Vol. 15—1961 - NorthEastern Weed Science Society

67.
"he two tests which dealt with time of applying CDECin relation to crop
seeding further substantiate the authors contention that the actual situation
regarding seed deVelopnent at tb8 time of CDEC"contact" is an imPortant consideration
often overlooked. It is belieVed "that 'this critical factor mS7
account for the 1n;Jury reported :from. CDECat high temperatures and' from more
frequent cases of injury on muck as comPared to mineral soUs. In both
instances if CDECis applied ~ planting, there is much greater likelihood
of more rapid germination and, 'conseqUently, a greater chance of CDECcontacting
the crop seeds in a critical stage of germination. The data in Table
4 illustrate conclusively that crop and weed seeds are both susceptible during
.sprouting and· quickly beecmeless suscetJtible to surface applications as the
plumule and hypocotyl develop. Linder (l954) working Under laboratory conditions,
concluded that the stage of seedling deVelopment most susceptible
to carbamate injury vas that when the seed coa't had Just been penetrated by
the radicle.
It is suggested by the authors that the controlling factor in. determining
CDECactiVity under practical field conditions is to have CDECpresent at the
actual zone of seed. germination whentbe radicle is emerging. Practics.lly
all of 'the apparent; contradictions in these tests and those discussed above can
be resolved on this basis. '
SUDJDlSry and Co~clusionS
, .
Three factorial experiments were conducted on a sandy loam s6i1 involving
watering, mechanical incorporation" formulation, and timing as possible field
factorEJ influencing ODEC' activity. 'fWOtests were conducted in which CDECwas
applied at two day' int;erials 'following seeding. By correlating ~uch factors
as temperature and soU moisture with treatmeni;s given and measuring weed and
crop response, and by interpreting the work of other investigators, the
authors attempted to evaluate the various factors pOssibly influencing cmc
activity. .
The fo:J.lowing~ints were fairly evident from the data presented:
1. Volatility from either' a dry or moist soU surface was unimportant
in determining CDECeffectiveness.
2. Formulations on dry"gr8nular cl87 or vermiculite performed as well as
the conventiQnal.l:tqui4,formulation. .,
3. Leaching was relatively unimportant. However, 1 1/2. i~ehes of water
gave better results than 1/2, inch when weed seeds were sprouting at the time
of CDECapplication. . . " "" ,
4. SoU fixation probably pla;;ys a minor direct role in determining
activity of CDEC. However, coupled with low solubUity, this results in very
little movement;in the soU. Lack of appreciable movement may enhance or
diminish weed control in the field depending on many factors.
5. Microbial actiVity probably had little to do with CDECfailures, but