Vol. 16—1962 - NorthEastern Weed Science Society

446
Another illus tration of .aplodve growth U '. very rapid increale in
erMka at the mout:lt of the ~ Il1ver. which ii.tl .. thervery importUf:
waterfowl ana. No Bur.. 1aD _CMtJll!dlfoU wu UO__ rtll .urve;ya made dur1111
the .UlE8r aod fall of 1958 aadli59, but it .. '-~ IIDd cODBpicUOUIby
1960. B;yOCtobc 1961, the creeb'1Ifte cOIIIpletet""'tted over with thil ;
.'plllDt, IIDd oati:vaplantl. indUldl1ll highly del1rllltle duckfood .pecie' .....
virtuallyabl81lt.
Ck"owthof Bur.. ian watermilf.U i. gel18r.ll,,"~ent alons • horeli.l·in
shallow watar expoled eo .ever.-).¥aVe lIDcl tidal ac'll\m. but oyster drel.gel
bave picUd up rooted .pec1.lD8U;, at: depths of 14 t;O'!'16feet offshore frOIl .
SC1118of thele ar.... 'lbe plllDt grows best en soft. mucky bottOlllS. but allo
rapidly invade8 hard IlIDcl in protected ar....'
Althoush Buraalan wat.ermilfoU is spreading'.' 'rapidly in the upt)er
part of Chelapeake. Bay. it .... to have reachecl'iblllllXim'JIII rar.ge in IIIIICb
of the Potomac River. In fact, ill recent yeat'sltJ'b .. decreased 80mewhat in
certain are .. , lIDcl cleQ8ity of· 8l'wth hal been ob...... d to fluctuate. !ti8
factors caudng these reductions in growth are un1cD.owD, although salinity,
turbidity, tidal currants, cal'J' i6fe.tation, aod "'ii1bly midge larvae
infe.tetions may be involved. 'c'
control ~1ments. Gr.. ·le81mpreguated1fitff'2.4-Dccmtinued to :,ive
better contro~the otherp .. ..,. cOlllpounds. ''iId:e:is significant d_e .
2,4-D also :ls the cheapest p~compound on the IlI8I'tcet. Accordingl,..,
telta were made pr·imarUy with ·f..-lations of 2.~.
'1be tlIr_ elter80f .2,4-» (bR~tball()l, 1860ec'tyl. and proPylenel1lcol
to. butyl ether) gave almolt cClll91eu control at ..... rate of 20 pOuDda
a.e. per acre. Under ideal situatioDB of limited watel:' movement. the 8Ill1De
salt of 2.4-D applied at a rate of 10 pounds a.e. per acre gave similar
results. Envirollllel!.tal conditioDB 'cIS\I&Uy did D.Otpermit maximlJllI co..trol
,wi th amine sal ts at· low dosages. hOW8"er. Under varying condi t:l.')DB of tidal
.movement IIDdwave actiOn. e.ters of 2.4-D gava 11IO:'&.'G.9IJs1stent control than
did the amines. 'lbis may have bean because the DGIIiIo801ubleas tel'S havellOre
residual effects .than the soluble a.1De salts of2i4-~
. Good control at high tide relAlltedfrQIII app1lOatious of esters of 2.4-D
on l-acre pIaU. On smaller plota and friDge areu, bowever.better c')ntrol
was obtained at low tide when the vegetationbel~' eo,contain t3herbic1de.
Molt herbicide granules una.1n this study __ of 8 to 15 inch IllUh
hard-baked attaelay. smaller .t&e.:were difflcultl~,u.e. Soft granulea
gave • faster diapersal of the. eatc and a sl1g1atql faster herbicidal
reaction thaD the ba:ked gr!lllUlu. .!be 80ft pellat.. 'bOwever, usually
crumbled more ~ly aod, for' tb1e rauen. were llICIIl'eQifficult to uae •
• j ..;.,..,