ERADICATION OF WEEDS.

Otago Witness, Issue 2811, 26 August 1908, Page 9

ERADICATION OF WEEDS.

THE CANADIAN THISTLE. ~ SUKSCESSFUL RESULTS: THe< telling of weeds, by means of spray- ' Bng'with various 'compounds,- is not 'A new iproposTtion. Until 'recently it" has never Ibeen very successfully demonstrated. For a number -of years Professor L. H. Bolley, of North -Dakota Experiment Station, has ibeen working' with this problem^ and in a a-ecent bulletin gives the results of -his very successful demonstrations^. He shows lihat Sfc is quite possible to go into the email grain fields .(writes the Orange Judd Faraner) and kill out the much-dreaded musitard, Canada thistle (what is called in, that region Jring- head, and in. most regions ragweed), so.w thistle, coiai- cockle, onickweed,' i^aridelion, bindweed, pjantain, coeklebur, _ and' a, few others-, without any"" injury to &he grain- growing in tie field. -He deanonstrates- this to his own satisfaction in .experiment on the station grounds, aawJ , £ Iqa-ge number of co-operative experiments j With.; farmers ,thjroagib.out;the : State. Tiie testimony of these farmers is included in the bulletin; and'"work has- been- widespread and very thoroughly done. —Why Weeds Are Killed:— . The explanation as . to why weeds are killed and 'grasses .and grains are not is I father complex, aaid to, many simply . a ifchebry.- - 'Professor BoHey calls 1 attention ' jbo the fact, however, -that in his work he ittas observed (1) that succulent plants of % particular species die more quickly than. $hose which are less succulent; (2) that {poung, rapid-growing plants of a particular . species are Jnore easily killed than those svhich for any reason have had a slow growth; (3) v tibat. flower parts and parts which are covered with bloom are moxe or less protected, according to the nature and quantity of the bloom> (4) that plants possessing a hairy .surface, as a rule/ are more easily destroyed^ than, those with smooth surfaces; (5) that chemicals" are observed ijo -act differently upon the members of different families' of pla-nte, even upon those the leaves of which seem to wet with equal readiness. He gives as example that aron sulphate (copperas) is exceedingly destructive to mustard: and dandelion, while 5t acts very slowly upon the leaves of clover, wild buckwheat, and Canada thistle, -one of wihich seeni» to wet as easily amd quickly. Professor Bolley (the journal continues) ■ lias worked otft a scheme of destroying fveeds by spraying^ which has given, most ' excellent results. He uses solution of common ealt, iron sulphate (ordinary copperas), copper sulphate, corrosive sublimate, and .sodium arsenite.. Because of its exceed; £ngly poisonous character, corrosive subliprate can never be generally used. The, also-, is a very dangerous com(pound, 'and must me handled with the ®watest of .care.' The other compounds, however, are not deadly poisonous, anfl can »c 'used generally. v —Applying the Spray. — • The method of .applying- the spray is to prepare the solution, sand apply it by means t>f one of the traction sprayers now manufactured by most makers of spraying compounds. The application should be made When the weeds and the email grain plants are a few inches high, say 3in or 4in. At *his stage it is not difficult to completely kill ..out most of the weeds which are detrimental to the development of a small grain crop. It requires about 52gal of the solution to spray aa. aoxe. The_coat, of tourfle," v will depend upon a great many things. Good field 1 sprayers cam be had from £12 to £30. Hand sprayers from 30s io £2. Iron sulphate uT'the powder form, • as available at from 4e, to 6s 6d per 1001b. 3Tor destroying mustard - 51b to 101b par acre were required. Copper sulphate can be had for about 6d per lb, and 121b to 141b are required' for an acre. Sodium tureenite is much higher. i The time of spraying, as noted above, ' is when the plants are a few inches high. ' However, mustard 1 is most easily killed ■when it is just beginning to blossom. But jTon sulphate i 6 effective against this weed »t any stago up to the time when the ( seeds are beginning to form. Ragweed is •readily destroyed at almost any stage of ate growth. Canada thistle must be sprayed as to prevent leaf growth as much as •possible. Professor -Bolley goes on to 6tate that the wheat crop may be sprayed at any time before heading, but suggests that x3ie it is the less harm will be jflone. He thinks that barley can stand quite -as severe treatment as wheat, but $hat flax should not be sprayed after it is 4in, or sin high. — Wihat Farmers Think of Spraying. — It is interesting to note- that some of fcho farmers who co-operate with Professor ' Bolloy are killing completely all the ragweeds in his wheat, so that no seed was formed. W. O. Wralstad, of Graf ton, jused iron .sulphate, on mustard, sunflowers, and ragweed. It worked exceedingly well on these. He_tried it on Canada thistle. J Four days after application the thistle was dead. Thirteen Jsaye after the application growth, started from- the roots, so that after harvest he sprayed a second time, and an autumn a third time. After that there was no growth. It must be remembered that Canada thistle ha 6 underground root stems, and that to kill them out completely $op-gro\vth must be prevented for at least one year. This is just what Mr Wralslad Bcooinplished. . , Another interesting test made by Mr iFrank S. Haynes, of Arvilla, shows that practically all his mustard was killed, except that which was past bloom. He found, further, tbat^bhe application of suljf^iate k>lled_ wild buckwheat and a groat many marsh jelders. At first th© -grain in jrfiich these weeds were growing "looked very black, -but the plants were not killed, and; they soon outgrew the discolouration. He says: "Personally, I feel very much satisfied with the experiment in weed- . killing." | While Professor Bolley was not able to Hetermine the exact effect on the yield by ■ jreatment, it is his opinion, based upon ' *Jhis experiments and considerable obsexva- j Jfcion, bhat the increased yield of small grain, due to the absence of weeds, is very considerable, in many cases amounting to sevefral busheJs to the acre. If to this is added the fact that the grain, comes fzom the

' threshing machine clean, and free from, weed seeds, it is easily 6een Jiow great is ; Hie value of this method 1 of destroying 1 '--weeds.