Chukrasia tabularis A. Juss produces a valuable timber but plantations are susceptible to attack by the shoot-tip borer Hypsipyla robusta Moore. An integrated pest management (IPM) approach is desirable to limit the extent of damage. Therefore, this study was undertaken to evaluate the deployment of IPM measures in plantations in Vietnam. Data on tree damage and the biology of H. robusta were gathered in 4 provinces over one year and used to build an investigation schedule. Two preliminary IPM trials were then established in which Bacillus thuringiensis and Metarhizium anisopliae were applied to the foliage when the damage incidence (P%) was in the range 5–10%; and insecticides (Carbaryl, Carbosulfan) were applied when the P% exceeded 10%. In addition, larvae and pupae were removed manually over time. In the first trial, the combination of manual and biological control methods reduced the damage index (DI) of trees from 4 tolerant families by 82% compared to the untreated control plots. In the second trial using standard planting stock, application of insecticides was required to reduce the DI by 83%. Six extended IPM trials were undertaken using the same IPM protocols and these reduced the DI to the same extent as in the preliminary trials. Over an 18-month period, the deployment of IPM increased height growth by 19–22% and diameter growth by 38–41% compared to the controls. These findings highlight the value of planting improved seed and the benefit of adopting an IPM approach to manage the shoot-tip borer.
Kamalia priapus (Schitlmeister, 1997) (Lepidoptera: Notodontidae) is a dangerous species which larva is bark-feeding and damaging Homalium ceylanicum trees in plantations and urban areas in Vietnam. Recent field surveys conducted in the central provinces of Quang Binh, Quang Tri, and Thua Thien Hue in Vietnam highlighted the significant impact of K. priapus on H. ceylanicum trees. Their findings reveal a damage incidence (P%) ranging from 30.6 to 36.5% and damage index (DI) between 1.01 to 1.33 in plantations. Furthermore, effects were observed in urban areas with P% increasing to 39.5–51.3% and DI reaching 1.50–1.68. The extensive damage caused by K. priapus has significantly affected the growth and quality of the trees, resulting in numerous large scars on the trunks of the affected trees. To effectively control the pest, breaking nests and killing the larvae may be helpful. However, it is crucial to implement these methods when the larvae are still young. Future research directions have been proposed to understand the biological and ecological characteristics of K. priapus and developed management solutions to control this pest.
Dalbergia tonkinensis is being promoted in Vietnam for the future supply of prized wood for furniture and chemical extraction. Expansion of the plantation area requires a reliable source of quality seed. This study evaluates the field performance of progeny from mature mother trees in natural forests and urban environments. Trials were established in Tan Son and Doan Hung districts of Phu Tho province and assessed 3 years later. There were significant differences in growth and survival between provenances. The best families reached heights of >3.5 m and came from mother trees in a natural forest. The number of leaflets per leaf on mother trees was positively correlated with height (Ht) and diameter at breast height (Dbh) of the trial trees. The individual heritabilities (ĥ2) for Ht and Dbh were 0.39 and 0.49 for Tan Son, and 0.33 and 0.48 for Doan Hung, respectively. The coefficient of additive variation (CVA) of Ht and Dbh were 36% and 58% for Tan Son, and 23% and 30% for Doan Hung, respectively. Interactions between the growth traits in the two trials were strongly correlated (R2 = 0.88 for Ht, 0.90 for Dbh). These results identify D. tonkinensis gene sources with advantages for early growth performance in plantations. These superior genetics can be used for seed orchards, clonal propagation and for implementing a breeding program.