Wednesday, October 15, 2008 Pest infestation spreads in 2 N. Cotabato towns
KORONADAL CITY -- A deadly pest occurring in lanzones trees has spread to two other towns in North Cotabato province.
Pepito S. Leyza, regional crop protection center head of the Department of Agriculture (DA), said the pests have spread from the towns of Magpet, Makilala and Kidapawan City to President Roxas and Kabacan, all in North Cotabato province.
Leyza said that by the middle of the year, the lanzones fruit could have already flooded the local markets in Central Mindanao region, but the infestation of mussel scale insects hardly made it visible in fruit stands.
In September last year, mussel scale insect (Lepidosaphes ulmi) infestation resulted in the losses of P5 million to lanzones growers in the town of Magpet alone.
The pests invaded at least 211,054 trees in 20 villages of Makilala, 15 in Magpet and 25 in Kidapawan.
"The pests, which are difficult to control, may now spread to the town of Arakan," Leyza said.
To date, Leyza noted the pests have invaded 550,976 trees in North Cotabato, with the number of trees dying tripling to 106. No figure for the damage, however, was given.
Mussel scale insects attack the leaves of lanzones, eventually rendering the fruit with a sour taste.
The Kendall Bioresearch Services said mussel scale (Lepidosaphes ulmi) insects "attack many deciduous trees and shrubs, including apples and other fruit and ornamental trees. Infestations are most severe on older trees and may impair plant growth and vigor. Eggs are laid under the scales in late summer."
Leysa said that treating the infected trees with chemicals -- Malathion 5 EC and Actara 25 WG -- have been ineffective.
Chemical spraying treatment was applied at weekly interval for three months, then two months bi-monthly application and once a month.
"Weekly spraying did not give in anyway positive results because of the defense mechanism [of the pests] characterized by the waxy substance which covers the body during molting of the nymphal stage," Leysa said.
"Once the nymphs settled down, insecticide spraying is not effective [even] to female adults," he added.
Trunk injection using Actara 25 WG was also resorted and gave a positive result in the five-month test period. Population of the pest was totally wiped out in two sites. However, climactic change occurred, resulting to high precipitation, thus refilling schedules were not followed including spraying, a regional crop protection report said.
"[Inclement weather] hindered all activities which contributed to the inconsistencies of scheduled activities. Translocation process in trunk injection has been affected resulting to the re-occurrence of the pest to trunk injected trees in almost all sites," it added.
A team from the University of the Philippines-Los Banos headed by Jose R. Medina meantime recommended a natural tack to eradicate the infestation.
Medina said they look for bio-control agents in infested trees and found two species of beetles -- the black and orange coccinellids -- feeding on the pests.
Samples of black coccinellid were brought to UPLB for identification and it has a scientific name of Chilocoros nigrilus, a predator that is a very voracious feeder, Medina said.
Leyza said the regional crop protection center has adopted the natural approach by mass-producing the two beetle species at their laboratory in Tacurong City.
Reproduction of beetles involves using squash as medium and coconut scale insect (Aspidiotus destructor), as host of the predators.
Kidapawan City, one of the localities ravaged by the pest, has established a laboratory for the production of the beetles, Leyza noted.
He urged the Agriculture main office to provide funds for the setting up of more laboratories that would reproduce the beetles, which could easily multiply in a week to three weeks' time.
