Investigation And Chemical Control Of Weed Occurrence And Damage In Tagetes Erecta Fields

Tagetes erecta L.is an annual herb of Asteraceae.It is the main raw material for extracting natural lutein and has high ornamental and economic value.However,with the continuous expansion of planting area,the problem of weeds in marigold is becoming more and more serious,which seriously restricts the development of marigold industry.This study systematically investigated the occurrence,distribution and harm of weeds in marigold fields in Qujing City,screened the most suitable herbicides(combinations),and formulated the corresponding chemical herbicide application technology.The main results are as follows:1.There are 24 species of weeds in 12 families in the fields of marigold without herbicide treatment in Qujing,including 5 species of weeds of the grass family:Digitaria sanguinalis,Echinochloa crusgalli and Setaria viridis dogwood,Broad-leaved weeds: Acroglochin persicarioides,Ageratum conyzoides,Galinsoga parviflora Cav.,Acalypha australis and Bidens pilosa 19 species.Considering weed field density,relative cover and hazard level,four species of Digitaria sanguinalis,Acroglochin persicarioides,Ageratum conyzoides and Galinsoga parviflora,Thistle were identified as the dominant weeds in Qujing city marigold fields at present.2.Through field plot experiments,considering the weeding effect,safety to marigold,yield and quality,and safety to subsequent crops,herbicides suitable for marigold fields were screened.The soil treatment herbicides were broad-spectrum herbicides 35% pendimethalin SC,48% butralin EC and 240 g/L oxyfluorfen EC before soil culture.The control effect of weed plant and fresh weight could reach more than 85% 30 days after application.The soil treatment herbicide after earthing was a ternary compound preparation 50% ethoxy·iso · methylpentyl EC,and the control effect on broad-leaved weeds and fresh weight was more than 70 % 30 days after application.The stem and leaf treatment herbicides for controlling broad-leaved weeds after hilling were 250 g/L fomesafen AS and 20% fluoroglycofen EC.After 30 days of application,the control effect of broad-leaved weeds and fresh weight were more than 75%.After hilling,the stem and leaf treatment herbicides for controlling grasses were 69 g/L fenoxaprop-p-ethyl EW,5% quizalofop-p-ethyl EC and 108 g/L haloxyfop-R-methyl EC.After 30 days of application,the control effects on gramineous weeds and fresh weight were more than 80%.The inter-row herbicides after hilling were 30% glyphosate isopropylamine salt AS,10% glufosinate ammonium salt SL and 200 g/L glufosinate-ammonium SL.The control effect of weed plants and fresh weight were more than 80% 30 days after application.Considering the weeding effect and the safety of marigold,soil treatment was dominant before earthing up,supplemented by artificial weeding.After earthing up,the stem and leaf treatment were mainly used,supplemented by soil treatment.