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 Herbicide application Fungicide application Growth regulator GS21 GS11 GS32 GS32 Slow N Uptake (kg/ha) 250 Rapid Slow Harvest 200 GS 61 150 GS 39 40 % of total N uptake in 4 weeks 100 50 GS 31 17 % of total N uptake 0 Feb Mar Apr May Jun Jul Aug 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/g49cereals-growth-stages-a-guide-for-croptreatments.pdf Seedling Growth Tillering Stem Elongation Booting Ear Emergence Flowering Milk Development Dough Development Ripening 11-19 20-29 30-39 41-49 51-59 61-69 71-79 81-89 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!
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