Vol. 16—1962 - NorthEastern Weed Science Society

FURTHEREVALUmONor HERBICIDESFal· WEEDCONTROL IH;BI!.WSEEIlOOSor WAIIA
R. Ao PetQe. and H. C. Ycmu.'1
299
~~ have been tried tt>r selective weed control in alraJ.tabut
to date none ot the materials CCIIlIIIIIl"oUJ.l1' available haw given broad
spectrum wed control as well as sutticient selectivit7.
Since the practice of usirlg P'atn companion cro~8 for new seedings ot
torage legumes is nowbeing quest1oned2, there is en· increasing need tor a
satistactor7 herbioide for use on nw seadings. Testing of some of the
older materials as well as an:vpraa1sing new materials should be done on a
continuing basis ..
Procedure: The experimental area'" on the .Agrcmom;y. Research Farm,
Uniwrsit:r otConnecticut, S!;orrs,Connecticut. The principal e:xper:iment .
discussed below was a SUlIIIIerseaclinB ot DuPuits alfalfa seeded on July 28,
1961.
Pre-emergence applicatioM were made on August 2, 1961. Approximat~
25%ot the alfalfa seedlings had snerged bY'the time or treatment. Postemergence
applications were made ClI'1'August 15, 1961 when the second. true
leaf ot the alfaJ.ta was about to e:xpand.
Plot size was 5 bY'15 teet repl1cated three times. Est:llllates ot stands
were made on October 10 and yields were determined on October ll, 1961 b7
harvesting a strip 39 inches wide on each through the centGr ot each plot.
The domina."lt weed species preSent in the experimental area was old
witchgrass (Panicum cap1llare) with an adm.i..xtu... ot large crabgrass
(Digitaria sanguinalia). Only a trace ot broadleaf weeds were present.
Sub-samples were taken tor determinaUon ot dry matter and, when
necess&r7, tor hand separation to determine the percentage ot alfalfa bY'
weight in the plot.
In another e:xperiment, not discussed in .full in this paper, several
herbicides were applied On a spring seeding (April 'Z7, 1961) of alfalfa..
Included was diphenamid at 4 pounds per acre and G.34696at 2 pounds per"
acre both applied as pre-emergence mater1Als and dalapon plus 2,lv-DB as
a poat-emergence material. Rainfall oocurred within two hours ot the time
the pre-emergence materials were appl'.ed.
Results: In the spring seadings,. the diphenamid ga-n outstanding resuJ.ts on
a'Uali'a in terms ot weed control ntb no indication ot injur;y to the alfalfa.
lAssooiate Professor"and, former~~ Research Assistant., UniversitY' of
Connec~icut, .S!;orrs, Connecticut. >
2 Peters, R. A. Legume Establishment as Related to the Presence or Absence
of an Oat Companion Crop. Agron. Jour. 53:195-198. 1961..