Project Objectives: MSU Organic Apple Project
Project objectives
Soil fertility and biology
Tree vigor and ground floor management
Pest and insects
Control of apple scab and fire blight
Costs of production
Education and certification
Objective 1: Soil Fertility and Biology (George Bird, Entomology)
Since 1999, tree rows have shown increases in nitrate, phosphate, potash and calcium. Nutrients have been applied primarily as dried alfalfa hay mulch. Current high levels of nitrate nitrogen indicate that soil bacteria are working hard. Improved, but not yet adequate, levels of phosphate indicate that soil fungi are gaining in activity, with even more needed. Soil quality within rows has improved dramatically. Management will now focus on improving areas between rows.
The soil quality associated with the organic apple orchard site at the Michigan State University Clarksville Horticulture Research Station site has been monitored since May 26, 1999 . The focus of this initiative has been to: 1) document the dynamics of the soil food web in relation to the transition process, 2) use recommendations from the Bio-Test of Bio-Systems Soil Testing and Consulting Services Inc. for the soil management decision-making process and 3) develop a comprehensive understanding of the vertical distribution of the soil organisms associated with the site. This summary is designed to compare selected aspects of the current state of the orchard with those at the start of the transition from a conventional corn-soybean system.
Soil Food Web. In 1999, the mean active bacterial biomass associated with the site was low, 13.2 ug/g soil. During the transition period this increased to a high level and currently at 71ug/g at a 0 to 6 inch soil depth. The active fungal biomass, however, has not improved. It started low at a mean of 9.1ug/g soil and currently remains low at 11.3/ug/g soil. All data associated with the soil quality aspect of the project as from six sampling areas in the southern two-thirds of the orchard. Soil population densities of flagellates and amoebae remain low in the soil in a significant number of areas, while densities of ciliates are high. This may be an indication of soil compaction.
Population densities of bacterial feeding nematodes started low at 381 per 100 cm 3 in the spring of 1999. By October of 2002, they had increased to a reasonably optimal level of 1,425 per 100 cm 3 soil. No similar increase was observed with fungal feeding nematodes. The initial population density was 55 per 100 cm 3 soil. The current population density is 19.1 per 100 cm 3 soil. The MSU nematode population density data are in direct agreement with the data from Soil Food Web, Inc. Current Fungal feeding nematode population densities are much higher at a commercial organic farm in Barry County that was certified 18 years ago. The site needs to be improved in relation to its fungal biology.
Bio-Test .- Initial 1999 data from the Bio-Test indicated that the conventional soybean-corn site was very high in potash, very low in calcium, had a CEC of 3.5 and SOM of 1.2. The nitrate and phosphorus levels were very low and the soil was not considered very active from the Bio-Test energy analysis. These and subsequent soil monitoring data were used for soil quality management decisions. Today, the soil is very high in potash, very high in phosphate with medium levels of calcium and appropriate levels of nitrate. The pH is about 6.9 and the Bio-Test energy levels are very good.
Vertical Distribution of Soil Microbes. - Initially, all soil samples were taken at a 0 to 12 inch soil depth. This was changed early in the transition because of literature indicating that the most active microbial are was at a 0 to 6 inch soil depth. Because of questions related to the length of soil food chains at different soil depths, the vertical distribution of soil microbes rapidly became a major focus of the soil quality component of this project.
In 2001 and 2002, the soil sampling protocol consisted of taking separate samples form the litter layer (o-horizon), 0 to 6 inch soil depth. Biomass of total bacteria, active bacteria, total fungi and active fungi are all significantly (P=0.001) greater in the litter layer than at the 0-6 or 6-12 inch soil depths. The same is true for population densities of flagellates, amoebae, ciliates, bacterial feeding nematodes, and fungal feeding nematodes, nematodes that function as omnivores or carnivores and oligocheates. The plant parasitic nematodes were the only group studied that differed from this pattern. Population densities of plant feeding nematodes are significantly (P=0.05) in the 0 to 6 inch soil depth than in the litter layer or at a soil depth of 0 to 12 inches.
View report on additional organic fruit projects with special reference to soil biology.
View Organic Apple Production: The Transition Process – Organic Orchard Examples.
View Organic Apple Production: The Soil and Organic Pest Management.
Objective 2a: Tree Vigor and Ground Floor Management (Ron Perry Lab, Horticulture )
In all orchard systems, it is important to manage plant growth beneath trees to reduce competition with the tree roots. In organic systems, herbicides are not used so competitive growth is usually managed by mulching or cultivation. We are testing an easier method of cultivation that reduces competition in a strip out away from the tree trunk (Swiss Sandwich System (SSS)) rather than around the trunk. Early indications are that growth (trunk diameter and branch length) with the SSS was as good as the traditional system where soil beneath the entire tree and around the trunk was clean cultivated with a flame weeder. Improvements were also made to the propane flamer equipment used for weed control to allow a better application of the heat reducing the risks of damaging trees.
A new root stock evaluation trial was added during 2002. The objective of this study is to evaluate the effect of two soil managements (mulch and SSS) on root development in an established orchard by measuring root growth ratio, turn over and root distribution on both systems. Image data of roots collected using 64 minirhizotrons (clear tubes placed in the soil) will provide information about the entire tree. Five sets of pictures have been already taken. Respiration of the soil microorganisms will also be measured to relate microorganism population to soil management.
Apple trees are also being grown in large aboveground containers for easier nitrogen availability monitoring. In the first year, the treatments led to differences in soil moisture that needed to be managed. To follow more precisely the soil moisture content a TDR system was used in the containers and in the field as well. Approximately 1626 solution samples were collected from the containers for nitrogen analysis. Tree height and width measured, and in the case of the containers the yearly growth of all the branches will be measured at the end of the season, to have more accurate evaluation of the growth of plants.
Objective 2b: Pest and Insects (Mark Whalon Lab, Entomology )
Previous experience at the Clarksville station in 8 IPM apple blacks since 1998 indicated that excellent control of codling moth (CM) and oriental fruit moth (OFM) is possible with mating disruption. In 2002, Isomate pheromone dispersers for disruption of CM, OFM and leafrollers (redbanded and obliquedbanded) at a rate of 275 pheromone dispersers per acre. Moderate to severe damage was observed because mated females from feral trees and local abandoned orchards migrated in the block, unaffected by the pheromone and oviposition was unobstructed.
The secondary pest management strategy was to monitor and manage using IPM treatment thresholds and organic amendments. We observed high leafhopper damage, moderate leafroller damage and low mite and white apple leaf aphid damage. Secondary pests were economically important but since crop was so poor early in season, no organic treatments were used against the pest since many organic pesticides kill natural enemies as well.
Because pesticide applications are restricted to a smaller range of more targeted compounds, and often used lower rates, natural predator populations are less likely to be affected by exogenous treatments allowing endogenous control of pests. Orchard insect diversity was monitored through the growing season with yellow sticky cards and pitfall traps distributed across the organic apple plots while predator populations, measured with pit fall traps, are significantly higher in the interior of the orchard. Since the predator and parasitoid populations are a critical component to the organic strategy, we have begun to install a plant diversity strip along the border of the orchard. This 16 foot wide irrigated section contains a replicated series of perennial herbaceous plants that provide nectar and refuge throughout the season. Since the plantings were immature, the diversity strips had only small impact on the edges of the orchard. In 2003, we will bolster the plant population by adding native Michigan perennial and annual flowing plants. In addition, pesticide treatments planned for the 2003 season will be much more aggressive. As a result, we expect that strips will have a very measurable impact of predator and parasitoid populations.
Below, planting of diversity strip.
In conclusion, the 2002 season was very unusual with extreme migratory pressure from key pests including plum curculio and codling moth, resulting in severe damage to a very spotty and uneven first crop of apples. Diversity treatments were a viable means of accessing predator and parasitoid numbers.
View report on Organic Apple Project: Pest and Disease Management.
Objective 2c: Control of Apple Scab and Fire Blight (Phill Schwaillier, Clarksville Horticultural Research Station)
Throughout the apple growing areas in the state of Michigan , the primary disease organisms of concern are apple scab and fire blight. Apple scab is a disease that depending on the severity limits the photosynthetic capacity of the trees and severely affects the quality of the finished fruit. Fire blight has an enormous potential to devastate an entire orchard or region of trees if insect vectors and favorable environmental conditions spread it. Farmers have several tools available in managing these diseases including: 1) varieties of apples that have varying degrees of resistance to the pathogens; 2) hygienic practices and scouting that limit that quantity of inoculum in and around the orchard; 3) a system of forecasting when cumulative environmental factors favor an infection by the pathogen; and 4) once such conditions are forecasted, spray applications may reduce infection. The control of Scab and Fire blight are limited to a few products for orchards using organic farming practices.
Two of the four approved products (lime-sulfur and copper) known to control the pathogens and two other products (Serenade and compost tea) were used in a comparative study of apple scab management. As there are many research projects overlapping within the five-acre orchard, the treatments for both the study and control, in regards to Scab and Fire blight, were assigned according to the degree of tolerable risk associated with each section. In one section, all risks of infection were kept at a minimum with a combination of forecasting and a calendar date spray program. In this section copper, lime-sulfur, and compost tea were applied. The remaining section for the study (2/3) of the area) was divided in to four equal zones. Within each zone there are three different varieties of trees ranging from non susceptible to very susceptible. To each section, lime-sulfur, Serenade, Compost tea, or water (as a control or no treatment) was assigned. Due to the severity of Fire blight it was determined that only under forecasted very high risk of infection would copper sprays be applied to this section of the orchard. This was done so as to minimize the effect of the copper spray on the infection rate of Scab.
Objective 3: Costs of Production (Bridget Behe, Horticulture)
In the summer and fall of 2002, all the initial costs associated with an organic orchard were imputed and programmed throughout an organic cost of production Excel workbook. Upon evaluation of the project this winter, the researchers are adding more strategies, scenarios, and options for growers to use as they evaluate the costs of both transitioning from conventional practices into organic as well as beginning an orchard with organic production. In the end, the workbook will hold all the current cost data on organic apple grower would need as they evaluate the profitability of growing organic apples choosing the options that best fits their soil, property size and orchard and pest management strategies.
Objective 4: Education and Certification (John Biernbaum, Horticulture; and Susan Smalley, M.S. Mott Group for Sustainable Food Systems )
A field day at the organic orchard on June 19, 2002, attracted about 75 participants—conventional and organic orchardists, organic organizational leaders, Michigan Department of Agriculture and Environmental Protection Agency staffers, MSU Extension agents, students and others. Three educational stations were established around the orchard where participants learned about soil quality, tree/ground floor management, and pest/disease management. Participants also received printed materials summarizing project work to date.
From the inception, the orchard was managed to be certified in accordance with a certifying agency of organic farming. The Organic Crop Improvement Association (OCIA) is a large organization that is recognized within the State of Michigan , the USA , and internationally by consumers, processors, and producers. OCIA inspectors made an annual inspection for the year 2001 and 2002 and currently the 20-plus page farm plan and inspection files are in the process of being reviewed. With a third inspection during the 2003 growing season, the fruit to be harvested will be OCIA certified organic in accordance with the guidelines of the USDA Federal Organic Program (FOP).
Several databases containing names and addresses of people interested in organic agriculture were consolidated this year to provide a more comprehensive mailing list for future Michigan organic efforts.
Visit the MSU Student Organic Farm.
Learn about MSU Organic Farm Apprenticeship Program.