Vol. 15—1961 - NorthEastern Weed Science Society

152 ...·
harmful to privet and azaleas at moderate rates and hydranges was actually
killed at 2 pounds per acre - the lowest ra.te used. ZiYtron, Da.cthal, CIPC, DNBP
a:cd CDEC,and Amibenwere not harmful at &D;y of the rates· ..nsecl. Atrazine end
Diuron at the higher rates caused yellowing of the lea,ves of llex.
Table 3 listschem1caLs a:cd minimum rateot application necessary
for commercially adequate weed control and, indicates which weeds tend to
be a problem at that otherwise useful rate. S1mazine granular at 6 pounds
per acre gave fairly-good weed control but a few mustard, ragweed, knotweed,
and nutgrass survived. .Atrazine that was not raked into the sol1 gave
better weed control that that raked into the soil. Crabgrass was.the only
problem on plots treated with Atrazin.e at 2 poutl4s per acre. The raked-in
plots had some mustard a:cd ragweed surviving. GeJ.insoga. was a problem in
Dacthal, EETC, and Amiben plots. Weed growth was not evenly distributed
in aU the plots. H~e, some weeds migh1; have been a problem in S()lIle treatments
even though they did Dot appear as suCh in the eXperiment because they were
not plentiful in tliat area.
Residual Effect
In another area granular herbicidal treatments have been repeated
on the same soil for 6 years for Diuron and. CIPC and: 3 years for S1UIaZine.
The rates used are .Diuron 1 1/2 pounds ,CIPC 8 pounds and S1maz1tle 6 pounds
actual per acre. Plants now in the pJ:ots are Berberis verruculosa, nex
crenata var. Helleri, Pieris japonioa, Rhododendron molle, Rhododendron
obtussum var. Hinodegeri, nex crenate. convexa, Taxus cu.spidata.,
Rhododendron cata.wbiense, Leucothoecaetsbei" Syringa vulgaris grafted on
privet, Ex:1kianthus campanulatus, Pieris floribunda, nex opaca, Juniperus
hetzii, Berberis julianae, Hedera helix, and Osmanthus ~icifol:tus.
Continued use of Diuron on the soil .was reducing growth or ;njur,ying Pieris
japonica second year pl$Ilts and Rhododendron obtussum second yea:r plants.
CIPC was injuring Pieris japonica second yea:r plants. Simazine was injury-ing
Rhododendron molle second year, Rhododendron obtussum second year plants 1
Syringa vulgaris third year plants and Enk1anthustirst year plants.
One nez crenata in the Simazine plot had extensive yellowing
of foliage. All the other kinds of plants were doing well in the three
treatments.
In plots where CIPC was used at 12 and 16 pounds per acre for 5
years and D1uron at 3 aud4 pounds for 5 years, Te.xus cuspidata Hicks1i
was doing well after two seasons •
Din1tro for Chickweed Control
Several years ago dormant Texus varieties and nex crenata convexa.
were spr8¥ed with DNBPat 3~4 1/2 pounds per 100 gallons of water to .
control chickweed that was growing over the plants. The results were
successful and cOlllllercial growers have since, used th1s treatment. On October
7, 1960 yound chickweed was .developing in established nursery stock. The
rows were treated with 4-6 pOUnds of DHBPby applying lO~ granular with a
Cyclone rotary spreader. By October 11, the chickweed was eliminated and
was not regrowing one month later·~ -­