Level II Agricultural Business Operations

Scale proposed by the Dutch phytopathologist, Jan C. Zadoks

Know as Zadoks scale, it gives the plant a figure based on the current growth stage of the plant.

Scales goes from 00-99.

Knowing the stages of development of a crop is critical in many management decisions that growers make.

Eg, Nitrogen application GS21 Herbicide application GS11

Fungicide application GS32Growth regulator GS32

0

50

100

150

200

250

Feb Mar Apr May Jun Jul Aug

N U

ptak

e (k

g/ha

)

GS 31

GS 39

GS 61

Harvest

Slow Rapid Slow

40 % of total N uptake in 4 weeks

17 % of total N uptake

T1, T2 & T3 are linked to timing of fungicide spraying.

T1 is generally GS 32-33

T2 is GS 39

T3 is a ear wash at GS 65

Some other T values have been developing e.g. T0.5, T1.5 etc. Becoming more popular in NI

Link from HGCA website.

http://www.hgca.com/media/180128/g49-cereals-growth-stages-a-guide-for-crop-treatments.pdf

Seedling Growth 11-19 Tillering 20-29 Stem Elongation 30-39 Booting 41-49 Ear Emergence 51-59 Flowering 61-69 Milk Development 71-79 Dough Development 81-89 Ripening 91-99

GS10 First leaf through coleoptile

GS11 First leaf unfolded (ligule visible)

GS13 - 3 leaves unfolded

GS15 - 5 leaves unfolded

GS19 - 9 or more leaves unfolded

GS20 Main shoot only

GS21 Main shoot and 1 tiller

GS23 Main shoot and 3 tillers

GS25 Main shoot and 5 tillers

GS29 Main shoot and 9 or more tillers

GS30 Ear at 1cm (pseudostem erect)

GS31 First node detectable

GS32 Second node detectable

GS33 Third node detectable

GS37 Flag leaf just visible

GS39 Flag leaf blade all visible

Very Important Period◦ Fungicide Timing◦ Growth regulator

For a quick, but crude assessment, fold back the leaf sheaths then count the slight 'bumps' caused by each node.

The exact stage is revealed by stripping off leaves and cutting the main stem longitudinally with a sharp knife.

GS41 Flag leaf sheath extending

GS43 Flag leaf sheath just visibly swollen

GS45 Flag leaf sheath swollen

GS47 Flag leaf sheath opening

GS49 First awns visible (if an awned variety) Barley only

GS51 First spikelet of ear just visible above flag leaf ligule

GS55 Half of ear emerged above flag leaf ligule

GS59 Ear completely emerged above flag leaf ligule

GS61 Start of flowering

GS65 Flowering half-way

GS69 Flowering complete

GS71 Grain watery ripe

GS73 Early milk

GS75 Medium milk

GS77 Late milk

GS83 Early dough

GS85 Soft dough

GS87 Hard dough (thumbnail impression held)

GS91 Grain hard (difficult to divide)

GS92 Grain hard (not dented by thumbnail)

GS93 Grain loosening in daytime

Correct timing of sprays and fertiliser treatments is critical to success in growing cereals.

Many instructions and guides state ‘Apply at GSXX.”

Take 5-10 typical plants from across the field, ideally digging them up rather than pulling up to avoid damaging stems and leaves.

Knowing the growth stage is important to ensure that timing of pesticides are applied in line with manufactures recommendations.

Correct timing can have a bigger impact on crop response/performance than product type!