Ceratocystis wilt disease surveys were conducted in three selected Malaysian Acacia mangium plantations. These completed surveys revealed the occurrence of the wilt disease, with the incidence of infection ranging from 7.5% to 13.6%. Signs of wood-boring insects, bark peeling due to squirrel activity, and pruning wounds were often associated with this disease. The fungus most frequently isolated from the diseased trees was the Ceratocystis fungus. The analysis on the morphological characteristics has identified the fungus as Ceratocystis fimbriata complex. Phylogenetic analysis based on the sequences of the ITS, and concatenated sequences of EF1α-βT regions grouped the isolates within the C. fimbriata sensu stricto, in comparison to other C. fimbriata isolates. Pathogenicity tests were conducted on six to nine-month-old healthy A. mangium seedlings by inoculating these seedlings with eight out of the 16 isolates. The results demonstrated that all the isolates were pathogenic, with mortality beginning as early as two weeks after inoculation. However, an ANOVA test indicated a significant difference between the pathogenicity levels among the fungal isolates. The results also showed that pathogen aggressiveness was not correlated with geographical origin. A host range test was also conducted by using C. fimbriata SSB3 and FRIM1162 isolates against several forest plantation species. The findings suggested that only A. mangium was susceptible to C. fimbriata. The other species remained healthy with no symptoms of infection even after seven weeks of treatment, as compared to the A. mangium species, where between 38 to 60% of the inoculated plants had died. This study provides new information on the status of Ceratocystis wilt disease, especially on the occurrence and effects on A. mangium plantation, by giving insights on how to control and manage this ferocious plant pathogen in the future.

Wodyetia bifurcata Irvine, commonly known as the foxtail palm, is a graceful palm species that has caught the interest of horticulturists and landscape architects due to the uniqueness of its foliage, fast growth, and lack of significant plant pests. In January 2016, a disease inspection carried out at the Royal Selangor Golf Club, Kuala Lumpur found four foxtail palm trees were infected by basal stem rot (BSR). In the field, the trees were observed to show pale green, wilted leaflets and collapsed fronds with only a single spear leaf remaining (Fig. 1a). At the base of infected trees, the presence of white fungal primorida, depression in outer bark and necrotic symptoms were visible on basal stem bark (Fig. 1b). Dead tissues underneath the outer bark were obvious; the tissues were brown, rotten and moist with the presence of white mottling mycelia (Fig. 1c). However, healthy tissues were found to be firm and cream in color. Rotten stem of the affected palm emitted a mushroom-like odor, brownish, dry and ...

Brown root rot disease (BRRD) is a highly destructive tree disease. Early diagnosis of BRRD has been challenging because the first symptoms and signs are often observed after extensive tissue colonization. Existing molecular detection methods, all based on the internal transcribed spacer (ITS) region, were developed without testing against global Phellinus noxius isolates, other wood-decay fungi, or host plant tissues. This study aimed to develop SYBR Green real-time quantitative PCR (qPCR) assays for P. noxius. The primer pair Pn_ITS_F/Pn_ITS_R targets the ITS, and the primer pair Pn_NLR_F/Pn_NLR_R targets a P. noxius–unique group of homologous genes identified through a comparative genomics analysis. The homologous genes belong to the nucleotide-binding-oligomerization-domain-like receptor (NLR) superfamily. The new primer pairs and a previous primer pair G1F/G1R were optimized for qPCR conditions and tested for specificity using 61 global P. noxius isolates, 5 other Phellinus species, and 22 non-Phellinus wood-decay fungal species. Although all three primer pairs could detect as little as 100 fg (approximately 2.99 copies) of P. noxius genomic DNA, G1F/G1R had the highest specificity and Pn_NLR_F/Pn_NLR_R had the highest efficiency. To avoid false positives, the cutoff quantification cycle values were determined as 34 for G1F/G1R, 29 for Pn_ITS_F/Pn_ITS_R, and 32 for Pn_NLR_F/Pn_NLR_R. We further validated these qPCR assays using Ficus benjamina seedlings artificially inoculated with P. noxius, six tree species naturally infected by P. noxius, rhizosphere soil, and bulk soil. The newly developed qPCR assays provide sensitive detection and quantification of P. noxius, which is useful for long-term monitoring of BRRD status.