Vol. 15—1961 - NorthEastern Weed Science Society

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270.
permanent , . injury
than the bent by October.
The calcium arsenate treatments affected only the fescue and bent.
The discoloration showed asa bluish wilted appearance in contrast to a
browning effect fronfDacth8:l and Zytrori. Injllrea'plots also resulted in retarded
growth. Fescue was 'Only' :siigl1tlJrthinned out whereas the colonial
bent showed moderate thinning. There were practically no differences in
injury between the two rates of calcium arsenate, whereas all other injurious
treatments showed very significant differences for the two rates used in this
study."·:"!"'"
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Crabgras s', Control. 'Results of preemergence c~~b~$S control, are shown in
Table$ Doth as, plant survival pe,r .square foot: and percent reduction 'based on
six c9ntrol plots~' Contr01:'plo~s 'averaged 20 plants 'With a range of 14 to
29 plants per sq. ft. Crabgrass data are shown onlY for test. area 1 (fescue)
due to best uniformity. ~f, stand.
Gr~ular chlordane proved to be the most effe~tive chlordane formulation
and gave 99 perc~t·contro~at the 120 lb. 'rate. The 60·1b. rate of
the granular and emulsion and H8lts at the recommended 6 Ibs/·M were not
satisfactory based on plant,survival.
Dacthal; Zytron and calcium arsenate treatments gave 97 to 100 per­
cent control except for the Zytron M-1329 at the lower 13 lb~ rate (93% .
control). Although the control range variable was small, crabgrass control
appeared correlated with turf injury between the Dacthal and Zytron formula­
tions, respectively. This sugge.iltstbe ppsai't)111t.y of variation in active
ingredient per formulation as applied in this studY. '
ReSUlts shoWed the lower rates of tile above three niaterials to be
at or' near their most' erfi6iertt levei for crabgrass eontr-ol.. Observations
on the other test areas showed similar material treatment effects on crabgrass
"germinatiOn~ ,'~ . ­
Other OOservations • 'Test area 4,:·commonKentucky-bluegrass, was selected due
to ,r-heavy crabgrass in:t'estation'dtiring the 1959 season.' "However; in 1960,
it changed from crabgrass to a knotweed economy. Knotweed wasirithe 2­
leaf stage at the time of ,'thefirs~ treatment, April 14.
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Zytron 1f8fj.' the~ onlYmlr~~r1ai to ~~ibi t post-emergence' control.
:K~1329.t' emw.si01l:;atlJ lbs.p~r '!1"cr~:res;l1ted in 'nearly 100 percent control
r~:r;' .the three tre$t.tnent d8tefi AprQ.14, May 2 andMai l? Granular M;';1662
'resulted in 60-80 percentcotltrol,'with better o011trol"at tlfe earlier date,
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"," " . Calcium arsens te .Weakened Poa. annua to the point where . it waskilled
during the first moisture'artd~higll'temJ?erature stress pe:r:'iod inJUly.- '
Conclusions'
, ; ChIordane,' except tor. c:ertain emulslPn' f6rri1ulations, was' nontoxic to '
bluegrass, fescue andberit turf.
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