In this example: The farmer tells you that he is having problems with his rice paddy -  a lot of rice plants are stunted and yellowish in color - and he doesn't know what is causing it. When you ask how the field has been managed and if there has been anything unusual, he explains that he tried using more nitrogen, treating for bacterial disease and recently increasing water levels but nothing seemed to help. He is very worried and invites you to have a look at the field.

The field is at flowering - a good time to view the crop.

For a check list of observations and questions: click here.

Ask the farmer about

1. the variety planted and
2. check the growth stage.
3. the weather

You can consider possible problems by checking the link growth stages and important management factors.

Use the check list of observations to help guide you: click here.

Observe the whole field.

"Does the field look uniform and healthy?" If yes, then everything is probably OK.

If not, then:

1. In what way does it vary (e.g., color, height, groundcover, damage)?

2. Is there a pattern across the field to the damage? Does the pattern suggest any probable causes?

In this case, you notice that there is a clear visible pattern of plant color variation with mostly dark green plants and some patches of lighter green or yellowish plants suggesting a "scattered cluster field pattern". The farmer tells you he si growing IR64.

Check typical problem patterns and probable cause for possible causes.

3. What percent of the area is affected?

Insects, weeds, rats, birds, crabs, snails, other?

In this case, you note there are more weeds in the places where plants are yellow.

Is field moisture adequate and the water level the same across the field and the affected areas?

In this case, you find that the water level in the affected parts is less than in the greener parts of the field. Some parts of the affected areas are even above the water and there are soil cracks.

In this case, the plant color in affected areas is different - older leaves are yellow or light green. Plants are somewhat stunted and tillering si reduced. Younger leaves appear slightly greener than older leaves. Some older leaves are dead. There are more weeds in the affected areas compared to the greener areas. Root growth and sheaths appear normal.

Use these symptoms to diagnose possible causes: plant symptoms or crop symptoms.

Note: the general types of symptoms can indicate the expected type of problem causing the effect.

Is the problem or problems you see, the "real" problem or is there some other factor (the root cause) leading to this problem?

Make your decision: Is the problem:

• Water stress?
• Nitrogen deficiency?
• Zinc deficiency?
• Insect damage?
• Improper field leveling?
• Weeds?
• Other?

Check the diagnostic summary here.