Survival of Fusarium oxysporum f. sp. lactucae on Crop Residue in Soil

Abstract

Fusarium oxysporum f. sp. lactucae, the cause of Fusarium wilt of lettuce, can survive on crop residue in soil. Persistence of the pathogen over time will be influenced by the rate at which residue decomposes. We evaluated the effect of drying and fragmenting crop residue on the rate of decomposition and survival of F. oxysporum f. sp. lactucae. In a controlled experiment that represented optimal drying conditions, fragmenting and oven-drying infested lettuce taproots at 30°C significantly reduced the frequency of recovery of the pathogen, compared to untreated tissue. However, in a field experiment, drying infested crop residue on the soil surface prior to incorporation did not significantly reduce survival of F. oxysporum f. sp. lactucae after one year. Regardless of treatment, there was not a significant decrease in soil inoculum density between one and 12 months after residue was incorporated. In a greenhouse experiment, fragmenting crop residue prior to incorporation in pathogen-free soil resulted in significantly higher inoculum densities of F. oxysporum f. sp. lactucae after one year. The increase in inoculum levels was associated with a faster rate of residue decomposition, which may be beneficial in the long run but not where lettuce will be replanted within the next year.

The Impact of the Soil Survival of the Pathogen of Fusarium Wilt on Soil Nutrient Cycling Mediated by Microorganisms

“…In contrast, the dynamic change of soluble organic material, in turn, affects the composition of the microbial community [ 40 ]. Crop disease residues in the soil increase the Fusarium wilt pathogen population and may accelerate plant residue decomposition [ 11 ]. We speculated that the pathogen causing Fusarium wilt may affect the soil nutrient cycling by mediating the decomposition process of plant residues, particularly diseased ones, thereby altering soil chemical properties.…”

“…The persistence of pathogenic F. oxysporum in the soil is affected by the host plant residues and its decay rate. The population of pathogenic F. oxysporum decreases naturally as its propagation vectors are consumed, but the pathogen may persist at low levels for several years [ 10 , 11 ]. The lack of protection from host plant residues may decrease the number of pathogens in the soil [ 12 ].…”

Uncovering the hidden within shipping containers: Molecular biosurveillance confirms a pathway for introducing multiple regulated and invasive species.

“…Although IAS eDNA detection does not translate directly into viable species or their propagules' presence in the containers, especially for macroorganisms, it might not be the same for the microorganisms detected. For example, Fusarium oxysporum viability in soil samples can be observed for at least one year (Vakalounakis and Chalkias 2004;Paugh and Gordon 2021). At the same time, Urocystis agropyri can survive for four years in soil samples and even longer in favourable storage conditions.…”

A fast approach to discard false negative susceptible lettuce genotypes to Fusarium oxysporum f.sp. lactucae race 1

“…In Italy, losses up to 70% were observed in susceptible lettuce varieties. Soil disinfestation and crop rotation can help avoiding the spread of the pathogen, but the ability of the fungus to survive beyond 2.5 years as dormant resting structures called chlamydospores in the soil and in the crop residues must be considered (Paugh & Gordon, 2021; Scott et al, 2012). Genetic resistance can provide a complete control of the disease if not compromised by the introduction of new pathogenic races (Scott et al, 2014).…”

“…Lactuca sativa L, qPCR, seedborne, varietal selection, wilt in the soil and in the crop residues must be considered (Paugh & Gordon, 2021;Scott et al, 2012). Genetic resistance can provide a complete control of the disease if not compromised by the introduction of new pathogenic races (Scott et al, 2014).…”