Picture of Joeven C. Calasagsag
PhilRice issues army worm management strategy
by Joeven C. Calasagsag - Monday, 13 September 2010, 09:02 AM
 
balita-dot-ph, September 10, 2010 9:14 am

SCIENCE CITY OF MUNOZ, Nueva Ecija, Sept. 9 — The Philippine Rice Research Institute (PhilRice) has released its general recommendations on the management of cutworms and armyworms following reports on the defoliators’ attacks in some parts of the country, including Bataan.

Arriving from his recent trip in Bataan where attacks on rice plants were reported, Genaro S. Rillon, head of PhilRice's Crop Protection Division, said infestations in the said province is “now under control except in Hermosa, where farmers apply insecticides to the larvae.”

Local units of the Department of Agriculture (DA) identified Bagac, Mariveles, Pilar and Limay as towns hit by the the insect pests.

Rillon said armyworms and cutworms are grass feeders that attack rice plants at any stage. The expert explained that the armyworm larvae feed mostly on leaves, often leaving only the midribs, while the cutworm larvae feed on shoots and roots.

“Prolonged drought followed by heavy rainfall encourages growth of young grasses, which provide good shelter for succeeding larval generations. Drought or floods kill natural enemies,” he said.
As management strategies, PhilRice recommends the following:

1. Establish seedbed in sites far from large areas of weeds and grasses;
2. Conserve the defoliators’ natural enemies such as: * Species of wasps and fly parasitoids, which include tachinids, ichneumonids, eulophids, chalcids, braconids. * Predators such as meadow grasshopper, ants, birds, toads eat the larvae. Birds are usually the ones that destroy larvae, * Fungal and bacterial diseases that commonly infect armyworms and cutworms especially during outbreaks. The nuclear polyhedrosis virus often eliminates populations during outbreaks especially when larvae are stressed due to lack of food or extreme weather;
3. Monitor fields at dawn because larvae are active at this time;
4. Do not spray during low pest populations. Leaf damage caused by larval feeding during the vegetative stage causes no significant yield losses. Rice plant can compensate by replacing damaged leaves with new ones;
5. Dig pits and trenches when population level is already high.Put leaves in these pits and trenches as caterpillars take shelter on these making them easier to collect;
6. Flood fields to reduce pest population as the defoliators prefer dry surfaces; and
7. Apply synthetic insecticides only when pest infestation is intolerable or beyond control to minimize the number of insects migrating to initiate outbreaks.

Spray at dawn because larvae and adults (they fly, mate, or lay eggs) are active at this time. Spot spraying should only be done at high population levels, he said.

Avoid indiscriminate use of insecticides as this will reduce naturally-occurring biological control agents and may lead to secondary pest outbreaks, he added. [(PNA)LDV/zst/MEG/ps]

Source: PhilRice issues army worm management strategy

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