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Dry Bean Production Guide (continued)

A-1133, July 1997

Relative Herbicide Effectiveness on Weeds and Persistence in Soil (continued)

Soil
Applied
Herbicides		 B
u
c
k
w
h
e
a
t,

W
i
l
d

 C
o
c
k
l
e
b
u
r,

C
o
m
m
o
n

 F
l
i
x
w
e
e
d		 K
o
c
h
i
a		 L
a
m
b
s
q
u
a
r
t
e
r
s,

C
o
m
m
o
n

 L
a
n
c
e
l
e
a
f

S
a
g
e

 M
a
l
l
o
w,

V
e
n
i
c
e

 M
a
r
s
h
e
l
d
e
r		 M
u
s
t
a
r
d,

W
i
l
d

 N
i
g
h
t
s
h
a
d
e,

B
l
a
c
k

 P
i
g
w
e
e
d,

R
e
d
r
o
o
t

 P
r
i
c
k
l
y

L
e
t
t
u
c
e

 R
a
g
w
e
e
d,

C
o
m
m
o
n

 S
m
a
r
t
w
e
e
d,

A
n
n
u
a
l

 S
u
n
f
l
o
w
e
r		 T
h
i
s
t
l
e,

R
u
s
s
i
a
n

 T
h
i
s
t
l
e,

C
a
n
a
d
a
Dual (PPI) P N — F F N N — P G G-E P P-F P N F N
Dual (PRE) P N — P-F P-F N N — P G F-G P P-F P N P-F N
Eptam (PPI) F P P F F N N P P F-G G P F P N P N
Frontier (PPI) P N — F F N — — P-F G-E E — P P N P-F N
Frontier (PRE) P N — P-F F N — — P-F G G-E — P P N P N
Lasso/generics (PPI) P N — F F N N — P G G-E P P P N F N
Lasso/generics (PRE) P N — P-F P-F N N — P G F-G P P P N P-F N
Prowl/Pentagon (PPI) P-F N P G-E E N F-G N N P E N F P N G N
Prowl/Pentagon (PRE) P N P F-G G N F — N N G N P P N F-G N
Sonalan (PPI) P-F P P G-E E N F-G N N F E P P P N G-E N
Trifluralin (PPI) P-F N P G-E G-E N F-G N N P E N P P N G N

PPI = Preplant Incorporated, PRE = Preemergence
1Except where resistant populations have developed.

 

Soil
Applied
Herbicides		 B
a
r
n
y
a
r
d
g
r
a
s
s		 F
i
e
l
d

S
a
n
d
b
u
r

 F
o
x
t
a
i
l,

G
r
e
e
n

 F
o
x
t
a
i
l,

Y
e
l
l
o
w

 Q
u
a
c
k
g
r
a
s
s		 V
o
l
u
n
t
e
e
r

C
e
r
e
a
l
s

 W
i
l
d

O
a
t

 W
i
l
d

P
r
o
s
o

M
i
l
l
e
t

 H
e
r
b
i
c
i
d
e

P
e
r
s
i
s
t
e
n
c
e
Assure II E E E G-E G-E E E1 E N
Basagran N N N N N N N N N
Gramoxone Extra G G G G P F-G G F-G N
Pursuit G P-F G F-G N G F P-F O
Roundup Ultra E E E E E E G-E E N
Ultima 160 E E E E G E G-E1 E N

1Herbicides will not control resistant biotypes.

Soil
Applied
Herbicides		 B
u
c
k
w
h
e
a
t,

W
i
l
d

 C
o
c
k
l
e
b
u
r,

C
o
m
m
o
n

 F
l
i
x
w
e
e
d		 K
o
c
h
i
a		 L
a
m
b
s
q
u
a
r
t
e
r
s,

C
o
m
m
o
n

 L
a
n
c
e
l
e
a
f

S
a
g
e

 M
a
l
l
o
w,

V
e
n
i
c
e

 M
a
r
s
h
e
l
d
e
r		 M
u
s
t
a
r
d,

W
i
l
d

 N
i
g
h
t
s
h
a
d
e,

B
l
a
c
k

 P
i
g
w
e
e
d,

R
e
d
r
o
o
t

 P
r
i
c
k
l
y

L
e
t
t
u
c
e

 R
a
g
w
e
e
d,

C
o
m
m
o
n

 S
m
a
r
t
w
e
e
d,

A
n
n
u
a
l

 S
u
n
f
l
o
w
e
r		 T
h
i
s
t
l
e,

R
u
s
s
i
a
n

 T
h
i
s
t
l
e,

C
a
n
a
d
a
Assure II N N N N N N N N N N N N N N N N N
Basagran F-G G-E E F-G F-G P E G-E E F F E G E E F F-G
Gramoxone Extra F F-G G G-E E E G G E G-E E E G-E E E E P
Pursuit F-G G E E2 F-G E P E E E E E P-F G G-E G-E N
Roundup Ultra P-F G-E G-E F-E G-E E E G-E G-E F-G G-E E E E G F-G G
Ultima 160 N N N N N N N N N N N N N N N N N

1Herbicides will not control resistant biotypes.




Weed Seedling Identification

Wild Buckwheat (46KB color photo)
Buffalo Bur (38KB color photo)
Cocklebur (56KB color photo)
Wild Mustard (28KB color photo)
Kochia (85KB color photo)
Pennsylvania Smartweed (46KB color photo)
Common Ragweed (43KB color photo)
Black Nightshade (82KB color photo)
Pigweed (40KB color photo)
Velvetleaf (65KB color photo)
Barnyard Grass (57KB color photo)
Large Crabgrass (80KB color photo)
Wild Sunflower (53KB color photo)		 Russian Thistle (70KB color photo)
Giant Ragweed (34KB color photo)
Giant Foxtail (22KB color photo)
Green Foxtail (28KB color photo)
Wild Oat (26KB color photo)
Yellow Foxtail (26KB color photo)
Wild Proso Millet (36KB color photo)
Field Bindweed (33KB color photo)
Yellow Nutsedge (19KB color photo)
Fall Panicum (16KB color photo)
Jerusalem Artichoke (47KB color photo)
Hedge Bindweed (32KB color photo)
Perennial Sowthistle (39KB color photo)




Disease Identification and Management

Principles of Disease Management

Fungi, bacteria and viruses cause important diseases of bean. Diseases reduce yield and quality of harvested bean and add to production costs. Diseases can be difficult to control, but management practices can reduce their impact. Management practices can be grouped into three principles.

  1. Keep Pathogens and Beans Separated. Observe geographic separation. The soybean cyst nematode, which can also attack dry beans, occurs in central Minnesota. Do not bring dry beans or soybeans from affected areas into bean growing areas.

    Use high quality seed. Certified seed must meet certain quality standards with regard to seed borne diseases. No seed is disease free, but certified seed produced under carefully controlled conditions in the West or in the Northarvest growing area is the best way to minimize the introduction of bean pathogens on the seed.

    Use crop rotation. A rotation of three or four years is desirable, and longer rotations may be required if disease is severe in a field. Avoid planting next to last year's bean field if diseases were severe.

    Avoid cultivating plants when wet. This helps prevent spread of pathogens, especially bacterial pathogens.
  1. Attack the Pathogen. Bury bean crop refuse by deep plowing. Foliar pathogens do not survive well in the soil.

    Scout fields for disease. Use early detection of disease to determine when to use a fungicide. Records of disease and weed problems help in planning crop rotations.

    Foliar fungicides help suppress disease development. Most fungicides protect against infection but do not cure established infections. They should be used to prevent infection or at the first sign of disease to prevent additional infections.

    Use seed treatments to reduce early season damping off. Some seed treatments, including streptomycin, captan and PCNB, may severely reduce the survival of Rhizobium nitrogen fixing bacteria. These seed treatments may not be compatible with inoculation of the seed. Some new strains of bacteria are less affected by seed treatment products. Another option is to use an in-furrow inoculant.
  1. Strengthen the Bean Plant. Plant disease-resistant varieties. Provide adequate soil fertility, according to soil tests, and adequate trace minerals such as zinc. Avoid excess nitrogen levels that stimulate lush plant growth. Control weeds. Plant in wide rows to help foliage dry quickly, reducing disease potential. Use deep shanking near the planter row if there is a hardpan. Handle seed carefully. Hill beans to stimulate lateral root development if root rot is present, but avoid root pruning by close cultivation.



White Mold

Visual Aid (40KB color photo)

White mold is a sporadic disease which is most serious when wet weather occurs at flowering. When the surface soil is wet, the hard black survival structures, called sclerotia, germinate to form tiny mushroom-like bodies that liberate millions of wind-borne spores. These spores colonize dead bean tissue, particularly the dead blossoms, then the fungus invades green tissues, causing a watery soft rot. In wet weather infected tissues are tan colored and soft, with tufts of fluffy white fungal growth. These tufts of "white mold" develop into hard black bodies, the sclerotia, some of which survive many years in the soil. Leaves of infected plants turn yellow and wilt. In dry weather affected stems have a bleached or whitish appearance. Infected seed is discolored, chalky and lightweight.

White mold is favored by rainy weather before and at flowering, moderate temperatures and long periods of high humidity, and keeping the lower canopy of plants wet more or less continuously for up to two days.

Management. Crop rotation is important but of only modest value in areas of intensive bean production, since the spores may blow in from nearby infested fields. Benlate and Topsin M are registered for white mold control. They are more effective when applied before infection occurs. Early bloom is the best time to apply these fungicides. Good canopy penetration is required so that the blossoms and lower stems are covered with fungicide. The most economical method is band application using drop nozzles, high pressure and high gallonage. High pressure broadcast application is not quite as effective but can also be used when band application is impractical. Aerial application using 7�-10 gpa also can be effective. Widely spaced rows may help enhance drying in the canopy. Upright varieties dry more quickly and may escape severe infection in years with conditions that are marginal for white mold development. Deep plow infected bean crop refuse and clean harvest equipment between fields. Avoid short rotations or rotation with other susceptible crops, especially beans, sunflower, canola, lentils and soybeans.



Rust

Visual Aid (44KB color photo)

Rust is a very common disease and can lead to partial or complete crop failure. The rust fungus forms pustules on the leaves and other plant parts. These pustules release a rusty-colored powder, the summer spores, that are responsible for disease spread. These spores may be wind blown for many miles. Infection occurs when the temperatures are moderate (60-75F) and the plant parts stay wet for 10-15 hours. The infection cycle repeats every 10-14 days. Pustules break through the leaf surface, opening up the interior of the plant to desiccation. Large numbers of pustules result in plants drying out and dying even when there is good soil moisture.

Late in the season the rusty powder in the pustules is replaced with a black powder, the winter spores. Both summer and winter spores overwinter on bean debris and can lead to infections next spring. The winter spores produce an inconspicuous sexual stage that can lead to the development of new rust races. The sexual stage often occurs on volunteer beans. The number of races has been increasing in recent years, and varieties and classes of beans previously showing field resistance may no longer be field resistant.

Management. Destroy volunteer bean plants in last year's bean fields to reduce early season rust pressure and to retard the development of new rust races. Monitor fields carefully for rust, particularly classes of beans known to be susceptible, such as pintos, pinks, small reds, and great northerns. Other classes, however, may be attacked by new races, so all beans should be monitored carefully. Protectant fungicides should be used as soon as there are two pustules per leaf on susceptible varieties or there are a couple of "hot spots" in the field. Once rust is present in an area, all susceptible varieties should be sprayed, even in fields where rust has not been detected yet. No fungicide is needed once the lower pods of pinto beans begin striping. Fungicides currently registered for rust control include chlorothalonil and maneb. Plow down infected crop refuse shortly after harvest. Use crop rotation and avoid planting next to a field that was severely diseased last year.



Root Rots

Visual Aid (37KB color photo)

Several fungi cause root rots, including Fusarium, Rhizoctonia and Pythium. Fusarium is the most common, particularly in drought years. Fusarium produces a dry rot with indistinct brown lesions, and occasionally a more general browning of the roots. Rhizoctonia is most common in warm moist soils when beans are grown in rotation with sugar-beets or soybeans. Rhizoctonia causes more distinct lesions that are chocolate-colored to dark red. Pythium develops in wet soils, causing a soft brown rot that results in a hollow tap root. Plants with root rot may be stunted with yellowed leaves. Infected plants form fewer pods and smaller seeds.

Management. Extend crop rotations beyond four years. Root rot is less severe following wheat. If Rhizoctonia is present, avoid sugarbeets in close rotation. Some varieties are tolerant. Plant high-quality seed. Deep shanking adjacent to the planter row can reduce damage. Cultivating soil to hill up around stems can encourage lateral root development, but close cultivation may trim shallow roots.



Bacterial Blights

Bacterial blights cause leaf and pod lesions, defoliation and shrunken discolored seed. All are seed borne, can be spread by splashing rain and their spread is aided by storms that cause small wounds in the leaves, allowing entry of bacteria into the leaf. All blight pathogens survive on bean crop refuse. The brown spot pathogen also survives on weeds. Common blight is the most prevalent of the bacterial blights but halo blight can be devastating.

Common blight lesions on leaves begin as small greasy green spots which later develop into large brown areas surrounded by a narrow lemon-yellow border. Veins near the lesions are darkened. Infected pods develop greasy green lesions with brick red margins. Pod lesions exude a yellow ooze in wet weather. Seeds may be shriveled and discolored.

Visual Aid (44KB color photo)

Halo blight first appears as small water soaked or greasy green spots. These spots develop into small dead spots. Nearby veins may be darkened. During cool weather the lesions are surrounded by light green halos up to � inch in diameter. Pod lesions are similar to those of common blight except that they exude a creamy ooze in wet weather. Occasionally halo blight infections may become systemic with stunted, yellow and malformed leaves. Plants also may be stunted.

Visual Aid (54KB color photo)

Brown spot first appears as small water soaked spots. These spots remain small, turn a reddish brown and are surrounded by a narrow light-green halo. Nearby veins may be darkened. Pod lesions are similar to those produced by halo blight.

Management. Disease management begins with prevention. Plant high quality seed which has been tested for low numbers of bacteria. Plow down old bean fields to bury bean crop refuse and use a three- or four-year crop rotation. Treat seed to suppress bacteria on the seed surface. Streptomycin does not control bacteria that are borne internally in the seed. Avoid cultivation when plants are wet. Copper fungicides are of little value for bacterial blight suppression.



Alternaria Blight

Visual Aid (30KB color photo)

This is a sporadic disease that may cause serious losses in some years. Irregular brown spreading lesions develop, often with light tan to whitish centers. The outer margin of the lesion usually is dark purplish to black. Lesions may be surrounded by a light yellow zone. After moist periods, the undersides of lesions are covered with black spores that give the area a dark gray appearance.

Management. No effective control is known. The pathogen enters bean leaves and stems through wounds. Alternaria is most severe after hailstorms and other events that cause wounding.



Damping Off

Severely infected plants die shortly after germination or emergence. Damping off also may be suspected when there are gaps in a row where plants have not emerged or if plants wilt shortly after emergence.

Management. Plant good quality seed. Cracks in the seed coat permit soil borne pathogens to enter. Poor quality, weathered seed may rot in the soil before germination. Treat seed with a fungicide.

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A-1133, July 1997

 

County Commissions, North Dakota State University and U.S. Department of Agriculture cooperating. Duane Hauck, Director, Fargo, North Dakota. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. We offer our programs and facilities to all persons regardless of race, color, national origin, religion, gender, disability, age, veteran's status or sexual orientation; and are an equal opportunity institution. This publication will be made available in alternative formats for people with disabilities upon request, 701 231-7881.