Photodynamic inactivation of Lasiodiplodia theobromae : lighting the way towards an environmentally friendly phytosanitary treatment

The fungus Lasiodiplodia theobromae is one of the main causal agents of trunk canker and dieback of grapevine. The objective of this work was to evaluate the efficiency of photodynamic inactivation (PDI) of L. theobromae with synthetic and natural photosensitizers and irradiation with either sunlight or artificial photosynthetically active radiation. Although the growth of the mycelium could not be completely prevented with natural sunlight irradiation, phenothiazine dyes (methylene blue, MB; toluidine blue O, TBO), riboflavin and a cationic porphyrin (Tetra-Py + -Me) caused complete inhibition under continuous irradiation with artificial light. Free radicals were the main cytotoxic agents in the PDI with MB, indicating the predominance of the type I mechanism. PDI with MB or Tetra-Py + -Me may represent a promising approach for the sanitation of vine material in greenhouse nurseries, in order to reduce the risk of infection upon grafting.

Genome sequence resource of Botryosphaeria dothidea CK16, a fungal pathogen causing Chinese hickory trunk canker disease

Botryosphaeria dothidea is a latent fungal pathogen that causes cankers or diebacks on a variety of host woody plants worldwide. The symptomatic necrosis on the host plants can be triggered by the abiotic stress, such as drought and soil acidification. Here we report a high-quality genome assembly and announcement of the B. dothidea strain CK16 (CGMCC 19654) which causes trunk canker disease on Carya cathayensis in China. The genome sequence of strain CK16 will be useful for studying the evolution, host adaption and pathogenicity of B. dothidea, which will be beneficial for a better understanding of the mechanisms of host-pathogen interaction during the endophytic period.

q-LAMP Assays for the Detection of Botryosphaeria dothidea Causing Chinese Hickory Canker in Trunk, Water, and Air Samples

Trunk canker disease caused by Botryosphaeria dothidea with a prolonged latent infection phase poses a serious threat to Chinese hickory production. To further understand the epidemiological characteristics and develop reasonable management techniques, a quantitative loop-mediated isothermal amplification (q-LAMP) assay was developed to quantitatively monitor B. dothidea in hickory plants, water, and air samples. Specific primers were designed based on the different sites of the β-tubulin sequence between B. dothidea and other fungi commonly found on Chinese hickory. At the optimum reaction temperature of 65.9°C, this loop-mediated isothermal amplification (LAMP) assay can specifically distinguish B. dothidea from other tested fungi. The limit of detection of LAMP assays for B. dothidea was 0.001 ng/µl of pure genomic DNA and 10 spores per 1 ml of water. The q-LAMP assay enables rapid detection of B. dothidea within 60 min in hickory trunk, water in hickory forests, and spores captured on tapes. These results provide a powerful and convenient tool for monitoring B. dothidea, which could be applied widely in epidemiology, forecast, and management of tree canker disease.

Key Plant, Key Pests: Chinese Elm (Ulmus parvifolia)

This series of Key Plant, Key Pests publications are designed for Florida gardeners, horticulturalists and landscape professionals to help identify common pests associated with common Florida flora. This publication, the second in the Key Plant, Key Pests Series, helps identify the most common pests found on the Chinese Elm (Ulmus parvifolia). This publication provides information and general management recommendations for anthracnose or black elm spot, powdery mildew, trunk canker, borers, eriophyid mites and leaf beetles.https://edis.ifas.ufl.edu/ep559

Factors Influencing the Regional Dynamics of Butternut Canker

Butternut (Juglans cinerea) is an important component of native biodiversity in eastern North America. Of urgent concern is the survival of butternut, whose populations are declining rapidly, in large part due to an exotic pathogen, Ophiognomonia clavigignenti-juglandacearum, that causes butternut canker. The disease presently occurs throughout the range of butternut in North America, causing branch and stem cankers, dieback, and tree mortality. Despite the existential threat posed by O. clavigignenti-juglandacearum to butternut, a detailed understanding of the factors that drive cross-scale disease patterns is lacking. Therefore, we investigated the association of a range of factors, including tree attributes, topography, and weather, with butternut canker spatial dynamics at different scales using data collected in the province of Quebec, Canada. Trunk canker damage and dieback showed distinct geographic patterns. Bark phenotype was not significantly associated with trunk canker damage. Results suggest that open or dominant trees may show less dieback than intermediate or suppressed trees. Probability of the presence of trunk canker and percent dieback were proportional to the tree diameter at breast height. Temperature was positively associated with disease severity at a 1-km2 scale. Our results provide strong evidence that multiple factors, notably weather, influence butternut canker epidemiology.