Five steps to determine field problems

Five steps to diagnosing your problem:

  1. Look at the crop (See A-D below) and determine the crop stage.
  2. Make a first guess at the problem - use the Identify the production problem key or the Identify the pest and disease key.
  3. The keys will take you to the relevant information sheet to confirm or reject your first guess.
  4. Is the problem important enough to fix? Estimate the extent of the problem.
  5. Record what you have observed.

A. Look at the crop as a whole. Is it uniform?

Color and color distribution

  • Is the crop a good colour; are there patches of off-colour?

Size and shape

  • Is the whole crop as tall and thick as you would hope?
  • Are there patches where the crop is short or too tall?
  • Patches where it is too thick or too spindly?

B. Look at the crop as single plants. Compare good and poor plants.

If you have decided there are patches of crop that are different, pull up a plant from inside a patch and compare it with one from outside the patch, one plant in each hand. Smell the roots; do they smell different, sour? Feel the leaves; are they soft but turgid, are they floppy?

Color and color distribution

  • Are the good and poor plants different colors?
  • Is the color difference all over?
  • Or is color just different on some parts?
    • Is it the old leaves that are different?
    • Is it the young leaves that are different?
    • Is it the stems or is it the roots that are different?

Size and shape

  • Are your plants different in size?

Is it because one has more leaves than the other?
Is it because the leaves are longer?
Is it because the plant is taller?
Always try to split up the problem into smaller things you can describe.

C. Reassess what you have seen.

Are the differences in your comparisons, different in other plants? Go back and take a few more samples and make sure. Are their symptoms more or less? Look back to the crop as a whole. Are these symptoms actually more widespread than the patches you first noticed but not quite so obvious as in the initial samples?

D. Use your information to identify the problem.

By now you should have enough information to make a good first guess of the cause of the problem using the information sheets. If you later want to assess the severity of the problem on a numerical scale, use these methods.