Plant pathogens as biocontrol agents of Cirsium arvense – an overestimated approach?

Abstract

Cirsium arvense is one of the worst weeds in agriculture. As herbicides are not very effective and not accepted by organic farming and special habitats, possible biocontrol agents have been investigated since many decades. In particular plant pathogens of C. arvense have received considerable interest and have been promoted as “mycoherbicides” or “bioherbicides”. A total of 10 fungi and one bacterium have been proposed and tested as biocontrol agents against C. arvense. A variety of experiments analysed the noxious influence of spores or other parts of living fungi or bacteria on plants while others used fungal or bacterial products, usually toxins. Also combinations of spores with herbicides and combinations of several pathogens were tested. All approaches turned out to be inappropriate with regard to target plant specificity, effectiveness and application possibilities. As yet, none of the tested species or substances has achieved marketability, despite two patents on the use of Septoria cirsii and Phomopsis cirsii. We conclude that the potential of pathogens for biocontrol of C. arvense has largely been overestimated

Survival and regeneration ability of clonal common milkweed (Asclepias syriaca L.) after a single herbicide treatment in natural open sand grasslands

“…Other example, hemp dogbane (Apocinum cannabinum), which has a similar biology and belongs to the Asclepiadaceae family of common milkweed, is sensitive to fluroxypyr [107] a herbicide that is usually favored during early reproductive stages because it can translocate toward roots [108,109]. In addition, the phenological state of the invasive clonal plant must be considered when applying any herbicides [36,102]. For example, herbicide treatment can be more efficient when assimilates translocate to the roots in the late summer, as reported in several studies on other invasive clonal plants [110,111].…”

“…Clonality is common among invasive plants [24, 25,26]. The common reed Phragmites australis [27], alligator weed Alternanthera philoxeroides [28,29], Japanese knotweed Fallopia japonica [30][31][32][33], Solidago species [14,34], and Canada thistle Cirsium arvense [35,36] are examples of problematic invasive clonal species. Their success is partly due to translocation of water, nutrients, and photoassimilates among physically interconnected shoots [37][38][39][40][41][42].…”

“…Their success is partly due to translocation of water, nutrients, and photoassimilates among physically interconnected shoots [37][38][39][40][41][42]. However, pathogens can also be transported through the same clonal network [36,[43][44][45] as can heavy metals [46,47] and herbicides [17,[48][49][50][51]. Bud banks on a clonal network play an important role in competition, vegetative multiplication, and resprouting [52,53].…”

Survival and regeneration ability of clonal common milkweed (Asclepias syriaca L.) after a single herbicide treatment in natural open sand grasslands

“…Clonality is common among invasive plants 24 – 26 . The common reed Phragmites australis 27 , alligator weed Alternanthera philoxeroides 28 – 30 , Japanese knotweed Fallopia japonica 31 – 35 , Solidago species 14 , 36 , and Canada thistle Cirsium arvense 37 , 38 are examples of problematic invasive clonal species. Their success is partly due to translocation of water, nutrients, and photoassimilates among physically interconnected shoots 39 – 44 .…”

Production and Stabilization of Mycoherbicides

“…or "Athletes foot or Achilles heel?" [4][5][6][7][8][9]. This is partly because the biological herbicides as distinct from chemical preparations are not "stand alone" products.…”