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

Caterpillars or grubs on vegetables
There are many different types of caterpillars or grubs whch occur from time to time,
and cause severe damage.
Control
Most species of these pests can be controlled by spraying with carbaryl (Bugmaster) or
diazinon (Diazinon 800).
White cabbage butterfly or cabbage grub
The larvae of this butterfly are velvety green grubs, up to 4 cm long, which devour the
leaves of cabbages and related species. They leave belund obvious black excrement.
Control
Dipel Bacterial Spray should be used when grubs or butterflies are seen.
Nematodes (eelwo
These pests are not confined to vegetables, but attack flowers, shrubs and trees as well.
However, as most enquiries are about root knot nematodes in vegetables, they will be
dealt with in this section.
Vegetables which are grown in western Queensland and which are affected by root
knot nematodes include beetroot, cabbage and related crops, carrots, parsnips, lettuce,
tomatoes and curcurbits such as pumpkins, melons and cucumbers.
Nematodes are microscopic: the majority of soil nematodes range in length from
0.5 mm to 2 mm and in width hom 10 to 50 microns.
The above-ground symptoms of root nematode infestation are, lack of vigour and
reduced tolerance to drought. With trees, foliage may be small and leaf-drop and
dieback may occur.
Below the ground, numerous irregular swellings or galls on the roots are a
characteristic symptom. ere fleshy tissues are present, extensive tissue destruction
causes rot to develop. Excessive root branching may occur, causing the development
of a densely matted root system on plants which are normally strongly taprooted.
Control - cultural practices
Crop rotation with resistant crops is effective in reducing the damage caused by many
nematodes. The incorporation of large amounts of organic matter into the soil and the
use of an organic surface mulch reduces the severity of injury because these practices
create conditions which are favourable to the natural enemies of nematodes. Organic
material should be incorporated into the soil well before planting and crops should not
be planted until decomposition is complete. The use of a period of bare fallow, with
the soil kept weed free, especially during hot weather, will reduce the nematode