A Study On The Occurrence Law Of Gramineous Weeds In Turf And Their Chemical Control Technique

Gramineous weeds in turf are obstinate and serious, and difficult to be controlled. An experiment of searching the occurrence law of gramineous weeds and selecting the effective herbicides was carried out with four kinds of gramineous weeds of crabgrass, barnygrass, yellow foxtailgrass and goosegrass from turf in Shenyang, 2001. The author commanded basically the biological characteristics and the occurrence law through investigations in field and laboratory and greenhouse.The biological characteristics of the four gramineous weeds include frequency (77.5%,70%,63%,14% respectively); the synthetic endanger index (35.2%); morphological features; and the occurrence law refers to the relationships between germination, dormancy, temperature and soil humidity(all weeds have dormancy trait, their bourgeon were affected by the ultimate and optimum temperature and humidity); emergence; the relationship between emergence and climate(all weeds are aestival weeds, their occurrence fastigium was from June 15 to July 1 ); phonological rhythm(weeds can all accomplish their life history ,whenever they sprout ,the earlier of sprouting, the shorter of growing period, and vice versa); and their reproduction and regrowth ability(they produce large amount of seed and own regrowing ability ). Under different densities , the competitions of weeds and turfgrass were also tested. On the bases of above studies, the herbicides and the bestdose were chosen to control the four kinds of gramineous weeds effectively and be safe to turfgrass : they are preemergence herbicides-48% Trifluralin EC at 100ml/666m2, postemergence herbicides-6.9% Puma water EC at 50ml/666m2 and 50% Quinclorac WP. At 50g/666m2 .The fresh weigh controlling ratios of weeds were 81%, 88%, 79% respectively. The control effect of non-selective herbicides (20% Quaraquat gramoxoneat at 40-60ml/666m2 )on weeds plant was 100% .The effect of Puma to crabgrass and Quinclorac to barnygrass were very satisfactory with the result of 92% and 93%.