188 Agroecology and Sustainability
off-type of rice) is already the key pest in most of the Latin American direct seeded
rice production areas. It seems clear that more direct seeding will lead to more
herbicide use in rice production. Yet herbicide resistance is also sure to eventually
emerge and there are obvious health and environmental costs associated with some
herbicides. Thus it is important that IPM for rice weeds be improved and consid-
ered in the broadest terms (e.g. promoting modern rice varieties that are red in
colour among consumers may be part of the solution to red rice problems). Crop
rotations are feasible in only some areas, while simple line sowers or tractor sowing
in rows combined with manual or tractor cultivation may provide some solutions
for lowland and upland rice.
Genetically modified herbicide-resistant rice will eventually be on the market,
but Asian consumer preference may not favour these varieties. However, the result-
ing increase in herbicide use could have obvious adverse effects on the aquatic
systems that are associated with most rice production. In addition, a major prob-
lem of herbicide resistant rice is the possibility of the transfer of gene resistance to
weedy rice, though such transfers would not occur to wild grass species. Use of
herbicide resistant rice in monocropping could also create, in the long term, seri-
ous problems of glyphosate resistance in weed species previously susceptible to the
herbicide. The ecosystem level interactions of herbicide resistant rice will need
careful assessment prior to their use.
Community pests
Insects, diseases (with the exception of tungro virus) and weeds in rice ecosystems
are generally managed with decisions on individual farms or plots. However, some
pests, particularly rats, snails and birds, require community-level planning and
action. Management of these pests requires facilitation of community organiza-
tions not generally supported by extension services with the possible exception of
some multi-purpose cooperatives and water-user associations.
Numerous species of rats occur in rice fields and can cause considerable
damage. Rats migrate from permanent habitats to rice fields as food supply
changes throughout a yearly cycle, with rice plants most preferred after the pani-
cles have emerged. Some natural enemies of rats, particularly snakes, are harmed
by pesticides and often killed by farmers, thus resulting in more rats. The most
effective management strategies are to ensure baits are appropriate to the species
present, and then carry out continuous trapping along feeding routes, fumiga-
tion or digging of rat holes, and establishing early season bait stations using
second generation anticoagulant baits (although more toxic zinc phosphide and
repackaged and unlabelled aldicarb is still commonly seen but strongly discour-
aged in most countries due to the deaths of children and small livestock). Com-
munity programmes can include educational activities on rat biology and
behaviour (Buckle, 1988), and an emphasis on action during the early season
vegetative stage is considered the key to rat management (Buckle and Smith,
1994; Leung et al, 1999). An innovative owl habitat programme in Malaysia has