CONTROL OF WEEDS

Press, Volume XCIX, Issue 29235, 20 June 1960, Page 3

CONTROL OF WEEDS

Investigation By D.SJ.R. ■ Tite difficulties of controlling regrowthof undesirable species in the natiiral vegetation When sowing for a grass seed crop are being studied by the Grasslands Division of the Department of Scientific and Industrial Research, says a report from the D.S.I.R. At present the main investigation concerns the dormancy of self-sown grass and seeds. Widespread field tests have shown great variation in the period of seed dormancy and time of germination. Under trial conditions using sterilised soil beds, all seedlings of the weed species, barley grass, and goose grass emerged within five weeks of being sown, but crabgrass took seven months longer before the first seedling appeared. Viable self-sown seeds of barley grass are not present in the ground in such large numbers as is often supposed. From soil samples taken at random from the countryside it was found that the proportion of seeds still viable at tiie beginning of spring was, with few exceptions, fairly low. Deep burial does not necessarily destroy the seed; a few of a group of seeds buried 12 inches deep were still viable after a year in the soil. The scientists at the Grasslands Division consider that, since the length of the dormancy period determines when germination will occur, a means of breaking dormancy at a suitable time might provide an opportunity for more economical weed control Knowledge of the length of the normal period of dormancy would give an indication of the time over which control measures would have to be applied.