For 2020 and newer grants, please go to https://grants.ipmcenters.org/
Home       Current RFAs       PD User Guide       Projects       Login

Funded Project

Funding Program: Regional IPM Grants (S-RIPM)

Project Title: Cultural Practices for Management of Pod Decay Diseases of Snap Bean

Project Director (PD): John Damicone [1]

Lead State: OK Lead Organization: Oklahoma State University

Research Funding: $64,676

Start Date: Jul-15-2004 End Date: Jul-14-2007

Pests Involved: pod decay diseases

Site/Commodity: snap bean

Summary: Snap bean is an important vegetable crop grown. for processing in Oklahoma and the surrounding states of Missouri, Arkansas, and Texas where up to 20,000 acres are grown. Because snap beans are machine harvested in bulk with non-selective harvesters, the crop is managed to be nearly free of blemishes from disease and without detectable levels of insect and weed parts. An increasing constraint to snap bean production across the four-state region is pod decay. Several water molds, Pythium aphanidermatum, P. ultimum, and a heterothalic Phytophthora spp. have been identified as causal agents in the disease complex. Pod decay is most severe in fields managed for high yield and under a dense foliar canopy. Because the water molds have similar disease cycles, we hypothesize that three mechanisms of pathogen dispersal lead to disease development: 1) direct contact of basal pods with infested soil and water, 2) splashing of infested soil and water on aerial parts and pods, and 3) direct contact of diseased pods with adjacent healthy pods. The proposed research will evaluate cultural modifications to current snap bean production practices in order to disrupt pathogen dispersal using an ecological approach. Planting into a no-till, small grain stubble should reduce splash dispersal, increase the height of lower pods, and provide physical support to reduce lodging. High nitrogen fertility is known to promote lodging, and create a dense foliar canopy which retains moisture and promotes disease development. High and low nitrogen rates will be evaluated under no-till and conventional tillage. Disease development within cultivars with prostrate vs. upright plant habits will be compared. It is anticipated that the combined effects of no-till production, reduced nitrogen, and an upright plant habit will alter plant canopy architecture and resulting microclimate to minimize pod decay without the use of an intensive fungicide program. However, modifications to tillage and fertility systems may also impact arthropod and weed pests. Insect and weed populations will be monitored under the different cultural regimes. Because insects such as thrips have been previously implicated in increasing disease in vegetable crops through wounds caused by their feeding, relationships between insect abundance and disease development will be explored. The impact of additional cultural practices such as row spacing, plant density; and crop rotation will be assessed through surveys of representative commercial fields. Objectives: 1. Assess the impact of an alternative production system that utilizes no-till into small grain stubble, reduced nitrogen fertility, and cultivar to modify canopy architecture on incidence of pod decay and yield of processing snap bean. 2. Determine the association of other cultural practices such as row spacing, plant density, and crop rotation on pod decay through field surveys.

Final Report:

Results PROGRESS: 2004/07 TO 2007/07 OUTPUTS: Pod rot is an important disease that affects snap beans grown for processing in OK and AR. Diseased pods were collected in OK and isolates of both Pythium and Phytophthora were recovered. Most of the Pythium isolates were P. ultimum or P. aphanidermatum. Two Phytophthora species were recovered, P. drechsleri and P. nicotianae. On pods, over 90% of isolates were pathogenic to detached snap bean pods. Most Pythium isolates were pathogenic to seedlings. The P. drechsleri isolates were aggressive and killed seedlings while P. nicotianae isolates were not pathogenic to seedlings. The effects of cultural practices on pod decay were evaluated for a third year in the field in 2007. Romano 942, previously shown to resist pod decay, and Roma II, a susceptible cultivar, were planted in no-till wheat stubble (residue), no-till bare ground, and conventional tillage with zero, low, and high nitrogen levels. Drought conditions during the fall and early winter of 2006 resulted in a sparse density of wheat stubble that did not greatly alter plant structure. Extremely wet weather was present throughout the 2007 growing season, while in previous seasons, moisture was limiting. Over the three years of trials, statistically significant reductions in pod rot were associated with the use of Romano 942 vs. Roma II (50%), no-till vs. conventional till (31%), and no nitrogen compared to both low and high nitrogen application (35%). However, yields were reduced where no nitrogen was used. PARTICIPANTS: B.A. Kahn and M.W. Smith, Department of Horticulture and Landscape Archetecture, Oklahoma State University IMPACT: 2004/07 TO 2007/07 Results show that pod decay is a disease complex caused by at least four different species of water mold fungi which may partly explain why fungicides are not very effective. Growers in the region can reduce, but not completely eliminate, pod decay by planting cultivars with partial resistance and by adopting no-till production practices. The use excessive nitrogen fertilizer did not increase levels of pod rot, but also did not improve yields. PUBLICATIONS (not previously reported): 2004/07 TO 2007/07 1. Dominiak, J.D., and Damicone, J.P. 2006. Identification and characterization of Pythium and Phytophthora spp. from snap bean pods in Oklahoma. (Abstr.) Phytopathology 96:S30. 2. Taylor, J.H., and Rothrock, C.S. 2006. Influence of cultural practices and the environment on pod rot incidence in green beans in the mid-south. (Abstr.) Phytopathology 96:S113.

Outcomes N/A

Impacts From report submitted by the PI to USDA CRIS system Results show that pod decay is a disease complex caused by at least four different species of water mold fungi which may partly explain why fungicides are not very effective. Growers in the region can reduce, but not completely eliminate, pod decay by planting cultivars with partial resistance and by adopting no-till production practices. The use excessive nitrogen fertilizer did not increase levels of pod rot, but also did not improve yields

Close Window

Southern IPM Center North Carolina State University 1730 Varsity Drive, Suite 110 Raleigh, NC 27606 p. 919.513.1432   f. 919.513.1114		Developed by the Center for IPM © Copyright CIPM 2004-2025