Insect Pest and Disease Threats to Forest Plantations: Comparison
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Please note this is a comparison between Version 2 by Rita Xu and Version 1 by Pham Quang Thu.

The planted forest area in Vietnam increased from 3.0 to 4.4 million hectares in the period 2010–2020, but the loss of productivity from pests and diseases continues to be a problem. During this period, frequent and systematic plantation forest health surveys were conducted on 12 native and 4 exotic genera of trees as well as bamboo across eight forest geographic regions of Vietnam. Damage caused by insects and pathogens was quantified in the field and laboratory in Hanoi. 

  • damage incidence
  • damage index
  • defoliation
  • forest health monitoring

1. Introduction

Vietnam has made great strides in regreening the country in recent decades [1,2][1][2]. Due to national policies and targets for afforestation and the rehabilitation of natural forests, the forest area expanded from 9.40 million ha in 1990 to 14.67 million ha in 2020 [3]. Vietnam’s 2006–2020 Forest Development Strategy expressed the goal of increasing the total forest cover from 37% in 2006 [4] to 42% by 2020 [3]. Forest development efforts of the past 10 years have greatly contributed to Vietnam’s sustainability strategy [5]. In particular, the plantation forestry sector has made a significant contribution to the growth in forest cover and now comprises 26.4% (ca. 4.4 million ha) of the total forest area in Vietnam [3]. About half of the forest plantations are managed by small stakeholders and the remainder by private companies [3,6][3][6]. Therefore, the plantation forest sector is vitally important to the livelihood of millions of rural households [7,8][7][8]. Exotic species, mainly acacias and eucalypts, have been widely planted in Vietnam [6]. It has been estimated that fast-growing Acacia hybrids can provide 33–56% of the total household income [9]. Furthermore, the export of wood and forest products earned US$9.4 billion in 2018 [6] and increased to US$12.3 billion in 2020 [10]. Even though the plantation area has continued to increase over time, it is insufficient to meet the demand of the local wood processing industry [11]. Reducing losses from damage caused by insect pests and pathogens can help to secure the future wood supply that Vietnam needs for its domestic and international markets.
Over time, the incidence of pest and disease problems in Acacia and Eucalyptus stands has increased globally [12[12][13][14][15],13,14,15], including in Vietnam. Old et al. described 13 fungal pathogens associated with Eucalyptus plantations in Vietnam [16,17][16][17]. The most common Eucalyptus diseases were caused by Cryptosporiopsis eucalypti, Cylindrocladium reteaudii, and Ralstonia solanacearum. Illustrations of the most common biotic problems (21 pests, 23 pathogens) in Acacia, Eucalyptus, and Pinus plantations were provided in a field guide for advisors and growers [18]. With the exception of native Pinus, most of the studies on forest health in Vietnam have focused on exotic species, mainly Acacia and Eucalyptus [19,20][19][20]. Currently, there are five major pest species (Ericeia sp., Helopeltis sp., Phalera grotei, Pteroma plagiophleps, and Xylosandrus crassiusculus) and four major pathogens (Ceratocystis sp., Corticium salmonicolor, Phytophthora cinnamomi, and Pythium vexans) threatening the productivity of Acacia plantations in Vietnam. Furthermore, six major pest species (Aristobia testudo, A. approximator, Biston suppressaria, Leptocybe invasa, Sarothrocera lowi, and Trabala vishnou) and five major pathogens (Cylindrocladium sp., Cryptosporiopsis eucalypti, Ralstonia solanacearum, Teratosphaeria destructans, and T. zuluensis) have been damaging Eucalyptus plantations. As the research effort on forest health in Vietnam has increased over the past two decades, many reports focusing on individual pests or pathogens of interest have been published [18,20,21,22,23,24,25,26,27][18][20][21][22][23][24][25][26][27].

2. Field Surveys—General Procedures

Forest health surveys were undertaken annually from 2011 to 2020, in the eight forest geographic regions of Vietnam (Figure 1), with support from the Ministry of Agriculture and Rural Development. Field observations were carried out on forests planted with 16 tree species (Table 1). We relied on information gathered by local foresters as well as our own observations to select the surveyed plantations in each studied forest region. Three fixed plots (40 × 25 m) were randomly set up in plantations comprising the tree species present in each region and they were assessed over ten years. Selected plots were at least 20 m from plantation edges, roads, or forest gaps. About 25% of trees (at least 30 trees) in each plot were randomly selected and assessed for damage from insect pests and/or pathogens. Surveys usually involved three repeat visits a year undertaken in spring (February–April), summer (May–July), and autumn (August–October). Where tree injury was observed (e.g., defoliation, leaf senescence, shoot dieback, tree death), we quantified the damage.
Forests 12 01301 g001 550
Figure 1. Map of Vietnam showing the eight forest geographic regions.
Map of Vietnam showing the eight forest geographic regions.
Table 1. Details of forest plantation species that were surveyed for pests and pathogens.
HostArea in 2020 (ha)Planting Region *Native/ExoticCommercial Use
Acacia spp. and hybrids2,000,000NE, NW, NP, NC, SC, HC, SE, SWExoticPaper, plywood, timber for construction and furniture
Ailanthus triphysa500NE, NC, SC, SENativePlywood
Chukrasia tabularis35,000NE, NW, NP, NC, SC, HCNativeTimber for furniture
Cinnamomum cassia210,000NE, NW, NC, SCNativeBark for export and seasoning, oil for medicine
Dalbergia tonkinensis2000NE, NW, NP, NC, SC, HC, SENative

* Forest zones (see Figure 1): NE, North East; NW, North West; NP, North Plain; NC, North Central; SC, South Central; HC, Highland Central; SE, South East; SW, South West.

3. Field Surveys—Insects

Insect survey methods included eye tracking, sweep netting, suction sampling, and lure traps. Adult folivores were captured with collecting nets on aluminum poles, and placed in killing jars. Plastic boxes (VietNhat Plastic Joint Stock Company, Hanoi, Vietnam) with nylon mesh covers were employed to transport the living larvae, pupae, and eggs to the laboratory. Fresh leaves were included for the larvae to feed.
For wood borers, samples were mostly obtained by the felling of affected trees, then chopping logs to obtain collections. When adults were not present, logs 1.0–1.5 m in length were transported to the laboratory in Hanoi. Some logs were dissected to capture the adults and/or larvae. The cuts of other logs were sealed with Parafilm® (Bemis Company Inc., Neenah, WI, USA) and were taken to the laboratory for rearing adults for identification.
In addition, more intensive sampling was undertaken through trapping in the field for adult ambrosia beetles. Black funnel Lindgren traps (BioQuip Products, Inc., Compton, CA, USA) and self-made plastic-bottle traps baited with 70% ethanol and para-menthenol (1S, 4R)-p-menth-2-en-1-ol) (Synergy Semiochemicals Corp. (Burnaby, BC, Canada) were used to attract adults. Propylene glycol (Merck, Darmstadt, Germany) and water (50:50) solution was used in the collection cups. Each trap was suspended at least 10 m apart in a plantation and 1.5 m above the ground to avoid damage by wild animals. The baits were replaced once a week. Baiting was undertaken from April to June. Trap collections were stored in 70% ethanol in Eppendorf® (Eppendorf Manufacturing Corp., Hamburg, Germany) tubes and then sorted in the laboratory.

4. Change over Time

Forest health surveys undertaken from 2011 to 2020 on the plantations of different tree species in Table 1 revealed 14 new or emerging insect pest species and major disease threats from two plant pathogens (Table 2). The total number of new or emerging insect pest species and pathogens increased from 2 in 2011 to 17 in 2020 (Figure 2). Hence, on average, 1–2 new pests per year were recorded damaging forest plantations in Vietnam. The temporal and geographical occurrence of the observed pests and pathogens is detailed in Table 3. Of particular note is the apparently rapid spread of Aulacapsis tubercularis in Cinnamomum cassia, Euwallacea fornicatus in Acacia spp. and C. cassia, Tapinolachrus lacordairea in Chukrasia tabularis, and Xyleborus perforans in Acacia and Eucalyptus. The two main types of damage from insect pest species are from foliar feeding by folivores (5 species of Lepidoptera), and bark and/or wood feeding (6 species of Coleoptera). The fungal pathogen Ceratocystis manginecans has extended its host range from exotic Acacia and Eucalyptus to the native Dalbergia tonkinensis and C. tabularis.
Forests 12 01301 g002 550
Figure 2. Change in the number of pest and pathogen species recorded each year.
Change in the number of pest and pathogen species recorded each year.
Table 2. Pests and pathogens recorded in forest health surveys in Vietnam causing significant damage to host trees.
GroupSpeciesTree SpeciesDamaged Part
Pests
ColeopteraBatocera lineolataEucalyptus hybridsBoles
Euwallacea fornicatusAcacia auriculiformis

Acacia mangium

Acacia hybrids

Cinnamomum cassia		Boles
Lycaria westermanniFernandoa brilletiiLeaves
Tapinolachnus lacordaireiChukrasia tabularisBolesTimber for furniture and handcrafts
Dendrocalamus barbatus120,000NE, NW, NP, NCNativeCulm for construction, activated carbon, handcrafts and paper, young shoots for food
Xyleborus perforansAcacia hybrids

Eucalyptus urophylla		BolesDendrocalamus latiflorus15,000NE, NW, NP, NC, SEExoticYoung shoots for food, culm for paper
Dipterocarpus alatus20,000NC, SC, HC, SENativeTimber for furniture, construction
Cinnamomum cassiaLeavesEucalyptus spp. and hybrids400,000NE, NW, NP, NC, SC, HC, SE, SWExoticPaper, plywood, timber for construction
Helopeltis theivoraAcacia auriculiformis

Acacia mangium

Fernandoa brilletii6000NE, NW, NCNativeTimber for furniture
Hopea odorata20,000
Xystrocera festivaAcacia mangiumBolesNC, SC, HC, SE
HemipteraAcacia hybrids

Cinnamomum cassia

Melaleuca cajuputi

Melaleuca leucadendra		Young leaves, shoots
LepidopteraAntheraea frithiNativeTimber for furniture and boat
Aulacaspis tubercularisDipterocarpus alatus

Hopea odorata		LeavesIllicium verum
 Arthroschista hilaralisNeolamarckia cadamba

Nauclea orientalis		42,000NE, NWNativeFruit for export and seasoning, oil for medicine
Leaves
 Atteva fabriciellaAilanthus triphysaYoung leaves, shootsMelaleuca cajuputi36,000NE, NP, NC, SC, SWNativePaper, activated carbon, poles for construction
 Krananda semihyalinaCinnamomum cassiaLeavesMelaleuca leucadendra32,000SE, SWExoticPaper, activated carbon, poles for construction
 Moduza procrisNeolamarckia cadamba

Nauclea orientalis		LeavesNauclea orientalis500SE, SWNativePlywood
OrthopteraHieroglyphus tonkinensisDendrocalamus barbatus

Dendrocalamus latiflorus		Young leavesNeolamarckia cadamba1000NE, NC, SE, SWNativePlywood
Pathogens
FungiCeratocystis manginecansAcacia auriculiformis

Acacia mangium

Acacia hybrids

Chukrasia tabularis

Dalbergia tonkinensis

Eucalyptus camaldulensis

Eucalyptus urophylla		Boles
Fusarium solaniDendrocalamus latiflorusShoots, roots
OomycetePhytophthora acaciivoraAcacia mangium

Acacia hybrids		Roots and dieback of seedlings
Table 3. Temporal and geographical occurrence of pest and pathogen species in forest health surveys in Vietnam from 2011 to 2020.
Organism2011201220132014201520162017201820192020
Pest
Antheraea frithi      SESE, SWSE, SWSE, SW
Arthroschista hilaralis    SWSWSWSWSWSW
Atteva fabriciella     NENENENENE
Aulacaspis tubercularis    SWSW, SCSW, SC, NE, NPSW, SC, NE, NPSW, SC, NE, NPSW, SC, NE, NP
Batocera lineolata        NWNE, NW
Euwallacea fornicatus  NE, SC, HCNE, SC, HCNE, SC, HCNE, NW, NC, SC, SE, HCNE, NW, NC, SC, SE, HCNE, NW, NC, SC, SE, HCNE, NW, NC, SC, SE, SW, HCNE, NW, NC, SC, SE, SW, HC
Helopeltis theivora         NC, NW, NE, HC, SE, SW
Hieroglyphus tonkinensisNW, NE, NCNW, NE, NCNW, NE, NCNW, NE, NCNW, NE, NCNW, NE, NCNW, NE, NCNW, NE, NCNW, NE, NCNW, NE, NC
Krananda semihyalina         NE, NP
Lycaria westermanni       NCNC, NE, NWNC, NE, NW
Moduza procris    SWSWSWSWSWSW
Tapinolachnus lacordairei        NWNE, NW, NC
Xyleborus perforans        NENE, SE, SW
Xystrocera festiva  HCHCHCHC, SCHC, SCHC, SCHC, SCHC, SC
Pathogen
Ceratocystis manginecansNE, NW, NCNE, NW, NCNE, NW, NCNE, NW, NC, SENE, NW, NP, NC, SE, SWNE, NW, NP, NC, SC, SE, SWNE, NW, NP, NC, SC, HC, SE, SWNE, NW, NP, NC, SC, HC, SE, SWNE, NW, NP, NC, SC, HC, SE, SWNE, NW, NP, NC, SC, HC, SE, SW
Fusarium solani        NENE
Phytophthora acaciivora  NENENENENENENENE

Note: NE. North East; NW. North West; NP. North Plain; NC. North Central; SC. South Central; HC. Highland Central; SE. South East; SW. South West.

References

  1. Meyfroidt, P.; Lambin, E.F. The causes of the reforestation in Vietnam. Land Use Policy 2008, 25, 182–197.
  2. Cochard, R.; Nguyen, V.H.T.; Ngo, D.T.; Kull, C.A. Vietnam’s forest cover changes 2005–2016: Veering from transition to (yet more) transaction? World Dev. 2020, 135, 105051.
  3. MARD. Decision No. 1439/QD-BNN-TCLN Dated 13/4/2021 of the Ministry of Agriculture and Rural Development of Vietnam on Announcing the State of Forests Nationwide in 2020; Ministry of Agriculture and Rural Development: Hanoi, Vietnam, 2021; p. 8.
  4. Vietnam Report on the Implementation Result of the Five Million Hectares New Afforestation Project and the Forest Protection and Development Program in the 2011–2020 Periods; The Socialist Republic of Vietnam: Hanoi, Vietnam, 2011; p. 34.
  5. Vietnam Decision No. 523/QD-TTg Dated 1/4/2021 of the Prime Minister of the Socialist Republic of Vietnam on Approving the Vietnam Forestry Development Strategy for the Period of 2021–2030, with a Vision to 2050; The Socialist Republic of Vietnam: Hanoi, Vietnam, 2021; p. 23.
  6. MARD. Wood Processing Industry, Wood and Forest Product Export in 2018-Successes. Lessons Learned. Breakthrough Solutions in 2019; Ministry of Agriculture and Rural Development: Hanoi, Vietnam, 2019; p. 15.
  7. Cuong, T.; Chinh, T.T.Q.; Zhang, Y.; Xie, Y. Economic performance of forest plantations in Vietnam: Eucalyptus, Acacia mangium, and Manglietia Conifera. Forests 2020, 11, 284.
  8. Khuc, Q.V.; Le, T.A.T.; Nguyen, T.H.; Nong, D.; Tran, B.Q.; Meyfroidt, P.; Tran, T.; Duong, P.B.; Nguyen, T.T.; Tran, T.; et al. Forest cover change, households’ livelihoods, trade-offs, and constraints associated with plantation forests in poor upland-rural landscapes: Evidence from North Central Vietnam. Forests 2020, 11, 548.
  9. Tham, L.T.; Darr, D.; Pretzsch, J. Contribution of small-scale Acacia hybrid timber production and commercialization for livelihood development in Central Vietnam. Forests 2020, 11, 1335.
  10. MOIT. Vietnam Import and Export Report 2020; Industry and Trade Publisher: Hanoi, Vietnam, 2021; p. 252.
  11. Iwanaga, S.; Hoang, D.T.; Kuboyama, H.; Duong, D.T.; Tuan, H.H.; Minh, N.V. Changes in the Vietnamese timber processing industry: A case of Quang Tri province, North Central region. Forests 2021, 12, 984.
  12. Andjic, V.; Dell, B.; Barber, P.; Hardy, G.; Wingfield, M.; Burgess, T. Plants for planting; indirect evidence for the movement of a serious forest pathogen, Teratosphaeria destructans, in Asia. Eur. J. Plant Pathol. 2011, 131, 49–58.
  13. Burgess, T.I.; Wingfield, M.J. Pathogens on the move: A 100-year global experiment with planted eucalypts. Bioscience 2017, 67, 14–25.
  14. Crous, P.W.; Wingfield, M.J.; Cheewangkoon, R.; Carnegie, A.J.; Burgess, T.I.; Summerell, B.A.; Edwards, J.; Taylor, P.W.J.; Groenewald, J.Z. Foliar pathogens of eucalypts. Stud. Mycol. 2019, 94, 125–298.
  15. Wingfield, M.J.; Roux, J.; Wingfield, B.D. Insect pests and pathogens of Australian acacias grown as non-natives—An experiment in biogeography with far-reaching consequences. Divers. Distrib. 2011, 17, 968–977.
  16. Old, K.M.; Dudzinski, M.J.; Pongpanich, K.; Yuan, Z.Q.; Thu, P.Q.; Nguyen, T.N. Cryptosporiopsis leaf spot and shoot blight of eucalypts. Australas. Plant Pathol. 2002, 31, 337–344.
  17. Old, K.M.; Wingfield, M.J.; Yuan, Z.Q. A Manual of Diseases of Eucalyptus in South-East Asia; CIFOR: Canberra, Australia, 2003; p. 106.
  18. Thu, P.Q.; Griffiths, M.W.; Pegg, G.S.; McDonald, J.; Wylie, F.R.; King, J.; Lawson, S.A. Healthy Plantations. A Field Guide to Pests and Pathogens of Acacia, Eucalyptus and Pinus in Vietnam; Department of Employment, Economic Development and Innovation: Queensland, Australia, 2010; p. 124.
  19. Dell, B.; Xu, D.; Thu, P.Q. Managing threats to the health of tree plantations in Asia. In New Perspectives in Plant Protection; Bandani, A.R., Ed.; InTech: Rijeka, Croatia, 2012; pp. 63–92.
  20. Thu, P.Q.; Dell, B.; Burgess, T.I. Susceptibility of 18 eucalypt species to the gall wasp Leptocybe invasa in the nursery and young plantations in Vietnam. ScienceAsia 2009, 35, 113–117.
  21. Thu, P.Q. Results of a survey of insect pests and diseases of the main forest plantation species in Vietnam. Vietnam J. For. Sci. 2016, 1, 4257–4264.
  22. Thu, P.Q. Status of a Pine wilt nematode in Vietnam. N. Z. J. For. Sci. 2003, 33, 336–342.
  23. Thu, P.Q. Die-back disease of Eucalyptus urophylla caused by bacteria Ralstonia solanacearum (Yabauchi et al. 1995) Smith. Sci. Tech. J. Agric. Rural Dev. 2006, 5, 90–91.
  24. Thu, P.Q.; Binh, L.V. Longhorned beetle (Aeolesthes holosericea (Fabricus)) damages stem of Melia azedarach Linnaeus. Sci. Tech. J. Agric. Rural Dev. 2010, 7, 84–88.
  25. Thu, P.Q.; Binh, L.V.; Sinh, L.V. Longhorn beetle damages Rhizophora apiculata plantation in mangrove forest in Can Gio, Ho Chi Minh city. Sci. Tech. J. Agric. Rural Dev. 2008, 8, 84–87.
  26. Thu, P.Q.; Quang, D.N.; Dell, B. Threat to cedar, Cedrela odorata, plantations in Vietnam by the weevil, Aclees sp. J. Insect Sci. 2010, 10, 192.
  27. Nguyen, B.T.; Dao, X.T. Pests and Diseases and Plant Protection Measures; Agricultural Publisher: Hanoi, Vietnam, 2004; p. 168.
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