Cereal: 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 > Cereals > Other Crop Problems

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

Table of Contents

• Insects and Diseases
  • Figure 4-6, Cereal Crops Scouting Calendar
• Winterkill
• Frost Heaving
• Ice
• Cold Injury

Insects and Diseases

Figure 4-6, Cereal Crops Scouting Calendar, shows insects and diseases that could be causing the symptoms in the field.

Text Explanation for Figure 4-6 Cereal Crops Scouting Calendar

Individual descriptions of insects 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.

Winterkill

Winter cereals can be destroyed during the winter and early spring period by frost heaving, ice, low temperatures and snow mould. Varieties differ in their ability to withstand these different winter stresses. This explains the regional adaptation of some varieties that may not perform well across the province.

Select varieties to address the winterkill concerns of your area. Varieties grown in the Ottawa Valley need ice tolerance; those grown in the Lake Huron snow belt need snow-mould tolerance, while those grown in the heavy clays of Essex, Lambton and the Niagara peninsula need resistance to frost heaving.

Frost Heaving

The freeze/thaw cycles of early spring are one of the main reasons for winterkill in Ontario. As frost goes into the ground, it works under the crown and "lifts" the plant up Plate 28. If these freeze/thaw cycles are repeated enough times, the plant is ejected or "jacked" out of the soil. Roots are broken and left exposed above the soil, causing death of the plant due to desiccation. This process is referred to as frost heaving.

Plate 28. Frost heaving of winter wheat is caused by freeze/thaw cycles of early spring, lifting up the crown.

Deep-seeded wheat is not more resistant to frost-heaving injury. The primary root system does not anchor the plant in the soil. The secondary root system anchors the wheat plant in the soil, protecting against frost-heaving injury. The secondary root system of the wheat plant cannot develop deeper in the soil than the depth of the seed Figure 4-1, Days to Emergence at Various Seeding Depths. When wheat is seeded deep, the plant develops the crown and secondary root system at about 2 cm (3/4 in.) deep, as the crown develops in response to light. Regardless of planting depth, the secondary roots will not develop below 2 cm (3/4 in.). To maximize resistance to frost heaving, wheat plants need an extensive secondary root system developed as deep as possible.

Ice

When a rapid snow melt or winter rain is followed by below-freezing temperatures, ice can form as a thick sheet across ponded areas. Even when the water is able to drain away below the ice sheet, the ice itself may prevent oxygen from getting to the plants and the wheat will suffocate and die below the ice.

Surface and subsurface drainage can help reduce the ponding, which leads to this problem. Should an ice sheet form (for example, during January and February), dormant wheat will only survive for approximately 2 weeks. Break the ice surface to allow gas exchange and to keep the wheat alive.

Cold Injury

Wheat will survive extremely cold temperatures before plant death occurs. Plants that have "hardened off" (gone dormant) can survive temperatures down to -24°C. Snow cover acts to insulate the crop from extremely cold temperatures, and even 7.5 cm (3 in.) of snow is sufficient to protect the crop from colder temperatures. Leaf tissue on plants that have not hardened off will withstand -9°C, making late spring frosts of little consequence. There was only 1 year in the last century when cold temperatures in Ontario destroyed the wheat crop.

While the wheat crop survives cold temperatures well, cold injury can reduce vigour and final yield.