly – 09 August 2019

Thiscropis targetedbya numberof pestsand

diseases,butthesethreatscanbe controlled,either

preventitivelyor bydirecttreatment.

This person will look at factors
such as the ratio of palatable
plants to unpalatable or
unwanted plants, the density
of plant cover, the percentage
of bare patches, erosion, and
other signs of degradation.
These are likely to vary from
camp to camp. The area near
the homestead, for example, is
typically more severely grazed
than the outlying camps.
Find out if you have enough
camps to implement a grazing
system, where to build more
camps, if necessary, and
howlargetheyshouldbe.

FENCING
Farmsoftenhavetoofewcamps.
Thisproblemis noteasilysolved,
duetotoday’sastronomicalcost
offencingmaterial(anything
uptoR30000/km).Oncefenced,
eachcampmusthaveatleast
onestockwateringpoint,
addingtothecost.However,you
shouldavoidsettingupcamps
nearwatercourses,mountain
veldoranyotherecologically
sensitiveareasofthefarm.
A soundveldmanagement
systemrequiresa minimum
numberofwell-fencedcamps
orpaddocks.Thiswillenable
sectionsoftheveldenoughtimeto
recoveraftereachgrazingsession.
Animalmovementcanalsobe
controlledbyelectricfencingand
herding,butthesemethodsare
expensive.It’sa surebet,though,
thatvirtualfencingorindividual
animalcontrolwillbecomemore
costeffectiveinthefuture.This
couldwellrendertraditional
fencingobsolete,enabling
precisionlivestockfarming
eveninanextensiveregion.
If cashflowis a problem,
fencethefarmovera number
ofyearsandwriteoffthe
costasyougoalong. ▪FW

Vegetables

Beetroot pest and disease control

Beetrootis susceptibletotwo

pestsinparticular:aphidsand

redspider.Importantdiseases

includeCercosporaleafspotand

downymildew,amongstothers.

• Aphids(Aphisfabae)
  Aphidsaredarkbrownorgreen
  insectsabout2mminlength.They
  suckonthelowersurfaceofthe
  leaves,butcausedamageonly
  whenpresentinlargenumbers.
  Infestedleavesarecurlyandrolled.
  Control:Useregistered
  chemicals.Croprotation
  canalsohelp.


• Redspider( Tetranychus
  cinnabarinus)
  Thesearesmall,darkredordark
  brownmitesabout1mmlong
  thatsuckonthelowersurface
  oftheleaves.Theirnumbersare
  usuallylow,butcanincrease
  rapidlyduringwarmweather.
  Control:Sprayneemoiland
  pyrethrindirectlyontothe
  adultmites,larvae,nymphsand
  eggstokillthemoncontact.
  Applyit toactivespidermite
  infestationsatthree-dayintervals
  untilcontrolis achieved.


• Cercosporaleafspot
  (Cercosporabeticola)
  Thiscommonbeetrootdisease
  is causedbya fungusthatenters
  theleavesandproducessmall,
  roundspotsofabout3mmin
  diameter.Spotscanalsobefound
  ontheflowersandseedofplants
  grownforseedproduction.
  Thespotsstartoffbrownwitha
  darkpurpleborderandlaterturn
  greyinthecentre.Thetissuein
  thecentrediesasthespotsage.
  Control:Croprotation,seed
  treatmentwithregistered
  chemicals,andavoiding
  over-wateringwillallhelp
  controlthedisease.


• Downymildew
  (Peronosporaschachtii)
  Thisseed-bornediseasecan
  affectthecropearlyintheseason.
  Leavesofinfectedplantsturn

yellow and curl downwards,

and a grey fungal growth is

visible on the underside of

the leaves. The flowers and

crown can also be infected.

Control: As the disease is

seed-borne, it is important to sow

good-quality seed in well-drained

soil. Avoid over-watering and

don’tplantata spacingthatis too

narrow.Controlweedsproperly.

• Scab(Actinomycesscabies)
  Beetrootinfectedwithscab
  developrough,irregular
  surfacescabs.Thedisease
  is mostcommoninsoils
  containingtoomuchlime.
  Control:Conducta soilanalysis
  todeterminetheleveloflime.


• Damping-offandrootrot
  (Phomabetae)
  Thesearecommonincompacted
  soil.Germinationis weakin
  infectedplants.Youngseedlings
  growpoorly,turnyellow,wilt,
  toppleoveranddie.Theroots
  turnblack.Seedlingsthatare
  lessseverelyaffectedproduce
  small,malformedbeetroot.
  Control:Treatseedwith
  Thiramandsowonlyinsoil
  witha goodstructure.Practise
  croprotation.Plantatthe
  correcttimeandnottoodeep.


• Heartrot
  Thisis causedbyboron
  deficiencyandis characterised
  byblackmarksontheroot
  surfaceandcracks.Black
  blotchesarevisibleintheflesh
  whenthebeetrootis cutopen.
  Control:Plant
  resistantcultivars.


• Source:‘Productionguidelinesfor
  beetroot’.DirectorateAgricultural
  InformationServices,Departmentof
  Agriculture,LandReformandRural
  Development.Retrievedfromhttps://
  http://www.daff.gov.za/Daffweb3/Portals/0/
  Brochures%20and%20Production%20
  guidelines/Production%20
  Guidelines%20%20Beetroot.pdf;
  arbico-organics.com. ▪FW

9 August 2019 farmer’sweekly 55

having enough

camps enables

the veld to

recover between

grazing sessions