Elimination of Clover from Fine Turf in Summer-sports Areas

New Zealand Journal of Agriculture, Volume 94, Issue 3, 15 March 1957, Page 260

Elimination of Clover from Fine Turf in Summer-sports Areas

By

L. J. MATTHEWS,

Weeds Research Officer, Department of Agriculture, Wellington

WHERE playing areas are not maintained at a degree of acidity which will eliminate all species other than the desired fine grasses, clovers will often become prominent competitors to the detriment of such sports grounds. In fact the extent to which clovers abound can be regarded as a fairly reliable indication of the degree of acidity that has been created. Such clovers may die out during dry spells, thereby leaving bare patches, which disfigure the surface and destroy its trueness. Though continued acidification will ultimately reduce and possibly eliminate clovers, it also has the effect of destroying grass thrift. Consequently it is sounder to maintain good thrift with reasonable acidity and to rely on spraying with hormone weedkillers to control unwanted species.

THE commonest clover infesting fine turf areas is white clover, a perennial species which usually persists throughout the year. Other common species are suckling clover and subterranean clover. Both are annuals and usually die out during the hot, dry months. Seed of all three clovers germinates in both spring and autumn. Weedicides for Control . Of all the selective weedkillers available in New Zealand, preparations of 2,4,5-T are the most toxic to clovers. Established white clover and subterranean clover may be greatly reduced. or even killed by one application of 2,4,5-T, and established plants of suckling clover and seedlings of all three are readily, killed by one application. Of the three species subterranean clover is the most difficult to kill at all' stages of growth, but up to the almost mature stage 2,4,5-T will give good control. Fortunately this plant is not so prevalent in lawns as the other two species. Time of Application / The best time to apply 2,4,5-T is 3 to 4 weeks before the playing season begins. As this will normally be in September the application will control both autumn and spring germinated seedlings and will keep greens free, from clovers right through the playing season. Where clover is particularly serious and some recovers after the initial

spring spraying a repeat application should be made in autumn about a month before the normal renovation work is carried out. . Rate of Application For established clovers the rate of application should be from 21b. to 31b. acid equivalent of 2,4,5-T per acre. This rate will control subterranean clover at all stages of growth, but for seedling white and suckling clovers

lib. acid equivalent per acre will suffice. ' Forms of 2,4,5-T The most suitable preparations of 2,4,5-T are the oil-soluble low-volatile esters applied in sufficient water to give an over-all foliage cover. Spot spraying is not recommended,. as it often leads to excessive concentration with consequent damage. Preparations of 2,4,5-T in water in all trial work to date have had no detrimental effect on established browntop and chewings fescue. Often these species seem to respond to the application, probably through the affected clover. releasing nitrogen that becomes available to the grass. Control of Flat Weeds in Addition Though 2,4,5-T will control most annuals and perennial . seedlings, it merely checks the growth of flat weeds such as daisy, dandelion, and

plantain. Effective control of these species is obtained with either 2,4-D or MCP preparations. Those of 2,4-D cause more damage-to browntop than do MCP preparations. Unfortunately, as there are no esters of MCP in New Zealand, a mixture of 2,4-D and 2,4,5-T has to be used if the object is to remove both flat weeds and clovers in one application. A suitable mixture is 1 quart of low-volatile oil-based esters of 2,4-D with 3 quarts of low-volatile oil-based esters of 2,4,5-T. The same type of ester and the same proprietary line should be used. The 2,4-D and 2,4,5-T should be mixed together before the water is added. Young clovers may be removed satisfactorily with 2,4,5-T from newly established grounds, but unless clover is competing seriously with the grasses, spraying of areas sown in autumn should be delayed until spring. The application should be made 3 to 4 weeks before the areas are required for play.

Type of weed Stage of growth Treatment (acid equivalent per acre) Light infestation (most plants in seedling stage) Heavy infestation (most plants established) White Suckling .. Sub .. Flat weeds and clovers Seedling .. Established .. Seedling .. Established Seedling .. .. Established Mixed stages 11b. 2,4,5-T 31b. 2,4,5-T lib. 2,4,5-T 11b. 2,4,5-T 31b. 2,4,5-T 31b. 2,4,5-T 0.51b. 2,4-D + 2.51b. 2,4,5-T Treat 3 to 4 weeks before play begins in spring Treat when weeds have recovered after the play- . ing season and again 3 to 4 we e k s before playing season begins

SUMMARY OF WEEDKILLER USE ON PLAYING SURFACES