Peete VO EGROVVW ERS Sr ee 
CHEMICAL CONTROL 
Several selective weed killers, such as Lawn Sinox, iron sulphate, arsenical com- 
pounds, chlorates and kerosene, all now appear destined to be replaced by the herbi- 
cide 2,4-D (dichloro-phenoxyacetic acid). 
The weed killing action of 2,4-D is based on its growth-regulating properties, which 
usually affect the broad leaved plants (including most weeds) and not the narrow 
leaved (including most lawn grasses). It is somewhat injurious to white clover and 
bent grasses and should be used with caution on lawns containing these plants. 
The United States Golf Association Green Section, in co-operation with the United 
States Department of Agriculture, reports 2,4-D effective in control of certain weeds 
to the degree indicated below: 
XX Satisfactory eradication at recommended rates 
X Weeds which have required much higher rates 
O Strikingly resistant 
No symbol Evidence at hand does not justify a conclusion 
O Bugleweed (Ajuga reptans) O Nimblewill 
XX Buttercup (Ranunculus spp.) (Muhlenbergia Scheberi) 
Carrot, wild (Daucus carota) XX Onion, wild (Allium spp.) 
Catchfly (Silene spp.) O Paspalum (Paspalum spp.) 
XX Chaerophylllum XX Pennywort as 
(Chaerophyllum procumbens) (Hydrocotyle bonariensis) 
XX Chickweed, common XX Pennywort 
(Hydrocotyle rotundifolia) 
(Stellaria media) See davon 
: ywort (Hydrocotyle umbellata) 
XX Chickweed, mouse-ear XX _ Peppergrass (Lepidium virginicum) 
_(Cerastium spp.) XX Plantain, broad-leaf 
XX Cinquefoil (Potentilla spp.) (Plantago major) 
XX Clover, white (Trifolium repens) XX Plantain, narrow-leaf 
O Crabgrass (Digitaria spp.) (Plantago lanceolata) 
XX Cress (Barbarea vulgaris) XX Purslane, milk (Euphorbia maculata) 
XX Cress, swine (Coronopus didymus) XX _ Pussy toes 
Daisy, ox-eye (Antennaria plantaginifolia) 
(Chrysanthemum leucanthemum ) Ragweed (Ambrosia artemisifolia) 
XX Dandelion (Taraxacum officinale ) O Sedges (Cyperus spp.) 
Dandelion, false (Krigia virginica) XX Shepherd’s-purse 
XX Dichondra (Dichondra repens) (Capsella bursa-pastoris ) 
XX Dock (Rumex spp.) X Smartweed (Polygonum persicaria) 
Dog fennel (Anthemis cotula) X Sorrel, [sheep’s] (Rumex acetosella) 
XX Fleabane (Erigeron canadensis ) O Sorrel, wood (Oxalis spp.) 
O Goosegrass (Eleusine indica) XX Speedwell (Veronica tourneforti1) 
XX Ground ivy (Nepeta hederacea) XX Speedwell, rock (Veronica arvensis) 
XX Heal-all (Prunella vulgaris) Sticktight (Bidens spp.) 
XX Henbit (Lamium amplexicaule) XX Strawberry, false (Duchesnea indica) 
XX Knotweed (Polygonum aviculare) XX Veronica, ivy-leaved 
X Lambs-quarter (Chenopodium album) (Veronica hederaefolia) 
XX Lespedeza (Lespedeza striata) O Violet (Viola spp.) 
XX Lippia (Lippia spp.) XX Whitlow grass (Draba verna) 
XX Moneywort (Lysimachia nummularia) Wormwood (Artemisia spp.) 
XX Mustard, wild (Brassica spp.) Yarrow (Achillea millefolium) 
As a result of further research, other weeds will undoubtedly be added to this list, 
and some of those that now appear to be resistant may be killed under proper treat- 
ment. In using 2,4-D, therefore, follow closely the directions furnished by the 
manufacturer. 
