Vol. 16—1962 - NorthEastern Weed Science Society

76
EFFECTSOF Nt1M!ImANDSIZE OF CLAr GRANULES
,ON PERFORMANO!iOF" GRANULARHERmCIDEs
(Abstract)
L. L. Danielson and W. A. Gentner !I
Uncalcined attapulgite granules of 15/30-. '20~5-, and 3O/60-mesh sieve
sizes were used in greermouse and'growthroom studieS to determine the etrects
of, size and number of granUles per uni t of soil arfA.or soil volume on tht
activity and persistence of soll-surface-appliedail4 Boil-incorporated ..
ethyl!! .!!-di-!!-propyltldolcarbaaiate [EpTC). '
EPTCwas applied at 2 Ib/A on.5. 10. 20. and 30 Ib of each clay carrier
mesh size. Granules were prepared by dissolving the-required amount of'
technical EPTC in kerosene at. rate of 20 ml of ~roe.ne to each lOOg1'am~
of clay carrier. The granular preparations were appiied simultaneously ..
surface treatments to soil in plasticized paper cups and as incorporated
treatments in' quart plastic containers of soil. '!tie so:l.:l lised was a It 1
potting soil-wuhed pit sand IIl1xture. Nine replicates' of each treatment!lere
prepared for bi~&ys with ryegraas on each ofthtee dates (ilJllllediatel;r.'
after treatment and 2 and 4 weea). The entire exPeriment was duplicate(f'('for
concurrent studies under greeDhoueeand controlled" grOwth-reom condi tiozut~
All containers were sub-irrigated., 'Average tempe1'8tur.s in the greenhause
were approximately 80 to 85°F for. days and 65 to 70 0 for nights., Growthroom
temperatures Were maintained at 70 0 • Air JIOvem.nt in the' greenhouse was
slight whereas it was rapid in the growth room. Glieenhouse light intenft~e8
were relatively high as cOlllpar8d with approximatelY l.5OOfoot-candles ilfthe
growth room. "
In 4 weeks surface_applied EPTCwas dissipated in the greenhouse and
the growth room irrespective ot carrier particle 'she ornumber, but n*'ot
~eoil-incorporated chemicalcwu'dissipated. ~ particle size and DUmber
therefore do not appear to be critical in the effeotive use of EPTCin
granular form ineurface or soil-incorporated treatilbents. Field experieftC'8
indicates that similar studies on slightly soluble, highly soluble, and'
vapor-active herbicides on granules are necessary.,
Soil-surface, chemical di~siP41'ed more rapidly,.1.rLthegrowth room in
initial and confirmatory experiments. Evaluation of greenhouse and growthroom'environments
suggests that air movement can facilitate dissipat10ftot
soil-surface-applied EPTC. '
!I Plant Physiologists, Crops Research Division, Agricultural Research Service,
U. S. Department of Agriculture. Beltsville, Maryland.