A discussion of the vital problems of lawn making and mainttrince P U B L I S H ED S E V E R AL T I M ES Y E A R LY BY - SEEDSMEN August 1932 - M A R Y S V I L L . E, O H IO No. 4 YELLOW TREFOIL Medic ago lupulina, L. O. M. S C O TT a S O NS C O M P A NY Vol. V YELLOW Not a Bad Weed, But Out TREFOIL of Place in a Lawn MOST weeds have flourished this season but Yellow Trefoil or Black Medick has outdone itself. Speci- mens of this weed have come in for iden- tification from almost every northern state and we are informed by several ex- periment stations that they have had the same experience. One authority says, "Yel- low Trefoil seems to be prevalent all over the country this sea- son. In 1928 we no- ticed it growing in our golf course fairways and this is the first year since that time it has put in its appear- ance." ONCE USED IN LAWN MIXTURES. While Trefoil is not considered a nox- ious weed it does n't belong in a lawn. Yet it is surprising to learn that Trefoil seed has in years past been used in lawn mix- tures as a substitute for White Clover. Perhaps that is where this weed got its first start in lawns. At present it is found most frequently in the seed of farm crops such as Alfalfa, Sweet Clover and Red Clover. Stock does not object to it so on the farm Trefoil causes very little concern. YELLOW BLOSSOM EASILY IDENTIFIES IT. The illustration is handicapped because of not being able to show the small clover-shaped yellow blooms. They make this weed very easy to identify. Trefoil is a member of the clover family and the small blossom, except for the color, is a miniature of White Clover. It is an an- nual and would be easy to destroy before the plants go to seed except that they grow v e ry the ground and the mower is apt to miss them. Its range is through- out the world in all temperate climates. itself T he branches out and creeping spreads fashion. The leaves are f i n e ly haired, rounded and slightly toothed at tips. The pods containing thin the shaped and slightly skinned, twisted. Each pod contains just one seed. seeds are f l at on kidney plant the in SEEDS RESEMBLE ALFALFA. The seeds themselves are yellow and very much resemble alfalfa and sweet clover seeds. When found in these seeds V O L U ME 5 [ 7] it is very difficult to remove as well as to recognize. We recall having once seen an almost perfect stand of Trefoil in an athletic field which had shortly before been sowed with a grass mixture. There was no accounting for the weed because Trefoil seed is not found in the grasses. Later it was discovered that several inches of topsoil had been brought in from bot- tom ground along a river. This soil was fairly alive with the seeds of Trefoil. They needed only cultivation to arouse them to activity. ACCOUNTING FOR PRESENT PREVALENCE. One of the best known seed analysts in the country volunteers this comment: likely soil conditions may have had something to do with its devel- opment. Undoubtedly the lack of mois- ture affects Trefoil and makes it more noticeable, because other grasses die out and this plant, having a deeper rootstalk, subsists. We have had an insufficient amount of rainfall the past five years. The plant may therefore have had an advantage over less deeply rooted plants and has obtained a good foothold. We have noticed the increase in the growth of this weed in lawns of this area" [New Jersey]. think "I METHODS OF CONTROL. A large area badly infested with Tre- foil should be rebuilt or, if there is no objection to White Clover, a heavy seed- ing of it will usually crowd the Trefoil out. When once discouraged by the crowding method, other grasses may be introduced since clover is not liked by many good Small patches of Trefoil may be removed by hand when the ground is wet. This should not be delayed until after the plants have gone to seed. Cornell Uni- versity, in one of its bulletins, advocates killing Trefoil by spraying with an iron sulfate solution, the same as for dande- lions. lawn enthusiasts. [ 8} V O L U ME 5 Because Trefoil is not unsightly it is sometimes disregarded in a lawn until it becomes so wide spread that its eradica- tion is a serious problem. We advise be- ing on the lookout for this weed and sup- pressing it before it becomes too ambi- tious. Vital Facts on Mowing THE general practice of mowing lawns closely is harmful to the turf. Except in the case of Creeping Bent, any grass will be much stronger and healthier if a growth of 1 Vi or 2 inches remains after clipping. Higher cutting of grass enables it to better withstand drouth because such grass has a more extensive root system which can reach the reserve moisture abundant at greater depths. Then, too, surface evaporation is reduced because the grass acts as a sort of mulch. authorities Agricultural Close mowing favors the encroachment of weeds. It leaves the grass weak and thin so that it cannot compete with dan- delions, crab grass, chickweed, etc. It is also more subject to injury by grubs and sod web worms as weak roots are unable to withstand attacks of these pests. agree that grass should be cut at a height not less than iy2 inches and preferably 2 inches. One difficulty encountered in following this practice is to secure suitable high cutting lawn mowers. Many mowers can be adjusted to cut this high or extension brackets can be obtained to lower the wooden roller. If this is not feasible the old rollers can be replaced by larger ones which will raise the knife the proper amount. The importance of high cutting can- not be over-emphasized. It is most im- portant during the summer months and again in late fall. Grass is less apt to winterkill if it goes into the winter with a growth of two or three inches.