Attacking the Aphids!


“The ants are getting crazy. They’re doing weird stuff on the thistles in my garden and our new honeycrisp apple tree. Anybody know what to do? I’m pulling the thistles, but I don’t know what to do for the apple. Ideas?

~D.

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Hi D.,

Thanks for the question. First of all, pulling the thistle is your best option — not only for the aphids, but also for the fact that one thistle now is about a million thistles next year (or at least it seems that way).

The wilt is indeed caused by the aphids and the ants are there to eat the ‘honeydew’ from the aphids.  Ants and aphids share a well-documented relationship of mutualism. In exchange, the ants protect the aphids from predators and parasites. It’s important to treat the aphids as soon as possible because they mouth parts can transmit viruses to the tree and they can reproduce live young without fertilization (essentially, aphids are born already pregnant because they have mini aphids rather than ova in them). You can effectively (and safely for the tree) kill them with:

1. Neem Oil
Pure neem oil, an oil derived from the neem tree, has long been used in many natural remedies, including pest control. The oil, or Azadirachtin, acts as a repellent and growth regulator. To the insects, the neem oil has a bitter taste, so they will not eat the leaves treated with it. Also, if the insects do come in contact with the Azadirachtin, it prevents the larvae from growing into adults. Neem oil can be purchased at various online stores or made from neem trees (in the event that you have one around…).

2. Homemade Lemon Spray
This natural aphid pesticide works as an instant remedy, killing the aphids on contact. To make this natural pesticide, grate the rind of a large lemon. Boil it in enough water to fill a garden spray bottle. Let the mixture sit overnight. Drain the liquid into the garden spray bottle. Spray the aphids and larvae directly. It will cause them to convulse.

3.Homemade Vinegar Spray
Get out a spray bottle and fill it 1/3 of the way with distilled white vinegar and the rest of the way with water. This will kill the aphids and larvae on contact. Some plants react badly to the vinegar. It’s important know which plants you can and cannot use this method with.

4. Aluminum Foil
Place a square of aluminum foil around the base of plants affected by aphids. This causes light to bounce around to the underside of the leaves, which repels the aphids. It is also good for the plants, as it brings them more natural sunlight.

5. Calcium Powder
Sprinkling calcium powder around the base of the plants is another natural aphid repellent. The aphids do not like the calcium and will generally stay away from it.

6. Yellow Plastic Bowl
Aphids are naturally attracted to the color yellow. Place a yellow plastic bowl filled about 1/3 of the way with water in the center of the infested area. Many of the aphids will be drawn to the bowl and will go into the water and die.

7. Banana Peels
Burying shredded banana peels around the base of plants is an odd, but effective remedy. It has been around for ages and many gardeners will swear by it.

8. Smash Their Buddies
Squashing a few aphids near the infested area will signify to the other aphids that it is time to go. It’s a chemical reaction.

9. Ladybugs
Ladybugs can be purchased at garden and home improvement centers. The ladybugs feed on the aphids and if you purchase enough, the aphids will be gone in no time. Ladybugs are also good for the garden in other ways.

10. Garlic or Onions
Planting garlic or onions is another natural aphid deterrent. They do not like garlic or onion and will not likely come near an area they are in.  You can also hang unpeeled cloves of garlic with a string poked through (I use a sewing needle to do this) in the tree if planting is not an option.

As mentioned by another on your Facebook post: if you do decide to use dish soap, be careful! In general, the more effective dish soap is in killing an insect, the more damage there is to the plant. Soaps work by penetrating and dissolving the cells covering the insect’s body, resulting in dehydration and death. Plants also have a wax covering called the cuticle that is affected by the soap. The plant may not die instantly; however, disintegration of the leaf’s outermost layer may result in the loss of water and dehydration of the plant.

As for the leaves, they will remain distorted for the rest of the summer simply because there is dead mesophyll (internal green cells that make up the leaf) from the aphids piercing them, but it will not adversely affect the future of the tree.

 

© Mertie Mae Botanics LLC and Horticulture Talk!, 2013. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Mertie Mae Botanics LLC and Horticulture Talk! with appropriate and specific direction to the original content.

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