The Wills Family Orchard (the orchard name was changed from Rainbow Ridge Orchard) is located on 32 acres in Dallas County Iowa within close proximity to the confluence of Panther Creek and the South Raccoon River. Two orchard blocks covering approximately 2 acres are located on south and west facing slopes. Ridge top ground is used for buildings and garden plots. Apple trees were first planted in 1992. Many trees were lost in the “flood year” of 1993 due to excessive rain. Replacement trees were planted in 1995. A second orchard plot was established in 1996.
Apples, though not the most perishable and sensitive specialty crop, must endure deer, insect, disease and weather pressure. Approximately 600 additional trees have been planted over the last 10 years only to be destroyed by deer. Growing deer pressure now requires fencing of each newly planted tree. The apple crop has also sustained hail three of the last six years. Only scab immune varieties have been planted until this year. However, this SARE project was conducted only within the scab immune blocks. These varieties make it possible to raise apples without the use of fungicides. However, it has taken effort to establish commercial acceptance of these unknown varieties.
The orchard has been maintained organically since its establishment in 1992. Organic certification was sought and obtained in 2000 and has been renewed each year to present. Poultry manure from on-farm and off-farm sources is added every two to three years to add to enhance soil fertility.
This is a family operation where every family member participates to the level of their capabilities and their own specific interest. The use of family labor and participation in every facet of this growing family operation adds to the sustainability of the whole enterprise. The use of on-farm hay is used as mulch under each tree. Over the years a family dairy cow, egg laying hens and goats have been kept on the farm. Manure from these animals has also been used in the orchard and on garden plots. These practices have also added to the sustainability of the farm.
Project Description and Results
This project set out to evaluate organic treatments for insect pest management on the Wills Family Orchard. Iowa State University under the direction of Dr. Kathleen Delate participated in the project design, data collection, sampling and analysis portion of this project in conjunction with the Wills family. Two new products for codling moth control available in 2003 were going to be used and evaluated. These products, Entrust™ and Last Call™, have been developed from natural sources. At the time of the grant proposal the manufacturer of Last Call™ believed that they could formulate their product to comply with National Organic Program regulations for purposes of this project. The product was formulated and shipped to the orchard for use. However, during review of the product formulation for the organic certifier it was learned that while the active ingredient (pyrethrum) in this product is allowed the inert that was used is not allowed. Only inerts identified on EPA List 4 – inerts of minimal concern may be used in organic input formulations. This product contained at least one inert from EPA List 3. Consequently, it was determined that this product would not be used in this project so that the organic certification status of the orchard would not be jeopardized.
Codling moth had become the primary pest of concern in this organic orchard system effecting 50-70% of the organic apple crop prior to this project. Fruit damage by other pests such as green fruit worm and apple fly maggot have been managed within commercially acceptable levels. The insect plum curculio still represents a significant concern for organic apple growers.
The most significant finding from this project is that apple damage from codling moth feeding dropped dramatically during this trial period. This decline in codling moth damage to commercially acceptable levels can be associated with the use of the spinosad product, Entrust™. Management of codling moth will allow organic growers to provide quality organic apples to their customers. Conventional growers struggle with codling moth resistance to conventional pesticides, consequently bio-insectides such as Entrust™ may prove beneficial to them. However, cost of bio-insecticide products and lack of premium prices for conventional apples may make the use of these alternative products prohibitive for conventional apple growers.
It should also be noted that while disease and other insect damage were identified during this trial they were not found to be commercially significant with the exception of plum curculio (PC). In fact some PC damage may not be accounted for as many PC damaged apples may drop from the tree in June and therefore not be counted at harvest time. It also appears that specific varieties are more susceptible to PC feeding.
Further research and product development is needed to provide products and methodologies that will successfully manage PC. The use of the kaolin clay product Surround™ to manage PC may prove to be too harsh on beneficial insects to use frequently. It may be better to limit the use of this product to early control of PC and discontinue after the primary egg laying period is completed. Given the fact that organic management strategies and inputs do not act quickly on organic systems the operator should establish thresholds unlike conventional thresholds for determining action levels whether it be for fertility, insect or disease challenges. Establishing action level threshold levels for organic apple growers should be researched.
Leaf analysis indicated some disease and variation in nitrogen content among cultivars. However, neither yield nor quality appeared to be effected by either. Composted poultry manure was applied at the base of each tree in this trial. This provides a slow release of nitrogen and other nutrients to the tree. It would take time before increased nitrogen levels would be seen in a foliar analysis even if a higher nitrogen level would be desired.
For a complete review of research results gained from this project please refer to the report entitled Evaluating Alternative Pest Management Strategies for Organic Apple Production / On-Farm Trial, Adel, IA-2003 and 2004 by Dr. Kathleen Delate, Iowa State University (ISU).