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Extension > Extension County Offices > Douglas > County Horticulture Educator > Articles > Aphids In Your Garden

Aphids In Your Garden

I am always thrilled when new plants pop up and perform. Walking the flower field on Sunday night I applauded my “Kew Blue” Salpiglossis, “Prince” Calendula and “Lacy” Didiscus. Then I passed by one of my favorites, “Verde” Talinum paniculatum, also known as Fame Flower, or Jewels of Opar.  (The latter sounds so exotic!) I have been carefully watching this plant. We got it into the ground late, and it’s been a little slow, but the flower stems have finally emerged.  Imagine my dismay as I bent over to examine them more closely, and noticed green, wiggly specks covering the stems and flower buds. My good friend, Jen, heard my lament from across the field, “OH NO! Aphids! Aphids have infested my Jewels of Opar!”

Aphids come in a variety of colors including, but not limited to: green, black, brown, red, and pink. Drawn to young plant growth, these pear-shaped, slow moving insects range in size from 1/16 to 1/8 inch long. Several generations may be present, forming dense colonies that are found along the stems or undersides of leaves.

Aphids have long, needle like mouth parts that pierce plant tissue and suck out the juices.  This results in variable damage, ranging from no apparent damage to off-color foliage, twisted and curled leaves, gall formation, poor plant growth, and plant dieback. Most secrete honeydew, a sweet, sticky substance which is a food source for ants, bees and flies. Some kinds of aphids may spread plant viruses from one host to another. Dripping honeydew also encourages sooty mold growth on many plants.


Here are some tips to control aphids in your home garden:

  • Keep your garden free of weeds to reduce potential aphid hosts. Weeds such as sow thistle and mustard can support large colonies of aphids.
  • Excessive nitrogen can favor aphid reproduction; therefore plants should be grown with appropriate soil fertility levels.
  • Aphids can be physically knocked off of plants with a strong spray of water from a garden hose. In addition, this will also help wash off any honeydew or sooty mold that may be present.
  • The best known natural enemy is the lady beetle. Both adults and larvae are voracious predators of aphids. Other predators include lacewing larvae, syrphid flies and aphid midges.
  • Choose a low impact insecticide when possible that is less toxic, and “easy” on natural enemies. Horticultural Oil, Insecticidal Soap, Pyrethrins and Azadirachtin are effective, low impact, choices.


Monitor plants throughout the growing season to keep aphid populations in check.  Early detection is always best.  I’m headed out to the field with my sprayer filled with insecticidal soap to thwart the marauding horde. Wish me luck!

Contacts

Robin Trott
Extension Educator, Horticulture
(320) 762-3890
trot0053@umn.edu
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