Few farmers routinely use pesticides on their perennial crops in the Amazon,
and then only sparingly. Vegetable growers, particularly near the major cities,
use the most pesticides. The high cost of pesticides is a major constraint to
their use. Experience is showing, however, that growing perennials in discrete
patches or in mixed cropping systems often reduces the need for pesticides.
Also, patches of forest and old second growth may allow biocontrol agents to
thrive, as appears to be the case with oil-palm plantations along the PA 150
road in Pará, Much research remains to be done, however, to understand the
interaction of crops and pest populations, and the role of vegetation in
suppressing or encouraging pests.
The owner of the Rio Branco ranch near Ariquemes, Rondônia, notes that orange
trees appear more vigorous near a strip of exotic bamboo he has planted along
the road dividing his property. The bamboo was originally planted for ornamental
purposes, but the rancher plans to plant more near his orange plantings.
Bamboo's effects on the orange orchards are unclear; the perennial grass may be
benefiting the orange trees by providing a haven for predators of insect pests,
or it may be serving as a windbreak. Elsewhere in pioneer areas of Amazonia,
bamboo is planted as a door yard plant for construction material;
Japanese-Brazilians also harvest bamboo shoots for a variety of