Vol. 15—1961 - NorthEastern Weed Science Society

)0.
Robbins et al(lO) state that "increase in polarity enhances the ap­
parent reactivity (of a herbicide) whereas .increase in its oil-like (a-polar)
properties promotes penetration. "
They conclude that since the two processes are apparently opposed,
there must be an optimum POint in-the balance between them; and this in
reality represents a compromise between toXicity and compatibility with the
.cuticle.
Orgell(9) has observed that cationic and anionic aurractants differ
markedly in their effects on absorption of acidic compounds .. and
Staniforth(11) states that npn-ionicwetUng agente differ hi action from that
of sodium laurel sulfate - an anionic w~tting agent.. . .
Currier's observation(l) that root absorptton of dalapon is enhanced
by the addition of a s.urfactant is of interest since roots are nor-mafly readily
wetted. by water, and thus. perhaps confirms Ennis' earlier observation(4)
by indicating some effect on root cell protoplasm. . Knowledge
of the effect of surfactants in herbicidal solutions is far from complete;
and a 1954 summary by Currier still represents the state of the art fairly
well.
Foy(5) using both C 14 and Cl 36 labelled dalapon demonstrated the
advantages of using wetting agents with dalapon, For example, on the basis
of growth inhibition, it appeared that as much dalapon was absorbed by
corn in one hour from sprays containing a surfactant as in two weeks from
. a solution without a surfactant.
Jansen(8) found a wide range .in response to dalapon by both soybeans
and corn in tests using 63 different wetting agents in combination with
dala:po~ ,
MATERIALS AND METHODS
Prior to the start of tpis experiment. Jansen's data had been re­
viewed and, on the basis of his r eaulte , a number of surfactants which had
improved the herbicidal effects of dalapon on corn and soybeans were ten­
tatively selected for use. Some of these were not readily available, so a
further selection was made .. and the following surfactants were obtained: