Vol. 16—1962 - NorthEastern Weed Science Society

.~ pattern following applications of herbicides was remarkably
similar in both tests. There waS sufficient precipitation for
activation of herbicides and for rapid germination of the corn
and weeds. Tabl~ I lists t~frates, application dates and forms
of the herbiciaes studied.' ." "
All plots were cultivat~ once after the first nutgrass
ratings were recorded. Ratinis of nutgrass and other weeds
present were also recorded atbarvest. In Test 1 the only weed
identified at the t1meof t~:fi~.t ~a~ing,'ias nutgrass. There
was a very llsht infestation pf commoncreDltas. (Dyitada
sanguinalis) and horse nettl~~(S9lamum carolinense) in some plots
by harvest time. In Te.t II l;he predominating grasses were nut.
grass, crabgrass&nd goosegra" (Eleusine indica); and the predominating
..broadleaveswere rllgweed (Ambrosia artemisi1folia ,
pigweed (Amaranthus retrof1exuS> and morning ,glory Ipomoea
purpurea) • l.) ,. '
Resul~
and Discussion
Test I: All of the weed. e~cept nutgra.s were initially controlled
by a pre-emergence ap,lication of three pounds of Atrazine.
Three weeks after planting, none of the Atrazine treatmenti were
providing nutgrass control. ~e Atrazine plus EPTCtreatment was
giving virtually 100 percent ~tgrass contro~ on the same date.
One week following the poet-emergence applications of
Atrazine, the nutsrass plants began to die where a total of six
pounds or more Atrazine were applied. Dying occurred somewhat
earlier in. the pre- plus the post-emergence treatments than in
those where the application wee totally pre-emergence. This could
have resyl ted from the s~l1 ~unt of absorption from the leaf .
surface.- Six pounds of Atrazin.e were giving 'effective control
when the seven-week ratings.wa~etaken. While the Atrazine had
not prevented the germinatiqn' of tubers, plants were killed when
the food reserves in the tub... were depleted. A total application
of ni~ or twelve pounds9f Atrazine gave complete nutgre.s
control.
The Atrazine plus EPTC~r.atment had lost its complete, ,
initial nutgrass control by the time of the seven-week ratings.
By this time it was ranked as .giving no bettyr control than six
pounds of Atrazine alone. The work of Raba "';.would suggest that
the dormant tubers, inhibited ,by the EPTCdudng the early weeks,
were now viable.
1 E. M. Rahn. Peraonal correspondence. November, 1961.
317