Prepared: December, 2003
For additional information and historical data about Georgia snap bean production, visit this web site.
http://www.nass.usda.gov/ga/pubs/agfacts/fnvsec.pdf
Production Regions
The southwest part of Georgia produces nearly all of the commercial snap beans in the state. More than half the Georgia snap bean acreage is in Sumter County. Other counties with significant acreage include Echols, Lee, Decatur, Tift, Mitchell, Macon, Crisp, Toombs, and Seminole. Additional production statistics can be found in the Georgia 2001 Vegetable Survey.
Cultural Practices
The large majority of snap beans grown commercially in Georgia are bush-type beans. All Georgia snap beans are directed seeded. More than 90% of the crop is irrigated. About 50% of the Georgia snap bean acreage is planted in the spring, and 50% is planted in the fall. Bush-type snap beans are usually planted one-inch deep with a plant population of approximately 170,000 plants per acre. Row width ranges from 18-36 inches, with 2-4 inches between plants in the row. Bush-type snap beans mature in 45-60 days.
Georgia snap bean acreage for processing beans has decreased substantially because the only processing plant in Georgia shut down. Snap beans for processing are now shipped to a facility in Texas.
Potential Worker Exposure
Nearly all commercial snap beans are treated with either a pre-plant incorporated or preemergent herbicide. Nearly snap beans are treated 5-6 times during the season with pesticides The grower or farm employee would typically make the applications and mix/load the pesticide. On a larger farm, the applicator could be in the field 1-2 days/week for several weeks because snap bean fields are planted sequentially. Nearly all applications are made with closed-cab equipment. Larger farms are more likely to have closed-cab equipment.
Snap beans are cultivated during the season before the plants become too big. The grower or an employee of a typical farm would cultivate beans 2-3 times. On large farms, it would take the operator 1-2 days per week (8 hours/day) to complete cultivation. Hand weeding is rare.
During the season, beans are scouted 1-2 times per week. Most farms hire professional consultants, but some farms are scouted by the owner or an employee. Scouting a large farm would take about 8 hours per week. Professional consultants could be scouting fields (beans and other vegetables) every day throughout the season.
Nearly all snap beans are irrigated with a center pivot system. It is not necessary for anyone to enter the field during the season to operate or move irrigation equipment. Sporadically, someone may have to go to the pivot for repairs or adjustments.
Commercial snap beans are all harvested by machine.
Weed control is important to insure maximum yields. Both herbicides and cultivation practices are used to control weeds. Growers typically cultivate snap beans until the plants become too large. After that time, herbicides become the primary tool for weed management.
Weed control involves the management of several grasses and broadleaf species. Particularly troublesome weeds include yellow nutsedge and larger-seeded broad leaves.
Herbicides.
Nonchemical alternatives and IPM. Growers incorporate other techniques in an IPM program for weeds, but nonchemical methods cannot replace the critical role of herbicides in bean production. Cultivation between the rows is common until the plants become too large.
Crop rotation is an important aspect of controlling some persistent weed species and problem weeds such as sicklepod, nutsedge and cocklebur.
Review pesticides recommended for weed management in the Georgia Pest Control Handbook
Insect pests that are important for commercial snap beans can be divided into two large groups, soil pests and foliar/pod pests. Soil pests, primarily lesser cornstalk borer, attack seedlings. Important foliar pests include lepidopteran larvae (e.g., corn earworm) and beetles (e.g., Mexican bean beetle). Whiteflies are also a serious pest for fall beans. Stinkbugs and corn earworm are the more important pests attacking the pods.
Fields are scouted weekly until blossom formation. The threshold for foliage feeders (Mexican bean beetle, bean leaf beetle, various caterpillars) is 25% defoliation prior to blossoming. As the pods begin to develop, close examination should be made for corn earworms, stinkbugs and other pod pests. The threshold for caterpillars is one per three feet of row or 3% or more of damaged pods.
In 2000, insects caused losses of approximately $4.4 million (damage + cost of control). Corn earworm and other lepidopteran pests caused the greatest damage ($1.6 million); followed by thrips ($1.4 million), stink bugs ($900,000), and European corn borer ($500,000). For more details, consult the Summary of Insect Losses and Cost of Control in Georgia .
Other arthropods that attack snap beans include aphids, European corn borer, thrips, cucumber beetle, weevils, tarnished plant bug, vegetable leafminer, potato leafhoppers two-spotted mites, and seed corn maggot. Any of these insects can cause substantial damage to snap beans if conditions favor insect populations, but these insects are not the usual target of foliar insecticides. Foliar applications of insecticides are applied based on scouting information. Insecticide applications targeted at other pests may also prevent these other pests from reaching damaging populations.
Insecticides. Nearly all commercial snap beans are treated with insecticides.
Nonchemical alternatives and IPM. Insecticide applications are based on scouting reports, and biological controls are included in the reports. For the major pests, insecticides are a critical component of IPM. Many growers shift production from fall to spring to avoid whitefly pressure.
Review additional insecticide recommendations in the Georgia Pest Management Handbook.
Although many different disease organisms can attack snap beans, seedling diseases and rust account for nearly all of the fungicides applied to commercial snap beans.
A number of different soil-borne fungi attack snap beans. Substantial stand losses are much more likely in fall planted beans. Pythium has been most commonly associated with stand failure of fall beans. However, Rhizoctonia and Fusarium may also cause seedling disease. Sclerotium rolfsii (white mold or southern stem blight) has been involved in the loss of stands also. Bean seedlings may be attacked from the time they first begin to germinate until they are several weeks old. They are much more susceptible in the young, tender, succulent stage.
Rhizoctonia
and Pythium cause young bean seedlings to wilt and collapse or damp-off from water-soaked rotting of the stem near the soil line. With Pythium, the stem has a more watery rot that is colorless to dark brown. The slimy outer tissue of the stem slips easily from the central core. With Rhizoctonia, the stem initially appears water-soaked, but may dry and turn brown or form reddish-brown to brick red, slightly sunken cankers on the stem. The plants may recover, but they will be stunted.Growers commonly apply fungicide at planting to control seedling diseases.
Rust
Rust (Uromyces phaseoli var. typical) attacks all above ground parts of the bean plant, but is most commonly seen on the underside of the leaves. The rust fungus is not seed-borne, but it overwinters on old bean plants. Spores produced on old bean plants are spread to new bean foliage by the wind. Early symptoms of the disease may be seen approximately five days after spores land on the leaves. A new crop of spores is produced about every 10 days. Cloudy, humid weather and an optimum temperature around 75 degrees F favor the development of rust.
The first symptoms of rust on the foliage are very small, white, slightly raised spots or pimples, which may be surrounded by a yellow halo. The white pimples later become raised, reddish-brown pustules. These rupture and release a powdery mass of spores (seed-like bodies), which give a rust, color to the fingers if rubbed across an infected leaf. As many as 2,000 individual spots may be found on a single leaf. Heavily infected leaves usually turn yellow, shrivel and fall, resulting in premature defoliation.
Most growers make several fungicide applications during the season to control rust.
Anthracnose
Anthracnose, caused by the fungus Colletotrichum lindemuthianum, is favored by cool, wet weather. It may cease to be active during hot, dry weather. It is more common in North Georgia than in other parts of the state, and occurs more commonly in home gardens where locally grown seed are used.
This fungus overwinters inside bean seed and diseased bean plants left in the field after harvest. This fungus can live in the seed as long as they remain viable. Fungus spores will survive in old bean debris under field conditions for more than two years. Once the disease is brought into a field on the seed, people and equipment can spread it by splashing rain and insects, or when the beans are wet.
The disease may show up on the leaves, stems or pods of bean plants. Dark brown to black, oval-shaped cankers with purple borders often occur on the bean stems and leaf veins. However, the most easily recognized symptom of anthracnose occurs on the pods as small, rust to reddish colored spots. This is the first evidence of the disease. These spots enlarge, turn dark brown to black and sink into the pods. A brownish, sometimes slightly raised border develops around each sunken spot, whose center may be covered with pinkish ooze during wet weather.
Growers rarely spray for anthracnose, but fungicide applications for other diseases help to control anthracnose.
Fungicides. Fungicides are critical for snap bean production in Georgia. Growers commonly apply fungicide at planting, and most growers make 3-4 foliar applications of fungicide during the season. The in-season applications are typically made on a seven-day interval until the disease is under control. The amount of fungicide applied in a season and the frequency of application can vary substantially when weather favors disease development.
Nonchemical alternatives and IPM. Growers utilize a wide range of nonchemical techniques in an IPM program to manage diseases. Fungicides are a critical element of IPM program.
Growers plant seed that is certified to be disease free. During cultivation, growers avoid throwing soil up on the plant stems. Deep plowing is also used to manage diseases. Many growers use some rotation system to reduce or eliminate disease inoculum.
Other diseases occur in commercial snap bean including nematodes, bacterial blight, and viruses. Growers rarely apply pesticides to control them.
Root-knot nematode is probably the most common nematode and causes the most damage to snap beans in Georgia. Due to the buildup of nematodes during the summer months, fall beans are more apt to be severely affected than are spring beans. Recommended bean varieties are susceptible to root-knot nematodes. If a high population of root-knot is present in the soil, beans may be stunted, produce low yields or be killed. Root-knot damage is usually more severe on light, sandy soils.
Bacterial blight, caused by the bacterium Xanthomonas phaseoli, overwinters inside bean seed and diseased bean plant debris in the soil. The bacteria survive only one year in old bean plants after the crop is harvested. Seed may introduce the disease organism into a new field. Splashing rain and contaminated equipment spread the disease organism from plant to plant.
A number of viruses, including common bean mosaic, Southern bean mosaic and yellow bean mosaic, may affect snap beans. Common bean mosaic and Southern bean mosaic may be seed transmitted. Insects vector all three virus diseases. Yellow bean mosaic is usually spread from clover fields to beans by aphids, and is found only on pole beans in North Georgia. It is usually widespread only where beans are planted after clover or adjacent to clover fields. Mosaic is considered a minor bean disease in Georgia, except in North Georgia near clover fields.
Review pesticides recommended for disease management in the Georgia Pest Management Handbook.
http://www.ent.uga.edu/pmh/
Stormy Sparks (Extension) asparks@uga.edu and
David Riley (Research) dgr@tifton.cpes.peachnet.edu, UGA Vegetable Entomologists
David Langston, UGA Vegetable Pathologist dlangsto@arches.uga.edu
Stanley Culpepper, UGA Vegetable Weed Scientist stanley@arches.uga.edu
George E. Boyhan gboyhan@arches.uga.edu
and W. Terry Kelley wtkelley@uga.edu, UGA Horticulturists
William C. Hurst, UGA Food Scientist bhurst@fst.uga.edu
The Georgia Pest Management Handbook. [Paul Guillebeau, ed.]. Published annually. Special Bulletin 28. The University of Georgia.
Crop Profile for Beans (Snap) in Florida was also a valuable resource. We thank the University of Florida for sharing information with us.Prepared by Paul Guillebeau, IPM/Pesticide Coordinator, Department of Entomology, University of Georgia, Athens GA 30602 pguillebeau@bugs.ent.uga.edu