Vol. 16—1962 - NorthEastern Weed Science Society

substantially until after 69 elvs. The 100 day _tment reduced stand of
all species by' 20.30 percent with continued discoJlin'ation 50 days after
application.
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481
ztirfiili showed the longest residuaJ. effeJi on grass germination
from comple ibi tion at the 0 day treatment to;ja maximumof 30 percent
on bluegrass after 93 days. Bent germination· was completely inhibited for
0, 32, and 63 day treatments and only 8 percent showed following 93 day
treatment. Seedling stand redu(lt1on was complete tor all species aj:; 6 days,
60·90 percent reduction at 38daye and 20-40 percaot reduction follcnJing 69
and 100 day treatments. The latter treatment continued to show discoloration
50 days after app1ication~ .::
Di~natrile showed the greatestspeciea:.'differential effect for
both ge:rmii'ia on ana stand. At 0 date bluegrass and bent were greatly inhipi
ted, followed by' a sharp increase at 32, 63 and 93 day treatments which
ranged from 67 to 98 percent. Fescue emerged at 80 percent at 0 day t;reatment
and ranged from 87 to 98peroent for following three treatment dates.
Bluegrass, bent and fescue stands were reduced 88;--58 and 40 percent,
respectively, at 6 day treatment, 2-15 percent at J.8 days and showed no
stand reduction for the following two treatment daities.
Under moisture stress, no treatments we~ observed to show possible
root reduction except for severely injured plots where all plant parts
appeared to be affected, even -at optimum moisture.:<
Oonclusions
The effects of preemergence crabgrass ohemicals on the germination
and seedUng stand of bluegrass, fescue and Q.itnt were studied. Differential
species effect was found with certain materials on both inhibition
ot gemination and, seedling tw:'f.In all instanoltii injury was correlated
with age of seedlings, but with varying effect. Provided that acceptable
levels of orabgrass oontrol can be aohieved, cer~ materials appear to
show promise for situations requiring use on seedllng turf and at periods
following seeding,
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