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Developing Optimized Organic Production Systems for Cucurbits and Apples
Department of Horticulture
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.
2011 Project Description
Objective 1. A field experiment was conducted to control the insect vector of bacterial wilt using row covers. Five treatments were used: T1, reemay removed after transplanting and no pesticides applied; T2, reemay removed at anthesis, organic pesticides applied afterwards; T3, reemay removed at anthesis and replaced 2 weeks later, organic pesticides applied while reemay was removed; and T4, reemay removed at anthesis and replaced 2 weeks later, organic pesticides applied while the reemay was removed.; and T5, standard organic, reemay removed completely at anthesis, organic pesticides applied afterwards, plus Blight Ban.
In order to track the progress of Erwinia tracheiphila as it develops, a new Real-Time PCR screen has been developed to quantitatively assess the presence of the bacteria and track disease development. Blight Ban A506 Pseudomonas fluorescens has been found to affect the progression of the pathogen after infection in the plant. Further investigation into mode of action is on-going. These three projects are being done by a graduate student as part of a PhD project.
Objective 2. This project was subdivided into 5 sub objectives:
- 1 compare shallow tillage to selected annual ground covers.
- 2, evaluate a liquid lime sulfur/fish oil mixture for fruit thinning.
- 3, assess the effectiveness of sulfur-bearing compounds and other non-sulfur materials for management of sooty blotch/flyspeck and cedar apple rust.
- 4, compare physical techniques for control of codling moth, plum curculio and other pests.
- 5, assess fruit quality at harvest and after 8 weeks of cold storage.
A presentation was made at the Organic Association of Kentucky annual meeting.
Objective 3. Two experiments were designed to evaluate soil quality and plant health responses to amendment driven changes in the soil microbial community. To evaluate soil quality responses, an 82 day incubation experiment was conducted across 3 central Kentucky soils. The experiment tested the effects of 4 amendment treatments on soil structure soil microbial community profiles. Amendment treatments consisted of hairy vetch residue, dairy manure, vegetable compost, and a non-amended control. Samples collected on incubation days 0, 5, 12, 30, and 82 were analyzed for water stable aggregation (a measure of soil structure which plays an important role in soil quality), microbial fatty acid methyl esters (FAMEs) and the fungal biomarker ergosterol.
To evaluate plant health responses an experiment is currently being conducted in which a Maury silt loam soil receives 5 amendment treatments: hairy vetch residue, dairy manure, vegetable compost, ammonium nitrate and non-amended control. Tomatoes have been planted in amended soil and selected tomato genes will be analyzed for responses to amendments and relationships to soil microbial biomarkers, including FAMEs and ergosterol.
Genes will be analyzed using quantitative real-time PCR and will include hormone response, nitrogen assimilation, and defense response genes. This project is being conducted by a graduate student as part of his PhD project and he presented the soil quality results at the Soil Science Society of America Annual Meeting.
Objective 1. Results indicate it is possible to reduce the number of pesticide treatments using row covers to exclude the insect vectors. The untreated control treatment performed poorly with a 25% - 27% yield reduction compared to the other treatments. T4 gave the highest yield, although it was only 2% higher then the standard organic practice of T2.
These results will be useful to organic growers by providing a system which they can reliably produce organic cucurbits and reduce pesticide inputs. Blight Ban was found to significantly reduce culls at the end of the season. This is significant given the difficulty of production due to extremely heavy insect pressure in the southeast, and the high cost and relative inefficiency of current organic insecticides.
Objective 2. Significant strides were made in 2011 in controlling pests organically. Codling moth pheromone traps were used, and a codling moth granulosis virus applied. Two physical barriers were used against insect and diseases, Japanese bags and deli bags. Both provided some measure of control against cedar apple rust, powdery mildew, sooty blotch, and flyspeck; as well as codling moth and plum curculio. An organically approved thinning spray of liquid lime sulfur and fish oil was used during apple bloom stage, with good results. A strict 7-day spray schedule for disease and insect control was designed and adhered to.
Taken collectively, these results indicate that it is possible to grow apples organically in Kentucky. This experiment has shown that almost all major production practices are now feasible and 2012 experiments will focus on further developing and fine-tuning control techniques. As it develops, this system will help guide production decisions for KY apple growers interested in organic production.
Objective 3. Results of the soil quality experiment demonstrated that in all three soils vetch, and dairy manure, stimulated greater soil structure formation relative to compost and non-amended soils. Vetch and manure also stimulated higher levels of the fungal fatty acids and the fungal biomarker ergosterol. Vetch promoted the greatest increases in fungal biomarkes as well as the greatest macroaggregate formation. When macroaggregate formation was analyzed against all measured microbial biomarkers it was most strongly related to 18:26 and ergosterol.
These outcomes provide evidence that organic soil amendments such as vetch and manure can be used to influence the microbial community in such a way that it favors formation of soil structure. Given the importance of soil structure and microbial diversity to overall soil quality, these outcomes would be useful to producers, researchers and extension specialists with an interest in building or maintaining soil structure through use of organic amendments. Data for the plant health experiment is currently being collected. We anticipate that the data will show that certain amendments promote a healthier genetic profile in tomato plants than other amendments. Given their important role in transforming organic amendments, we anticipate tomato gene responses to be related to amendment driven changes in the soil microbial community profile.
Scott, D, and M. Williams. 2011. The impact of row cover placement for the organic production of muskmelon and butternut squash in Kentucky. University of Kentucky Fruit and Vegetable Research Report PR 608: 34-38.