For most PNW backyard orchardists, hopefully just covering apple fruitlets with untreated individual barriers (for example, footies) or draping fruitlet-laden trees or branches with netting provides sufficient protection from insect damage. For more about fruitlet barrier protection, fruitlet thinning and insects that damage PNW apple fruitlets, check out STFS USP newsletter 39 05 2021 May.
Scroll down this page for instructions on how to thin fruitlets and cover with untreated maggot barriers.
If basic barrier protection proves ineffective, the next step next spring might be to soak footies in a NovaSource Surround kaolin clay water solution before covering fruitlets. See details below.
No-spray application of NovaSource Surround kaolin clay for possible protection of PNW apple fruitlets from insect damage
Instructions from STFS Life Member Lori B. for coating individual barriers (for example, maggot barriers or footies) with NovaSource Surround kaolin clay before covering apple fruitlets. Edited by Trent E.
INGREDIENTS:
1 package of maggot barriers (aka footies or water impermeable nylon stockings) containing up to 144 individual footies
1 quart of water
1 Cup NovaSource Surround kaolin clay
TOOLS & PROTECTIVE EQUIPMENT:
12 quart (3 gallon) or larger dish tub or similar container
rubber or nitrile or similar water impermeable gloves
Step 1 Place 1 bag of footies (up to 144 Maggot Barriers) into a 12-quart dish tub or similar container.
IMPORTANT: Kaolin clay is drying to the hands: Wearing rubber or nitrile or similar water impermeable gloves helps protect hands.
Step 2 Sprinkle 1 Cup kaolin clay over the footies then moisten with about 1 quart water poured into tub.
Step 3 Mix and fold in the clay into the footies until it’s not clumpy or very noticeable. You don’t want much water left in the bottom of the tub.
Pics of Steps 1, 2 and 3:
Step 4 Cover apple fruitlets as soon as possible after blossoms fade. The fruitlets should have a diameter less than a USA dime coin.
Start covering fruitlets from the top of the tree downward for several reasons: Fruit at tree’s top most likely will be better quality because of better sun exposure to adjacent leaves. Also, if you bag bottom fruitlets first, you might break them off soon afterwards as you reach for overhead fruitlets.
Thinning excess fruitlets should occur at the same time of fruitlet covering; After covering the “best” fruitlet of the cluster, carefully remove (aka thin) the remaining fruitlets of the cluster. By covering the “best” fruitlet first before thinning the remaining fruitlets, the chance of accidentally removing all the cluster’s fruitlets is lessened.
If thinning is done early enough in fruit development, the remaining fruitlets will pop off with fingernail pressure and not require clippers.
As a reminder: you don’t want to damage the covered “best” apple fruitlet while removing the cluster’s excess fruitlets.
SUGGESTION: For more about fruitlet covering and thinning strategies, check out STFS USP newsletter 39 05 2021 May
Step 5 Cover the fruitlets while the footies are wet; when the footies dry out, the clay blows away as dust in the air. Gloves can be a challenge in tying them on; I gave up on the gloves for ease of installation. Wash your bare hands often and use lotion.
Step 6 Open the footie, pull it up and over the apple fruitlet while lightly pinching the footie to the stem for support. You don’t want to remove the fruitlet by pressing against it too strongly. If it does break off- oh well! Consider it thinning and move on to the next fruitlet.
Step 7 While supporting the stem and footie with one hand, twist the opening of the footie so that it can be wrapped in toward the stem and tucked under the footie stem opening.
Step 8 The fruitlet in the wet footie will hang loosely, but when it dries, it will shrink up some. You can curl the hanging end up and around the fruitlet. As the fruit grows, the footie will expand.
Pics of Steps 4, 5, 6, 7 and 8:
More about NovaSource Surround (WP Crop Protectant) from Fedco:
“This crop protectant is 95% kaolin clay, but this ain’t pottery-grade kaolin. A patented process of centrifuging and filtering delivers a critical particle size of 1.4 microns and a pure white color. Prevents insects from recognizing their targets, and, if they land, inhibits their access to the plant’s surface and causes irritation and excessive grooming.
Particle sizes larger than 1.4 microns do not form an effective barrier to insects, and impurities in unrefined kaolin may injure plant health.
Recommended for controlling European apple sawfly, plum curculio, Japanese beetle, leafhopper, Colorado potato beetle, thrips and other maleficial insects on fruit crops and field crops. Effective against cucumber beetles on cucurbits. The white surface also reflects sunlight, preventing sunburn and heat damage. …
Please see pesticide label here. EPA reg. 61842-18.” From NovaSource: “Surround is OMRI and WSDA-listed for organic pesticide use”. Surround Safety Data Sheet
Here are two methods for applying the Maggot Barriers to your fruit. One is with tiny 3/8” Orthodontic rubber bands or similar rubber bands and the other way is without rubber bands.
#1 – Thinning apples and applying Maggot Barriers with a Rubber Band.
Find the one with the sturdiest stem and most developed fruit.
Pinch out the smaller ones.
Don’t leave any that are yellow . Keep the healthiest one.
Very sturdy keeper.
Slip the 3/8″ orthodontist rubber band onto the opening end of the Maggot Barrier.
Spread the Maggot Barrier open along with the rubber band. Slip over the apple.
Get the apple into the Maggot Barrier an inch or two not more.
Lots of room to expand and grow.
The Second Technique:
#2- Thinning apples and applying a Maggot Barrier without a Rubber Band.
Best apple of the cluster.
Pinching off the smaller apples
You can tell the best one.
It has a thick stem and larger fruit size.
Open the Maggot Barrier.
Spread the opening to fit over the little apple
Slide it over the apple.
I only put if an inch or 2 into the Maggot Barrier.
Hold the apple stem steady and pull the extra opening to the side and twist.
Tuck the twisted length back inside the Maggot Barrier.
Stick the end back up inside so it won’t slip out.
That’s it!
Fig 1. Adult maggot flies
What are apple maggots?
Adult female apple maggots are small fruit flies (about ¼ inch long) that lay their eggs just below the skin of apples. They can attack immature fruit starting in June or July and successive flights can continue laying eggs into the fall. The eggs hatch within a few days as larvae.
What are apple maggots?
Adult female apple maggots are small fruit flies (about ¼ inch long) that lay their eggs just below the skin of apples. They can attack immature fruit starting in June or July and successive flights can continue laying eggs into the fall. The eggs hatch within a few days as larvae.
Fig 2. Interior damage
What happens to the infected apple?
While the larvae lack legs, they are prolific tunnelers and will proceed to lay tracks throughout the flesh of the apple. While in some cases you can see the tiny entry wound or the skin will reveal the presence of an infestation, often you won’t know until you cut the apple open after harvest! In most cases, the infected apple is useless.
Fig 3. Exterior damage
What non-chemical control measures are available?
Over the years various ideas have been tried. One is to hang colored sticky traps (yellow sheets or red balls) in the trees with an attractant designed to lure the fly. These may be useful to monitor the presence of maggot flies but are usually ineffective in controlling apple damage. Other approaches involve protecting the apple with a physical barrier. One is to apply a kaolin clay covering but these require re-application (every week or 2) until harvest. Some folks have had luck with paper or plastic bags.
Fig 4. Maggot barrier on apple
Maggot Barriers to the rescue!
Years ago, Seattle Tree Fruit Society members started experimenting with nylon footies donned at retail stores when trying on shoes. Repurposing, these nylon footies (renamed maggot barriers) are applied over developing fruitlets when the apple fruit is between a dime and a quarter in diameter. A good time to do this is when thinning excess fruitlets in May or early June. Once applied the nylon maggot barriers (MBs) stretch as the apple fruits mature and stay on the apple fruits until harvest. In our experience, the MBs have proven effective in significantly limiting the damage from the apple maggot larvae.
Credits Above: Fig 1, 3: Jack Kelly Clark, courtesy Univ. California Statewide IPM Program; Fig 2: Marilyn Tilbury, Fig 4: L. Brakken, STFSCredits Above: All Maggot Barrier photos above: L. Brakken, STFS
As of February 2023, Seattle Tree Fruit Society (STFS) no longer is selling maggot barriers (MBs) for funding STFS educational activities.
MBs can now be easily purchased over the internet (search: maggot barriers), through Amazon or at area nurseries. Recently, in the Seattle area, nurseries stocking MBs have included Sky , Swansons , Cloud Mountain (Everson) , West Seattle , Sunnyside (Marysville) , Squak Mountain (Issaquah) , City People’s Sandpoint , & My Garden Nursery (Bellingham). Please contact these reputable nurseries directly to check for MB availability.
The STFS website still provides instructions for covering fruitlets with MBs.
STFS’s limited remaining MB inventory will be available to STFS members at upcoming in-person STFS events.
MBs protect apples, pears and other fruits from apple maggot flies, codling moths and other pests.