The effectiveness of phytosanitary controls in preventing the entry of Colletotrichum acutatum in the UK strawberry sector

Abstract

Phytosanitary legislation is widely thought to be the most effective means of limiting the entry of alien pathogens without hindering trade. However, there is increasing evidence of limitations and weaknesses in phytosanitary systems worldwide. One such case is the entry and establishment of Colletotrichum acutatum in the UK in the 1980s. To investigate this further, data sets of disease incidence gathered by the authorities responsible for plant health between 1984 and 2008 were analysed to determine how and why the pathogen entered the UK and became established on strawberries. Results suggest that the disease entered the UK in 1982 on plants originating from the USA, a year earlier than the first UK record of the disease was reported. At least 54 further cases of infested plant material breached phytosanitary procedures and entered the UK, 75% of which originated from EU countries. Moreover, internal trade transmission was found to be highly influential in the successful spread of the disease. The effectiveness of phytosanitary procedures is limited when the sector is importing large numbers of plants from nurseries that have a track record of selling infested plant material, even if they are accompanied by a plant passport. By taking greater responsibility in limiting the spread of quarantine diseases, nurseries throughout the EU have an important role to play in limiting the entry of alien pathogens.

Latent entry and spread ofColletotrichum acutatum(species complex) in strawberry fields

“…Latently infected planting material can be an important source for C. acutatum inoculum in the field (Calleja et al, 2013). In the present study, a standard protocol was developed for molecular detection of the latent presence of C. acutatum in the old petioles and runners of planting material.…”

“…Planting material that is latently infected with C. acutatum is believed to be the main inoculum source (Sreenivasaprasad & Talhinhas, 2005;Smith, 2008;Calleja et al, 2013). Colletotrichum acutatum has been detected on strawberry planting material in Switzerland (Bosshard, 1997), Finland (Parikka & Lemmetty, 2004) and Belgium (Debode et al, 2009).…”

“…For example, Debode et al (2009) and Parikka & Lemmetty (2004) extracted DNA from 100 mg plant tissue taken from only one plant; a sample of 100 mg plant tissue may not be representative of the whole plant and one single plant is unlikely to represent all plants in the batch. Therefore, a protocol appropriate for testing large batches of planting material to detect the presence of C. acutatum is needed to reliably estimate the extent of fungal presence on a batch of plants (Calleja et al, 2013).…”

Pest risk assessment of Radopholus similis for the EU territory

“…A study in the UK (Calleja et al., ) found for a specific pest ( Colletotrichum acutatum ) that border inspections intercepted about 50% of infested strawberry plants using data of traceable outbreaks on farms. The FVO () carried out an audit in 2011 in a Member State and reported that the inspections cannot in all cases be considered to be based on representative samples.…”

Comparative pathogenicity of Colletotrichum spp. against different varieties of strawberry plants (Fragaria ananassa) widely grown in Morocco

“…In Europe, C. acutatum is the most prevalent species causing anthracnose, whereas C. gloeosporioides is found only occasionally, and C. fragariae has not yet been observed (Denoyes and Baudry, 1995;Garrido et al, 2008). In UK, the first incidence of anthracnose disease in strawberries caused by C. acutatum was attributed to the importation of infected strawberry runners from the USA (Calleja et al, 2012). These fungal species affects fruit quality and causes significant pre-and post-harvest fruit losses, especially during wet weather (Prusky and Plumbey, 1992;Prusky, 1996;Arauz, 2000;Chrys, 2006).…”