The Host Range of &lt;i&gt;Phomopsis cirsii&lt;/i&gt;; a Potential Biological Control Agent of &lt;i&gt;Cirsium &lt;/i&gt;&lt;i&gt;A&lt;/i&gt;&lt;i&gt;rvense&lt;/i&gt;

Vibeke Leth,Christian Andreasen

doi:10.5923/j.ijaf.20120206.03

The Host Range of Phomopsis cirsii; a Potential Biological Control Agent of Cirsium Arvense

Vibeke Leth, Christian Andreasen

Open Access

https://doi.org/10.5923/j.ijaf.20120206.03

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Abstract

Cirsiumarvense is a noxious perennial weed which has become an increasing problem in North European countries partly because of restriction in use of effective herbicides.Mechanical weedingislabour intensive and expensive and therefore there is a need for an additional method likebiological control. An isolate PKDK101 of the fungus Phomopsiscirsii, which is virulent to C. arvense causing stem canker and die back was chosen to test the specificity of the fungus. A series of infection trials were successively carried out on 127 plant species (incl. ssp. and var.) belonging to 16 families in greenhouses in order to encircle the host range of P. cirsii. Susceptible plant species were found only in the thistle group (Cardueae) which contained 34 species belonging to 12 genera. Susceptible species were found in thirteen of these genera. Highly susceptible species included Carduusacanthoides, Carduuspycnocephalus, Cirsiumeriophorum, Cnicusbenedictus, Galactitestomentosa, Notobasissyriaca, Silybummarianum and Tyrimnusleucographus, which showed symptoms from girdling of stem, heart rot in rosettes to death of entire plants. Mild and restricted symptoms were observed on Carduuscrispus, Carduusnutans, Cirsium echinus, Cirsiumvulgare and Cynaracardunculusvar.scolymus (artichoke) with symptoms such as restricted necrotic leaf spots and too early senescence or death of entire leaf. Eleven hosts for P. cirsii were recorded but despite the expanded range of hosts we expect that its host range will be within Cardueae.P.cirsii,poses multi-target potential against several annual and biennial weedy thistles from warmer climates. The pathogenicity of P. cirsii towards the artichoke, however, could limit its field of application especially in the Mediterranean area. The potential of P. cirsii as a control agent, in areas where artichokes are cultivated, would depend on the existence of P.cirsii resistant varieties or the existence of P.cirsiiisolates non-pathogenic to artichoke.

Highlights

Cirsiumarvense (L.)Scop.is one of the wo rld’s most troublesome and persistent perennial weeds[1],[2]
According to Whapshere[36] it should be e xpected that a bio-control agent isrelativelyspecific ifit only attacks some of the plant species closely related to the target plant.due to the weak species concept of the form-genus Phomopsisand its importance as pathogens ofmany different crop plants[22],[28], it was decided that the present experiments should include an extended number of plant genera and species
Whapsheres assumption did hold true fo r the present P. cirsii isolate which kept its host range within the tribe Cardueae, and even with great variation in susceptibility of the closest related species to C. arvense (Cirsium, Carduus), reaching fro m resistant (0) to h ighly susceptible (9-13) Increasing knowledge about the biology of the genus Phomopsis has revealed that some species are endophytes and invaded the host without creating symptoms or resulting in latent infect ions on some of the apparently resistantspecies of the Cardueae, especially,on the true thistlesCirsium and Carduus spp..none of the symptomless plants expressed symptoms during the pro longed incubation period, until senescence occurred

Summary

Introduction

Cirsiumarvense (L.)Scop.is one of the wo rld’s most troublesome and persistent perennial weeds[1],[2]. In dense stands crop loss can exceed 70%[3]. Contamination of seed, grain or crop straw reduces quality, and spines are a source of physical damage to animals. C. arvense has become an increasing problem in No rth European countries especially in organic agriculture[4],[5],[6],[7],[8]. The plant produces an extensive far-creep ing and deep root system, which insures survival and rapid vegetative spread. New aerial shoots can arise at any point along the horizontal root resulting in dense patchesonly a few years after infestation [2],[9]

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