Information On Common Bean Problems – Tips On Growing Beans

Information On Common Bean Problems – Tips On Growing Beans

Growing beans is easy as long as you provide their basic requirements. However, even in the best of situations, there may still be times when problems growing beans becomes prevalent. Knowing about common bean problems and utilizing important bean tips are the best line of defense when these issues arise.

Bean Tips for Insect Pests

Several insect pests attack beans. However, most of them can be easily removed by hand or with soapy water. If you’re having problems growing beans, you may want to check the garden for evidence of insect damage. Frequent inspection and prompt removal are important steps in order to control or alleviate the development of heavy infestations, which usually require more drastic measures, such as the use of pesticides.

Many insects overwinter in nearby shrubs, trees, and brush. Keeping the garden area free of debris can help control bean problems associated with insect pests.

Tips on Growing Beans Affected by Disease

Many types of beans are affected by disease. However, most of these bean problems can be prevented by choosing and planting disease-resistant varieties. Rotating beans at least every other year and practicing proper watering and spacing guidelines also help. Numerous types of fungus live in soil, which can wreak havoc on bean crops, especially seedlings, and result in beans not growing.

Roots may die and leaves may yellow. Plants may exhibit discoloration and poor growth. Make sure beans are planted in well-drained soil, as excessive moisture is an ideal environment for the development of fungus.

Stem anthracnose is a fungus that commonly causes bean problems in severely wet conditions. Beans may exhibit dark colored lesions or blotches. There are no remedies but with proper preventative measures, such as avoiding overhead watering, it can be avoided. Sclerotina fungus causes pods to become soft. Leaves form watery spots and stems rot. Cool, moist conditions trigger this common bean problem. Improve air circulation and discard plants.

Bean rust is another common problem caused by fungus. Affected plants develop rust-colored spots and leaves may yellow and drop. Plants should be removed and discarded. Avoid humid conditions and rotate plants.

Bacterial blights are also common in wet environments. Halo blight attacks in cool temperatures. Bean plants develop dark spots surrounded by yellowish halos. Common blight occurs in warm weather. This also causes dark spots but without the halo. Both are caused from infected seeds and spread easily in wet conditions.

Mosaic viruses are caused from herbicide use, infections, or nutrient deficiencies. Many are transmitted through pests, such as aphids, or infected seeds. Plants exhibit unusual color patches. White or gray powdery growth may signal powdery mildew, which is spread through wind and rain.

Bean Tips

Beans prefer warm weather, full sun, and well-drained soil. Growing beans from disease-tolerant seeds or plants helps minimize bean problems. Keeping the area free of debris, including post-harvest plants, is another way to alleviate problems growing beans.

Excessive heat and humidity are responsible for most pest and disease problems. Allow extra space between plants for better airflow, especially in humid areas. Keep leaves dry by avoiding overhead sprinklers to cut down on the development of fungus.

Finally, make sure to practice crop rotation in the garden at least every other year to avoid bean problems associated with soilborne agents.

Learn About Beans

How to Sow

  • Because beans are members of the legume family of plants, they can benefit from an application of a soil inoculant designed for beans and peas, prior to planting. The inoculant will enable the plants to take nitrogen from the air to use as fertilizer, which can increase crop yield and quality.
  • Sow in average soil in a sunny location after danger of frost and soil has warmed, from spring to early summer. Sow after the soil has warmed, as seeds may rot in cooler soils.
  • Coat untreated seed with an inoculant.
  • Sow in rows 24 inches apart. Sow seeds 3 inches apart and cover with 1 inch of fine soil. Firm lightly and water gently.
  • Seedlings emerge in 10-14 days depending on soil and weather conditions.
  • Keep sowing bush bean seeds every 2 weeks for a constant supply of beans.
  • Thin gradually to stand 6 inches apart when seedlings are 1-2 inches high.

Insect Pests

The western spotted cucumber beetle is one of the most potentially devastating insect pest that preys on green bean plants. This beetle is identified by its yellow-green back spotted with 12 large dots, not unlike a ladybug. Green bean seedlings are most vulnerable and may be completely devoured by the beetle, although even mature plants can be affected. Aphids are another pest that attacks green bean plants, sucking liquid from stems and leaves. Aphids also can transmit disease from one bean plant to another, which makes their control essential. Other insect pests of green beans include thrips, whiteflies, leafhoppers and Mexican bean beetles.

Comments on the Disease

Bean common mosaic necrosis virus strains were previously referred to as necrotic strains of Bean common mosaic virus but it was found that the necrotic strains were actually a distinct virus species. Thus, these strains were given the name Bean common mosaic necrosis virus. Since both Bean common mosaic virus and Bean common mosaic necrosis virus cause similar symptoms on bean varieties without the I gene, they are distinguished by their reaction on I gene-containing varieties or other tests, such as ELISA or PCR-DNA detection methods.

Bean common mosaic necrosis virus is considered to be endemic to Africa. It has been spread throughout the world in infected seeds of non-I gene varieties, and it has been introduced into Idaho, Michigan and New York. In California, Bean common mosaic necrosis virus was detected in a single bean field in 1996, and it has not been detected since.

Bean common mosaic virus and Bean common mosaic necrosis virus are members of the potyvirus family of plant viruses, and both are related to Bean yellow mosaic virus (BYMV) and Clover yellow vein virus (ClYVV), two other potyviruses that infect common bean in California. Bean common mosaic virus and Bean common mosaic necrosis virus are differentiated from Bean yellow mosaic virus and Clover yellow vein virus based on symptoms, host range, seed transmissibility, antibody tests (e.g., ELISA) or PCR-DNA detection methods. However, because the symptoms of these viruses can overlap in certain bean varieties and mixed infections are not common, antibody tests (ELISA) are the most reliable method for identifying these viruses.

Common Pests and Diseases

Lots of insects and animals love beans as much as you do, including:

  • Mexican bean beetles: These pests will eat the flowers, the beans, and especially the leaves.
  • Spider mites: These tiny pests pierce the leaf surface and suck the sap, often causing leaves to die.
  • Japanese beetles and aphids may also attack bean plants.
  • Bean leaf beetles can girdle the stems near the soil line and chew holes in the plant's leaves.
  • Deer and groundhogs will eat entire bean plants, and fencing is necessary to stop them.

Fungal diseases, such as Alternaria leaf spot, can be a problem in damp conditions. Other diseases, like Anthracnose, bacterial blight, white mold, bean rust, and mosaic virus can also affect bean plants. Help prevent diseases by keeping the vines dry don't overcrowd the plants, and provide plenty of good air circulation. You can also look for plant varieties that are bred for disease-resistance.

Population Size

For Viable Seeds: 1 plant
For Variety Maintenance: 5–10 plants
For Genetic Preservation: 20 plants

For more on seed saving, see our Seed Saving Guide.

Reprinted with permission from The Seed Garden, by Micaela Colley & Jared Zystro, edited by Lee Buttala & Shanyn Siegel and published by Seed Savers Exchange, 2015. Buy this book from our store: The Seed Garden.

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