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Biostimulants such as silicate (SiO32−) compounds and antagonistic bacteria can alter soil microbial communities and enhance plant resistance to the pathogens and Fusariumoxysporum f. sp. cubense (FOC), the causal agent of Fusarium wilt disease in bananas. A study was conducted to investigate the biostimulating effects of SiO32− compounds and antagonistic bacteria on plant growth and resistance of the banana to Fusarium wilt disease. Two separate experiments with a similar experimental setup were conducted at the University of Putra Malaysia (UPM), Selangor. Both experiments were arranged in a split-plot randomized complete block design (RCBD) with four replicates. SiO32− compounds were prepared at a constant concentration of 1%. Potassium silicate (K2SiO3) was applied on soil uninoculated with FOC, and sodium silicate (Na2SiO3) was applied to FOC-contaminated soil before integrating with antagonistic bacteria; without Bacillus spp. ((0B)—control), Bacillus subtilis (BS), and Bacillus thuringiensis (BT). Four levels of application volume of SiO32− compounds [0, 20, 40, 60 mL) were used. Results showed that the integration of SiO32− compounds with BS (108 CFU mL−1) enhanced the physiological growth performance of bananas. Soil application of 28.86 mL of K2SiO3 with BS enhanced the height of the pseudo-stem by 27.91 cm. Application of Na2SiO3 and BS significantly reduced the Fusarium wilt incidence in bananas by 56.25%. However, it was recommended that infected roots of bananas should be treated with 17.36 mL of Na2SiO3 with BS to stimulate better growth performance.

White root rot (WRR) disease caused by Rigidoporus microporus is a major disease affecting tropical rubber tree (Hevea brasiliensis) and some agricultural crops throughout the world. In Malaysia, rubber industry is an important revenue as natural rubber for export and domestic consumption. The objectives of this study were to determine WRR disease prevalence and characterise R. microporus isolates collected from different regions in Malaysia using cultural and molecular characteristics. During July 2017 to May 2018, diseased samples showing WRR symptoms such as presence of basidiocarps and rhizomorphs in five states of Malaysia including Kedah (Baling), Kelantan (FELCRA Machang and Smallholder in Machang), Perak (Ipoh) and Selangor (Sungai Buloh and UPM Serdang), Sarawak (Bintulu) were obtained. In the field observation, all sampling areas were infected by the root rot disease. Findings revealed that field disease incidence was in the range of 5–40% based on random sampling. The collected R. microporus isolates were pure white and displayed fluffy mycelial growth when cultured on malt extract agar (MEA) medium. For molecular identification, BLASTn analysis showed 98–100% identical to existing reference sequences in the GenBank database. All 27 isolates of R. microporus were characterised based on internal transcribed spacer (ITS) and Beta-tubulin (β-tubulin) gene sequences data. Phylogenetic tree analyses of R. microporus isolates formed two major clades, i.e. Asian and African clades. There was also no clear geographical origin structuring observed within the Asian clade. However, phylogenetic analysis of Beta-tubulin (β-tubulin) gene region revealed distinct geographical origin amongst 27 local isolates. The outcomes of this study provide useful information to improve the existing disease control strategy, hence improving the rubber production in Malaysia.

Similar to animals, plants possess ‘immune memory’ in response to invading pathogens that lead to enhanced defense reaction following pathogen exposure. Systemic acquired resistance (SAR) is a well-characterized type of plant immunity and is associated with coordinated expression of a set of pathogenesis-related (PR) genes and proteins also known as SAR markers. Induction of SAR in plants was shown to be initiated by group of chemicals and biological compounds known as SAR inducers that can be used for the management of important plant diseases. Elucidation and characterization of potential SAR inducers as potential elicitors that can protect papaya from the papaya dieback disease pathogen were carried out using HRPX protein, which was produced as a recombinant protein in an Escherichia coli system. Disease severity analysis in a glasshouse experiment indicated lower disease infection rates in the HRPX-treated plants than in water-treated plants. Selected SAR-associated defense gene expression was also shown to increase in treated plants, via quantitative real-time PCR analysis, confirming enhanced disease response through SAR activation. In this report, the selected recombinant protein was shown to activate the SAR mechanism in papaya for increased tolerance against papaya dieback disease, which was proven via physiological and molecular analysis.

The effects of plant growth-promoting (PGP) compost, conventional fertilizer (NPK), and their combination on fresh and dry herb yield, nutrient uptake, total phenolic content (TPC), total flavonoids (TF), and antioxidant activity (DPPH and FRAP) of Orthosiphon stamineus and Cosmos caudatus were determined. The highest values for each measured variable of O. stamineus and C. caudatus were obtained when both herbs were cultivated in soils supplemented with PGP compost and NPK at halved rates. Considering the effect of treatments on herb nutrient composition, a marginal but significant rise was detected in macro- and micronutrient contents (N, P, K, Ca, Mg, Fe, Zn, and Mn) in both herbs grown in soils supplemented with PGP compost and NPK. TPC ranged from 121–172.6 mg GAE g−1 DW, TF from 95.4–125.4 catechin CE g−1 DW, FRAP from 42.2–58.3 mmol Fe2+equivalent g−1 DW, and DPPH from 185.1–279.4 μmol Trolox equivalent g−1 DW in O. stamineus. TPC, TF, DPPH, and FRAP activities in C. caudatus were 176.1 mg GAE g−1FW, 152.49 catechin CE g−1 FW, 174.86 μmol Trolox equivalent g−1 FW, and 154.68 mmol Fe2+ equivalent g−1 FW, respectively. It is suggested that the usage of PGP compost in combination with NPK at halved rates can reduce the indiscriminate use of mineral fertilizers in greenhouse soil and that a combination treatment had better effects in terms of yields and phytochemical composition in both of the herbs compared with conventional mineral fertilization and unfortified or fortified compost alone.

Eggplant is an essential vegetable crop that is rich in health-related compounds, and the content of these compounds can be increased through grafting. It was reported that grafting with vigorous wild relatives’ rootstocks can improve eggplant’s fruit quality. The study was conducted to investigate the fruit yield, composition and physicochemical traits of Solanum melongena ME, CE, NE and TE scions grafted on wild relatives’ rootstocks of ST, SM and SI. The results show that a notable graft success (100%) was recorded in grafted (TE/ST) and self-grafted (TE/TE) plants using the cleft technique. Growth and yield traits indicated that CE and TE scions grafted onto ST, SM and SI showed better performance in all of the traits mentioned above in an open field across two years, except first flower formation which was displayed on non-grafted CE. In all the rootstocks studied—ST, SM and SI—there was no noticeable effect on carbohydrate, fibre, ash, pH and dry matter content. There was a notable effect of grafting ME/ST, CE/ST, ME/SM, CE/SI, ME/SI, ME/SI and NE/SM on the fruit length, fruit width, total soluble solids, fruit firmness and fat and protein content, respectively. Furthermore, antioxidants such as DPPH (ME/SM), total flavonoids (NE/SM) and total phenolics (TE/SI) had remarkable content of the above-mentioned physicochemical properties. Results show that ST, SM and SI represent a viable rootstock alternative to Solanum melongena or Solanum lycopersicum production.

The threat of Ganoderma boninense, the causal agent of basal stem rot disease, in the oil palm industry warrants finding an effective control for it. The weakest link in the disease management strategy is the unattended stumps/debris in the plantations. Hence, this study aimed to determine whether the selected phenolic compounds could control G. boninense in inoculated oil palm woodblocks and restrict wood biodegradation. Results indicated a significant reduction in the wood mass loss when treated with all the phenolic compounds. Surprisingly, syringic and vanillic acids behaved ambivalently, at a lower concentration, the wood mass loss was increased, but it decreased as the concentrations were increased. In all four phenolic compounds, the inhibition of mass loss was dependent on the concentration of the compounds. After 120 days, the mass loss was only 31%, with 63% relative degradation of lignin and cellulose, and 74% of hemicellulose and wood anatomy, including silica bodies, were intact in those woodblocks treated with 1 mM benzoic acid. This study emphasizes the physicochemical and anatomical changes occurring in the oil palm wood during G. boninense colonization, and suggests that treating oil palm stumps with benzoic acid could be a solution to reducing the G. boninense inoculum pressure during replantation in a sustainable manner.

Watermelon (Citrullus lanatus) accounts for almost 13% of all tropical fresh fruit production in Malaysia. They are grown, mostly in Johor, Kedah, Kelantan, Pahang, and Terengganu areas of Malaysia on 10,406 ha and yielding 172,722 Mt. In 2019, a new fruit rot disease was observed in two major production areas in Peninsular Malaysia. Disease symptoms included water-soaked brown lesions on the fruit surface in contact with the soil. The lesions enlarged gradually and ultimately covered the whole fruit with white mycelium leading to internal fruit decay. Disease surveys were conducted in December 2019 and November 2020 in fields at Kuantan, Pahang and Serdang, Selangor. Disease incidence was 10% in 2019 and 15% in 2020. Infected fruits were collected and washed under running tap water to wash off adhering soil and debris. Fruit tissue sections 1 to 2 cm in length were surface sanitized with 0.6% sodium hypochlorite (NaOCl) for 3 min. and washed twice with sterile distilled water. The disinfected air-dried tissues were then transferred onto potato dextrose agar (PDA) media and incubated at 25±2℃ for 3 days. Fungal colonies with whitish mycelium and pink pigment isolated using single spore culture. The pure cultures were placed onto carnation leaf agar (CLA), and the culture plates were incubated at 25±2℃ for 15 days for morphological characterization. On CLA, macroconidia were produced from monophialides on branched conidiophores in orange sporodochia. Macroconindia were thick-walled, strong dorsiventral curvature, 5 to 7 septate with a tapered whip-liked pointed apical cell and characteristic foot-shaped basal cell, 21.9 to 50.98 μm long and 2.3 to 3.60 μm wide. Typical verrucose thick chlamydospores with rough walls were profuse in chains or clumps, sub-globose or ellipsoidal. Based on morphological characteristics they were identified as Fusarium equiseti (Leslie and Summerell 2006). Molecular identification of both U4-1 and N9-1 pure culture isolates were carried out using two primer pair sets; internal transcribed spacer (ITS) ITS-1/ ITS-4 and translation elongation factor 1 alpha (TEF1-α) (EF-1/EF-2). A Blastn analysis of the ITS gene sequence of U4-1(MW362286) and N9-1 (MW362287) showed >99% similarity index to the reference gene sequence of F. equiseti isolate 19MSr-B3-4 (LC514690). The TEF1-α sequences of U4-1 (accession no. MW839563) and N9-1 (accession no. MW839564) showed 100% identity; with an e-value of zero, to the reference gene sequence of F. equiseti isolate URM: 7561 (accession no. LS398490). Each isolate also had a >99% identity with isolate NRRL 34070 (accession no. GQ505642) in Fusarium MLST database that belongs to the F. incarnatum-equiseti species complex (O'Donnell et al. 2015). Based on phylogenetic analysis of the aligned sequences (TEF1-α) by the maximum likelihood method, the U4-1 and N9-1 isolates were confirmed to be F. equiseti as was reported in Georgia, USA (Li and Ji 2015) and in Harbin, Heilongjiang Province, China (Li et al. 2018). Finally, the two pure culture isolates of U4-1 and N9-1 were used to fulfill Koch's postulates. Stab inoculations of five healthy watermelon fruits (cv. 345-F1 hybrid seedless round watermelon) were performed with a microconidial suspension of individual isolates (4x106 spores/mL). Five control fruits were stabbed with double distilled water. The inoculated fruits were incubated under 95% relative humidity at a temperature of 25±2℃ for 48 h followed by additional incubation inside an incubator at 25±2℃ for 8 days. Ten days post-inoculation, the control fruits showed no disease symptoms. However, inoculated fruits exhibited typical symptoms of fruit rot disease like water-soaked brown lesions, white mycelium on the fruit surface and internal fruit decay, which is similar to the farmer's field infected fruits. The suspected pathogen was successfully re-isolated from the symptomatic portion of inoculated fruit and morphologically identified for verification. To our knowledge, this is the first report of F. equiseti causing fruit rot of watermelon in Malaysia. Malaysia exports watermelon year-round to many countries around the world. The outbreak of this new fruit rot disease could potentially pose a concern to watermelon cultivation in Malaysia.

Essential oils protect plants, and due to their natural origin, there is much interest in using them as antimicrobial agents. The purpose of this study was to determine the phytochemical constituents of ginger essential oil (GEO), antimicrobial activity, and mode of action against Burkholderia glumae (Bg). In addition, the volatile active compounds (AIs) were studied using GC-MS, FTIR, and Raman spectroscopy. A total of 45 phytochemical components were detected and the most prevalent bioactive compounds were Geranial, 1,8-Cineole, Neral, Camphene, α-Zingiberene, and α-Farnesene. Furthermore, it was found that the most dominant terpenes in GEO were monoterpenes. The diameter zone of inhibition values varied from 7.1 to 15 mm depending on the concentration tested. In addition, the MIC and MBC values were 112.5 µL/mL. Faster killing time and lower membrane potential were observed in 1xMIC treatment compared to 0.5xMIC treatment, whereas the control had the maximum values. From observations of various images, it was concluded that the mode of action of GEO affected the cytoplasmic membrane, causing it to lose its integrity and increase its permeability. Therefore, the antibacterial study and mechanism of action revealed that GEO is very effective in suppressing the growth of B. glumae.

Grafting is regarded as an integral component of sustainable vegetable production. It is important in the management of soil-borne diseases, and reports suggest that grafting with viable rootstocks can enhance crop growth and yield. This research was conducted using splices and cleft grafting techniques to investigate graft compatibility among varieties of high yielding eggplant scion (MCV1, MCV2, CCV1, CCV2, CCV3, NCV, and TCV) grafted onto wild rootstocks (MWR, BWR, and TWR) to study their morphophysiological and yield characteristics. High yielding scions grafted onto wild relative rootstocks were compared with two controls including self-grafted and non-grafted. All the scion had a high rate of germination (&ge, 95%) and remarkable graft success (100%) was recorded in MCV1, MCV2, and TCV using the cleft techniques. Generally, the use of rootstocks resulted in higher total and marketable fruit yield compared to the non-grafted and self-grafted scion plants, respectively. In particular, MWR and TWR rootstock conferred the highest vigour to the scion, resulting in the highest values recorded for total and marketable fruit yield, number of fruits per plant and average fruit weight. A similar result was obtained in fruit length and diameter, where long and wide fruits were observed in scions grafted onto MWR and TWR rootstocks, respectively. Grafting of high yielding eggplant scion onto resistant MWR, BWR and TWR eggplant rootstock was found to be beneficial for eggplant cultivation. The remarkable compatibility and vigour of the rootstock with scion led to the improvement in total and marketable yield of the fruits. As such, it can be concluded that the use of wild relative rootstocks of eggplant species can be a valuable method of improving eggplant production.

Fusarium wilt disease incited by Fusarium oxysporum f. sp. niveum (FON) is the utmost devastating soil-inhabiting fungal pathogen limiting watermelon (Citrullus lanatus) production in Malaysia and globally. The field disease survey of fusarium wilt was carried out during December 2019 and November 2020, in three major production areas (3 farmer fields per location) in Peninsular Malaysia namely, Mersing, Serdang and Kuantan and disease incidence of 30 and 45%, was recorded for each year, respectively. Infected watermelon plants showed symptoms such as vascular discoloration, brown necrotic lesions to the soil line or the crown, one-sided wilt of a plant, or a runner or the whole plant. Infected root and stem tissues, 1-2 cm pieces were surface sterilized with 0.6% NaOCl for 1 minute followed by double washing with sterile water. The disinfected tissues were air-dried and transferred onto semi-selective Komada's medium (Komada 1975) and incubated for 5 days. The fungal colonies produced were placed on potato dextrose agar (PDA) to attain a pure culture and incubated at 25±2℃ for 15 days. The pure fungal colony was flat, round and light purple in color. Macroconidia were straight to slightly curved, 18.56-42.22 µm in length, 2.69-4.08 µm width, predominantly 3 septate and formed in sporodochia. Microconidia measured 6.16-10.86 µm in length and 2.49-3.83 µm in width, kidney-shaped, aseptate and were formed on short monophialides in false-heads. Chlamydospores were single or in pairs with smooth or rough walls, found both terminally or intercalary. To confirm their pathogenicity, two-week-old watermelon seedlings (cv. NEW BEAUTY) were dipped into spore suspension (1 ˟ 106 spores/ml) of representative isolates of JO20 (Mersing), UPM4 (Serdang) and KU41 (Kuantan) for 30 second and then moved into 10 cm diameter plastic pots containing 300 g sterilized soil mix. Disease symptoms were assessed weekly for one month. Control seedlings were immersed in sterile distilled water before transplanting. The inoculated seedlings showed typical Fusarium wilt symptoms like yellowing, stunted growth, and wilting, which is similar to the farmer field infected plants. However, the seedlings inoculated by sterile distilled water remained asymptomatic. The pathogen was successfully re-isolated from the infected seedlings onto Komada's medium, fulfilling the Koch's postulate. For the PCR amplification, primers EF-1 and EF-2 were used to amplify the tef1-α region. A Blastn analysis of the tef1-α sequences of the isolates JO20 (accession nos. MW315902), UPM4 (MW839560) and KU41 (MW839562) showed 100% similarity; with e-value of zero, to the reference sequences of F. oxysporum isolate FJAT-31690 (MN507110) and F. oxysporum f. sp. niveum isolate FON2 790-2 (MN057702). In Fusarium MLST database, isolates JO20, UPM4 and KU41 revealed 100% identity with the reference isolate of NRRL 22518 (accession no. FJ985265). Though isolate FJ985265 belongs to the f. sp. melonis, earlier findings had revealed Fusarium oxysporum f. sp. are naturally polyphyletic and making clusters with diverse groups of the Fusarium oxysporum species complex (O'Donnell et al. 2015). The isolates JO20, UPM4 and KU41 were identified as F. oxysporum f. sp. niveum based on the aligned sequences of tef1-α and molecular phylogenetic exploration by the maximum likelihood method. To the best of our knowledge, this is the first report of F. oxysporum f. sp. niveum as a causative pathogen of Fusarium wilt disease of watermelon in Malaysia. Malaysia enables to export watermelon all-year-round in different countries like Singapore, Hong-Kong, The United Arab Emirates (UAE), and Netherlands. The outburst of this destructive soil-borne fungal pathogen could cause hindrance to watermelon cultivation in Malaysia. Thus, growers need to choice multiple management tactics such as resistant varieties, cultural practices (soil amendments and solarization), grafting, cover crops and fungicide application to control this new pathogen.

Ganoderma boninense is a causal agent of basal stem rot (BSR) and is responsible for a significant portion of oil palm (Elaeis guineensis) losses, which can reach US$500 million a year in Southeast Asia. At the early stage of this disease, infected palms are symptomless, which imposes difficulties in detecting the disease. In spite of the availability of tissue and DNA sampling techniques, there is a particular need for replacing costly field data collection methods for detecting Ganoderma in its early stage with a technique derived from spectroscopic and imagery data. Therefore, this study was carried out to apply the artificial neural network (ANN) analysis technique for discriminating and classifying fungal infections in oil palm trees at an early stage using raw, first, and second derivative spectroradiometer datasets. These were acquired from 1,016 spectral signatures of foliar samples in four disease levels (T1: healthy, T2: mildly-infected, T3: moderately infected, and T4: severely infected). Most of the satisfactory results occurred in the visible range, especially in the green wavelength. The healthy oil palms and those which were infected by Ganoderma at an early stage (T2) were classified satisfactorily with an accuracy of 83.3%, and 100.0% in 540 to 550 nm, respectively, by ANN using first derivative spectral data. The results further indicated that the sensitive frond number modeled by ANN provided the highest accuracy of 100.0% for frond number 9 compared with frond 17. This study showed evidence that employment of ANN can predict the early infection of BSR disease on oil palm with a high degree of accuracy.

Yellowing disease is one of the most important diseases of black pepper (Piper nigrum L.). To characterize the pathogen(s) responsible for yellowing disease of black pepper in Malaysia, 53 isolates of Fusarium were collected from the roots of diseased black pepper plants and from rhizosphere soils from major growing areas in Sarawak and Johor. A total of 34 isolates of F. solani and 19 isolates of F. proliferatum were obtained and identified based on morphological characteristics and molecular techniques. DNA sequencing of the internal transcribed spacers (ITS1 and ITS2) and 5.8S ribosomal DNA regions was conducted to identify Fusarium species. Nucleotide sequence analysis of the ITS regions revealed that this molecular technique enabled identification of Fusarium at the species level as F. solani and F. proliferatum. In a pathogenicity test on 3-month-old black pepper plants, F. solani was pathogenic, but F. proliferatum was not. On the basis of morphology, DNA sequences and pathogenicity of the fungal isolates from the diseased plants, we showed that yellowing disease on black pepper is caused by F. solani

The effect of Ca, Cu and Zn ions on plant recovery and disease severity following infection of huanglongbing disease was carried out at a commercial citrus orchards belonging to Lembaga Pertubuhan Peladang (LPP) Terengganu, situated at Durian Mentangau, Dungun, Terengganu. Application of Zn or Cu ions in combination with Ca was able to delay disease incidence and severity of hunglongbing disease. These treatments (C/Ca/Cu and C/Ca/Zn) also showed slightly reduction of AUDPC value on infected citrus trees. In general, analysis of macronutrients and micronutrients content in citrus leaves showed significantly different at the beginning of the study (0 to 6 months after treatment) but no significant different were observed at the end of the study period (6-9 months after treatment) as noted on Mg, P, Ca and Zn analysis. Results for specific leaf area showed no significant different among treatment as observed in leaf area, total leaf length and total leaf width. However, specific leaf area was increased gradually in all treatments over the period of the study. The overall results of field trial showed that infected citrus trees treated with combination of Ca and Zn ions at 600 and 10 ppm, respectively resulted in significant increase (P≤0.05) in terms of fruit production and total soluble solid (TSS) content only. Key words: Huanglongbing, candidatus liberibacter asiaticus, field assessment, micronutrients and macronutrients.