Influence of Formononetin and NaCl on Mycorrhizal Colonization and Fusarium Crown and Root Rot of Asparagus

Abstract

Replanted asparagus fields commonly fail to produce a profitable stand due to alleopathic residues left behind from the previous asparagus crop, elevated densities of pathogenic Fusarium spp., and low densities of vesicular arbuscular mycorrhizae (VAM). Formononetin, a plant isoflavone that stimulates VAM spores to germinate, and sodium chloride (NaCl), a disease-suppressing amendment, were evaluated alone and in combination for their effect on reestablishing asparagus at two locations in abandoned asparagus fields. Greenhouse studies also were conducted with naturally and artificially infested soils. Formononetin was applied as a crown soak or soil drench, and NaCl was applied as a granular treatment. Feeder roots from soil cores sampled from field plots and from greenhouse transplants were assayed for colonization by VAM and for lesions caused by Fusarium oxysporum and F. proliferatum. Formononetin increased the number of VAM vesicles in roots from the field and greenhouse studies and reduced the percent root lesions caused by Fusarium spp. when compared with the nontreated controls. NaCl was more effective than formononetin in reducing the percentage of root lesions in both field and greenhouse experiment when compared with untreated plants but had no effect on VAM colonization. However, there was evidence that NaCl negated the effect of formononentin on VAM colonization. The NaCl treatment increased the May 2001 spear number by 15% and marketable spear weight by 23%. At one site, treatment with formononetin increased mean number of stalks per plant by 29% in 2000 and 14% in 2001. Both formononetin and NaCl improve growth and reduce disease of asparagus in replanted asparagus and may be useful in reestablishing asparagus in abandoned asparagus field.

Combining nonpathogenic strains of Fusarium oxysporum with sodium chloride to suppress fusarium crown rot of asparagus in replanted fields

“…Asparagus is very NaCl‐tolerant (François, 1987), and applications in the range 500–2000 kg NaCl ha −1 can stimulate asparagus growth, suppress fusarium crown and root rot (Walker, 1905; Elmer, 1992; Poll, 2000; Reid et al ., 2001), and reduce slug damage (Ester & van Rozen, 2003). Furthermore, applications of NaCl have benefited asparagus that was cropped in replanted fields (Elmer, 2002). It is most beneficial when plantings are under stress from drought or disease (Elmer, 1992; Reid et al ., 2001).…”

Negative feedback on a perennial crop: Fusarium crown and root rot of asparagus is related to changes in soil microbial community structure

“…Mycorrhizal fungi were associated to reduced severity of FCRR (Elmer, 2002;Matsubara et al, 2002). Some arbuscular mycorrhizal isolates were found more effective than others, in this regard (Matsubara et al, 2001).…”

“…In contrast, formononetin, a molecule that stimulates arbuscular mycorrhizal fungi, has reduced the percentage of asparagus root lesions caused by Fusarium spp. when compared to a non-treated control (Elmer, 2002). Arbuscular mycorrhizal fungi are well known as wide spectrum biocontrol agents (Dehne, 1982;St-Arnaud et al, 1995), and were associated to reduce severity of FCRR in asparagus seedlings (Elmer, 2002) and in commercial asparagus plantations (Matsubara et al, 2001).…”

“…when compared to a non-treated control (Elmer, 2002). Arbuscular mycorrhizal fungi are well known as wide spectrum biocontrol agents (Dehne, 1982;St-Arnaud et al, 1995), and were associated to reduce severity of FCRR in asparagus seedlings (Elmer, 2002) and in commercial asparagus plantations (Matsubara et al, 2001). Higher FCRR incidence was also associated with reduced populations of Mn-reducers, mostly fluorescent pseudomonads, among which some had biocontrol activity (Elmer, 1995a(Elmer, , 2003.…”

Management of Fusarium crown and root rot of asparagus

“…to germinate (Nair et al, 1991). When formononetin was applied to transplants and one-year-old crowns, the percentage of roots colonized by arbuscular mycorrhizae increased in the greenhouse and field (Elmer, 2002b). Another method that promotes increased mycorrhizal colonization of asparagus is the incorporation of charcoal or biochar into soil (Elmer and Pignatello, 2011;Matsubara et al, 2002).…”