PLANT PROTECTION 4

LEGISLATION
BEFORE YOU
‘GROW’ THE
CROP
RECURRING
PROBLEMS
EARLY
DETECTION AND
IDENTIFICATION
The early bird catches
the worm…………
WHEN TO DIAGNOSE PLANT PROBLEMS
Legislation may require that certain pests, diseases and weeds are detected and identified.
Quarantine regulations for state/regional areas and export/import markets require that
plants must look healthy, show no visible signs or symptoms and be free of specified
pests. This may require continuous or intermittent monitoring during certain seasons.
Quality standards to meet contractual arrangements with buyers.
Production and sale of disease-tested planting material, eg seeds, potato tubers,
strawberry runners.
Before implementing certain control measures, eg pesticide applications, release of
biological control agents.
Expert assistance may be required to help you comply with legal requirements.
Chemical, physical and biological analyses of soil and water are essential for
particular crops and prudent for many other crops where sites have been repeatedly
cropped.
Before purchasing a property.
Before selecting and planting crops.
During the growth of the crop.
Between crops.
Know what pests, diseases and weeds to expect in your crop in your region. In any
one crop there are usually recurring pests, eg twospotted mites may always show up first in
the same plants in a greenhouse. Rhizoctonia may appear on certain plants at the beginning
of autumn. This information can be built into your crop management plan. Regional
advisors know which problems are expected at particular times of the year.
List present and potential problems for your crop or situation.
Obtain pest information sheets for each problem.
The commonest problems really are the commonest problems. Be able to
recognize the signs and symptoms of the problems you have to look out for, know
what tests you can do yourself and what samples have to be sent for analysis.
Decide if monitoring is necessary, and if so, what has to be monitored.
Pest calendars indicate the time of the year certain problems are likely to occur.
A realistic goal for a grower is to select 6-10 important recurring pests in their crop,
learn how to correctly identify them and build up a general knowledge and
understanding of them and their control.
Accurate, rapid and early detection of present and potential pests is a critical step in
implementing effective control strategies. This will minimize their impact, avoid the
possibility of epidemics developing and may prevent recurrences in later plantings.
Good diagnostic work begins before or when the first signs or symptoms are
expected. Once signs and symptoms appear it may be too late to apply control
measures that season. Many growers diagnose common pest problems but often not
until damage is excessive.
Regularly monitor crops for the early detection of pests, diseases and weeds. Scout
crops, gardens and quarantine areas regularly. Look under leaves, carry a hand lens and
see what you can find. Growers, with today’s wealth of information from books, the
internet, industry groups and colleagues, should be able to scout their crops and detect
key pests (see page 175). Fungal diseases such as powdery mildews may cause
severe economic loss. Crops can be monitored for early microscopic evidence of
fungal growth so that control can be implemented effectively.
Early warning services (predictive pest services) monitor temperature, moisture and
other parameters which favour pest development, so that growers can apply
preventative measures. Early Season Diagnostic (ESD) tools monitor and compare
crop vigour and environmental parameters for crops such as cotton so that any problem
can be corrected before yield is affected.
Soil and water analysis and seed tests can be carried out before planting.
References can be used to identify weed seedlings.
Indicator plants detect the presence of virus diseases.
Eradication of exotic introductions depends on early detection by diagnosticians
capable of identifying a pest not seen before in Australia. Students at Charles Sturt
University learn to identify the main exotic threats to Australia’s crops as part of their
course.
24 The diagnostic road map