IRISH GARDENING. 



171 



The Eradication of Weeds* 



By Joiix Adams. ^f.A., Assistant Dominion 

 Botanist ; late of the Royal Colleae of Scienro. 

 Dublin. 



AccOEDiNG to their manner of growth, weeds 

 nxay be grouped under three heads : — 



1. AxNUAi. Weeds. — These complete their 

 whole life-history in one year or less. The seed 

 germinates sometimes in the fail, but more often 

 in spring, the plant grows rapidly, produces 

 flowers, I'ipens and scatters its seeds, and then 

 dies before winter. Wild nmstard and wild oats 

 are ann vials. 



2. BiEXNiAi- Weeds. — These during the first 

 season of growth produce a tuft of leaves close 

 to the surface of the ground ; during the second 

 season a tall stem is produced wiiich bears flowers 

 and ripens seeds, and then the whole plant dies. 

 The life-history is thus comprised inside two years. 

 Biennial wormwood and burdock are ex<amples. 



0. Pe^kexniat. Weeds. — These produce flowers 

 and seeds, but after ripening the seeds only those 

 parts of the plant above ground die down, ^\ bile 

 the underground laarts live on for many years. 

 Three types : — 



{(i) »s'/)rt/-bo»/id. — Weeds of this class do not 

 spread readily in the ground beyond the spot 

 where they first take root. Their seeds may, of 

 course, be distributed over a wide area. Examples 

 are dock and dandelion. 



(b) Crecj)in(j ou the surf a re. — The parent plant 

 sends out runners in all directions along the 

 surface of the grovind. which eventually take root. 

 Examples are silverwood and orange hawkweed. 



{r) Creeping belotr ih< surface. — The parent 

 plant sends out shoots or, in some cases, roots, 

 which travel horizontally at a considerable depth 

 below the surface of the ground. New shoots 

 grow vip from these above the sui'face of the soil 

 and eventvially become independent plants. 

 Likewise, a siuall piece of the underground shoot 

 an inch or two long is capable of producing a new 

 plant. Field liindweed and Canada thistle are 

 examples. 



How Weeds Sfread.— Weeds may gain 

 entrance to the farm or, if already there, may be 

 dispersed over a wider area in one of the following 

 ways : — 



1. As impiirifies in the seed soicu. — :\Iost samjiles 

 of agricultural seeds contain weed seeds in greater 

 or less amount, which are sown with the useful 

 seeds and tluis the weeds may, <|uite unknown 

 to the farmer, gain an entrance on to his land. 

 The seed sown should be aijsolutely fi^ee from 

 weeds of all kinds — a condition of things which 

 is seldom realized. 



2. By the (ujeucy of threshing machi)ies. — The 

 threshing machine should be thoroughly cleaned 

 before it is allowed to begin operations on the 

 farm. 



f{. In fyfable manure and feeding stuff. >. — Hay 

 and feeding stvilfs often contain weed seeds, some 

 of which are liable to find their way into the 

 manure heap and eventually on to the land. 



4. Bg the action of iciud. — JMany seeds, such as 

 those of dandelion and thistle, are furnished with 

 a t uft of hair which enables them to float in the 

 air for long distances. In other cases the seeds 



or even the whole plant may be blown over the 

 frozen surface of the snow. 



o. By the agriicy of animals. — The seeds or 

 adjacent parts of some plants, such as blue bur 

 and burdock, are provided with hooks by means 

 of which they become attached to the wool of 

 sheep or the clothing of workers on the farm and 

 in this way may be carried into fields where 

 formerly they did not exist. 



6. By cultlration. — In some plants, especially 

 those with creeping, undei'ground stemf, the 

 broken pieces may be carried all over the field 

 Ijy farm implements and thus dispersed over a 

 iiiuch wider area than the parent plants originalh- 

 occupied. 



METiioDs oi' Destkoyixg Weed.s. — 1. By 

 destroying the need seeds already in the soil.— 

 Where the ground has been badly polluted with 

 weed seeds through net^lect in former years the 

 surface should be disturbed to a depth of a few 

 inches and the seeds encouraged to germinate 

 either after harvest or in spring. If the land is 

 then plowed deeply the seedlings will be buried 

 and the fresh supply of weed seeds brought up 

 should be encouraged to grow in the same 

 manner and should then be destroyed. A hoed 

 crop !-.hould be planted and the spaces between 

 tiie rows ought to be cultivated regularly through- 

 out the season. When the ground has been 

 liadly polluted w4th weed seeds, some of them 

 may lie dormant for several years and germinate 

 when tiie soil is again disturbed. 



2. By preventing them from ripening seeds. — 

 The formation of seeds can be prevented in 

 various ways, such as mowing several times 

 during the season, or cvitting the roots with a 

 hoe or spade, or freqvient cultivation of the land 

 by horse labour, or by pasturing the ground 

 closely with sheep. Annuals and biennials will 

 eventually die out if the production of seeds is 

 prevented. 



3. By frequent cultivation and dcstrintion of 

 the green parts as often as they appear. — In^evention 

 of seed-formation will serve somewhat to check 

 the spread of perennial plants, Init as they can 

 live for nuvny years, and even continue to occupy 

 new ground by the growth of underground 

 shoots, ttc, some more thorough methods are 

 required to get rid of them. The implements 

 eni ployed for this purpose should be such as will 

 loosen the soil to such an extent that the \^•eeds 

 can be readily pulled out and collected into heaps, 

 after whicli they should be burnt when dry. It is 

 very important that the underground parts of 

 sucii weeds as field bindweed should not be 

 l)roken into small pieces difiicuit to collect and 

 lia))le to be scattered over a wider area. But, 

 however carefully the w^ork of collecting and 

 burning may be done, some of the weeds are sure 

 to be left in the soil, and, if undisturbed, will 

 grow again. Consequently ground that is badly 

 infested with such weeds will require to have the 

 surface disturbed by frequent cultivation. This 

 can only be done if the land is left without a crop 

 (summer- fallowed) or bears a crop of such a 

 nature that it can be planted in rows with 

 sufficient space between the rows to admit of 

 ready cultivation without injury to the plants. 

 The cultivation should be done sufficiently often 

 to destroy all green parts as quickly as they 

 appear and the implements vised should be of 

 such a natvire that they will cut all vmderground 

 stems and roots in the area covered by them 



