western-queensland-gardening-guide.pdf - South West NRM

Chapter 6. Common pests and diseases of horticul
in western Queensland
There are many diseases and pests whch attack horticultural crops. Adequate control
may be obtained by carrying out correct cultural practices and by a few established
pest and disease control procedures.
Good gardening practices reduce pest problems
It is no accident that pest and disease problems are usually less severe in neat nurseries
or gardens than in unkept ones. The chances of pests and disease attacking
horticultural plants are reduced when the surrounding area is clean and in good order.
Weeds not only compete with the crop for moisture and nutrients, but provide cover
for pests and diseases. Diseased plants should not be dug into the soil or left to lie in
the area, but should be burnt to destroy the disease causing organisms.
Chemicals are no remedy for poor cultural practices, and growers cannot hope to reap
the full benefits from applied insecticides, fungicides or herbicides unless they practise
correct cultural procedures.
Lack of vigour because of low soil fertility is often associated with a disease outbreak.
Attention should constantly be given to the provision of better soil fertility and
improved soil structure for healthy plant growth. Practices which should be
considered to help alleviate poor growth are:
the addition of artificial fertiliser at planting time and in the spring
the addition of animal manure or compost
the building up of beds to give greater topsoil depth and better drainage.
Other factors which may be the cause of lack of vigour include trace element
deficiency, too much or too little moisture and nematode (eelworm) infestation.
Crop rotation, that is, the planting of a succession of different types of crops, is a
cultural practice which tends to prevent any undue increase in the pest and disease
population associated with one particular crop. A two-year rotation will greatly assist
in suppressing soil-borne disorders.