PLANT PROTECTION 4

PRELIMINARY
DIAGNOSIS
CONFIRM OR
REJECT A
PRELIMINARY
DIAGNOSIS
DIAGNOSES THAT CAN BE MADE AT ENQUIRY
.
A preliminary diagnosis is based mainly on knowledge and experience.
• One should be cautious about being too definite about a diagnosis at enquiry unless
the problem is obvious, ie striking in appearance and abundant.
• Telephone enquiries are particularly difficult because there is no sample or
photograph. You have to rely on the client for all the information relating to the
problem, eg identity of affected plants, description of signs and symptoms (see
page 117).
• Sometimes further investigation is not justified, eg if only one plant is affected in a
home garden.
If the client’s enquiry or situation requires a more definite and more reliable
diagnosis, you will need to proceed through further diagnostic steps. Samples and
further information would be requested. Examples of this situation include:
• Legislative requirements.
• Commercial growers.
• Quarantine matters.
• Certification schemes that provide guaranteed disease-free planting material.
• When control of a pest with pesticides has been unsatisfactory, eg possible resistance
problems.
• A need to know what the problem is not, eg that it is not a parasitic pest which can
spread from one plant to another, but some environmental or cultural problem.
• If a client requires more information about a problem than they originally thought.
32 Diagnosis – Step 1. The client’s enquiry