Peach palm - World Agroforestry Centre

5 4 Peach palm. Bactris gasipaes Kunth
9.7 Pests and pathogens
Several pests and pathogens may create problems during seed storage, in the
nursery, and in fruit and heart-of-palm plantations. Some of these develop because the
plants are stressed, and can be avoided by maintaining the plants in healthy condition.
Effective chemical controls exist for some pests and pathogens, but these imply additional
costs, which may not be appropriate for many small-scale farmers. Biological control
within an integrated pest management programme should be promoted. Peach palm
plantations are visited by many insects, some of which provide biological control of insect
pests. With this in mind, selective weed control should be practised, since some weed
species may serve as hosts for beneficial insect species (Mexzon 1997).
It seems that there is a higher incidence of pests and pathogens on cultivated peach
palm in Costa Rica than in the Amazon basin, which is perhaps related to the more extensive
cultivation of peach palm in Costa Rica (Villachica 1996). For example, some small-scale
farmers in the Peruvian Amazon Basin state that peach palm fruit yield is higher and has
less insect damage if plants are grown at very low density (about 10 plants/ha) in mixtures
with other secondary forest species (J.C. Weber, pers. observ.). These traditional agroforestry
systems may provide useful models for research on integrated pest management if
intensive agriculture is not practised.
The most common pathogens of fruits, seeds, leaves and stems are listed in Table 12.
Fungal infections on fruits in the field are generally associated with high relative humidity,
and may be controlled agronomically (e.g. improve drainage and air circulation, eliminate
shading). The ‘black rot’ fungus develops on fruits damaged during harvest. Some fungi
may destroy peach palm seeds after fruit harvest, in storage or during germination (Coates-
Beckford and Chung 1987). According to Vargas (1993), fungi do not normally penetrate
the seed before fruit harvest. Fungal infections in seed storage and during germination are
generally due to excessive humidity (see Section 8.2) and/or inappropriate treatment with
fungicide. Leaf and stem infections probably indicate that the plant is stressed, and efforts
should be made to identify and correct the stress factors (e.g. soil/plant nutrient
analysis). The two ‘spear rot’ infections kill the affected stem, but normally do not
spread to other stems in the cluster, so a multistemmed plant normally survives.
Various fungicides and bactericides are used to control pathogens on peach palm
(contact researchers listed in Appendix I for appropriate treatments).
Several small mammals and birds can be serious pests. For example, the gopher
(Orthogeomys cherriei) is the most economically important pest in peach palm
plantations in Costa Rica (Delgado 1990). Gophers live underground in a network
of tunnels, and eat bulbs, tubers and roots. Young peach palm roots and stem tissue,
when available, seem to be a preferred part of their diet. They can be controlled by
poisons and traps. Rats and mice eat peach palm seeds and young plants, and may
become serious pests in nurseries and plantations if the surrounding area offers them an
appropriate habitat (very weedy or with piles of dry plant material). Keeping the
surroundings clean is the best preventive measure. If rats and mice are already present,
they can be controlled with commercial rodenticides. Rats and mice apparently
find fungicides unpalatable, so seeds can be treated with fungicide to protect