COCKTAIL OF ORGANIC SPRAYS TO BOOST TREE HEALTH

SPRAY SEASON

POP has really been buckling down with organic sprays this season and expanding our spray regiment at our partners sites. More specifically, there has been a lot of effort put towards bio fungicides, kaolin clay, compost tea, and neem oil sprays. We are curious to see what impact this has this year on our fruit trees!

Organic sprays are one powerful tool in our pest and disease management toolkit, one that requires some amount of diligence and consistency, but can have good results down the line. The organic sprays are not as immediately effective as synthetic ones, and if not done properly, can do little. If done properly, they can really make an impact down the line!

Choosing organic, naturally-derived sprays is a more sustainable, holistic approach to pest and disease management, and feels better than using synthetic counterparts. Ultimately, when growing plants for food, we are functioning within the ecosystem and want to integrate in a somewhat balanced manner with the surrounding lifeforms. There will always be competition between organisms out in nature, but many of them can coexist if the habitat is healthy.

It must be noted that some organic sprays, though they are naturally derived, can still be harsh and have negative impacts on animal life and pollinators. Many toxic substances come from the Earth, so with this understanding, it is important to tread lightly and not automatically assume an organic spray has zero negative impact. This is all to say that is it important to read the label and spray properly.

SPRAY TIMING

Late winter and spring is the key moment for pest and disease prevention. Dormant oil sprays are typically sprayed in the late winter. Once trees begin to bud, biofungicide spray regiments often being, often going till petal fall. are in full leaf, most sprays are less effective, though can still be employed.

Morning or evening application is best. An overcast day also works! Sunlight tends to affect the spray effectiveness, especially if its a “live” spray (like EM-1, compost tea, biofungicides, etc.). Additionally, intense sunlight can scald the leaves and stress out a tree. Try to avoid spraying during or before a rain.

SPRAYS

There is a wide variety of organic sprays we use for pest and disease management. It depends on what you are targeting and the timing.

  • Overall tree health and soil health
    • Effective microorganisms (EM-1)
      • What: EM-1 is a naturally occurring blend of beneficial microorganisms used to improve soil health and plant growth and vitality.
    • Compost tea
      • What: Compost tea is a solution of water and compost that is infused with the nutrients and beneficial microorganisms found in the compost.
  • Fungal pathogens
    • Bio-fungicides (Regalia and Serenade brands)
      • Targets: Fungal and bacterial diseases on fruit trees
      • How: Biofungicide protects trees against a variety of bacterial and fungal diseases by deploying beneficial bacteria, that both form a protective barrier around roots and foliage and can also directly attack fungal pathogens.
    • Copper sprays
      • Targets: Fungal and bacterial diseases on fruit trees.
      • How:  Begin the application at the first sign of disease, typically around leaf emergence, and repeat at 7-14 day intervals as needed. Spray ground and tree.
    • Sulfur sprays
      • Targets: Sulfur affects fungal diseases.
      • How: As soon as leaf tips emerge, apply with reapplication 10-14 days later if rain continues, and a third spray toward the end of the bloom period after petals have fallen. Spray ground and tree.
  • Insects
    • Dormant oil/horticultural oil
      • Targets: Dormant oil affects overwintering insects and insect eggs in late winter and early spring.
      • How: It smothers eggs and prevents them from hatching. It also affects immature insects and interferes with their ability to breath and feed.
Scale insects look like small bumps, vary in color, and can sometimes result in sooty mold and can weaken or even kill trees. Dormant oils can combat scale. Source: POP
  • Neem oil
    • Targets: It affects most insects but is more effective against immature insects and eggs. Avoid using around beneficial insects, both in their immature and mature stages.
    • How: It acts as insect repellent. It ‘s main function is killing insects by suffocation, covering their bodies with oil that blocks their breathing openings. It also disrupts insect hormones that control growth, feeding, and reproduction when it is eaten.
  • Bt
    • Targets: It affects mostly immature insect, specifically in larvae form (larva of caterpillars, beetles, mosquitos, and flies). Avoid using around beneficial insects, especially butterfly larvae.
    • How: It damages the gut of insect larvae after the larvae eat leaves covered in Bt. The larvae die of starvation and infection.
  • Pyrethrin
    • Targets: It is a broad spectrum insecticide that targets most insects. Avoid using around beneficial insects.
    • How: It affects an insect’s nervous system through a deadly toxic effect. Almost immediately upon contact with this compound, the insect dies from a form of paralysis.

Pyrethrin comes from chrysanthemum flowers. Source: POP
  • Spinosad
    • Targets: It is a broad-spectrum insecticide that targets most insects, especially chewing insects (larva and beetles). Avoid using around beneficial insects, especially bees.
    • How: It is affective by contact and through ingestion.
  • Kaolin clay
    • Targets: Most insects
    • How: Kaolin clay is most commonly used for pears, apples, citrus, and stone fruit.  Kaolin clay repels pests by creating a protective barrier on plant surfaces, making the fruit tree an unsuitable environment for certain insects to land, feed and lay eggs.
Kaolin clay should look like a grey film on the tree. Source: POP

Fire blight can be combatted with copper and sulfur fungicides. Source: POP

SPRAY RECOMMENDED PRACTICES

Most organic sprays don’t require an applicator license, but it is very important to always read and follow the label.  Mix and apply at the recommended rate, wear protective gear when advised, and follow all other instructions. Remember: organic sprays can still be harsh and toxic if improperly applied! Avoid windy days and consider who is nearby.  Each spray also has a different pre-harvest interval, so think about the time between when you spray and when the yield will be harvested. 

When using a sprayer, make sure to:

  • For live ingredients like compost tea, biofungicides, and EM-1, it is important to use dechlorinated water. 
  • Live sprays, like compost tea, biofungicides, and EM-1, can be combined with each other, but should not be mixed with fungicidal sprays like copper, sulfur, or neem
  • For best mixing, add some of the water, then the ingredients, and then the rest of the water.
  • When applying foliar sprays, aim for full coverage of the top and underside of leaves, the branches, and trunk
  • Clean out the sprayer after using it by flushing it with water by filling sprayer partially with water and spraying out water for at least a minute

SOURCES

This POP Blog was written by Orchard Assistant Simone Shemshedini.

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