Dry Bean Production Guide

Anthracnose is a potentially serious disease, but it is not common in the Northarvest area. Linear or angular dark, brick-red to purplish-brown to black lesions or slightly sunken cankers appear on veins on the lower leaf surface. Older lesions become darker, extend to the upper leaf surface and proceed along the veins. Severe infection may cause leaf tip and edge burning or death of the entire leaf and growing point. Pod lesions are sunken, circular, tan to rust-colored with a raised margin surrounded by a thin zone of reddish tissue. Dark granular masses of tan spores develop on the surface of pod lesions.

Management. Many varieties have resistance to certain races of the anthracnose pathogen. Plant seed tested to be free of the pathogen. Use tillage to bury crop refuse after harvest. Use crop rotation. Do not cultivate fields when plants are wet. Benlate, chlorothalonil and maneb are registered for anthracnose control.

Bean Common Mosaic

Bean common mosaic virus-infected plants are often stunted and spindly. Infected leaves have irregular areas of yellowish tissues intermixed with areas of green. Leaves may be puckered, twisted and elongated. Few pods are set and seeds are off-color and small. Plants are seldom killed and yield loss depends on time of infection. Plants with the I gene for resistance to certain common virus strains can be killed if infected when temperatures are high. This reaction is called "black root." Certain other genes for resistance may provide resistance to many or to all strains of the virus.

The disease is spread by infected seed, aphids and by plant sap contaminating wounds.

Management. Use high quality, virus-tested seed. Many varieties have resistance to certain strains of the virus.

Fusarium Yellows

Initial symptoms are yellowing and wilting of lower foliage. Plants become stunted and leaf margins die. Severely infected plants wilt permanently, lose their leaves and die. Vascular (water-conducting) tissues are discolored. The Fusarium pathogen is soil borne and penetrates the roots directly or through wounds.

Management. Use crop rotation, plant high vigor seed and use a fungicidal seed treatment. Cultivate so as to promote good root growth.

Fungicides


			Disease Control³

Chemical	Application¹	Dosage²	Rust	Halo Blight	White Mold	Remarks

Benomyl
Benlate, 50%	Spray or fungigation	2 lb/A - 1 application 1.5-2 lb/A - 2 applications	(P-F)	No	G-E	Use 2 sprays of benomyl for white mold one at early bloom and one at peak bloom (usually 7-10 days after early bloom). A single band application of benomyl may be used if applied at 10-20% bloom. Complete coverage of all parts of plant is essential for control of white mold. Do not apply benomyl within 14 days of harvest.

Chlorothalonil
Bravo 500 or Ensign, 40.4%	Spray or fungigation	2-3 pt/A	E	No	No	Do not apply chlorothalonil within 14 days of harvest. See Circular PP-576, Dry Edible Bean Diseases. Carefully monitor fields for disease.
Evade, 40.4%	Spray or fungigation	2 1/4 pt/A	E	No	No
Bravo 720 or Echo 720, or Ensign 720, or Terranil 6L 54%	Spray or fungigation	1.38-2 pt/A	E	No	No	Ensign registered for navy, pinto and kidney beans only (not pink, black turtle, small red, great northern, etc.)
Bravo Ultrex DG, 82.5%	Spray or fungigation	1.25-1.8 lb/A	E	No	No
Bravo Zn, 40.4%	Spray or fungigation	2-3 pt/A	E	No	No	Bravo Zn also contains zinc.
Terranil 90 DF WSP, 90%	Spray or fungigation	0.5-0.67 packet/A	E	No	No

Copper
Basicop, WP, 53%	Spray	4 lbs/A	(F)	P	No
Champion WP, 77%	Spray or fungigation	1-3 lb/A	(F)	P	No
Champ Formula 2, Flowable, 37.5%	Spray or fungigation	0.66-2 pt/A	(F)	P	No
Kocide 101, 77%	Spray or fungigation	1-3 lb/A	(F)	P	No
Kocide 2000, 53.8%	Spray or fungigation	0.75-2.25 lb/A	(F)	P	No
Kocide DF, 61.4%	Spray or fungigation	1-3 lb/A	(F)	P	No
Kocide LF, 23%	Spray or fungigation	1.33-4 pt/A	(F)	P	No

Maneb
Maneb 80, 80%	Spray or fungigation	1.5-2 lb/A	E	No	—	Do not apply within 30 days of harvest. Do not exceed 9.6 lb ai/A per season of total maneb products (12 lb/A of Maneb 80 or 12.8 lb/A of Maneb 75; 9.6 qt/A of Manex).
Maneb 75 DF, 75%	Spray or fungigation	1.5-2 lb/A	E	No	—
Manex, 37%	Spray or fungigation	1.2-1.6 qt/A	E	No	—

Sulfur
Thiolux, 80%	Spray	3-10 lb/A	G-E	No	No

Thiophanate-methyl
Topsin M WSB, 70%	Spray or fungigation	1-1.5 lb/A - 2 applications 1.5-2 lb/A - 1 application	(P-F)	No	G-E	Use 2 sprays of thiophanate methyl for white mold, one at early bloom and one at peak bloom (usually 7-10 days after early bloom). The first application of thiophanate methyl should be applied at 10-30% bloom (when 10-30% of the plants have one open blossom); a single application of thiophanate methyl can be used, if applied at 50-70% bloom. Complete coverage of all parts of plant is essential for control of white mold. Do not apply thiophanate methyl within 14 days of harvest.

Iprodione
Rovral, 50% or Rovral 4 Flowable, 41.6%	Ground spray or fungigation	1.5-2.0 lb/A 1.5-2.0 pt/A	(F)	No	G-E	Apply at first bloom (10% of plants with 1 open blossom) and again at peak bloom, if needed. Do not apply after full bloom. Use 50-100 psi and 3 nozzles, 1 over the row and one on each side. If pH of spray water exceeds 7.0, buffer it to pH 5.0-7.0.

¹Spray = ground or aerial, Fungigation = application through sprinkler irrigation system. ²Dosage = Amount of formulated product to apply. ³P = Poor; F = Fair; G = Good; E = Excellent; ( ) = Not registered for disease; No = No control.

Non-Parasitic Disorders

Baldhead

Seedlings have no growing point. Cotyledons may or may not be attached; often they are broken. A few weak stems may develop from the axils of the cotyledons. Roots may be damaged and grow poorly. The problem is caused by mechanically damaged seed. Damage may be more severe on navy than on pinto beans.

Management. Purchase high quality seed. Seed producers should thrash full windrows, harvest when pods are limber and use low cylinder speeds. Carefully handle seed during conditioning and shipping.

Bronzing

Upper leaf surfaces are covered with small golden-brown spots which makes the leaf appear bronze in color. Bronzing is caused by ozone from industrial or urban pollution or meteorological phenomena.

Chimera

Genetic abnormalities may occur in plants, resulting in variegated leaves with patches of green, yellow and/or white tissue. Some branches or the entire plant may be affected. Pods also may be affected. Cool temperatures (below 61F) for long periods during germination may increase the frequency of leaf variegations.

Sunscald

Small brown patches appear between the main veins. These expand, often leaving large areas of dead tissue between apparently sound green veins. Sunscald is most liable to occur when warm, sunny and windy weather follows cool, cloudy and humid weather.

Insect Management in Dry Beans

In general, insects have not been a major production problem for dry beans in the region. However, the potential does exist each year for certain insects to cause injury. The most important are seedcorn maggot, potato leafhopper, cutworm, and green clover worm. Some insects, such as the European corn borer, can be found in dry bean fields, but information on field scouting and possible treatment thresholds is unavailable.

Estimating Damage

In dry beans, insect field scouting to assess insect populations is based on either the number of insects per foot of row, insects per trifoliate leaf, or the level of defoliation.

Insects per foot of row is determined by shaking plants over the inter-row space, on which a strip of cloth has been laid. Count the total number of insect pests per foot of row that fall on the cloth.

Insects per trifoliate is determined by selecting leaves and examining the under surface. It is recommended that 35 leaves in each of three to five locations per field be examined.

Percent defoliation is determined by estimating the amount of leaf loss based on visual inspection of randomly selected plants.

The growth stage of the dry bean plant is important. Under most conditions, moderate defoliation early in the season has little effect on final bean yield. As plants reach the flowering and pod filling stages,defoliation poses a greater threat to yield. For example, research indicates that the soybean plant (similar to dry beans) can sustain a 35 percent leaf loss prior to the pre-bloom period. From pod-set to maturity, the plant can tolerate only a 20 percent defoliation level.

Potato Leafhopper

The adult is wedge shaped and pale green in color. Adults are very active, jumping or flying when disturbed. Nymphs are wingless. Both adults and nymphs will run backward or sideways rapidly. Large numbers of adults may appear early in the season. Nymphs usually complete their growth on the leaves near where they hatched, feeding on the underside of the leaf.

Damage by leafhoppers is referred to as hopper-burn. Foliage becomes dwarfed, crinkled, and curled. Small triangular brown areas appear at the tips of leaves, gradually spreading around the entire leaf margin.

The threshold for basing spray decisions is when an average of one leafhopper nymph per trifoliate leaf is found. The nymphs are sampled by selecting leaves and counting the number present. Sample for the presence of adult leafhoppers by using a sweep net. Do not let infestations and damage progress to the point that yellowing of foliage is easily detected.

Aphids

The bean aphid has not been a major pest in North Dakota, though it can be found. It is nearly black in color and 1/8 inch long. They feed along stems and the underside of leaves. Infestations may result in a build-up of honeydew on leaf surfaces, promoting the growth of a black "sooty" fungus.

Armyworms

Armyworms are greenish-brown with longitudinal stripes. They are inactive during the day, resting under plant trash, clumps of grass or lodged plants. They feed at night by crawling up on plants and consuming foliage.

The armyworm moths migrate from southern states in late spring and early summer. The moths prefer to lay their eggs in moist, shady areas, usually where grasses have lodged. Armyworms are more of a problem in small grains and corn. Damage to dry beans can occur when their usual host plants become depleted or are unavailable.

Control of armyworms is recommended when 25 to 30% of the foliage is destroyed or if significant injury to pods is evident.

Bean Leaf Beetle

This beetle can vary in color from yellow to reddish brown and may have three to four black spots with a black border on the wing covers. Adults emerge from overwintering, moving into bean fields as the seedlings emerge. The white larvae develop in the soil, feeding on the roots and nodules. New adults emerging in July feed on foliage and pods. The injury to pods results in secondary infections by fungi and bacteria, causing rotting and discoloration.

Due to low incidence of this insect in North Dakota, no local control guidelines have been developed. Entomologists at the University of Missouri suggest treatment when 40 to 70% of the bean plants show feeding injury on one or more of the pods per plant.

Cutworms

Most damage by cutworms occurs when bean plants are in the early stage of development. Damage consists of young plants being chewed off slightly below or at ground level. Some cutworm feeding injury may occur on foliage. Cutworms primarily feed at night. During the day, they rest in the upper 2 inches of soil at the base of the plants. When checking bean fields for cutworms during the day, dig down into soil an inch or two around recently damaged plants; there you can find the gray to gray-brown larva.

Treatment is warranted when one cutworm or more is found per 3 feet of row and the larvae are small (<� inch long).

Green Clover Worm

Populations of this insect have been negligible in North Dakota and little treatment for control has been required. The caterpillar is green with two narrow white stripes down the side. When mature, the worms are 1� inches long. These caterpillars have only three pairs of fleshy prolegs on the abdomen, plus the pair on the back tip. When moving, the worms move by arching the body. Young worms scrape leaf tissue creating a transparent skin, or "window," on the leaf surface. Older clover worms eat holes in the leaves.

Control of clover worms is normally not warranted until 25 to 30% of the foliage is destroyed. This usually requires an average infestation of 10 to 15 larvae per row foot.

Grasshoppers

In the northern plains, grasshopper egg hatch normally begins in late April to early May. Most grasshoppers emerge from eggs deposited in uncultivated ground. Bean growers should expect to find grasshoppers feeding first along bean field margins adjacent to non-crop sites where the nymphs are hatching. Later infestations may develop when grasshopper adults migrate from harvested small grain fields. Grasshoppers will attack leaves and pods, creating holes. Due to these migrations, bean fields become sites for significant egg laying.

Grasshopper control is advised whenever 50 or more small nymphs per square yard can be found in adjacent, non-crop areas, or when 30 or more nymphs per square yard can be found within the field. When 20 or more adults per square yard are found in field margins or 8 to 14 adults per square yard are occurring in the crop, treatment would be justified. Defoliation levels may also be estimated to determine the need for treatment.

Seedcorn Maggot

Seedcorn maggot attack bean seed, preventing sprouting or weakening the seedlings. The yellowish white maggot is found burrowing in the seed or emerging stem. The adult flies emerge in spring when soil temperatures reach 50^o. They deposit eggs in soil where there is abundant organic matter and decaying crop residue, or on the seed or seedling. Seed corn maggots are usually most severe in wet, cold seasons and on high organic matter soils.

When conditions are wet and cool, or when planting into high crop residue conditions, seed treatments will provide the best defense against injury.

Other printed resources available through NDSU Extension Service

Band and Directed Spraying

Band application is applying a chemical in parallel bands, leaving the area between bands free of chemical. This reduces the area sprayed and substantially reduces the herbicide applied. Usually, the weeds between the rows are controlled with cultivation.

Directed spraying is application of a pesticide to a specific area such as a plant canopy, a row, or at the base of the plants.

Several nozzle configurations are often used when foliage penetration or row crop height present a problem. Two- and three-nozzle configurations with drop nozzles between the rows usually give better bottom leaf coverage than a single nozzle. This can be important with many fungicides.

Dry Bean Production Guide (continued)

Anthracnose