Primary symptoms
Plants flattened. If lodging before flowering, then plants may recover and grow upwards.
Root or stalk lodging? Confirm the type of lodging you have by checking the charts below.
Summary
Maize is often affected by lodging, either of the root or stalk. A plant is said to be root lodged if the lower stalk forms an angle of 45o or less with the soil surface. It is stalk lodged if the stalk is broken below the ear and the broken portion forms an angle of 45o or less with the soil. Root lodging and stalk lodging are often poorly correlated; root lodging tends to be associated with environmental factors such as heavy rains coinciding with wind or management factors like high densities or poor plant distribution, while stalk breakage is often closely related to genetic characteristics such as disease and insect resistance, prolificacy, and senescence patterns.
The effect of lodging on yield depends on when it occurs and whether the ears remained in contact with the soil long enough for rotting or germination to occur. Economic loss from lodging also depends on the harvesting method used in the region. If harvest is by machine, many lodged plants will not be harvested. If the farmer harvests by hand, lodging will increase the time required and labor costs.
Root lodging
| Causes of lodging (principally root lodging) | Additional evidence required |
|---|---|
| The variety is susceptible to lodging due to plant type. | Observe other fields in the area with different varieties. Examine the plant height and ear placement. If the ear height is above 60% of the plant height when growing under good conditions and the plant height is over 2 m, the variety may be susceptible. |
| Heavy rains and wind after stem elongation. | Review climatic data, talk to farmers about winds and rain. |
| Lodging caused when the farmer knocked plants over or cut roots while cultivating. | See if lodging occurs in specific areas. Ask the farmer about cultivation. |
| Limited rooting depth because of shallow soils, hardpan, acid soils. | Measure soil factors. |
Stalk lodging
| Causes of lodging (principally stalk lodging) | Additional evidence required |
|---|---|
| The plants lodge due to stalk rots or stem borer damage. | Cut open the stalk and look for brownish, rotten areas or insect tunnels. |
| The density is too high for the variety. | Compare the observed density with the optimum for the variety. Look at the stalks. Are they thin and weak? |
| Too many plants per hill or competition due to weeds or an intercrop. | Count plants per hill. If > 3, this may be the cause. Examine weed or intercrop competition for light. Examine stalks. |
| There was a loss of effective leaf area during grain filling, so the stem reserves of sugar were exhausted. | Look for defoliation due to drought, frost, insects, etc. Check for stalk rots which often infect plants with low stalk sugar concentrations. |
| Excess N applied to unimproved germplasm. | Ask farmer how much fertilizer was applied. |
| Severe potassium deficiency. | Look for leaf symptoms of K deficiency (See mineral nutrition). Examine plants for thin stalks. |
Is lodging a problem?
Evidence: measurements.
Make a count of plant density (See plant density) and include a count of lodged plants. It is often helpful to count root and stalk lodging separately. Note the crop growth stage and whether ears are in contact with the ground. Look over the field, and notice if there are any specific areas which are very badly lodged. If so, estimate the area which is lodged. The coefficient of variation for percent lodging is generally very high. Therefore these measurements should always be made on a number of fields in the area, and they should be combined with observations and discussions with the farmers.
Evidence: questions.
Ask the farmer when lodging occurred, and relate the date to a growth stage. If lodging occurs before the R5 stage, yield of the lodged plants will probably be affected due to decreased interception of sunlight. Farmers usually have a good idea of the amount of lodging in an average year, and when it occurs. Ask the farmer how this year compares to other years.
Possible solutions
- Change to a shorter variety with lower ear placement.
- Alter density or spatial arrangement; reduce the density of the intercrop; control weeds.
- Cultivate earlier in the season to avoid damaging plants.
- Increae soil depth by subsoiling. The effective soil depth can also be increased by ridging or hilling up around the plants.
- Control insect pests which lead to lodging.
- Reduce N application to an unimproved variety, or change to an improved variety which responds more positively to applied N.
- Correct K deficiency.