Proceedings of the Fifth Asian Regional Maize Workshop - Search ...

Heavy incidence of
diseases and insects
B. Pest Management.
Mainly for hybrid
Increases cash costs for pest
control. Reinforces need to
cultivate in appropriate season
and least risky locations.
Among the strategies designed to control maize borer
(Ostrinia furnacalis Guenee) damage, resistant cultivars are still the technology most economical
and easily adopted by maize growers. Researchers from IPS led by Legacion and salazar (1990)
have supplied significant information on the development of maize varieties or hybrids with
resistance to the maize borer:
1. Many corn cultivars found to be resistant to pretasseling maize borer attack were
susceptible to post-tasseling attack.
2. Antigua Group 1 is a reliable source of resistance to pretasseling maize borer attack.
3. Heavy fertilization favors corn borer damage.
4. Maize borer infestation is worse during the wet season, especially when planted late.
5. Insecticide treated plots 'have greater borer damage than untreated plots. This may be
due to the killing of biological enemies of maize.
6. DIMBOA, a biochemical substance found in young maize seedlings, is positively corre
lated with pretasseling maize borer damage.
7. Plants with erect leaves tend to show less borer damage.
S. Yield loss due to maize borer could run up to 95%.
For the control of storage pests of maize, chloropyrifosmethyl and deltamethrin are found
to be effective and safe. Pesticide residue in maize stored for nine months in sacks sprayed
with a solution of 14 cc chloropyrifos and formulated products remained unchanged for 30 days but
increased in the second and third months. This indicates pesticide absorption from the sacks.
The residue in corn grains increased while the residue in the sack decreased. Washing caused 7S­
100% reduction of residue in treated maize stored for six months, although detectable amounts
were noted at the third washing. This study concludes that washing reduces chemical residues.
COOking can do the same for some chemicals but not all. It may even enhance the toxicity of some
residues.
Several technologies of controlling maize borer through the integrated pest management
(IPM) approach had also been generated earlier in the Philippines. These include the detasseling
technique, the use of microbial insecticide, and biological control with Trichogramma species.
Recently, its was found that the establishment of T. evanescens (Westw.) in maize growing areas
was possible and could effectively minimize the damage of Asian maize borer. The technology
developed by the Department of Agriculture - Regional Crop Protection Center (DA-RCPC) includes
three-time releases of 50 cards containing T. evanescens Westw. in a hectare at a distance of 14
m x 14 m between cards. Close monitoring of maize borer infestation and T. evanescens parasitization
throughout the cropping season is recommended. When releases were done, 30-SO% parasitization
of maize borer egg masses were observed. The parasitoids were able to establish in three
different maize areas thus controling the pest population to an acceptable level.
some technological options designed to control maize borer and other insect of maize are
in Table 5.
A strategy on pest management for maize production for specific maize growing areas like
Bukidnon was developed by Josue and co-workers at CMU. The technology includes the following:
1. Land preparation. Disc-plow the land, then disc-harrow twice. Another alternative
is to disc-harrow twice as the only form of land preparation.
2. Varietal selection. Select an OPV with known resistance to downy mildew and other
major diseases.
3. If the variety is susceptible to downy mildew, control of the disease can be obtained
by using Apron 35 SD (= Ridomil) as a seed treatment. Mix 6 g of fungicide wi~h 10 ml
water to form a slurry. Mix this with 1 kg seeds in a suitable container.
4. Seed treatment for the control of soil-borne insects. Treat seeds with Malathion
103