(1999 Data)
Southeast District Counties:
Goshen, Laramie, Platte
Cropping system:
Beans should be planted between May 25 and June 20 in firm, non-compacted
soil. The following seed bed requirements optimize germination and growth:
temperature of at least 60 F, a pH of 8 or less, and a salinity level that
does not exceed 3 millimols. Inoculating the soil with Rhizobium
bacteria during planting will encourage a symbiotic relationship between
the nitrogen fixing bacteria and the root nodules of dry beans. These bacteria
add useable nitrogen to the soil for plant uptake. Moderate fertilizer
application may also be required, especially if there is no nodulation.
Fertilizer recommendations range from 50 - 60 lbs. of nitrogen, 0 - 75
lbs. of phosphorous and 0 - 5 lbs. of zinc. Row spacing should not exceed
30", and seeds should be planted about 2" into the soil (but no more than
4").
Crop rotation is imperative to the success of the crop. For irrigated beans, a 3 - 4 year rotation with corn, barley, wheat and alfalfa is recommended, whereas dryland beans should be part of a 3-year rotation with grain sorghum, wheat, sunflowers, and a year of fallow preceding the beans. An alfalfa crop should not directly precede dry beans because of the volunteer perennial weed aspect of alfalfa. Dry beans should not be planted after potatoes or sugarbeets if either crop was affected by rhizoctonia root or crown root. Avoid planting after potatoes for three years. They also should not be planted after irrigated sunflowers due to white mold susceptibility.
Tillage is necessary for the success of dry beans. Deep ripping of the soil reduces the weed seed population. Ridging soil around the base of plants is necessary to promote secondary root development and to facilitate bean cutting and pulling. Beans are ready for cutting and pulling when 33 - 50% of the pods turn yellow. All harvesting should be done before the fall frost.
Critical Pest Management Issues:
Disease problems are the most critical pest management issues for dry
bean production. Therefore, fungicides and other disease management strategies
are imperative to the continued success of dry bean production in Wyoming.
There are no adequate controls for Canada thistle or field bindweed that do not cause damage to the dry bean plants.
Cultural Controls:
Minimal stress during the growing season will encourage healthy crops
and reduce the risks of pest infestation. Begin with high quality certified
seed and dry bean varieties that are resistant to pests. Proper and timely
preparation of the soil and seed bed prior to planting includes treating
seeds with soil fungicides, destroying volunteer grains and beans, planting
away from wheat crops due to problems with onion thrips, and complete incorporation
of previous crop residues. Thoughtful crop rotations and irrigation control
will avert many pest problems; if the soil is too moist, it will encourage
disease and mold, and the soil should be as dry as possible after pod formation.
Recommended crop rotations are listed in the cropping systems section.
Lay-by applications of Frontier may extend weed control.
The beet leafhopper feeds on the undersides of dry bean leaves. Severe
infestation, a rare occurrence, can cause leaf cupping and discoloration.
The adult beet leafhopper is a pale green, active insects about 0.125"
in length. There are three or more generations per year, and the insect
can be found throughout the bean growing season. Hot dry conditions favor
development of this insect, which is a vector of curly top virus. Control
of beet leafhopper in dry beans is generally not recommended.
Potato Leafhoppers
The potato leafhopper can be a serious problem in dry beans early in
the season. It overwinters in the Gulf Coast area, and its migration into
this region usually occurs in low numbers and too late in the season to
cause serious damage. The potato leafhopper is a wedge shaped, green insect
with six white spots on the prothorax. The leafhopper injects a toxin during
feeding that damages the plant and results in leaf discoloration and stunting.
The threshold for treatment is one leafhopper per trifoliate.
Onion Thrips and Western Flower Thrips
Two kinds of thrips, onion thrips and western flower thrips, attack
dry beans in the region. Thrips are small, active, cigarette-shaped, yellow-to-brown
insects. They rasp the tissue and drain the exuding sap, causing stunted
and deformed plants. Thrips are usually a pest of seedling plants but may
attack plants in any stage. Onion thrips are most commonly associated with
furrow irrigated beans grown in close proximity to winter wheat. Onion
thrips feeding results in leaf cupping and distortion that is made more
severe by plant stress. The crop often outgrows the damage with little
loss in yield. Infestation and damage are often more severe at the edge
of the field. Western flower thrips feed in developing flowers and can
cause flower and pod abortion. Five Western flower thrips per blossom can
reduce the number of pods per plant. Onion thrips have not been difficult
to control, but flower thrips may prove difficult to reach with contact
insecticides. Both of these thrips can transmit tobacco streak virus.
Seedcorn Maggots
The adult seedcorn maggot is a hairy, gray fly about 0.2" long that
lays eggs in areas high in decaying organic matter. The maggot is yellowish
white, legless and about 0.25" long. The first adult activity in the spring
occurs in early May during corn planting. Offspring of these adults mature
to form a second generation of adults late May or early June when beans
are planted. These adults are attracted to areas of high organic matter
that have just been tilled. Maggots will feed on the germinating bean seed
and hollow out or otherwise damage cotyledons. If maggots damage the growing
point of the plant, a "snakehead" plant may result. Later feeding by the
maggots may be evident as burrowing within the stem. This feeding may increase
the incident of secondary rotting within the stem.
Mexican Bean Beetle
The Mexican bean beetle can be a serious pest of beans in Wyoming. The
adult Mexican bean beetle is 0.25 - 0.33" in length and has an oval, pale-yellow,
convex body when newly emerged. As the adult matures, it changes to a coppery-brown
color. It has 16 black spots on its back. Mature larvae are yellow-orange
in color, about 0.33" in length, and are covered with dark, branched spines
that give them a fuzzy appearance. The adults overwinter at the soil surface
under plant debris and sometimes in large groups in hedgerows adjacent
to bean fields. When temperatures warm in the spring, the beetles fly into
alfalfa and clover fields to feed but do not lay eggs there. As soon as
beans begin emerging, the beetles abandon alfalfa and clover fields to
colonize bean fields. Seven to 10 days after feeding, females will begin
to lay yellowish-orange eggs in clusters of 40 - 60 on the undersides of
the bean leaves. Each female may lay up to 500 eggs in a 5-week period.
In the early part of the season, the eggs take approximately 12 days to
hatch, while later in the summer they will take only five days to hatch.
The larvae take about 25 days to mature. The mature larvae attach themselves
to the underside of the leaves and weeds to pupate, and are inactive for
about a week. The pupae are round, smooth, yellow in color, and quite often
have the last larval skin still attached. Generally, two generations develop
in Wyoming. Eggs of the first generation will hatch in late June or July,
and larvae develop through July into August. The next generation of adults
will emerge in late July or early August and lay eggs in early August.
Larvae of the second generation will mature through August and pupate in
late August or early September. Larvae and adults feed on the undersides
of leaves, leaving the upper surface intact. The upper leaf surface dries
up and falls out so that damaged leaves have open, ragged holes. The larvae
feed along parallel lines, leaving strips of uneaten leaf in between. When
abundant, these pests also feed on bean pods and stems. Their injury reduces
plant vigor and in extreme cases the foliage is reduced to shreds and the
plant dies.
Western Bean Cutworm
Young larvae are light-colored with three short, wide, dark stripes
running lengthwise on the first segment behind the head. The western bean
cutworm overwinters as a pre-pupa within earthen cells formed in the ground.
They pupate in May and emerge as moths in July and August. Rainfall and
irrigation aid emergence of adults from soil. Peak moth activity in Wyoming
usually occurs in the last half of July. Shortly after emergence, they
lay clusters of eggs, usually 15 - 50 dome-shaped eggs, on the lower surface
of the leaves. The larvae mature and stop feeding. They then enter the
soil for overwintering. There is only one generation per year. Damage by
young western bean cutworm larvae is not very noticeable, as they feed
primarily on tender leaves and flower parts. As pods form, worms chew holes
in the pod walls and feed on developing seeds. Feeding occurs primarily
at night and during cloudy days. During a sunny day, worms hide in soil
at the base of plants.
Bean Leaf Beetle
Bean leaf beetles are about 0.25" long, with considerable variation
in color patterns. The background color may be yellow, green, tan, or red.
Most beetles' wing covers have four black spots and black stripes along
the edges, although these markings may be absent. A black triangle is always
present at the base of the wing covers just behind the prothorax. The larvae
are white, with dark-brown areas at both ends. When mature, the larvae
are about 0.375 to 0.5" long. Bean leaf beetles overwinter as adults under
debris in protected areas. When temperatures warm in the spring, the beetles
fly into alfalfa and clover fields to feed but do not lay eggs there. As
soon as beans begin emerging, the beetles abandon alfalfa and clover fields
to colonize bean fields. Females lay eggs in the soil around the base of
the plant. The lemon-shaped eggs are laid in clusters of 12 - 24 and are
orange in color. The eggs hatch in one to three weeks depending on the
weather. The larvae feed on the roots and nodules of the plants. When the
larvae finish feeding, they form an earthen cell in which to pupate. The
pupal stage lasts approximately 1 - 2 weeks. Adults feed on the foliage.
In most of Wyoming, bean leaf beetles complete one generation per year.
There has been some indication that a complete or partial second generation
may occur in the southern parts of the state. The injury caused by the
bean leaf beetle is twofold. The adults feed on the leaves of the plants
causing the characteristic "shot hole" appearance on the leaves. The larvae
feed on the roots and underground portion of the stem, girdling and killing
the plant. Late in the season, bean leaf beetles may chew on pods. Their
feeding creates scars that open the way to spores of some fungal diseases.
Mild infection results in seed staining; severe infection results in seed
contamination.
Aphids
Aphid life cycles vary with species. Aphids are small, soft-bodied insects
found singly or in clusters on stems or undersides of leaves. Aphids overwinter
as eggs and adults. The tiny aphids hatch in the spring, mature rapidly
and give birth, without mating, to living young. Mature aphids fly to cultivated
crops during the spring and summer where they start new colonies. Only
females are produced during the summer and with their rapid rate of reproduction,
it is possible for large numbers to develop in a short time. They may be
a problem throughout the season. As cool weather approaches in the fall,
both males and females are produced. The females then mate and lay fertile
eggs that overwinter. Aphids attack the leaves, blossoms, pods and other
parts of their host plants, sucking plant juices through their tiny needle-like
beaks. Heavily infested plants become stunted and do not produce normal
crops. Migrating aphids also transmit several important plant diseases.
Flea Beetles
Adult beetles are typically small, often shiny, and have large rear
legs that allow them to jump like a flea when disturbed. Flea beetles overwinter
in the adult stage hidden under leaves, dirt clods, or in other protected
sites. They begin to become active during warm days in mid-spring but may
straggle out over several weeks. Many flea beetles are strong fliers and
seek out emerging host plants that they locate by chemical cues the plants
produce. The adults feed for several weeks. Soon the females intersperse
feeding with egg laying. They lay eggs in soil cracks around the base of
the plants. The minute, worm-like larvae then move to feed on small roots
and root hairs. The larval stage is completed in about a month. The insects
pupate, then emerge from the soil as adults. There may be a second generation
during the summer and, with a few species, a third generation. The adults
chew many small holes or pits in the leaves, which make them look as if
fine buckshot has damaged them. Young plants and seedlings are particularly
susceptible. Growth may be seriously retarded and plants even killed. Although
flea beetles are common, injuries are often insignificant to plant health.
On established plants, 10 - 20% or more of the leaf area must be destroyed
before there is any effect on yields.
Grasshoppers
Grasshoppers follow a roughly 22-year cycle in Wyoming, with the last
major outbreak occurring in the late 1970s and early 1980s. Grasshoppers
vary considerably depending on the species. Grasshopper nymphs have a similar
appearance to adults but are smaller in size. Grasshopper eggs are laid
in undisturbed areas, usually in late summer and early fall. Small nymphs
or "hoppers" hatch the following spring. The usual pattern of grasshopper
damage in field crops is for early development to occur in weedy areas
of roadsides, fence rows, irrigation ditches, and other non-crop areas.
As these food plants are eaten or dry down, the grasshoppers leave in search
of other food. They will first feed in the field margins and then, conditions
permitting, spread throughout the field. Most field crop damage is caused
by the differential, redlegged, two-striped, and migratory grasshoppers.
Insecticide Matrix
| acephate | carbaryl | dicofol | propargite | dimethicote | esfenvalerate | |
| Colorado Potato Beetle | X | |||||
| Grasshopper | X | X | X | |||
| Leafhopper | X | |||||
| Mexican Bean Beetle | X | X | X | X | ||
| Spider mites | X | X | X | |||
| WBC/Other cutworms | X |
Data from pesticide use survey, 1997
Management:
Insecticides:
Bacterial brown spot is a pathogen that affects the leaves, stem, pods
and seed of bean plants. Lesion size varies, but they are usually small
and brown, surrounded by a narrow yellow zone. Water soaked tissue may
not be noticeable, but if present it appears as small circular spots on
the lower leaf surface. The centers of old lesions fall out, leaving tattered
strips of holes on affected leaves. If the disease becomes systemic in
the plant, lesions can occur along the stem. Pods from infected plants
are bent or twisted with visual ring spots. Water-soaked brown lesions
can form on pods. Older plants and plant parts are more resistant to infection.
Rainstorms and sprinkler irrigation promote bacterial spread.
Bean Common Mosaic
Bean common mosaic virus causes a systemic mosaic or darkening (necrosis)
in susceptible plants infected by the virus. Symptoms appear as a green
to bluish-green mottled or mosaic pattern on leaves which usually exhibit
a downward curling or cupping. This mosaic symptom is often associated
with and follows the network of leaf veins which become slightly darker
than the areas between the veins. These symptoms are more easily observed
by shading the leaf from direct sunlight. Severe, early infections greatly
reduce plant vigor and productivity, and increases seed transmissions.
The virus is transmitted by aphids or by seed. In some cases there are
resistant cultivars. Virus-free seed should be used. Field sanitation,
early planting, reflective mulches, crop-free period and vector control
can be helpful.
Common Bacterial Blight
Small water soaked spots on the underside of leaflets are the first
symptoms. These spots enlarge and merge, becoming dried and brown. A narrow
bright lemon-yellow border of tissue encircles the lesion. Infected pods
develop circular water soaked spots, and yellow masses of bacteria may
appear at their center. Later, the spots dry and become reddish-brown sunken
lesions. Early pod infection causes shriveled seeds, and the bacteria may
cause yellowing under the seed coat of infected seeds. A stem girdling
or joint rot occurs above the cotyledonary node of plants grown from infected
seeds. Planting infected seed favors early infection and disease spread.
Warm weather also favors infection and symptom development. The bacteria
survive in the field in infected seeds. Planting beans on or next to a
field blighted the previous year exposes the current season's crop to inoculum.
The pathogen will spread from the surface of the infected leaves and pods
to healthy plants by storms, people, and machinery moving through the field
when plants are wet. Rain and hail also spread the pathogen within and
between bean fields.
Fusarium Root Rot
Fusarium root rot initially appears as red to reddish-brown streaks
(lesions) on the hypocotyl and primary root 2 - 3 weeks after planting.
These affected areas enlarge with age, may merge and gradually become brown.
The symptoms may extend up the main root to the soil surface, and longitudinal
cracks can develop in older lesions. Severely infected primary and secondary
roots are commonly killed but can persist on the plant as dried remnants.
Lateral roots can develop from hypocotyl above the initial infection site
if sufficient soil moisture is available. Infected plants are stunted with
yellow leaves but are seldom killed. The fusarium root rot fungus occurs
in most cultivated soils of the region where beans have been grown previously,
and most plants grown in these soils will become infected to some degree
before they mature. Root rot severity depends on factors such as cropping
history, plant spacing, moisture and temperature stresses and soil compaction.
Early planting in cool, moist soils favors the disease, as does soil compaction
in the form of tillage or hardpan layers.
Halo Blight
The first symptoms of infection are small water soaked spots on the
leaflets. In a dry climate, this infected tissue dies and is tan-colored.
A broad yellow-green halo helps distinguish halo blight from common bacterial
blight which exhibits a narrow, lemon-colored border around leaf lesions.
Presence of the halo blight is absent under high temperatures. Systematic
infection causes younger leaflets to curve and exhibit considerable yellowing
on these leaves with no dead spots or distinct halos. Halo blight symptoms
on pods begin as water soaked circular spots which appear light cream or
silver colored. Early pod infection causes shriveled seeds. Stem girdling
and joint rot occur above the cotyledonary node of plants grown from infected
seed. Planting infected seed, or clean seed in the presence of infested
debris in the area enhances early infection and disease spread. Cool weather
favors the disease and production of the toxin that forms halos and systemic
yellowing. Wet weather, hail and violent rainstorms enable the pathogen
to be spread rapidly within and between fields.
Rhizoctonia Root Rot
Rhizoctonia solani can cause seedling death, root and hypocotyl
rot, stem canker and pod rot. Initial symptoms appear on roots or the hypocotyl
as linear or circular reddish-brown sunken lesions of cankers delimited
by a brown to reddish-brown margin. Over time Rhizoctonia cankers enlarge,
become darker, rough textured, and retard plant growth. The fungus can
invade the central part of the lower stem and produce a brick-red discoloration.
Disease symptoms often occur on scattered plants in a somewhat circular
field pattern. Severe seedling infection causes plant death. Later in the
season, mixed infection with the fusarium and pythium root rot organisms
are common. Lesions may also develop on pods that are in contact with the
moist soil surface and cause pod rotting or seed discoloration.
Rust
Rust symptoms first appear on the upper and/or lower surfaces of leaves
as small yellow or white slightly raised spots. Green pods, and occasionally
stems, also may become infected and develop typical rust-colored pustules.
These spots enlarge and raise further to form reddish-brown or rust-colored
pustules which are about 0.125" in diameter and contain thousands of microscopic
spores called, urediniospores which allow the fungus to spread within and
between fields. Pustules may be surrounded by a yellow border. Spores are
readily released from the pustules and give a rusty appearance to anything
they contact. Severe infections result in premature leaf drop. Pod set,
and especially pod fill, can be reduced if infection is severe during early
reproductive development of the bean plant. Near the end of the season,
many pustules change color, and form dark brown to black teliospores which
allow the fungus to overwinter in some production areas. Rust development
is favored by cool to moderate temperatures less than 86 F with moisture
conditions that result in prolonged periods of free water on the leaf surface.
Rusts overwinter in debris, volunteers and alternate hosts or are blown
up from the south each year.
White Mold
White mold initially appears on plants after flowering as water soaked spots on infected leaves, stems, branches and pods. These areas enlarge into a watery rotten mass of tissue that becomes covered by a white fungal growth. Stem infection causes the part of the plant above the point of infection to wilt and die. Affected stems appear bleached and dry which differs from the tan color characteristic of mature, dry plant tissue. White mold development is influenced by prevailing weather conditions and certain cultural practices. High plant populations, narrow row widths, vigorously vining varieties, excessive fertilizers and abundant irrigation or rainfall all favor the development of white mold. High humidity and a wet plant canopy and/or soil surface are necessary to spread. The disease may cause serious losses during wet, and cool periods near the end of the growing season and even when the beans are in the windrow.
Bean Yellow Mosaic
Bean common mosaic virus causes a systemic mosaic or darkening in susceptible
plants infected by the virus. Symptoms appear as a green to a bluish-green
mottled or mosaic pattern on leaves which usually exhibit a downward curling
or cupping. This mosaic symptom is often associated with and follows the
network of leaf veins which becomes slightly darker that the areas between
the veins. These symptoms are more easily observed by shading the leaf
from direct sunlight. Severe, early infection greatly reduces plant vigor
and productivity, and increases seed transmission.
Fusarium Wilt
Fusarium oxysporum symptoms are seen are drooping and epinasty
(downward twisting) of leaves followed by yellowing, stunting and death.
Symptoms may be one sided and progress upward, killing foliage. A cross
section of the stem near the base will have characteristic vascular discoloration.
Fusarium wilt is favored by high air and soil temperatures and occurs most
frequently in temperate areas. Both these diseases overwinter in soil,
plant debris and weeds. Control is primarily through use of resistant cultivars.
Pythium
Pythium spp. may infect planted seeds prior to germination, germinating
seedlings, young plants, or older plants blossoming and forming pods. It
is one of the pathogens capable of causing seed decay and seedling death.
Initial root rot symptoms appear as elongated water soaked areas on the
hypocotyl and roots, within one to three weeks after planting. The pathogen
will extensively prune roots, reduce overall plant growth and destroy much
of the hypocotyl and main root system. The water soaked area eventually
dries out, becomes somewhat sunken, and tan to brown in color. After this,
plants will die.
Damping Off
Pre- and post-emergence damping-off and seedling blights occurs in dry
edible beans. Soil-inhabiting fungi (Fusarium spp., Penicillium
spp. Pythium spp., and Rhizoctonia solani) cause these diseases.
They are characterized by missing or collapsed plants. When pre-emergence
damping-off occurs, seedlings fail to break the soil surface. The germinating
seed rots while still in the ground. With post-emergence damping-off, seedlings
still in the cotyledon stage will rot at the soil line. The stem appears
pinched and plants fall over. Seedling blights occur after true leaves
emerge and the developing root system rots and plants collapse. Seedling
diseases are problems when soils are cold and wet at or immediately following
planting. These conditions can delay germination or stress developing seedlings,
which allows pathogens to attack. Crusting caused by poor soil preparation,
hard rain, or excessive trash on the surface also contributes to disease.
Fungicide seed treatment combined with avoiding cold wet soils and good
soil preparation will best manage these diseases.
Fungicide Matrix
| benomyl | copper hydroxide | copper sulfate | maneb | propiconazole | sulfur | thiophanate-methyl | |
| Bacterial Blight | X | X | |||||
| Bacterial Leaf Blight | X | ||||||
| Bacterial Leaf Spot | X | ||||||
| Brown Leaf Spot | X | ||||||
| Cercospora Leaf Spot | X | ||||||
| Dwarf Bunt | X | ||||||
| Early Blight | X | X | |||||
| Halo Blight | X | X | X | ||||
| Late Blight | X | X | X | ||||
| Powdery Mildew | X |
|
|||||
| Rust | X | X | X | X | X | ||
| Seedling Blight | X | ||||||
| White Mold | X | X | X | ||||
| Blight | X | TD> | X | X |
Data from pesticide use survey, 1997
Management:
Fungicides:
Solanum rustratum is native to the Great Plains of the US. It
is a drought tolerant species that can grow in a wide variety of environmental
conditions. Buffalobur spreads exclusively by seeds, which are enclosed
within the spiny calyx. Buffalobur is an annual, with spiny leaves, flowers,
and stems, that grows up to 2' tall. Leaves are deeply lobed like a watermelon
leaf, and up to 5" long. Flowers are borne from the midsummer until frost,
are 1" across, 5-petalled, and bright yellow in color. One of the anthers
in each flower is longer than the other four. The fruit is a dry berry
that is overgrown by the calyx, forming a bur-like fruit. Seeds are black,
flat and wrinkled.
Canada Thistle
Cirsium arvense is a member of the Aster or Sunflower family.
Canada thistle was introduced from Europe. It is a creeping perennial which
reproduces by seeds and fleshy, horizontal roots. The erect stem is hollow,
smooth and slightly hairy, 1 - 5' tall, simple, and branched at the top.
The leaves are set close on the stem, slightly clasping, and dark green.
Leaf shape varies widely from oblong to lance-shaped. Sharp spines are
numerous on the outer edges of the leaves and on the branches and main
stem of the plant. The flowers are small and compact, about 0.75" or less
in diameter, and light pink to rose-purple in color, occasionally white.
The seeds are oblong, flattened, dark brown, and approximately 0.125" long.
Canada thistle emerges in April or May in most parts of Wyoming. It is
one of the most widespread and economical damaging noxious weeds in Wyoming.
Because of its seeding habits, vigorous growth, and extensive underground
root system, control or eradication is difficult. It is distributed across
Wyoming from 4,000 to 9,500'.
Jimsonweed
Datura stramonium is a rank smelling annual with stems 0.75 -
5' tall. Leaves are alternate, large, usually unevenly toothed to shallowly
lobed. Flowers are trumpet-shaped 3.5 - 5" long. Jimsonweed has very large
leaves with spiny capsules which contain several hundred seeds. As the
capsule matures it splits at the top and the plant tips it over so that
all of the seeds fall out.
Kochia
Kochia scoparia, a member of the Goosefoot family, was introduced
from Europe and is an annual, reproducing by seed. The stems are erect,
round, slender, pale green, branched, and 1 - 6' high. Leaves are narrow,
bright green, hairy, numerous and are attached directly to the stem. The
upper leaves are narrow. The flowers are inconspicuous in the axils of
upper leaves. Seeds are about 0.0625" long, wedge shaped, dull brown, and
slightly ribbed. Kochia can be found throughout the state up to 8,500'.
In autumn the plants may become red and later turn brown, breaking away
from the root, and tumbling over the ground scattering large amounts of
seed.
Lambsquarters
Chenopodium album was introduced from Europe. It reproduces by
seeds. The stem is erect, stout, smooth, grooved, often striped with pink
or purple, branched and grows 1 - 6' high. The leaves are alternate with
the lower ones being ovate and upper ones becoming narrower. The flowers
are small, green, and crowded in the axils and at the tips of the stems
and branches. It is a succulent, fast-growing plant which rapidly removes
moisture from the soil.
Black Nightshade
Solanum ptycanthum is a native weed. Flowering season is from
May to October. Seeds are the only source of reproduction. Black nightshade
plants vary greatly in form and color. Seed leaves of black nightshade
are elongate-oval and pointed. Lower surfaces are often purple. Berries
turn from green to black when mature and the calyx covers only a small
part of the fruit surface. Petioles, stems and leaves have some hairs but
are not densely hairy or sticky.
Hairy Nightshade
Solanum sarrachoides leaves have wavy edges and prominent veins.
The leaves have numerous fine, short hairs, especially along the underside
of the main vein. Berries are green or yellowish brown when mature, never
black. The calyx covers the entire upper surface fruit. The pedicel, like
stems and leaves, is usually hairy. Mature plants reach about 2' in height.
Venice Mallow
Hibiscus trionum originated from Europe. It is an annual, typically
growing 10 - 18" tall. Stems and petioles are usually covered with stiff
hairs. Stems generally originate from a central base, and tend to be more
spreading than erect. The showy flowers are light sulfur-yellow with a
purple or blackish center, reaching up to 1.5" in diameter. Flowering season
is from June to September. Seeds are the only source of reproduction.
PigweedAmaranthus spp.
Pigweeds are weed pests in several cropping systems. A. hybridus,
smooth pigweed was the first triazine resistant plant documented. A.
retroflexus, redroot pigweed is probably our most common one. A.
lividus, is a prostrate species with a notch in the tip of the leaf.
A.
spinosus, spiny amaranth, has sharp, strong spines on the stem.
A.
graecizans, breaks off at the ground line and being round shaped is
blown around by the wind.
Toothed Spurge
Euphorbia dentata is native to the Great Plains region. It spreads
by seed and grows under a wide range of environmental conditions. Toothed
spurge is an annual that grows up to 3' tall. Leaves are up to 3" long,
ovate to linear, coarsely toothed, mostly opposite, hairy and often dotted
with a few purplish red spots. Stems are many branched and generally curve
upwards. Both stems and leaves exude a milky latex when broken. The inconspicuous
flowers are born in late summer, followed by 3 sided, turban-shaped, 0.25",
smooth, green fruits. Seeds are rough, bumpy, oval and gray.
Barnyardgrass
Echinochloa crusgalli is an annual grass that prefers wet sites.
It is not usually a problem in well drained cultivated fields but can grow
heavily around irrigation pipe leaks and other wet spots in the field.
It is a vigorous, warm season annual grass reaching 1 - 5' in height with
bases of many stems reddish to dark purple. Leaf blades are flat, broad,
smooth, and without a ligule or auricle at the junction of sheath and blade.
Seeds are the only source of reproduction. Barnyardgrass flourishes in
warm conditions.
Field Bindweed
Convolvulus arvensis is a member of the Morning Glory family.
This creeping perennial was introduced from Europe. It reproduces by seeds
and horizontal roots. The stems are smooth, slender, slightly angled, 1-
4' long, and spread thickly over the ground or wind around erect plants
or other objects. The leaves are alternate, 1 - 2" long, with great variation
in shape. They are somewhat arrow-shaped with spreading, pointed, or blunt
lobes at the base. The flowers are bell or trumpet-shaped, white, pink,
or variegated, and about 0.75 - 1" broad. Field bindweed is a problem throughout
Wyoming. It is one of the most competitive perennial weeds. A two or three-year
food supply is stored in the extensive underground root system. This makes
it hard to kill by cultivation because roots will live as long as their
food reserve lasts. Seeds can also stay viable in the soil for up to 40
years. It is widespread throughout Wyoming from 4,000 - 8,000'.
Foxtail
Setaria spp. are native to Eurasia, but common throughout most
of North America. These plants are responsible for reductions in yield,
increased cleaning costs and expensive control measures. Flowering and
seed production occurs in July to September. A primary control method for
foxtail is the application of preemergence grass herbicides. These herbicides
provide early season control, reducing early season competition.
Knotweed
Polygonum aviculare is an early germinating member of the smartweed
family. It normally shows up around mid-March and is often mistaken for
a grass because of the long narrow cotyledons. It is an extremely variable
annual with a wiry stem. Nodes are somewhat swollen, often surrounded with
the torn remnant of a short, papery leaf sheath. Leaves are generally lance-shaped,
blue green and alternate. Inconspicuous, greenish-white flowers are borne
in the leaf axils. Knotweed thrives in dry compacted soils.
Purslane
Portulacca oleracea is a fleshy, prostate annual with smooth
reddish or flesh colored stems. Branches radiating from a central rooting
point reach lengths in excess of 12" and form dense vegetative mats. Smooth,
shiny, succulent leaves are somewhat teardrop-shaped, wider at the tip
than at the base. Five petalled yellowed flowers are borne singly in leaf
axils, and open only in sunshine. Production of numerous seeds throughout
the growing season and the ability to root again after cultivation make
this plant especially difficult to control.
Quackgrass
Elytrigia repens is an aggressive perennial grass reproducing
by seed, or spreading by a shallow mass of long, slender, branching rhizomes.
Rhizomes are usually yellowish-white, sharp-pointed and somewhat fleshy.
They are able to penetrate hard soil, tubers and roots of other plants.
Stems are erect and usually 1 - 3" tall. Leaf blades are 0.25 - 0.5" wide,
flat pointed and have small auricles at the junction of blade and sheath.
Leaf sheath and the upper surface of leaf blades may be thinly covered
with soft hairs. Spikelets are arranged in two long rows, borne flatwise
to the stem. Florets are awnless, or with short straight awns. These rhizomes
are effectively spread by tillage, increasing the scope of the population
in a field. Tillage is an effective control by depleting food reserves
and bringing rhizomes to the surface.
Russian Thistle
Salsola iberica is a member of the Goosefoot family. It was introduced
from Russia and is an annual which reproduces by seed. It is a round, bushy,
branched plant growing 1 - 3.5' high. The branches are slender, succulent
when young, and woody when mature. The leaves are alternate with the first
ones being dark green, soft, slender, and 1 - 2.5" long. These drop off
and later leaves are short, stiff, spiny, and not over 0.5" long, with
two sharp-pointed bracts at the base. The flowers are small, inconspicuous,
green-white or pink, and are usually solitary in the leaf axils. Seeds
are about 0.0625" in diameter and conical. At maturity, the plant breaks
off at the base and because of its round shape becomes an excellent tumbleweed,
scattering seeds for long distances. It is widespread over Wyoming up to
8,500'.
Sandbur
Cenchrus pauciflorus is a warm season annual grass with tufted
stems. It grows 8" - 3' tall, occasionally erect, but usually spreading
horizontally and forming dense mats. Leaf sheaths are flattened, very loose
and smooth with hairy margins. Burs are thickly set with stiff, sharp,
spreading spines. They usually contain two light brown, oval to oblong
seeds.
Shattercane
Sorghum bicolor is an annual that often becomes a nuisance in
cultivated fields. It probably developed from outcrosses of cultivated
sorghum. Therefore, it is highly variable. Seeds are the only source of
reproduction. It is a major problem because seeds are several inches deep
and keep coming up through the soil throughout the summer. Shattercane
flourishes in warm conditions and usually requires postemergence herbicides
for control.
Sunflower
Helianthus annuus is a native weed. It is an annual, 1 - 10'
tall. Stems are erect, simple to branched and rough. Leaves alternate and
are simple, rough, and are hairy. The flowers are yellow to orange-yellow
ray flowers and brown disk flowers. The flowering season is from July to
September. Seeds are the only source of reproduction.
Velvetleaf
Abutilon theophrasti is an annual, completely covered with soft
hairs, with stems erect, branched, and 2 - 7' tall. Leaves alternate are
heart shaped, pointed at the apex with 5" of more in width and attached
on slender petioles. Flowers are solitary in leaf axils with 5 petals and
numerous fused stamen that form a tube. Fruit are rounded with 9 - 15 arranged
in a disk. The seeds retain viability in soil for more than 50 years, making
eradication difficult. Flowering and seed production occurs from late June
to October.
Wild Buckwheat
Polygonum convolvulus is an annual weed with arrowhead shaped
leaves. It has trailing stems, often mistaken for field bindweed, with
leaves that are more pointed. Stems can be 8 - 40" long. Clusters of inconspicuous,
green flowers form in leaf axils or at the end of stems. Cotyledons are
long and broad with a granular bloom and rounded tips. First true leaves
are arrowhead-shaped with a rough stalk that forms a tight sheath around
the stem at the base.
Wild Proso Millet
Panicum miliaceum is an annual, reproducing by seed. Once in
the soil, wild proso millet seed can remain viable for five or more years.
Wild proso millet plants range in height from 1' in dry areas to 4 - 6'
on irrigated sites. As plants grow larger, they lodge and put down additional
roots wherever stem joints touch the ground. Plants can begin flowering
in July and continue throughout the summer. The inflorescence produced
by wild proso millet is large and bushy. Seeds mature in late August through
September. Once mature, it readily shatters when the plant is disturbed.
Wild proso millet plants produces 400 - 12,000 seeds per square foot, depending
upon the degree of plant competition. One wild proso millet plant per square
foot of dry edible beans may produce 2,100 seeds per square foot. Stems
of wild proso millet are characterized by an abundance of hairs located
at right angles to the stem.
Herbicide Matrix
| benefin | bentazone | clethodim | clopyralid + 2,4-D | dimethenamid | EPTC | ethalfluralin | glyphosate | imazethapyr | metolachlor | metribuzin | metribuzine + metolachlor | paraquat | pendimethalin | picloram | quizalofo-p-ethyl | sethoxydim | trifluralin | alachlor | 2,4-D | |
| Bindweed | X | X | ||||||||||||||||||
| Canada thistle | X | X | X | |||||||||||||||||
| Foxtails | X | X | X | X | X | X | X | X | X | X | X | X | ||||||||
| Johnsongrass | X | X | X | |||||||||||||||||
| Kochia | X | X | X | X | X | X | X | X | X | X | ||||||||||
| Lambsquarters | X | X | X | X | X | X | ||||||||||||||
| Pigweed | X | X | X | X | X | X | X | X | X | X | ||||||||||
| Sunflower | X | X | X | |||||||||||||||||
| Venice Mallow | X | |||||||||||||||||||
| Nightshade | X | X | X | X | X | X | ||||||||||||||
| Blue Mustard | X | |||||||||||||||||||
| Diffuse Knapweed | X | X | ||||||||||||||||||
| Quackgrass | X | |||||||||||||||||||
| Russian thistle | X | X | X | X | X | X | ||||||||||||||
| Cocklebur | X | |||||||||||||||||||
| All vegetation and foliage | X | X | ||||||||||||||||||
| Shattercane | X | X | X | X | X | |||||||||||||||
| Corn | X | |||||||||||||||||||
| Velvetleaf | X | X | ||||||||||||||||||
| Wild Oat | X | |||||||||||||||||||
| Yellow Nutsedge | X | |||||||||||||||||||
| Sandbur | X | X | X | |||||||||||||||||
| Proso Millet | X | |||||||||||||||||||
| Smooth Brome | X | |||||||||||||||||||
| Musk Thistle | X | |||||||||||||||||||
| Barnyard grass | X |
Data from pesticide use survey, 1997
Management:
Herbicides: