Vol. 15—1961 - NorthEastern Weed Science Society

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Simazine 2 and 2 1/2 lb./A and atrazine 2 and 2 1/2 tb./A were appl~ed
September 23 or October 14, 1959, to quack in established Globe Arborvitae,
Hemloek, Taxus, and Carolina Rhododendron.' Quack sprou~ed~n April but showed
evidence or having been weakened in May. Cultivation tmproved control, 'an~'
by June the"population and vigor of quack was markedly les8 than untre£ed'('l".':;
areas. Crabgrass grew vigorously in the treated area, but quack did not:·. ;~L~'ti'~
return. The nursery plants did not show injury. . !S; "',,;
Propazine at 2 1/2 Ib./A was applied September 23, 1959 to quack in
Glohe Arborvitae. The results were about equal to,bUt not better than,
simazine and atrazine at the same rate.
,~., '~, :j t~
A combination of dalapon 6 Ib./A with atrazine 2 lb./A applied
October 14, 1959 gave no better control than the saenerate of atradne alone'.
Conclusion ' ,J
Fall applications of stmazine or atra~i~e at 5 Ib./A gave excellent control.
Simazine, atrazine, or propazine at 2 and ,2 112 lb./A resulted in marked' "
reduction of quack in most of the plots. Quackgrass sprouted in early, spring:
(following the fall application) but was obviously weakened. Spring and summer
cultivation appeared to aid in destroying the remaining quackgrass. Globe
Arborvitae, Hemlock, and Taxus appeared eo tolerate ..fall application of
simazine and atrazine as high as 5 lb./A. Carolina Rhododendron appeared
to, tolerate simazine and atrazine at 2 lb./A.,
Sprins ApplIcation of Dalapon ~ Amitrol
Crop: Pyramidal Arborvitae (Thuja occidentalle) 4 '.5'
high in quackgrass sod.
Date of Treatment: April 29, 1960, when quack was:4" high; repeat sprays
, applied May 12, 1960., , ,
Method: Sprays were directed to quack around ,bastl~ofplants at 100 gal./A.
Area Treated: Twofeet of row, 100 feet long. The remaining middle, about
3 feet, was cultivated with tototiller. ',,' , ,.;,:
T~e~~~nts applied: , ., :t
(1) dalapon 8 1b./A (repeated)
(2) dalapon 6 lb./A (repeated)
" ,;() .da1apon 6 Ib./A + "Plyae" sticke,t: (l'epeated··w.tthout sticker)
J:L"}.; :(4h dalapon 6 1b./A + simazine 2 1/2, Ib.iA ,(repeated wit.hout: .Jimaz-lnft),
.{~).,. da,lapon 6 lb./A + atrazine 2 1/2 Ib~/A (r"eated;witl\out ,e.t:r:azine)
'':lr.i.!{~''.daJ-~p,01'\ 6 Ib./A + Karsil 4 lb./A ,(repeated) >',
'1~d7r) ,pal~p'o'Pt)6 lb. + amitrol"T 1/2~-1b.JA{notlrepeated) .
(").111 (8) "W"'~l'ol"T 2 Ib./A (not repeated)
C)b' (9) ,am,-trol"T 1 lb./A (not repea,te4l ",
(10) :a~il;rol-T 1 lb./A + "Plyac" sticker (not rep...-ted) , "
(11) ~~troJ·T 1 Ib.tA + simazine·2 1/2.lb./A,.(not,repeated)