Field, screenhouse, and laboratory experiments were conducted to
study weed interference in rice grown on hydromorphic soils at the
International Institute of Tropical Agriculture (IITA) at Ibadan, Nigeria.
Rice and weeds emerged at the same time, 1 week after planting.
Weed dry weight was significantly reduced when the crop was...
Apoplastic distribution patterns of atrazine [2-chloro-4-(ethylamino)-
6-(isopropylamino)-s-triazine], glyphosate [N-(phosphonomethyl)-
glycine], the naturally occurring apoplastic leaf solutes, and
the apoplastic dye PTS (trisodium 3-hydroxy-5,8,10-pyrenetrisulfonate)
were compared. Aliquots of sap were expressed from intact
sunflower leaves in a pressure chamber over intervals of 0.2 to 0.4
bars. Three distinct fractions were detected...
The behavior of metribuzin [4-amino-6-(1,1-
dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one] and
ethyl-metribuzin (4-amino-6-(1,1-dimethylethyl)-3-
(ethylthio)-1,2,4-triazin-5(4H)-one] in soil was studied to
determine if differences in herbicide behavior in soil could
explain (a) the inconsistent herbicidal activity of these
chemicals and (b) the greater activity of metribuzin, as
compared to ethyl-metribuzin.
Metribuzin had higher activity than ethyl-metribuzin...
Tuber oatgrass (Arrhenatherum elatius (L.) Presl. var.
bulbosum (Willd.) Spenn.) is a perennial grass that often
becomes a weed problem in Western Oregon. Control efforts
using glyphosate often give unsatisfactory results. The
effects of several factors on development of tuber oatgrass
were investigated. Long days and cool temperatures (16/8h,
20/10C...
Cyperus esculentus L. var. esculentus is a serious weed
problem in northwest Spain. Long-term control from glyphosate and
other herbicides has been inconsistent. Field, greenhouse, and
laboratory studies were conducted on factors influencing the
activity of glyphosate on C. esculentus.
In field studies, glyphosate controlled foliage growth at most
growth...
EPIC (S-ethyl dipropylthiocarbamate) is a selective herbicide
which controls some annual grasses, annual broadleaves, and perennial
grasses when incorporated into the soil before planting. In the last
few years, reports have been received of certain fields in the
Willamette Valley of Oregon in which EPIC was no longer effective.
Preliminary...
Growth of individual goosegrass (Eleusine indica (L) Gaertn.) plants of
three dinitroaniline-herbicide resistant (R) and three susceptible (S) biotypes from
North Carolina, South Carolina, and Mississippi was analyzed in greenhouse
experiments. Leaf area and biomass measurements, including root, shoot,
above-ground, and total dry weights were similar among the biotypes studied....
Applications of ethofumesate in Oregon have been observed from
previous research and from commercial use to be less effective when
applied to dry soils, even if subsequent precipitation occurred
within a few days. Two field studies were established in the
summer of 1979 using sweet corn (Zea mays L. 'Jubilee')...
Paraquat (1,11-dimethy1-4,4'-bipyridinium ion) and glyphosate [N (phosphonomethyl)glycine] are herbicides utilized for chemical seedbed preparation in the establishment of grass and legume seed crops. When these herbicides are applied after seeding the crop, seeds which are not protected by a layer of soil could be exposed to the herbicide. Effects of...
Time-course growth chamber studies were conducted on little mallow
(Malva parviflora L.) to determine whether sublethal doses of lactofen
(1'-(carboethoxy)ethyl-5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-
nitrobenzoate) would enhance uptake of glyphosate (N'-(phosphonomethyl)
glycine) by altering membrane permeability. Lactofen-induced membrane
peroxidation was determined by harvesting leaf discs, measuring stress
ethylene evolution, and recording increases in...
Weedy rye (Secale spp.) is a weed in the winter-wheat- growing
regions in the Pacific Northwest and surrounding regions. Ethiazin
(4-amino-6-(1,1-dimethylethyl)-3- (ehtylthio)-1,2,4-triazine-5 (4H)-one)
has shown selective control of weedy rye in the cultivar 'Stephens',
(Triticum aestivum). Field, greenhouse, and outdoor pot experiments
were conducted to determine factors influencing selectivity.
Field...
Diclofop (2- [4 -(2, 4-dichlorophenoxy)phenoxy] propanoic
acid), formulated as the methyl ester, selectively kills
barnyardgrass [Echinochloa crus -galli (L.) Beauv.] in several
crops when applied postemergence. Studies were conducted
to determine the effect of soil moisture, barnyardgrass age, and site of exposure on control of barnyardgrass with diclofop. Soil moisture...
Equipment for strip-till planting is under development in wheat-fallow
rotations in the Columbia Basin of Oregon. This involves the
absence of tillage during the fallow season. At planting time, the
strip-till planter creates a narrow band into which the wheat seed is
placed. The area between the rows is undisturbed...
Laboratory and field studies were conducted at Pendleton, Oregon, during 1983 and 1984 to evaluate germination and growth characteristics of five jointed goatgrass (Aegilops cylindrica Host) accessions collected from sites in Echo, Ione, Pendleton, Condon, and Elgin, Oregon. Spikelets were germinated for 27 days at room (23 +̲ 2 C)...
Liming has been shown to increase the activity of certain soil-applied herbicides. One research worker reported improved weed control with diuron after lime had increased soil pH levels. This could be caused by improved competitive ability of the wheat, greater availability of the herbicide, or a combination of the two...
Previous studies have shown loss of ethofumesate activity when
the herbicide was applied to dry soil (2% w/w moisture content) in
both field and greenhouse studies, even when rainfall or irrigation
was received within a few days. Laboratory studies were conducted to
determine the mechanism for this activity loss. Dry...
The interference of barnyardgrass (Echinochloa crusgalli),
pigweed (Amaranthus retroflexus),downy brome (Bromus
tectorum),and tumble mustard (Sisymbrium altissimum)
with alfalfa was studied. Alfalfa was seeded with each of
the four weeds on August 14 and September 15, 1981, and on
April 13, 1982. Alfalfa also was seeded on August 27, 1981,
with...
Living mulches are vegetative covers that can grow in association with row crops and may prevent soil erosion and suppress weeds. Crop reduction from association with the living mulch is a frequent problem with this cultural practice. The interference between a white clover (Trifolium repens L. "New Zealand") living mulch...
A series of experiments were conducted from 1983 to 1985 to
determine the effects of dinoseb [2-(1-methylpropyl)-4,6-dinitrophenol]
on winter wheat (Triticum aestivum L. em Thell) yields. Field trials
on dinoseb timing and dinoseb plus supplemental pesticides were
established in an effort to elucidate the possible factors involved in
the yield...
Norflurazon [4-chloro-5-(methylamino)-2(3-(trifluoromethyl)
phenyl)- 3(2H)- pyridazinone] and prodiamine (N3, N3-di-n-propy1-2,4-
dinitro-6-(trifluoromethyl)-m-phenylenediamine) are two herbicides
being considered for weed control in alfalfa. Rotational crops
following alfalfa may be sensitive to residues of these herbicides.
Studies were conducted in Oregon and Washington to examine the soil
persistence and activity of these herbicides on...
Volunteer winter wheat (Triticum aestivum 'Daws')
severely suppressed growth of fall-planted alfalfa
(Medicago sativa (L.) 'Vernal') seedlings. Wheat
competition began soon after alfalfa emerged and continued
until the first forage harvest the following May. Alfalfa
yield at the first cutting was reduced by 1% for each day
volunteer wheat was...
The herbicide rate required to reduce growth by 50% (GR₅₀) of 11
cultivars of red fesue (Festuca rubra L. and F. rubra ssp. commutata)
and for four cultivars of bentgrass (Agrostis tenuis Sibth. and A.
stolonifera L. var. palustris) to sethoxydim (2-[1-(ethoxyimino)
butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one) was
determined in greenhouse and laboratory experiments....
Napropamide [2-(alpha-naphthoxyl)-N,N-diethylpropionamide], a
preemergence herbicide, is widely used in the United States on a
variety of tree fruits, nut crops, vegetables, and mint for annual
grass and broadleaf weed control. When napropamide has been left on
the soil surface without incorporation through irrigation or mechanical means, inconsistent results have been...
Glyphosate (N-(phosphonomethyl)glycine) is an effective
foliar-applied herbicide with broad-spectrum activity. Greenhouse
and laboratory experiments were conducted to determine the
importance of soil moisture, autoclaved soil, soil type, sphagnum
peat, soil pH, added phosphorus, and plant residues on crop
establishment and growth when glyphosate was applied before
emergence of the crop....
The influence of certain environmental and edaphic
factors on the germination and emergence of downy brome
(Bromus tectorum L.) was investigated in the laboratory. A
preliminary study was conducted to determine the osmotic
stability of mannitol and polyethylene glycol 20,000 (PEG)
solutions, which are commonly used to simulate water stress...
