Control of Soilborne Plant Pathogens by Incorporating Fresh Organic Amendments Followed by Tarping

Abstract

A new method for the control of soilborne plant pathogens was tested for its efficacy in two field experiments during two years. Plots were amended with fresh broccoli or grass (3.4 to 4.0 kg fresh weight m(-2)) or left nonamended, and covered with an airtight plastic cover (0.135 mm thick) or left noncovered. In plots amended with broccoli or grass and covered with plastic sheeting, anaerobic and strongly reducing soil conditions developed quickly, as indicated by rapid depletion of oxygen and a decrease in redox potential values to as low as -200 mV. After 15 weeks, survival of Fusarium oxysporum f. sp. asparagi, Rhizoctonia solani, and Verticillium dahliae in inoculum samples buried 15 cm deep was strongly reduced in amended, covered plots in both experiments. The pathogens were not or hardly inactivated in amended, noncovered soil or nonamended, covered soil. The latter indicates that thermal inactivation due to increased soil temperatures under the plastic cover was not involved in pathogen inactivation. The results show the potential for this approach to control various soilborne pathogens and that it may serve as an alternative to chemical soil disinfestation for high-value crops under conditions where other alternatives, such as solarization or soil flooding, are not effective or not feasible.

Biological Soil Disinfestation (BSD), a new control method for potato brown rot, caused by Ralstonia solanacearum race 3 biovar 2

“…In a study in which we tested disease suppressiveness against Fusarium oxysporum f.sp. asparagi immediately after BSD, thus at the most vulnerable stage, we found similar suppressiveness levels for the BSD and the untreated soil (Blok et al, 2000). A possible explanation for this result is that, unlike broad spectrum soil fumigants, BSD does not create a temporary biological vacuum but a gradual shift from an aerobesdominated microbial community to an anaerobesdominated microbial community and vice-versa upon return to aerobic conditions.…”

“…Such effects have been reported for soil flooding and for soil fumigation (Kreutzer, 1965;Stover, 1979). However, we have obtained indications that for BSD, in contrast to soil flooding and chemical disinfestation, the risk of a significant decrease in disease suppressiveness of the soil is limited (Blok et al, 2000;Goud et al, 2004). In a study in which we tested disease suppressiveness against Fusarium oxysporum f.sp.…”

“…The effect of BSD was further studied using glass mesocosms under laboratory conditions and then in microplots consisting of concrete rings (1.2-m diam) filled with soil, which were positioned in the outdoor quarantine field of the Plant Protection Service and had a cage of metal wires around and above it. Anaerobic soil conditions were induced by increasing microbial respiration through incorporation of fresh organic amendments (grass or potato haulms) and by reducing re-supply of oxygen by covering with airtight plastic sheets (Blok et al, 2000). The soil was covered with airtight plastic tarps (Hermetix, a three-layered coextruded plastic ensilage film, 0.135 mm thick, produced by Klerks Plastic Industry, Noordwijkerhout, the Netherlands).…”

“…Candidate methods include solarization (Gamliel & Stapleton, 1993;Katan, 1981), organic amendments (Conn, Tenuta, & Lazarovits, 2005;Gorissen, van Overbeek, & van Elsas, 2004;Lazarovits, Tenuta, & Conn, 2001) and Biological Soil Disinfestation (BSD). BSD is a new method, first described by Blok, Lamers, Termorshuizen, and Bollen (2000). With BSD, anaerobic soil conditions are induced by increasing microbial respiration through incorporation of fresh organic amendments (e.g.…”

“…With BSD, anaerobic soil conditions are induced by increasing microbial respiration through incorporation of fresh organic amendments (e.g. grass) and by reducing re-supply of oxygen by covering with airtight plastic sheets (Blok et al, 2000). Under these conditions the survival of a number of persistent soilborne pathogenic fungi and nematodes, including Fusarium oxysporum, Meloidogyne spp., Rhizoctonia solani, R. tuliparum, Sclerotinia sclerotiorum and Verticillium dahliae, was strongly reduced or completely eradicated in repeated field experiments over the last ten years (Blok et al, 2000;Blok et al, unpublished;Goud, Termorshuizen, Blok, & van Bruggen, 2004;Lamers, Wanten, & Blok, 2004).…”