Determining efficacy of Waste Lime in Managing Fusarium Root Rot of Field Peas

Determining efficacy of Waste Lime in Managing Fusarium Root Rot of Field Peas

Summary

North Dakota is the largest producer of field peas in the US with an area of 515,000 acres planted to pea in 2008 and contributes to more than 60 per cent of value of production. Area under this crop has rapidly increased from 337,500 acres in 2003 to 847,500 acres in 2007 and this has also resulted in a rise in disease pressure. Root rot caused by Fusarium spp. has become a major constraint for pea production in the north central region over the past years. At present there is a dearth of satisfactory methods to control this disease. No cultivars with complete resistance to Fusarium root rot are currently available, and seed treatments used are also limited in their efficacy. This proposed project is to determine the efficacy of waste lime or spent lime (a byproduct of the sugar industry) in managing Fusarium root rot of peas through laboratory, greenhouse and field trials. The expected outcomes of this project include an increase in awareness among pea growers regarding alternatives to chemical control and efficacy of waste lime against root rot, bring changes in management decisions and recommendations, and provide cost effective, eco-friendly approach for root rot management and thereby increase profitability and sustainability of pea production. The research methods include laboratory, greenhouse and field experiments. One of the two field trials will be conducted in grower’s fields. The results from this project will be made available to pea growers through extension bulletins and websites, and the findings will be presented at grower meetings and seminars at local and national level and publications in scientific journals.

Objectives/Performance Targets

The short term outcomes of this project include increase in awareness and knowledge among pea producers regarding alternatives to chemical control and efficacy of waste lime against root rot diseases. The findings are also expected to lead to changes in management decisions and recommendations, and adoption of this control measure. In the long term this method will provide cost effective, eco-friendly alternative to the use of chemical control measures, help reduce risk of losses due to root rot and other soil borne diseases and increase profitability and sustainability.

Accomplishments/Milestones

Stage1 (Laboratory Experiments):
Initially, the efficiency of waste lime in controlling Fusarium species the most commonly associated with root rots in North Dakota, namely, F. acuminatum, F. avenaceum, F. solani, F. graminearum, F. oxysporum, and F. redolens, was evaluated under in vitro conditions. All the experiments consisted of three replications, and were repeated three times. In studies conducted using solid media, no significant reduction in the radial growth, and growth rate of the fungi were recorded in the lime amended plates. However, differences in the mycelial density were observed. The mycelium in the lime amended plates was always sparse, i.e. less dense compared to the control plates, and a tendency towards aerial growth appeared to be favored. Significant differences in sporulation were detected in all species where sporulation was observed. Spore germination was also affected by the presence of lime in the growth media. The germination percentage of spores of F.graminearum, F.oxysporum, and F.redolens, was reduced only at higher concentrations of 5, and 10 t/ac, but in the other species studied, spore germination was significantly reduced at all concentrations i.e., 1, 2.5, 5, and 10 t/ac. In studies conducted using liquid growth media, the dry mycelial weight of all the Fusarium species was found to be significantly lower in the presence of lime as compared to the control.
Stage 2 (Greenhouse trials):
Greenhouse experiments were conducted to ascertain the efficacy of lime in reducing root rot severity on field peas. Lime efficacy was tested by applying varying rates of lime (equivalent to 0, 1, 2.5, 5, and 10 t/ac) to pots containing soil inoculated with F. avenaceum, and F. solani, the most common pathogens associated with root rot. The experiments showed significant reduction in root rot disease severity, in both F. avenaceum, and F. solani at all the rates of lime application compared to control.
Stage 3 (Field trials):
Two field trials were conducted during the 1st year (2010), at Hickson, ND and Moorhead, MN. The results from 1st year field trials showed the ability of lime application to reduce root rot severity on both field peas and dry beans. The experiments consisted of four treatments i.e., no lime application (control), and lime applied @ 5, 10, and 15t/ac, each treatment had four replicates, laid out in randomized complete block design. Initially, it was proposed to use one resistant and one susceptible field pea cultivar for the field trials. However, we could not find any resistant cultivar in our screening experiments (conducted in a separate study). So, instead of a resistant pea cultivar, we included a root rot susceptible dry bean cultivar to broaden the scope of this trial. Significant differences in root rot severity were recorded between the treatments. Lime applied at higher rates always had lesser root rot severity as compared to the control. At the Hickson site, lime application at all the rates i.e., 5, 10, and 15t/ac showed significantly lower amounts of disease compared to no lime application in both crops. However, at the Moorhead site, lime application only at the rates of 10, and 15t/ac showed significant reduction in root rot severity compared to the control. The trials were affected by high weed pressure at both locations and no significant differences in either stand counts or yield were observed with the application lime in either site.

Impacts and Contributions/Outcomes

Parts of the results from this study (laboratory and greenhouse experiments) were presented as poster at the Annual meeting of the American Phytopathological Society in August 2010 at Charlotte, NC. The results of the laboratory, greenhouse, and 1st year field trials were presented at the Pulse Convention in Minot, ND in January, 2011. Growers showed interest in knowing more about waste lime application for managing root rot.
The abstract of poster presentation can be found here:
http://www.apsnet.org/meetings/Documents/2010_Meeting_Abstracts/a10ma142.htm
Copy of the power point presentation (pdf format) at the Pulse Convention 2011 can be found here:
http://www.northernpulse.com/uploads%5Cresources%5C680%5C2011-rubella-goswami—pulse-disease-research.pdf

Collaborators: