Vol. 16—1962 - NorthEastern Weed Science Society

D~ed. 011\., the 1961 tr~~epp:rteClhe1.'el ,~~um.·prCWl arsonate
showt!defirt1te p~~genoe ac:~i, tr on crab~8 !p,to the 4 to Sled'
stage,•....The best treatments lfi~)~ .oOll1poundw~e;)liW).1ed in May, 'about
two'weeks after orabgrass eimergenoe. Rates of lt _ lllb/1OOO sq.£t.
gave cc)ntrol comparable to pre-emersenoe treatments at 15 lb/A of zytron
~ far SUPlil:rj.~ ~o~$~emergenoe treatments with recanmended rates of
dacthal, cb,lo~an., ,diphenatrile, tr1oaloium. arsenate and lead arsenate
compJ.~ ", ..',' .:; . ; ';;,
501
.' >" Tl:J,e. oomb1nat1on,of caloi Ulll methyl arlf()~~ and calcium. propyl
ar~te may1'lave s~ht~lncreased initial pos~enceact1vity,
but"d1d not increase pre-emergenoe residual aotiviV in comparison to
oalcium proWl ars~te alone. . "
Turf tolerance
T6,; only,~ounds oausing o1m,ous ~$,~ur:r in these test/.
plots were ~ur~ and trioalci~:arsenatee: .~uralin thinned the
turf slowl\r".aver ail6riodof severallllOnths. ~1um. arsenate caused
a general fo1iage ~ within a week after appl1catlon, and much of 'the .
g1'a8.l!l neverl'eco~ d~ the remainder of the,.e,ason. ' .'nL"
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Conq1l1sion
"l:"
: . De,oause~ a c0lll1!;lnat1onof weather o:on91101ons in 1961 - coldt'cF"
wetltpring,dela;re4;;crabgrass genrdnat1on, warm)..wet;sumrner- all the
prirtl:l~:pal s~1~t1~(llrabgrass control; chemicals ~t~ av8ilable produced
uns&¥sfactory crablfass ,control~.,WhUe QO de~tf reason for this can be
presented at this tillie, possible' explanations for these failures are
exc~s1ve or,abgras8,:~ergenQe"1clachi~ and b1olog1,qal breakdown. "1." '
Calcium.propyl arsonate, applied as an earl\r'pos~rgenoe
treatlllent ra;t~er th~ a standard pr~ergence trea,t-nt, produced seaecndi.' :('
crabgrass oontrol eqUivalent to the best of the long r8aldual pre-emergenoa:',
crabgrass killers ;lncluded in our 1961' tests. .
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