Research Accomplishment Reports 2009

Developing Optimized Organic Production Systems for Cucurbits and Apples

M. Williams
Department of Horticulture

 

Non-Technical Summary

This project is focused on developing organically-managed production systems for select fruit and vegetable crops. A focus on two very economically important and difficult-to-grow crops is proposed. Additionally, the effects of organic soil amendments will be evaluated to determine ways to maximize and improve soil quality attributes that impact plant growth.

This project will attempt to alleviate one of the major constraints in organic melon production thereby facilitating the production of this family of crops by Kentucky growers. This project also had the potential to develop a sustainable organic apple production system for Kentucky growers, which currently does not exist.

Lastly this project seeks to scientifically show the benefits of cover cropping in a way that will direct their use in the production systems in the first two objectives. It is believed that this information would be applicable to a range of other crops and systems.

2009 Project Description

Objective 1: Field experiments in 2009 were conducted to evaluate the efficacy of using exclusion to control cucumber beetle and the bacterial disease it vectors in an organic melon production system. This experiment tested the ability of extended duration row covers to control the beetle. Typical organic control uses row covers until flowering with pesticide application for the rest of the season. This does not work in areas of the country with heavy beetle infestation such as Kentucky. This season allowed us to determine the most effective ways to integrate row covers and results will guide 2010 experimental changes. This project is the main component of a PhD thesis for a graduate student. Findings from this year were presented in a Horticulture departmental seminar and at the 2010 Kentucky Fruit and Vegetable Growers annual meeting in Lexington, KY. The audience was around 100 people. The field site was used for two grower's tours (20-30 per tour) and as part of a half day extension agent training in organic production methods. Data from the project was also published in the 2009 KY Fruit and Vegetable Research Report.

Objective 2: During the first three years of this project, which was started in 2007, diseases and insects were managed by adhering to a spray schedule timed to coincide with apple bloom stages. In the third year of establishment (2009), the orchard was allowed to bear fruit. Only preliminary data was obtained from the fruit as the growing season was particularly difficult due to abnormally high rainfall amounts, which led to significant problems with disease. However, main disease and insect problems were identified, and plans for the fourth year of the orchard, are based on the problems from the third year. Results were presented at the at the 2010 Kentucky Fruit and Vegetable Growers annual meeting in Lexington, KY, and the site was used on numerous farm tours for growers, students, and the public.

Objective 3. The research associated with this objective is currently in progress. Three soils (a sandy loam, a silt loam and a silty clay loam) have been identified, collected, and characterized for carbon content, fertility, pH, cation exchange capacity and other physical and chemical soil properties. Baseline microbial community analysis on these soils has also been performed using an ester-linked fatty acid methyl ester method (EL-FAME). Amendments have been produced or obtained and have been characterized for carbon content and nutrient content. A preliminary incubation has been carried out to determine the best method with which to analyze soil aggregate formation: wet sieving or dry sieving. An amino sugar method for analyzing bacterial and fungal cellular residues in soil is currently being optimized for use in our laboratory. This project is the main component of a PhD thesis for a graduate student.

2009 Impact

Objective 1. Experiments in 2009 confirmed that it is possible to obtain economically viable harvest and levels of cucumber beetle control in melons using an integrated organic system. One of the main objectives was to evaluate the use of bumble bees as alternative pollinators under extended-duration row covers. This treatment was shown to be ineffective and will not be recommended to growers in the future. Data from this project was used as preliminary data for a USDA-OREI grant. That grant was successfully obtained as part of a multi-state project and is funding an expansion of the work proposed in this objective.

Objective 2. The 2009 year allowed the main disease and insect problems that are limiting for organic apple production to be identified. Fire blight, cedar apple rust, sooty blotch, and flyspeck were the most significant diseases present. Most significant insects included plum curculio, codling moth, and stinkbug. New control methods for the future will include the use of trunk banding and codling moth granulosis virus (CpGV) for codling moth, as well as increased sanitation to control plum curculio. Additionally three physical barriers against insects and diseases were tested in 2009. These were Japanese bags, deli bags, and nylon footies all applied to the fruit for disease and insect exclusion.

The Japanese bags and deli bags provided some level of control against rust, powdery mildew, fungal diseases, and codling moth. The nylon footies had higher incidence of fungal diseases than the other treatments. This experiment is already confirming that organic apple production is possible in KY. The most difficult to control factors have been identified and 2010 experiments will focus on developing suitable controls. Once developed this system could help guide production decisions for KY growers.

Objective 3. Although most of the work in this objective is still in the early stages, preliminary results were used in a successful SARE grant that will partially fund the graduate student that will use this project for his PhD research.