Biological control of brown rot disease caused by Monilinia Laxa in cherries and plums

Monilinia laxa is the causal agent of brown rot disease on stone fruits, and also causes blossom wilt and twig canker. The common practice used to manage this disease is through fungicide treatments, especially during the flowering and fruiting period. However the demand to reduce fungicide input has been increasing and there is a growing number of reports of M. laxa strains that are resistant to fungicides. This study is based on the development of biological control agents (BCAs) as an alternative strategy for disease control using either existing BCA products or new indigenous isolates from UK orchards. Efficacy of exotic commercial BCAs against M. laxa was investigated using in vivo tests on cherries and plums. Serenade partially inhibited M. laxa while the other four BCA products (BioPK, BoniProtect, Prestop and Trianium) had no effect against the pathogen. Indigenous BCAs were isolated from healthy leaves, intact fruits and mummified fruits of cherries and plums collected from orchards in Kent. A total of 217 isolates were screened against two strains of M. laxa in a series of in vitro tests using a dual culture technique. From these tests, 12 isolates were selected for further screening. The final screening based on in vivo tests on cherries and plums narrowed these down to two isolates with good potential for development. They were further tested under post-harvest conditions by dipping cherries and plums in suspensions of cells of the individual control agents and storing treated fruit under standard storage conditions. The two BCAs did not control brown rot on cherries under these conditions, and the low incidence of natural infection by M. laxa in plums also meant that significant control could not be demonstrated. The two BCAs were identified as Bacillus amyloliquefaciens/subtilis (isolate B91) and Aureobasidium pullulans (isolate Y126). Their modes of action were investigated. Bacillus sp. B91 was shown to produce soluble and volatile organic compounds which inhibited M. laxa, while A. pullulans Y126 apparently competes with the pathogen for nutrients and did not produce inhibitory compounds. The capability of B91 and Y126 to grow and survive at low temperatures was studied. Bacillus sp. B91 was shown to be a mesophillic bacterium that could grow at 10-25°C but suffered significant mortality at 0 and 5°C, while A. pullulans Y126 was both mesophilic and psychrotolerant because it grew between 0-25°C, although 20°C was the optimum temperature. Once all nutrients were removed, Y126 was able to survive for several weeks in all test temperatures (0-25°C) but showed significant mortality at 25°C. The capability of B91 to survive at 20 and 25°C was higher than low temperatures (0-15°C). Molecular studies were used to show that M. laxa populations on mummified fruits were likely to be responsible for fruit rot infection in the same orchards the following season. Geographical origin and host also influenced the population structure of M. laxa. Field trials were conducted in which mummified fruits were either treated with a commercial fungicide (Indar) or BCAs to investigate whether these treatments would significantly reduce sporulation of the pathogen in the field thus reducing the infection load in the spring. Spraying in Winter alone was not sufficient to significantly suppress sporulation of M. laxa but the efficacy was improved when the control agents were applied in Spring either as a single spray or in combination with a Winter spray. Sprays of Indar or A. pullulans Y126 greatly suppressed sporulation on mummified fruits if the fruits were treated on both occasions. It was concluded that the two novel, indigenous BCAs have potential to control M. laxa but more research is necessary to develop these two potential BCAs for field use

Identification and Characterisation of New Microbial Antagonists for Biocontrol of Monilinia laxa, the Causal Agent of Brown Rot on Stone Fruit

Monilinia laxa is the causal agent of brown rot disease on stone fruits, and also causes blossom wilt and twig canker. The common practice used to manage this disease is through fungicide treatments. However the demand to reduce fungicide inputs has been increasing and there is a growing number of reports of M. laxa strains that are resistant to fungicides. There is an urgent need to search for an alternative strategy to control the disease. This study focused on the isolation and characterisation of biological control agents (BCAs) using indigenous isolates isolated from cherries and plums collected within the UK. A total of 192 isolates were screened against two strains of M. laxa in a series of in vitro dual culture tests. From this in vitro screen, 12 isolates were selected for a subsequent in vivo screen on detached fruits, which then narrowed these isolates down to two potential BCAs. These two strains were identified as Bacillus amyloliquefaciens/subtilis (isolate B91) and Aureobasidium pullulans (isolate Y126). The capability of these two potential BCAs to grow and survive at a range of temperatures likely to be experienced under field and storage conditions was studied in order to gain knowledge for product formulation and field application. Bacillus sp. B91 was shown to be a mesophilic bacterium that could grow at 10–25 °C but suffered significant mortality at 0 and 5 °C, while A. pullulans Y126 was both mesophilic and psychrotolerant as it grew between 0–25 °C with the optimum at 20 °C. When all nutrients were removed, Y126 was able to survive for several weeks in all test temperatures (0–25 °C) but showed significant mortality at 25 °C. The capability of B91 to survive at 20 and 25 °C was higher than at low temperatures (0–15 °C). In addition, the modes of action of the potential BCAs were studied. B91 was shown to produce soluble and volatile organic compounds that inhibited M. laxa, while A. pullulans Y126 did not produce inhibitory compounds, but appeared to inhibit the pathogen via competition for nutrients. This study shows that microbial antagonists against M. laxa can be found from indigenous sources and that they are capable of preventing brown rot disease in controlled conditions, thus demonstrating a potential to be developed into commercial products

<I>Lauriomyces</I>, a new lineage in the Leotiomycetes with three new species

Lauriomyces is an anamorphic genus comprising nine species, found growing on terrestrial leaf litter and wood in tropical habitats. The genus is characterized by solitary or synnematous, pigmented conidiophores bearing acropetal chains of unicellular, hyaline conidia. A multigene (SSU, LSU &amp; 5.8S) analysis of Lauriomyces strains reveal three cryptic new species, which are described, illustrated, and published here: L. acerosus, L. basitruncatus, and L. glumateus spp. nov. Lauriomyces glumateus is characterized by narrowly oval conidia while conidia of L. acerosus are cylindrical with acute ends and those of L. basitruncatus are cylindrical with truncate base. The nine Lauriomyces species sampled form a monophyletic clade in the Leotiomycetes, with high molecular support and all with a morphology typical for the genus. The new combination Dematioscypha catenata is made for Haplographium catenatum in compliance with the one name protocol.</p

Epidemiology and management of brown rot on stone fruit caused by Monilinia laxa

Stone fruit is attacked by various pathogens, of which brown rot disease is one of the important diseases. There are three Monilinia species mainly responsible for the brown rot disease: Monilinia fructicola is mainly found in North America and Australasia, and M. laxa and M. fructigena mainly in Europe. Both M. fructicola and M. laxa can infect flowers, resulting in blossom blight, as well as both healthy and wounded fruit, resulting in brown rot. On the other hand, M. fructigena can only infect wounded fruit. Compared to the two other species, M. fructicola has been extensively studied, whereas the equally important M. laxa has had less attention. This paper addresses this imbalance and reviews research on the biology, epidemiology and management of M. laxa on stone fruits. Due to EU regulations, the number of fungicides available for controlling plant diseases has been steadily decreasing, particularly in the post-harvest environment. This has placed much more emphasis on alternative control methods, a focus of the present review. Numerous physical and biological approaches to control have achieved successful outcomes but often in small-scale trials and in isolation from integrated strategies. Promising physical control methods include removal of mummified fruit in orchards and post-harvest hot-water treatment. Many micro-organisms have been shown to have biocontrol potential against brown rot but only a few have been commercially formulated. It is generally agreed that the use of biocontrol agents needs to be integrated with other measures. Current research focuses on disease management from flowering to post-harvest period. Recent results have suggested that reducing overwintering inoculum should be considered as one of key aspects of integrated management of brown rot on stone fruit. Finally, we make recommendations about future research and development on integrated pest management strategies for control of M. laxa, especially on strategic deployment of biocontrol agents and interactions among brown rot pathogens

A novel strategy to reduce overwintering inoculum of Monilinia laxa.

Brown rot on cherry and plum, caused by Monilinia laxa, is an important disease, for which overwintered mummified fruit is a significant inoculum source for infection of flowers and fruit in the spring. Experiments were conducted to assess the potential of applying plant protection products in winter and/or early spring to suppress sporulation on mummified fruit. Products tested included Indar 5 EW (a commercial fungicide, a.i. fenbuconazole), Aureobasidium pullulans Y126 [a candidate biocontrol agent (BCA)]), Bacillus sp. B91 (a candidate BCA) and Serenade (a commercially formulated BCA of Bacillus subtilis strain QST 713) in addition to control treated with tap water. Indar and A. pullulans Y126 significantly reduced sporulation when applied once in winter. Overall, a single treatment in early spring (February) was slightly more effective than single treatment in winter (November). Application of all products in both winter and early spring led to significant reduction in sporulation. Indar had the highest efficacy, reducing the number of spores from 9?×?105 to 5?×?103 per mummified plum when applied twice. Of the three BCAs applied on both occasions, A. pullulans Y126 had the highest efficacy, reducing the number of spores from 9?×?105 to 5?×?104 per mummified plum. There were no synergistic but additive effects between the two applications in winter and early spring based on the Bliss independence test. These results suggest that reducing overwintering inoculum in dormant season is effective and may be part of an integrated management strategy for brown rot on stone fruit

Isolation and Identification of Fungi with Glucoamylase Activity from Loog-pang-khao-mak (A Thai Traditional Fermentation Starter)

Loog-pang-khao-mak is a Thai traditional fermentation starterthat has been used for production of Thai fermented foods for decades. This research aimed to isolate and identify the fungi that produce effective glucoamylase but low ethanol content from the starter. A total of 166 isolates were screened from twelve samples of Loog-pang-khao-mak accumulated from 12 provinces in Thailand using dichloran rose bengal chloramphenicol agar (DRBC Agar). Seventy-nine isolates that effectively hydrolyze starch were selected for glucoamylase activity and alcohol production assay. Three yeast isolates exhibited high glucoamylase activity ranging from 139.14 to 140.94 unit/ml and lowest alcohol yield of 0.41% (v/v) were Saccharomycopsis fibuligera using morphological and molecular identification. The five isolates of mold exhibited high glucoamylase activity (149.20 to 152.60 unit/ml) were identified as Aspergillus niger, Aspergillus oryzae and Amylomyces rouxii. These findings provide further knowledge on the fungi and their potential use as traditional inocula for fermentation of food products

Isolation and evaluation of biocontrol agents in controlling anthracnose disease of mango in Thailand

The agricultural based economy is a core business in Thailand and food export is one of the main sources of income for the Thai population. However, pesticides are overused and misused. As a result there is an urgent need to reduce the use of synthetic chemicals. Biological control offers an alternative to the use of pesticides. Mango (Mangifera indica L.) is widely planted in Thailand and is one of the major cash crops for international export. However, mango suffers from various diseases especially anthracnose, a fungal disease caused by Colletotrichum gloeosporioides. One hundred and twelve isolates of epiphytic microbes were isolated from healthy leaves and fruits of mangoes; this included 93 and 19 isolates of epiphytic bacteria and yeasts, respectively. They were screened for bioactivity against a pathogenic strain of C. gloeosporioides isolated from diseased mangoes using a dual culture technique. Out of 112 isolates, eight isolates exhibited at least 60% inhibition. These isolates were further screened for their inhibition on mango using fruit inoculation. Two isolates reduced the lesion sizes caused by C. gloeosporioides compared to control treatment. These two isolates, based on phenotypical and biochemical tests, were identified as Bacillus sp. MB61 and Bacillus sp. LB72