Table 2.

List of biological control agents (BCAs) in in vivo studies.

BCAs	Oil palm varieties	Effect	References
Trichoderma harzianum, Glomus etunicatum	Dura x Pisifera	In oil palm infected with T. harzianum and G. etunicatum, the density of the soil microbial population rose.	(Alizadeh et al., 2013)
Aspergillus sp., Bacillus spp., Lactobacillus, Nattobacillus, Pseudomonas spp., Saccharomyces cerevisiae, Trichoderma spp.	AVROS (Dura x Pisifera)	A field trial revealed that TR1 (Bacillus spp. & Trichoderma spp.) and TR3 (Lactobacillus, Nattobacillus and Saccharomyces cerevisiae) significantly reduced the disease index (DI) to 12% and 24%, respectively, and the amount of ergosterol in trunk tissues to 0.663 g g-1 and 1.817 g g-1. The BSR disease was successfully controlled by TR1, TR2 (Bacillus spp., Pseudomonas spp. & Aspergillus sp.), and TR3 in both the nursery and the field.	(Alexander and Chong, 2014a)
Bacillus spp., Trichoderma spp	No stated	The soil’s beneficial microbe population grew as a result of the addition of BCAs viz. Bacillus spp. (TR1) and Trichoderma spp (TR2), which can be used in conjunction with BCAs to control BSR.	(Alexander and Chong, 2014b)
Bacillus spp., Trichoderma spp.	No stated	The antimicrobial compounds N-methyl-a-aminoisobutyric acid, pyrene-1,6-dione, 12-deoxyaklanonic acid, halstoctacosanolide A, N-acetyl-leu-leu-tyr-amide, and 12-oxo-10Z-do 4-O-8’,5″-5’-dehydrotriferulic acid found in TR1 (Bacillus spp. and Trichoderma spp.) that can inhibit G. boninense.	(Alexander et al., 2017b)
Trichoderma harzianum Bacillus cereus	GH500 (Dura × Pisifera)	With a reduction of 94.75%, B. cereus single applications outperformed T. harzianum (78.98%) and T. harzianum and B. cereus combined applications as the most effective treatments for controlling Ganoderma disease of oil palm.	(Nusaibah et al., 2017)
Diaporthe phaseolorum WAA02, Trichoderma asperellum T2, Penicillium citrinum BTF08)	Tissue-cultured oil palm ramets	Induction of β-1-3-glucanase (EgGLC), phenylalanine ammonia-lyase (PAL) and nitrate reductase (EgNR) by Endophytic BCAs were possibly responsible for the defense responses.	(Chow et al., 2018)
Trichoderma asperellum LF11 Diaporthe miriciae LF9	No stated	Oil palm seedlings with D. miriciae LF9 infection had lower disease incidence (DI) in non-metal (33%) and multi-metal (67%) treated soils, indicating that the seedlings were more resistant to infection. T. asperellum LF11 performed less well than D. miriciae LF9.	(Sim et al., 2019)
Trichoderma virens	Dura x Pisifera	The isolate’s hexane extract inhibited G. boninense at a rate of 62.60%. The enzyme activity of peroxidase, polyphenol oxidase, superoxide dismutase, and phenylalaninelyase were noticeably increased in the leaves of oil palm seedlings following treatment with T. virens isolates via plant roots. T. virens can function as a biofungicide.	(Paudzai et al., 2019)
Trichoderma asperellum, Trichoderma virens	No stated	When compared to the control treatment, the illness was reduced by 38.59% and 50.87%, respectively, in treatments employing T. virens T29-palm press fibre (PPF) surface mulch (T5) and T. asperellum T9-PPF surface mulch (T4).	(Sundram, 2013)
Trichoderma asperellum, Trichoderma harzianum, Trichoderma virens	No stated	The combination of Trichoderma spp. decreased the disease by 83.03% and 89.16%, respectively, in foliar and bole symptoms. Treatment for BSR disease results in significant alterations in peroxidase, polyphenol oxidase, and phenolic content. The link between oil palm metabolism and defense mechanisms may be the subject of future study.	(Musa et al., 2018)
Streptomyces sanglieri	No stated	It has been discovered that S. sanglieri produces the antifungals cycloheximide and actiphenol, both of which may be effective against G. boninense.	(Nur Azura et al., 2016)
Scagelonema parasiticum	Dumpy Yangambi Avros (Dura x Pisifera)	Cellulolytic and xylanolytic antifungal activity was displayed by Scagelonema parasiticum. S. parasiticum has a mycoparasitic growth pattern and produces fluorescent pigments and/or metabolites, making it a potential biocontrol agent for G. boninense.	(Goh et al., 2016)

BCAs indicated as biological control agents.

BSR indicated as basal stem rot.