Growing Gmelina (Yemane) and Its Benefits Part 3 Pests

a. Lepidopterous defoliators

b. Chrysodeixis chalcites, Archerontia lachesis and Attachus spp. These have been observed seriously infesting seedlings in nurseries and plantations in Nueva Ecija. Their larvae feed occasionally on leaves, leaving only the midribs. Infestation occurs every year. While some plants succumb completely to the attack, some recover to produce new shoots.

Control: Spray any of the Carbaryl insecticides such as Sevin 85S, Vetox 85 WP or Carbin 85S at the rate of 15 – 25 tablespoons per 100 li of water at a five-day interval. Spray the leaves when egg masses and larvae are noticed.

c. Ozala minor

A monophagous species which occurs in the early part of May and in the middle part of July, recurs in the latter part of November and ends in the latter part of January. It actively feeds at early in the morning and late in the afternoon. Newly hatched larvae feed on any part of the leaves which later become perforated. Leaf margins are sometimes eaten. Young larvae prefer newly opened leaves although mature larvae also feed on older leaves. When infestation is extremely heavy, the entire leaf may be consumed except the midribs and large margins. Pest is likely to be serious in seedlings and young stands where more growing shoots occur.

Leaf cutter ants. These can be controlled by insecticides or poisonous gases provided the expenditure or cost is justified and application is done with proper caution. It can also be controlled by the use of small explosives.

Issues and Facts

Yemane (Gmelina arborea Roxb.) has gained prominence not only in the Philippines but also among our Asian neighbors because of its economic importance. It is a raw material for pulp and paper making, posts, house timbers and poles while rotary cut veneers are utilized for plywood. It is also utilized as fuelwood and sometimes as feed for cattles, being a multiple-use species.

Nueva Vizcaya and Cebu were the two provinces that pioneered in planting yemane. Other plantations were established later in Mindanao and Luzon. Martin Reyes, retired assistant director of then Forest Research Institute, visited the Nasipit Lumber Company (NALCO) in 1975 and 1992 and observed that NALCO had extensive plantations of yemane. Pulpwood-sized yemane logs have practically replace lauan mill wastes and logs from damaged residual trees and thinnings as raw materials for lawanit (hardboard) factory (lawanit is a form of reconstituted wood).

However, in August 1993, the Ecosystems Research and Development Bureau (ERDB) received inquiries and reports from Region X pertinent to the following allegations:

  • Yemane depletes the acquifers of water and affects water quality
  • It is allelophatic to other vegetations, and
  • Toxic to animals like cattle.

But there is no existing literature on the harmful effects of yemane on the environment and animals. Hence, this primer tackles some issues and facts about yemane to shed light on reports spreading in Mindanao.

Issue No. 1. Does yemane deplete the acquifer of water and affect its quality?

Yemane does not affect water in streams. It cannot deplete acquifers of water because the roots of the species are mostly situated within 3 m below soil surface, whereas water tables are located several meters deeper.

Experiments in ERDB have proven that when yemane was planted in the Bureau’s gauging station in San Lorenzo, Angat, Norzagaray, Bulacan, water yield increased by as much as 12%. Thus, the drying up of streams in some localities may be attributed to the loss of vegetation cover in the head waters which are principal sources of underground water in acquifers. This groundwater feeds the stream after occurrence of rainfall and more particularly during the dry season.

Results of a one-year study in Diadi, Nueva Vizcaya indicated that yemane is an excellent plantation species. It can easily be established in plantations because survival of the seedlings is not adversely affected by the extremities of site, soil, and biotic factors. Yemane was observed to be resistant to drought, fire, wind damage, and exposure to intense heat of the sun.

Issue No. 2. Is yemane allelophatic to other vegetations?

So far, observations in Burma and India indicate that yemane is normally mixed with other tree species like teak (Tectona grandis), Anogeissus acuminate, and Carega arborea. They are situated mostly in flat or nearly flat ground in deep, alluvial soils.

In Cavite and Bukidnon, growth of young crops is not affected by yemane. In fact, coffee under yemane plantation grows vigorously in the province of Cavite (Limsuan 1993).

While Reyes (1993) observed that in Benguet, three-year-old coffee plants interplanted under seven-year-old yemane plantation spaced at 2 m x 2 m appeared to be stunted and remained 10 cm – 15 cm in height. This could not be attributed to the allelophatic effects but rather to the very close spacing of the plantation. The roots of some coffee seedlings are observed to have been intertwined with the rootlets of two adjacent yemane trees 5 m – 8 m tall. Fallen leaves of yemane partially covered the ground which may be another cause of the stunted growth of coffee plants.

Issue No. 3. Is yemane toxic to animals like cattle?

No documented report has been published on the toxicity of yemane on animals. Conversely, the National Academy of Sciences (1981) reported that yemane produces abundant nectar from which high quality honey is processed. Hensleigh (1988) and Little (undated) also reported that deer and rabbits eat yemane seeds and foliage. Likewise, cattle feed on foliage and bark of trees.

In Cebu, yemane fruits are made into jam, while in an experimental farm in Angat, Bulacan, the bark was observed to be eaten by deer.

These reports showed the nontoxic properties of yemane to animals and man.

Issue No. 4. Is the wood of yemane durable or nondurable?

Generally, the wood of yemane is rated as nondurable. However, denser heartwood is moderately durable and resistance to termite attack varies.

For more information, contact:

Department of Environment and Natural Resources
Visayas Avenue, Diliman, Quezon City
Telephone: (02) 929-6626
Email: [email protected]
Web: www.denr.gov.ph

Bureau of Plant Industry
Tel. No. (02) 525-78-57
Fax No. (02) 521-7650
Email: [email protected]
Web: www.bpi.da.gov.ph

Plant Nurseries and Seedlings

Manila Seedling Bank
EDSA, Quezon City

Ato Belen Farm
Brgy. San Juan, San Pablo City, Laguna
Phone: (049) 5621215 or 5623379,
Mobile: 0916-4337388 or 0916-3244952
Email: [email protected]
Web: atobelen.mybesthost.com

Dizon Farm
Email: [email protected]
Web: www.dizon-exoticfruittrees.com

Angeles Seedling Bank
360-A Miranda St., Angeles City, Pampanga
Mobile: 0917-511-10-09

Compiled by Levi V. Florido, Apolinaria T. Cornejo, Concepcion M. Palaypayon, Jose M. Batalon, photo from www.jabonjawa.com

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