Dry Edible Beans: Other Crop Problems

| Corn | Soybeans | Forages | Cereals | Dry Edible Beans |
| Spring and Winter Canola | Other Crops | Soil Management |
| Soil Fertility and Nutrient Use | Field Scouting |
| On-Farm Stored Grain Management | Weed Control |
| Insects and Pests of Field Crops | Diseases of Field Crops | Appendices |

Pub 811: Agronomy Guide > Dry Edible Beans > Other Crop Problems

Excerpt from Agronomy Guide for Field Crops
Order OMAFRA Publication 811: Agronomy Guide for Field Crops

Insects and Diseases

Figure 5-1, Dry Edible Bean Scouting Calendar, shows insects, pests and diseases that could be causing symptoms in the field. Individual descriptions of insects, pests and diseases, scouting and management strategies can be found in Chapter 13, Insects and Pests of Field Crops, and Chapter 14, Diseases of Field Crops.

Recommended treatments to control insects, pests and diseases can be found in OMAFRA Publication 812, Field Crop Protection Guide.

Frost and Hail Damage

Both frost and hail can be devastating to a bean crop. The extent of early-season frost damage will depend upon where the plants were damaged. If the plant is damaged below the cotyledons, it will not recover. If the growing point is damaged, but the lower stem remains intact, the plant will send out new shoots from the base of the leaves or cotyledons. Wait a few days before replanting to see if these shoots appear.

When evaluating hail damage, check for bruising on the plant stem. Damage to the stem will make it more difficult for the plant to recover. It can also lead to increased stem disease. When the pods are damaged by hail, the seeds or entire pods will often rot. Dry edible beans have much more limited ability to recover from hail than soybeans.

If frost occurs close to maturity, pods that are yellow-to-brown are often sufficiently mature to escape damage. Green beans will shrivel, retain their off-green colour and increase "pick." Delaying harvest until the beans dry down sufficiently will help prevent staining and improve separation.

Bronzing

Bronzing is not caused by a living organism or pathogen but instead is the result of ozone damage to the leaf surface. A reddish-brown flecking or "bronzing" occurs on the upper leaf surface (Plate 29). Affected leaves are often the highest leaves on the plant. Bronzing often occurs shortly following an ozone event. The number of leaves affected varies, depending on exposure duration. Symptoms may be more severe on plants under moist conditions. Under dry conditions, plants are more tolerant to ozone. The amount of damage found on the plant or in an area often corresponds to air pollution alerts or heavy thunderstorms. These conditions can result in atmospheric ozone being forced down onto the crop. Ozone is also produced when lightning strikes. The higher the concentration of ozone and the longer the duration, the greater the impact on the crop. Use tolerant varieties in areas that have a history of ozone events.

Plate 29. Ozone (bronzing) injury. High levels of ozone can injure the leaves and cause bronzing of the upper leaf surface.

Seed Quality Problems

Poor seed quality reduces germination and vigour of seedlings. Mechanically damaged seed may cause bald-headed beans (beans that emerge, but have no growing point). This injury should not be confused with symptoms of seed corn maggots, which will leave the seedlings ragged in appearance. Poor-quality seed can also cause seedlings to have broken or cracked cotyledons, or hypocotyl. Damaged seedlings are more prone to diseases and insect damage. Plant only high-quality certified seed. Treat seed with a fungicide at planting to protect against seedling disease. Handle seed gently to minimize mechanical damage.