Hafizi Rosli

Incidence and remediation of fungi in a sick building in Malaysia: a case study

Problems caused by indoor microbial, especially fungal growth, have been further exaggerated by the increased incidence of water intrusions, condensation from air-conditioning system, and other factors. While fungal contamination in a building can be one of the indicators of indoor air quality (IAQ), air quality assessment and remediation should be considered as important and should be carried out systematically. This study reports the incidence and remediation of an excessive fungal growth in a building in Universiti Sains Malaysia (USM), Pulau Pinang, Malaysia. Acting on an official report by the building owner and occupants, an immediate walk-through investigation was carried out between June and December 2009. A thorough sampling comprising swab and spore impactor techniques showed that the colony-forming unit per cubic meter of air (CFU/m3) levels were far above those in the guidelines of most developed countries. Thus, the building was declared a ‘sick building’ and closed to the publics. However, through immediate action with recommended methods to overcome the problem, the premise has been pronounced safe. This is a good example of successful teamwork that involved a continuous investigation by a team of experts along with comprehensive action taken by the occupants and other authorities responsible for the building.

Peltaster gemmifer: A new species in the sooty blotch and flyspeck species complex from the United States

ABSTRACT Sooty blotch and flyspeck (SBFS) fungi infect the cuticle of fruit, including apple fruit, and produce pigmented colonies. A new member of this fungal complex in the genus Peltaster is described on the basis of molecular and morphological evidence. The SBFS complex is a diverse group of ectophytic fungi that reside primarily within the order Capnodiales. Sooty blotch and flyspeck isolates from apple orchards in the central United States were subjected to parsimony and Bayesian analyses based on the internal transcribed spacer regions of nuc rDNA, the partial translation elongation factor 1-α gene, and the partial mitochondrial small subunit rRNA gene. Phylogenetic analysis delineated a new species, Peltaster gemmifer, from P. cerophilus and P. fructicola. Peltaster gemmifer conidiophores bear primary conidia that produce secondary conidia either through budding or through microcyclic conidiation; these were not seen in cultures of P. cerophilus and P. fructicola. On cellulose membrane that was placed on water agar amended with apple juice, P. gemmifer produced brown to black pycnothyria in a superficial brownish mycelial mat, similar to the colonies produced on apple fruit. Findings from the present study add to the >80 named and putative SBFS species so far described worldwide.

First report of strawberry leaf spot caused by Alternaria alternata in Pakistan

Strawberry (Fragaria × ananassa Duch.) has recently become an economically important fruit crop in Pakistan and is cultivated on approximately 1500 ha. A survey across Punjab, Khyber Pakhtunkhwa (KPK) provinces and Islamabad (Islamabad Capital territory) was conducted during March and April of 2015-2016 growing season revealed black leaf spot symptoms on strawberry leaves. Leaf spots were irregular in shape, 3 to 6 mm in diameter, and blackish brown. Disease incidence was found 17 to 55 % in visited fields. Portions of symptomatic leaf tissue (3 × 5 mm) were excised from the margins of lesions; surface disinfected with 2% sodium hypochlorite for 2 min, rinsed three times in sterile distilled water (SDW) and blotted dry. Leaf tissue was then placed on Czapek Dox agar (CDA) and incubated at 25 ± 2°C with a 12-h photoperiod for 3 to 6 days. Morphology of the 78 isolates was examined; colonies were initially white, then turned light to dark brown and greyish black and produced abundant aerial hyphae. Conidiop...

Evaluating the Performance of a Relative Humidity-Based Warning System for Sooty Blotch and Flyspeck in Iowa

A warning system for the sooty blotch and flyspeck (SBFS) fungal disease complex of apple, developed originally for use in the southeastern United States, was modified to provide more reliable assessment of SBFS risk in Iowa. Modeling results based on previous research in Iowa and Wisconsin had suggested replacing leaf wetness duration with cumulative hours of relative humidity (RH) ≥97% as the weather input to the SBFS warning system. The purpose of the present study was to evaluate the performance of a RH-based SBFS warning system, and to assess the potential economic benefits for its use in Iowa. The warning system was evaluated in two separate sets of trials-trial 1 during 2010 and 2011, and trial 2 during 2013-2015-using action thresholds based on cumulative hours of RH ≥97% and ≥90%, respectively, in conjunction with two different fungicide regimes. The warning system was compared with a traditional calendar-based system that specified spraying at predetermined intervals of 10 to 14 days. In trial 1, use of the RH ≥97% threshold caused substantial differences between two RH sensors in recording number of hours exceeding the threshold. When both RH thresholds were compared for 2013-2015, on average, RH ≥90% resulted in a 53% reduction in variation of cumulative hours between two identical RH sensors placed adjacent to each other in an apple tree canopy. Although both the SBFS warning system and the calendar-based system resulted in equivalent control of SBFS, the warning system required fewer fungicide sprays than the calendar-based system, with an average of 3.8 sprays per season (min = 2; max = 5) vs. 6.4 sprays per season (min = 5; max = 8), respectively. The two fungicide regimes provided equivalent SBFS control when used in conjunction with the warning system. A partial budget analysis showed that using the SBFS warning system with a threshold of RH ≥90% was cost effective for orchard sizes of >1 ha. The revised warning system has potential to become a valuable decision support tool for Midwest apple growers because it reduces fungicide costs while protecting apples as effectively as a calendar-based spray schedule. The next step toward implementation of the SBFS warning system in the North Central U.S. should be multiyear field testing in commercial orchards throughout the region.