Tree Fruit: Practical Guide for Organic Apple Production

Organic Integrated Pest Management (IPM)

General - Diseases - Arthropods - Pest Management Throughout the Season - Weed Management Strategies - Protecting Trees From Wildlife - Sprayer Calibration

IMPORTANT: It is the grower’s responsibility to ensure that any crop production practice or material used in the orchard is acceptable in their particular state’s organic certification program. Some materials deemed organically acceptable on the National List may not be acceptable in some states. Contact your federally accredited certifying agency to know what is acceptable and to ensure compliance with regulations in your state.

General

What is Organic IPM?

Organic Integrated Pest Management (IPM) is an approach to managing pests that integrates organically-approved biological, cultural, physical, and chemical tools in a way that minimizes economic, health, and environmental risks.

What is a pest?

The Environmental Protection Agency (EPA) defines pests as "living organisms that occur where they are not wanted or that cause damage to crops or humans or other animals. Examples include:

• arthropods,
• mice and other animals,
• unwanted plants (weeds),
• fungi,
• microorganisms such as bacteria and viruses, and prions."

(Source: http://www.epa.gov/pesticides/about/index.htm)

What is an organically certified pesticide?

The EPA defines a pesticide as "any substance or mixture of substances intended for:

• preventing,
• destroying,
• repelling, or
• mitigating any pest.

Though often misunderstood to refer only to insecticides, the term pesticide also applies to herbicides, fungicides, and various other substances used to manage pests.

Under United States law, a pesticide is also any substance or mixture of substances intended for use as a plant regulator, defoliant, or desiccant."

(Source: http://www.epa.gov/pesticides/about/index.htm)

The Organic Materials Review Institute (OMRI) provides organic certifiers and growers with a product list of materials approved for use in certified organic production systems according to the National Organic Standards. A material approved for use in organically certified production is generally derived from natural resources: Directory of OMRI Approved Organically Certified Products

Pesticide Safety in Organic Orchards

Chemical tools will most likely be a necessary component of an organic IPM system in New England apple orchards and therefore, the proper training and safety precautions are essential. Anyone using pesticides, even organically certified ones, needs to be knowledgeable about their safe use and storage.

For more information:

• Pesticide Education and Safety Program (University of Vermont)
• A Grower’s Guide to Organic Apples (Cornell University)
• Searchable Database of Pesticide Labels and MSDS
• Understanding the Pesticide Label (University of Missouri)
• Pesticide Application Safety (University of Missouri)
• Personal Protective Equipment for Working with Pesticides (University of Missouri)
• Penn State Tree Fruit Production Guide

Diseases

It is important to be able to identify disease symptoms and understand disease life cycles before forming a management strategy. It is essential to find and eliminate sources of disease inoculum surrounding the orchard. Abandoned apple trees nearby can provide high levels of disease inoculum and arthropod pest pressure.

For more information:

• Tree Fruit Disease Factsheets (Cornell University)
• Index of Fruit Disease Photographs and More (West Virginia University)
• Disease Management in Apple Trees and Fruit (eXtension)
• Organic Apple Disease Spray Guide (Ohio State University & West Virginia University)
• A Grower’s Guide to Organic Apples (Cornell University)
• Apples: Organic Production Guide (ATTRA)
• Organic Apple Production Guide for Atlantic Canada (Agriculture & Agri-Food Canada)

Arthropods

It is a significant challenge to produce a high quality apple crop while minimizing spraying. A high level of knowledge of the crop, the various arthropod pests, the beneficial organisms, and how they interact and affect each other within the apple ecosystem is required.

For more information:

• Tree Fruit Insect Fact Sheets (Cornell University)
• Beneficial Insects Fact Sheet (NYSIPM)
• Arthropod Management in Apple Trees and Fruit(eXtension)
• A Grower’s Guide to Organic Apples (Cornell University)
• Evaluation of Pest Management Tactics for Organic Apple Production (Cornell University)
• Evaluation of Organic Pest Controls and Fruit Thinning on Multiple Apple Cultivars (Cornell University)
• Apples: Organic Production Guide (ATTRA)
• Organic Apple Production Guide for Atlantic Canada (Agriculture & Agri-Food Canada)

Pest Management Throughout the Season

We are in the process of examining Organic IPM using organically approved materials, reviewed and approved by the Organic Materials Review Institute (OMRI) and the state's certifying agency. Thresholds used in standard IPM orchards should be viewed as provisionary in organic apple orchards until more experience is gained.

It is the grower's responsibility to ensure that any crop production practice or material used in the orchard is acceptable in their particular state's organic certification program.

See also An Organic IPM Checklist for Vermont

December to March

• Evaluate completeness of your organic IPM records from the previous growing season. In addition to legal requirements, do they reflect scouting information and application of findings in decision-making, do they include tree health information, foliar and/or soil analyses? Does your organic certification record-keeping system need improvement?
• Use records to review pest management strategy and results from the previous growing season and make necessary adjustments.
• Read fact sheets, articles and other resources on the biology and life cycles of different orchard pests and beneficial organisms; attend fruit workshops and meetings to obtain updates on thresholds and improvements to organic IPM strategies and options; get on the mailing and email lists for newsletters and alerts.
• Review materials approved by the Organic Materials Review Institute (OMRI) and accepted by the state's certifying organization for any changes or new organic options.
• Review information on any potential non-target effects of organic options on biological control agents and determine what materials will be effective yet conserve beneficial organisms if intervention is needed.
• Investigate sources of local weather information; determine what equipment will be used to monitor environmental conditions (i.e., rain, temperature, leaf wetness) in the orchard for pest models and for assessing spray conditions.

  Network for Environment and Weather Applications (NEWA) provides New England growers with useful local weather data and pest and disease predictions, from which to make more informed management decisions.

  
  How To Use NEWA

• Start any major repairs to orchard spray equipment so that it will be ready to calibrate and function properly when the season begins.
• Order organic IPM monitoring supplies.
• Clean and sharpen pruning tools.
• Prune trees to provide good tree structure but also to open canopy for light and air penetration, which will have both horticultural benefits (i.e., better fruit coloring with more light) and pest management benefits (i.e., make conditions less favorable for disease development; allows better pesticide penetration). Remove cankers, dead or weak wood. Remove mummified fruit.
• While pruning, note any sections of orchard that have high numbers of overwintering European Red Mite eggs.

  
  European Red Mite eggs

• Check for winter damage. Look for peeling or cracked bark.
• Contact beekeeper and write a pollination contract
• Review foliar and soil analysis recommendations. Weak or overly vigorous trees will be more susceptible to certain arthropod pests and/or diseases.

March to Silver Tip Bud Stage

• Conduct final pre-season maintenance check of sprayer(s). Replace worn nozzles, weak hoses, and inaccurate pressure gauges.
• Calibrate sprayers; test spray pattern with water sensitive paper.
• Review tree-row-volume calculations for each orchard block.
• Set up map and record-keeping system for monitoring of orchard blocks
• Check for bud winter damage.
• Remove prunings and brush piles from within and around orchard and burn or chip if possible since they can harbor inoculum for wood and fruit rot diseases and provide habitat for voles.

  
  Meadow vole (top), Pine vole (bottom)
  http://www.hort.uconn.edu/ipm/imgcatlg/homectlg.htm

  
  Vole trunk girdling damage after snow melt in early spring

• Note vole activity during snow melt; a lot of activity in the snow could mean high overwintering populations
• As soon as snow cover is gone and the rows are drivable, flail-mow as a sanitation practice for management of apple scab (reduces overwintering inoculum).

  
  Flail mowing to reduce apple scab overwintering inoculum

• At bud break, begin to calculate and record degree-days for use in predicting scab ascospore maturity.
• At Silver Tip phenological bud stage, place visual sticky traps for tarnished plant bug and leafminers in the orchard.

  
  Putting Out Early Season Leafminer Traps

  
  Putting Out Tarnished Plant Bug Traps

• In very young, or dwarf high density, orchards, maintain an 18 inch reduced-weed area next to tree to increase air circulation around tree, to eliminate competition for water and nutrients, and to remove habitat for voles. An option to maintain a reduced-weed area is bark mulch spread over entire area, but make sure the mulch is pulled away from tree trunks.

  
  Bark mulch is spread to maintian a reduced-weed area along organic orchard rows

Green Tip through Pink Bud Stages

• Check for bud winter damage.
• Remove solid plastic vole guards and replace with mesh guards that allow air, light and pesticide penetration. [Impacts borer management]
• Scout your orchard at least once a week to be aware of what is going on so that if problems are developing, corrective or preventative measures can be taken.
• Monitor weather/environmental conditions for degree-day calculations, disease models, etc., and if intervention is necessary, to determine optimal time to spray to minimize drift.
• At Tight Cluster bud stage and again at the late Pink bud stage, determine the necessity to manage tarnished plant bug and leafminers.

  
  Tarnished plant bug adult

• 
  Spotted tentiform leafminer adult

• Apply oil application(s) for management of European red mites and San Jose scale. [Oil acts to coat and suffocate the overwintering stages.]
• At early Pink bud stage, place visual traps in the orchard to monitor for European apple sawfly. Check at late Pink to see if traps have already reached threshold.

  
  European apple sawfly sticky trap

• Manage apple scab infections in the primary stage to reduce the need for fungicides during the latter part of the growing season.
• Determine when environmental conditions are favorable for apple scab infection periods.
• Begin checking for primary apple scab lesions about 9 days after first infection period to determine the effectiveness of your scab program.

  
  Primary apple scab lesions on underside of leaf

Bloom

• Monitor environmental conditions to determine the risk of fire blight infection.
• Continue management of apple scab.
• Hang codling moth pheromone traps in orchard to monitor this insect.

  
  Assembling Pheremone Wing Traps

  
  Codling moth baited pheromone sticky trap

• During late Bloom, begin to inspect fruit on early-blooming cultivars in perimeter rows for fresh plum curculio egg-laying scars.

  
  Fresh plum curculio egg-laying scars with ooze

  
  Crescent-shaped plum curculio egg-laying scar

• Bring bees colonies at 10% to 15% bloom
• Monitor pollination conditions.

Petal fall through June

• Scout your orchard at least once a week to be aware of what is going on so that if problems are developing, corrective or preventative measures can be taken.
• If a fire blight infection period occurred during Bloom, monitor degree day accumulation and observe blossoms and developing shoots for first signs of blight. The first symptoms of blossom blight is predicted to occur when an additional 103 degree-days have accumulated (base 55F). Depending on how extensive the number of "strikes" are, cut out strikes to reduce inoculum for further disease spread on sunny days when rain is not predicted. Follow recommended procedure for the "ugly stub" method for removing strikes.

  
  Fire blight damage to young fruit

  
  Fire blight damage to tree

• Check to see if European apple sawfly captures have reached threshold levels.
• Inspect fruit for evidence of first signs of plum curculio damage; begin to accumulate degree-days for use in model to determine when insect activity is over.
• Examine middle-age fruit cluster leaves to determine if threshold has been reached for European red mites.
• Check codling moth traps daily and begin to calculate degree-days (base 50F) from first adult catch. An effective time for management of first generation is at 250-360 DD in orchard blocks where the insect is a problem.
• Check for first generation sap-feeding larval mines in leaves to determine if leafminer threshold has been reached.

  
  Sap-feeding leafminer larval mines on underside of leaf

• Remove fruit drops, if feasible, to potentially reduce plum curculio populations
• Examine leaves for presence of first generation leafhopper nymphs and adults to determine if threshold has been reached.

  
  Leafhopper adult

  
  Leafhopper nymph

• Assess level of infestation by aphids and presence of natural predators to determine if biological control is likely.

  
  Predatory Cecidomyid larvae (orange larvae) and aphids on underside of leaf

  
  Predatory lacewing eggs on underside of leaf

  
  Predatory Syrphid larva

• Hang apple maggot fly traps in orchard during the last week of June to monitor activity and to determine if and when threshold levels are reached.

  
  Apple maggot fly sticky red ball trap

• Use the apple scab ascospore maturity model to determine the projected end of the primary infection season. As a conservative estimate, the final scab ascospore release in commercially managed orchards can be assumed to have occurred when 900 DD have accumulated before a daytime rain of at least 0.1 inch and temperatures of at least 50F during the wetting period.
• Before disease management intervals are extended, assess the foliage and fruit for apple scab incidence approximately two weeks after the last primary infection period.

  
  Scab lesions on fruit

  
  Severe scab symptoms on leaf ('sheet' scab)

• Keep track of the hours of leaf wetness starting at ten days past Petal Fall in order to determine the period of greater risk of fly speck.
• Assess fruit set by monitoring fruitlet growth and weather conditions.
• Thin the fruit.
• Mow row middles (if possible, delay mowing until 10-14 days after petal fall).
• Begin organically approved calcium sprays to decrease incidence of Ca deficiencies disorders.
• Monitor soil moisture conditions and irrigate when necessary to avoid dry conditions that can stress trees making them more vulnerable to disease.

July

• Check sprayer calibration and adjust for summer applications.
• In blocks were codling moths are a problem, determine if 1260-1460 DD (base 50F) have accumulated from first trap capture in pheromone traps since this is the most effective time for management of second generation.

  
  Codling moth adults on sticky trap

  
  Internal damage caused by codling moth larvae

• Check for second generation sap-feeding larval mines in leaves to determine if leafminer threshold has been reached.
• Examine middle-age terminal leaves to determine if threshold has been reached for European red mites.
• Check apple maggot fly traps on a regular basis to determine if threshold has been reached. Clean traps and replace lure every 3-4 weeks.

  
  Apple maggot fly adult on red sticky trap

  
  Apple maggot fly red sticky ball trap (not all insects on trap are apple maggot flies)

• In late July, examine leaves for presence of second generation leafhopper nymphs and adults to determine if threshold has been reached.
• Continue to keep track of the total number of hours, starting ten days past Petal Fall, that the leaves were wet. Risk of fly speck infection increases when 270 hours of leaf wetting have accumulated.
• Begin summer pruning in mid- to late-July to open up the canopy, improving light penetration for better fruit quality, faster drying conditions, and better spray coverage.

  
  Summer pruning

• Mow grass to discourage vole populations and to aid in air circulation for disease management.
• Monitor soil moisture conditions and irrigate when necessary.
• Collect leaves for foliar nutrient analysis in late July to early August. Contact your Extension office for specific instructions. Next year's fertilizer program should be based on the foliar and soil analyses.

  
  Collecting leaves for foliar nutrient analysis

August

• Continue to examine leaves for presence of second generation leafhopper nymphs and adults to determine if threshold has been reached.
• Examine middle-age terminal leaves to determine if threshold has been reached for European red mites.
• Check apple maggot fly traps on a regular basis to determine if threshold has been reached. Clean traps and replace lure every 3-4 weeks.
• Continue summer pruning.
• Clean and repair harvesting bags and fruit storage containers.
• Check predicted harvest dates.
• Monitor soil moisture conditions and irrigate when necessary.
• Mow grass to discourage vole populations and to aid in air circulation for disease management.

September

• Remove or mow fruit drops where feasible as they are a source of food for voles.
• Note any pest damage during harvest so it can be addressed in IPM planning for the next growing season.
• Mow grass to discourage vole activity.

October

• Check trunks (small diameter trees especially) for signs of borers.

  
  Roundheaded borer adult

• After harvest and before leaf fall, estimate the orchard's level of "scab risk" by following the sequential sampling procedure (Potential Ascospore Dose assessment).
• Check placement and condition of vole guards; repair and re-position if necessary.
• Remove or mow fruit drops where feasible as they are a source of food for voles.
• Mow grass to discourage vole activity.
• Collect soil for analysis. Contact your Extension office for specific instructions. Next year's fertilizer program should be based on the foliar and soil analyses.

  
  How To Take A Soil Sample

• Lime soil if recommended by soil analysis.

November

• After leaves have fallen to ground, perform apple scab sanitation practices, like leaf removal or flail mowing.

  
  Overwintering scab lesions on fallen leaves

• White paint, which is normally painted on the trunk to protect the tree from sudden temperature changes and sunscald, is prohibited by most organic certifying agencies. Therefore a slurry of kaolin clay and water can be used instead to cover the bottom of the trunks. However, this solution is not as permanent as paint and needs multiple reapplications.
• Replace solid plastic vole guards if mesh guards were not put on in the spring. (These white plastic guards will also help protect the trees from sunscald like paint would)

  
  White plastic guards on a new high density planting

• If organically approved deer repellents will be used, set them before deer establish a feeding habit. Inspect and make repairs to deer fence.
• Clean, service and properly store equipment and pesticides.

Photo credits: L.P. Berkett; Integrated Management of Apple Pests in Massachusetts and New England, Coop. Ext. Sys., University of Massachusetts. 1984.; Instructional Media Center, Michigan State University, East Lansing, MI.; W. MacHardy; T.S. Sutton.

Weed Management Strategies

Preventing weed growth is critical during the establishment phase of an orchard when strong tree growth is needed to build a fruit bearing framework of trunk and limbs. Weed management following the establishment phase can be important for dwarf trees and for orchards planted in sandy soils. Orchards planted to semi-dwarf trees have been shown to be productive with minimal weed management, but fruit size and flower bud development are likely to improve where some weed management occurs. Weed management during the first half of the growing season will have a large impact on tree productivity because late spring into early summer is the time for rapid growth of shoots and early development of fruits.

Mowing, cutting back weeds, is commonly employed in established orchards with deeply rooted trees on semi-dwarfing rootstocks. However, mowing weeds is insufficient for trees on dwarfing rootstocks and newly planted trees with shallow roots.

Cover crops that grow in the tree row will act as weeds and compete with trees. No ideal cover crop has been found for orchards. Additionally, they create a habitat favorable for voles which can feed on trunks.

Mulching suppresses weeds by blocking sunlight. Different types of materials can act as mulch, but some types are detrimental to fruit trees. Hay, straw, plastic and fabric mulches encourage voles. Wood chips and bark mulch have been shown to effectively reduce weeds for one to three years depending on depth to which they are spread. A minimum depth of 3-inches is recommended to block out enough light to prevent weeds. Unless an inexpensive source can be found, mulching is a costly method of weed management.

Different Types of Weed Management

Herbicides are an option for weed management where organically approved products are allowed. Herbicides have a temporary effect particularly where weed pressure is strong and soil moisture is abundant. Corn gluten will not effectively manage established weeds, but works as a preemergent and must be applied as weeds are germinating. Weak acids and essentials oils act as "burn-down" herbicides and kill the above-ground succulent plant tissue, but will not effectively kill some weeds. Different materials that act as burn-down herbicides include concentrated vinegar (acetic acid), citric acid, clove oil and citrus oils. Because the weeds are not entirely killed by the herbicide, rapid regrowth occurs with these materials. Reapplication is needed for a sufficient duration of management in most years. Citrus oil (d-limonene) has been shown to keep weed growth in check for a period of two weeks at which time visible weed regrowth occurs.

There may be others in addition to these, and very little information is available on their effectiveness in apple orchards. Many products are available containing these compounds for use as organic herbicides, so contact your certifying agency to find out which are allowed for use in your orchard. These products can irritate and damage skin, eye and respiratory tissues so protective apparel should be used when applying them.

Flaming weeds can also temporarily kill above-ground weed tissue. It is typically accomplished with a propane burner, and works best on small weeds. It may be less costly than other methods, but potential damaging to irrigation systems and trees if fires start in the orchard and therefore is not recommended.

Shallow cultivation disrupts the surface weeds and roots and can be effective if performed early in their growth. Disadvantages of surface cultivation include the need for specialized equipment, the risk of damaging tree trunks, disruption of surface roots, and increased chance for erosion. To prevent trunk damage, adopt the "Sandwich System" which is a one-foot strip of weeds allowed to grow on either side of the tree with an area of cultivated soil in the rest of the tree row.

In a research comparison of alfalfa hay mulch, flaming and the Sandwich System, mulches outperformed other weed management methods during the establishment years, but not subsequent years.

For more information:

• A Grower’s Guide to Organic Apples (Cornell University)
• Apples: Organic Production Guide (ATTRA)
• Groundcover Management (University of Vermont)

Protecting Trees From Wildlife

Voles, or meadow mice, girdle young trees when they feed on the lower trunk. To prevent feeding, protect trunks with hardware cloth so that it encircles the lower part of the trunk. It should be 12-18 inches in height, but not tight against the trunk. Plastic spiral guards can also be used, but should be removed in spring since they encourage trunk boring insects.

Deer feed on the new shoots of fruit trees and can severely stunt trees of short stature. An 8' fence is the most effective method of keeping deer away from fruit trees, but is also the most costly. A shorter fence is less expensive, but also less effective.

Birds become a problem when they peck small holes in fruit. In some years, this can be prevalent in fruit that are nearly ripe. Visual repellents, such as reflective tape, or acoustic bird deterents can help protect fruit from bird damage.

For more information:

• Wildlife Problems of Apple Trees and Fruit (eXtension)
• A Grower’s Guide to Organic Apples (Cornell University)
• Apples: Organic Production Guide (ATTRA)
• Penn State Tree Fruit Production Guide

Sprayer Calibration

For more information:

• Sprayer Calibration (New England Apple Pest Management Guide)
• Calibrating Your Orchard Sprayer (Utah State University)
• Airblast Sprayer Calibration (Virginia Tech University)
• A Grower’s Guide to Organic Apples (Cornell University)
• Apples: Organic Production Guide (ATTRA)
• Penn State Tree Fruit Production Guide