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Peanut smut, caused by the soil-borne pathogen Thecaphora frezii, has increased in incidence in the main Argentinian peanut-growing regions. Smut-affected pods transforms the kernel into a mass of teliospores, which survive long-term in the soil. This study is the first large-scale (regional) survey to determine the occurrence and distribution of peanut smut in the main growing area of Argentina. Surveys were conducted in Córdoba province, in randomly selected commercial peanut fields (n = 217) grown from 2015 to 2020. A five-score severity scale has been used to quantify the smut severity on pods (0 = healthy kernels and 4 = totally smutted kernels) and a disease severity index (DSI) is calculated. Pods with severity scores of 3 and 4 are rejected by the industry and produce a high volume of spores that spread among fields increasing the inoculum in the soil. Those pods were classified as severely damaged pods (SDP). We evaluated the relative frequency of smut classes during the years and established the relationships between the yearly incidence and DSI. The mean of the incidence was variable (never zero) across the years and increased from 1.66% in 2015 to 11.47% in 2020. More than 80% of the affected pods belonged to SDP group. The variable SDP, a more time and cost-effective method for quantifying peanut smut, best explained the variation in DSI values. Our results suggest that that visual estimates of incidence and SDP should be useful for disease monitoring, screening genotypes, or treatments comparisons in smut management experiments. Our data update knowledge of the distribution of T. frezii in the peanut-growing area of Argentina.

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The incidence and prevalence of strawberry viruses were determined in surveys of randomly selected strawberry plants grown in different regions of Argentina. In 2009 and 2010, 1034 plants from 28 fields and 1060 plants from 33 fields, respectively, were collected from Lules and Coronda. The samples were analysed by double‐antibody sandwich enzyme‐linked immunosorbent assay to detect Strawberry mild yellow edge virus (SMYEV). In 2014, 606 plants from 43 fields in Lules, Coronda and Mar del Plata were analysed by reverse transcription polymerase chain reaction with primers specific for SMYEV, Strawberry crinkle virus (SCV), Strawberry mottle virus (SMoV) and Strawberry polerovirus 1 (SPV1). The SMYEV incidence was 4–35%, while prevalence was 60–100%, depending on the year and region sampled. Meanwhile, SMoV and SPV1 incidences were 8–17%, and prevalences were 46–62%, depending on the virus and region sampled. SCV was observed relatively low (incidence was 0.5–8% and prevalence was 8–50%), although it was more abundant in Mar del Plata than in the other analysed regions. Spearman's correlation analysis indicated that SCV and SMYEV were correlated with disease symptoms (P < 0.005). A principal component analysis revealed a close relationship between SMYEV and SCV in Mar del Plata, in which the lowest temperatures were recorded. Interactions among viruses, regions and climatic conditions will need to be studied in greater detail. Accurately determining the incidence and prevalence of viruses in different regions will improve estimations of possible damages or yield decreases caused by viral infections during strawberry production.

Peanut smut caused by the soil-borne pathogen Thecaphora frezii, has increased in incidence in the main Argentine peanut growing region. Smut affected pods transforming the kernel into a mass of teliospores, which survive long-term in the soil. This study is the first wide-scale survey to determine the occurrence and distribution of peanut smut in the main growing area of Argentina. Survey was conducted in Córdoba province, in commercial peanut fields (n=217) randomly selected from the 2015 to 2020. The intensity of disease was explored, analyzing the distribution of classes of disease severity from peanut fields, and assessing the relationship between disease parameters. No field with 0% incidence was recorded, being the mean of the incidence increased from 1.66% in 2015 to 11.47% in 2020. Smut symptoms varied from a small sori to the complete transformation of the kernel (severity classes). Severely damaged pods (SDP) were considered severity class 3 and 4, where at least one or both kernels were transformed into a mass of spores, producing a high volume of spores that spread among fields increasing the inoculum in the soil. More than 80% of the infected pods in samples corresponding to SDP. A strong relationship was observed between the disease severity index and incidence (R = 0.99), and between incidence and severity class 3 and 4 (R = 0.97 and R = 0.93), being the linear regression a model that explained the data. The results obtained contribute to progress in the knowledge of the distribution of T. frezii in the peanut-growing area of Argentina. Severity can be estimated by incidence, incidence assessment is faster, more accurate, and reproducible. This is a good technical criterion for monitoring the disease annually, and it can also be used to screen materials in breeding programs or treatments implemented as management strategies for peanut smut.