EVENNESS OF COMMERCIALLY-APPLIED FERRAX SEED TREATMENT ON WINTER BARLEY

Lots of seed barley (Hordeum vulgare L.) commercially treated with 'Fe rrax' flowable concentrate were sampled as close to the point of appli cation as practicable from fourteen seed treatment machines of five ty pes and from sacks on pallets. Loss of formulation due to handling was avoided; the general sampling incidence was one from each 500 kg. Eig ht hundred and fifty samples were analysed by HPLC for ethirimol (labe l application rate 2000 mg/kg). The combined sampling and analytical v ariation was found from pairs of 'at machine' samples taken simultaneo usly; the mean differences were usually below 100 mg/kg with maximum d ifferences mostly around 200 mg/kg. When differences between successiv e samples during a run were calculated these values were nearly double d. Despite the variety of machines and sites from which samplings were obtained it was usual for 90% or more of results to be within +/- 10% of the relevant mean. Variation for 'on pallet' samplings was rather wider but the values obtained for mean loadings proved to be very simi lar. It was concluded that procedures similar to those in the Rules of the International Seed Testing Association might be used to obtain re presentative samples. It is suggested that a sampling incidence of one from each 1000 kg is suitable for seed lots of small-grain cereals of 5 000-10 000 kg. Fewer than half the samplings gave mean loadings abo ve 1750 mg/kg ethirimol; poor calibration and maintenance seem likely to be the causes of flow loadings as the evenness of application was s imilar, despite the various machines and sites sampled.