when to apply weed killer

{"cid":"91224562","title":"Glyphosate 720 WG Herbicide Glifosato Herbicida Glifosato Glyphosate 757 roundup weed killer spray","imgUrl":"https:\/\/img.chinax.com\/nimg\/6d\/3b\/32f3c6a166ea464e2fce0c83148d-200x200-1.jpg","attrs":{"Price":"1-10 per kg","Brand Name":"Averstar","Model Number":"720 WG","Minimum Order Quantity":"1000","Delivery Time":"15-20 work days","Other Name":"Glyphosate 720 WG","EINECS NO.":"213-997-4","Origin":"China","Supply Ability":"100000kg per month","Packaging Details":"500g","Place of Origin":"China","Classification":"Herbicides","Certification":"COA, MSDS","MF":"C3H8NO5P","PD NO.":"PD20254081","Payment Terms":"L\/C,T\/T","Brand":"Averstar","CAS NO.":"1071-83-6"}}

{"cid":"91193628","title":"28\/410 28\/400 Plastic Garden Trigger Sprayer for Car Cleaning and Gardening","imgUrl":"https:\/\/img.chinax.com\/nimg\/3f\/15\/616aac72c640cce7c687defe8c16-200x200-1.jpg","attrs":{"Price":"0.048","Brand Name":"SWJ","Minimum Order Quantity":"10000pcs","Delivery Time":"30days","Place of Origin":"ZHEJIANG","Payment Terms":"T\/T","Supply Ability":"50K\/day","Packaging Details":"Carton","Neck Size":"28\/410 28\/400","Lightweight":"Yes","Customize":"yes","Tube length":"Customizable","Triggertype":"sprayer","Durable":"Yes","Easy To Clean":"Yes","Sample":"available","Material":"PP","Lead Time":"30days"}}