Utilizing a Preplant Soil Test for Predicting and Estimating Root Rot Severity in Sugar Beet in the Central High Plains of the United States

Abstract

Aphanomyces cochlioides and Rhizoctonia solani are important soilborne pathogens causing root diseases that are primary constraints to sugar beet production in Nebraska, Colorado, and Wyoming. These types of diseases are difficult to control because they are often not noticed until substantial damage has already occurred. Efforts to manage them would be more effective if techniques were available that were more predictive than reactive. Therefore, a preplant soil test was developed to estimate the relative pathogen populations in the soil and to predict potential root disease problems later in the growing season. Preplant soil samples collected from fields to be sown with sugar beet were planted with a susceptible cultivar and tests were conducted for 1 month in the greenhouse. A preplant disease index was developed based on the time period during the test that seedlings became infected and was calculated on a 0-to-100 scale. Disease index values were compared with yields obtained from the same fields after harvest. Analysis of data collected for 5 years (2003 to 2007) with analysis of covariance revealed a strong relationship between the preplant disease index values and recoverable sucrose and root yields but not sucrose concentration. Results indicated that, for each unit increase in the preplant disease index, root yield decreased by 0.27 metric tons (270 kg) per hectare (P < 0.05, R2 = 0.44) and recoverable sucrose decreased by 49 kg/ha (P < 0.05, R2 = 0.45). We concluded that this preplant soil test can accurately predict root disease potential due to R. solani and A. cochlioides, and has the potential to help producers make effective management decisions in production fields using the index procedure. This soil assay has additionally provided new information on the biology, incidence, and distribution of root pathogens in production fields throughout the Central High Plains.

Challenges and Prospects for Building Resilient Disease Management Strategies and Tactics for the New York Table Beet Industry

“…However, in many cases, risk-averse growers may apply pesticides unnecessarily and make false-positive decisions with adverse effects on crop returns, beneficial soil microorganism populations, and potential for off-site deleterious environmental effects [97]. These practices are due to the inability to adequately evaluate the population of the predominant fungal pathogens causing root disease in a timeframe of practical significance to growers.…”

“…These practices are due to the inability to adequately evaluate the population of the predominant fungal pathogens causing root disease in a timeframe of practical significance to growers. The traditional means of evaluating fungal populations in the soil are bioassays [97] or counting colony-forming units through plating to selective media. To improve site selection to mitigate risk from root diseases significant advances are possible through the provision of knowledge on the levels of DNA of the specific pathogens prior to planting [98].…”

Biochemical characterization and ecofriendly field application of the plant growth-promoting rhizobacterium Bacillus amyloliquefaciens MH046937 isolated from Salsola imbricata in Tur Sinai, Egypt

“…The disease index (DI) was estimated on a scale from 0 to 4. The statistical design work was completely randomized according to the work of Harveson et al (2014).…”

“…PGPR has been considered as one of the most promising tools to achieve the elimination and even prevent soil-borne disease and hence maximize crop yields (Aruna et al, 2020;Devi et al, 2011;Hass and Defago, 2005). It has been proved that PGPR has either indirect or direct effects on plants in order to promote their growth and to increase crop yields through several mechanisms (Devi et al, 2011), nitrogen fixing and phytohormones production (Cattelen et al, 1999), nitrogen availability stimulation, increase of phosphate solubilization and minerals in the soil (Richardson, 2003), and above all control or even prevention of plant pathogens' activities (Babu et al, 2015;Glick, 1995;Glick et al, 1999;Hayat et al, 2010). Several research works studied the mechanisms which microorganisms may use to overcome the disease stress in plants including the production of hydrolytic enzymes (Maurhofer et al, 1994;Mostafa and Abd El Aty, 2013) and siderophores production and hydrogen cyanide (HCN) synthesis (Buysens et al, 1996;Naureen et al, 2017).…”

Inoculum dose–disease response relationships for the pea root rot pathogen, Aphanomyces euteiches, are dependent on soil type and other pathogens

“…In areas with endemic A. euteiches problems, the most recommended practice is disease avoidance based on determining inoculum potential of field soil indexing through greenhouse grow-out tests in field soils ( Levenfors et al., 2003 ; Hughes and Grau, 2007 ; Sauvage et al., 2007 ; Gangneux et al., 2014 ; Harveson et al., 2014 ). Inoculum potential is an index of potential disease activity of the soil dependent on pathogen infectivity and density and soil factors that can either inhibit or promote infection ( Malvick et al., 1994 ; Moussart et al., 2009 ).…”