Vol. 15—1961 - NorthEastern Weed Science Society

69.
CONTROLOF WEEDSIN VEGETABLECROPS
WITH A SUBSTITUTEDDIPHENYLACETAMIDE
E. F. Alder, W. L. Wright, and Q. F. Sop~rl/
Introduction
Extensive studies in the greenhouse and field have been conducted
on a l~rge number of substituted diphenylacetonitriles and
diphenylacetamides. Special a;ttention has been given to a neW
selective herbicide, N,N-dimethyl-~,~-diphenylacetamide. This
compound was coded as L-343l4 and now bears ,the tenta~ive generic,
name diphenamid.
In greenhouse tests diphenatl11.dgave good pre-emergent activity
against all seedling grasses tested and against broadleaf weeds
such as pigweed and smartweedat rates of 4, s»)«, A number of important
horticultural andagr.onomic- crops Were tolerant- to the
material. Structure-ac1iivity stUdies reveaLed that lengthening the
chain of the. alkyl substit'uents of the amide portion of dip hen amid
resulted in reduced activity. .
Field
Tests
The promising greenhouse results with diphenamid led to its
inclusion in thirteen field tests on a total of 28 different crops.
Major emphasis has been on tomatoes, other vegetable crops, and
forage legumes.
Diphenamid has a rather low solubility in water (260 ppm) and
in most organic solvents. It was, theretore, formul.ated as a
, wettable powd~r and on clay granul~s. Applications,f)f \ the wettable
powder formulation were made with,a small: plot sulky spray rig.
Granules were applied with a lawn -spreader •. Slightly 'better results
were generally obtained with the wett.ble powder formulation. All
field tests were replicated and of a randomized block design.
Tomatoes -- Four pre-emergence field tests were conducted on
tomatoes; three with field-seeded tomatoes, one with tomato transplants.
In all tests, 4 to 6 lb/A of diph~namid gave satisfactory
control of weed grasses with no damage to tomatoes. Table 1
11 Eli Lilly and Co., AgriCUltural ~esearch Center,
Greenfield, Indiana