Vol. 16—1962 - NorthEastern Weed Science Society

lContribution No. 1046 Rhode Island Agricultural Experiment Station.
306
Nutgrass control stUdi_a:!n corn with .~zine and
its '-residual effecb on a foragese.-dingl.
r
, R. S. Bell arlCFP. B. Gardner2..J'
" ~:"
~irazine has proven·to be an efficient herbicide' ·t~r the control of c&:t1:&in
weeds in corn (1). ~r1Jninary repma(3) indicated'tfiat early post-eme:t'g4!nt '
appW1ations of atrazine., at 3 t04pounds per acre '9'&'"'seasonal control of~tgrass.
Donnalley and Rehn (2) reported tha·t autoradi~raphs from foliage ~pl1­
cations ofami't:roleand atrazine to nutgrass plants !:leiring tubers showedthat
atrazine dio not aCCUlll.Jlatein the nUtl'ets but was re'8dl1y translocated throu.9h~
out the plant. Atratineresiduesdlilappear slOWlyfi'&t the soil and rnayc:~U~e:
some dilll!ageto a forage seeding the following spring.,."
"J:'
Procedures
1960 Tests
~nn. 602Acorn was planted on May25, 1960 inBHdgeharnpton silt lO~,$oi1 .
fertilized with 1000 Ib/A of an8~12"12..2 grade. The;'Subplots were l5'x 3~~'
and ther~ were 4 replicates of each'treatment.One ~Hof plots received' 2•.5
lb/A of atrazine BONshortly after planting 'and 5 Ib¥A'\¥tienthe plants were.l~.
inches high on June 30. Other ploti5 received atrazin~~atthis later date at 5,
7.5, 10 and 12.5 lb/A, respectively. Fifty gallons per acre of spray was used.
Four randomized plots received no herbicide.
The tests were not cultivated during the month of June so that the nutgrass
stand on each plot could be estimated. Several'randomized counts of one foot
square plots indicated a range from 1000 to 2000 nutgrass plants per plot. After
the post-emergent herbicides were applied the area was CUltivated twice to loosen
the soil. This incorporated the atrazine between the rows and dislodged much of
the nutgrass.
The 1960 rainfall and weather in general favored the growth of corn. There
were over 3 inches of rain during the 3-week period following the post-emergent
applications of atrazine. The corn was harvested September 6.
Results
The yields and various nutgrass counts are shown in table 1. The corn
yields ranged from 4.2 T/A of oven-dry material from the check plots to 4.8 T/A
from the area which received 5 lb/A of atrazine. The check plots were heavily
infested with yellow foxtail grass. Analysis of variance showed no significant
difference in yields due to treatment. After harvest the nutgrass plants on
each plot were counted. The average number per plot ranged from 21 on the
check plots to only 1 where high rates of atrazine were used. The reduction of
nutgrass in the control plots after CUltivation is striking. This reduction is
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