Study On Occurrence Rule And Control Techniques Of Weeds In Summer Maize Fields Of Anyang Region

This study investigated systematically the diversity and occurrence of weeds in summer maize field of Anyang region. Control efficacy of chemical herbicides commonly used in maize fields was tested and integrated control techniques were proposed. The major results of this study are as follows:1.There are 107 species of weed in summer maize field of Anyang region. They belong to 31 families separately. There have 17 species of Damaging seriously in maize fields, which belong to 10 families separately. Dominant gramineous weeds included:Digitaria snagunalis (L.) Scop., Setaria Viridis (L.) Beauv.,, Echinochloa crusgalli (L.) Beauv.Var., Eragrosis pilosa (L.) Bearv., and spontaneous wheat. Dominant broad-leaved weeds included:Portulaca oleracea L., Acalypha auseralis L., Amaranthus retroflexus L., Abutilon theophrasti Medic., Chenopidium aibum L., Cephalanoplos spp., Xanthium sibiricum Patin., Calystegia hederacea Wall., Potentilla chinensis Ser., Hibiscus trionum L., Polygonum lapathifolium L., etc. Weed density was generally 150 to 300 plants per square meter, but it might reach 1000 plants per square meter in some case.2.The Relative abundance (RA) of the following weed species were above 15:Digitaria snagunalis (L.) Scop., Setaria Viridis (L.) Beauv., Eleusine indica (L.) Gaerth., Echinochloa crusgalli (L.) Beauv.Var., Eragrosis pilosa (L.) Bearv., spontaneous wheat, Cyperus rotandus L., Portulaca oleracea L., Calystegia hederacea Wall., Amaranthus retroflexus L., etc. The field uniformity (U) of Digitaria snagunalis (L.) Scop., Portulaca oleracea L. and Setaria Viridis (L.) Beauv. reached 54.63,36.21, and 34.65 respectively. The field frequency (F) of nine species of weeds were above 90. Field density (MD) of 7 species reached 1 plant per squaremeter, including Digitaria snagunalis (L.) Scop., Setaria Viridis (L.) Beauv., Eleusine indica (L.) Gaerth., Echinochloa crusgalli (L.) Beauv.Var., Eragrosis pilosa (L.) Bearv., spontaneous wheat, and Calystegia hederacea Wall.. Among the seven species, field density of Digitaria snagunalis (L.) Scop., Setaria Viridis (L.) Beauv., and Portulaca oleracea L. was significantly higher than that of other weeds, so these species were regarded as Worst Weeds.3. Mixture of acetochlor and atrazine, acetochlor, and atraizine proved to be ideal herbicides for weed control in ploughing fields. Among various compound herbicides, control efficacy of on-spot mixing of acetochlor (50 g/mu) and atrazine (75 g/mu) (Once acetochlor and atraizine has been mixed, it should be used right away.) was notably higher than that of mixture of acetochlor and atrazine (200 ml/mu). Herbicide application in the former style was reduced by 31.1% when compared with the latter one. From an environmental and economic perspective, on-spot mixing of acetochlor and atrazine should be advocated. The mixture of acetochlor and atrazine, acetochlor were more efficient than other herbicides for preventing monocotyledonous weeds and atraizine and the mixture of acetochlor and atrazine were more effective to dicotyledonous weeds in summer maize field. It used the mixture of acetochlor and atrazine when both monocotyledonous and dicotyledonous species were occourred seriously. From the aspect of controling the number of the weeds, it showed that 4% Yunongle suspension (200ml/667m2) added 15% Thifensulfuron (20g/667m2),4%Yunongle suspension (100 ml/667m2), 4% Yunongle suspension (100ml/667m) added 15% Thifensulfuron (10g/667m2) have a better efficiency, and the control effect was 86.5%,81% and 76.6% respectively.4. In free ploughing fields, application of certain herbicides before maize seedling emergence might achieve ideal control efficacy. These herbicides included:40% suspension concentrate of acetochlor and atrazine mixture (200 ml/mu)+41% glyphosate (75 ml/mu), with a relative control efficacy of 95%; and 40% suspension concentrate of acetochlor and atrazine mixture (100 ml/mu)+ 41% glyphosate (150 ml/mu), with a relative control efficacy of 94%.