Category Archives: Plant pests and diseases

Deformed Flowers? It May Be Aster Yellows

Lately I have seen a lot of chatter on Facebook about distorted Echinacea and Rudbeckia flowers in the garden. I too noticed this in my Virginia garden, so I looked it up.

Sure enough, my plants have “aster yellows.” Aster yellows is caused by a phytoplasma, a small bacterium. This is a disease that affects more than 300 species of plants, including asters, coneflowers, zinnias, marigolds, heleniums, and chrysanthemums. And it is not just ornamental plants but edibles such as garlic, lettuce, carrots, tomatoes, and celery. Continue reading

Wanted Dead or Alive: Spotted Lanternfly

Spotted lanternfly (Lycorma delicatula) is a non-native, invasive insect first seen in September 2014 in Berks County, PA, when a shipment of stone arrived from China with the eggs attached. The insect is native to China, India, Japan, Korea, and Vietnam. By 2017, the insect moved to 13 Pennsylvania counties and a single county in both Delaware and New York. It is highly invasive, has a wide host range, and lacks natural, native enemies. To date, spotted lanternfly, also known as SLF, has been identified in 11 states: New York, Maryland, Virginia, West Virginia, Pennsylvania, Massachusetts, Ohio, Connecticut, Delaware, Indiana, and New Jersey. Continue reading

Wanted Dead or Alive: Spotted Lanternfly

Recently an article appeared in FFXNow.com (Fairfax County local news) with the headline “One of the world’s most wanted insects has landed in Fairfax County.” I immediately contacted Adria Bordas, Fairfax County’s Virginia Cooperative Extension (VCE) agent for horticulture. Spotted lanternfly is one insect I do not want in my garden. If you think a downpour of 17-year cicadas is gross, try looking at a tree dripping with spotted lanternfly. Continue reading

Remove the Bagworms in Your Shrubs and Trees

Bagworms are common pests in the Washington DC metro area. Usually we do not see the actual worms (Thyridoptery x ephemeraeformis), we see their “homes,” which are 2-inch long “bags” they have spun from silk and plant debris. These bags are hung like small, brown ornaments on shrubs and trees. At this time of year, they are prominent and should be removed.

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Got Deer? Try These Tactics in the Garden

deerNewcomers to this area will eventually see deer standing on the roadside or venturing out of the woods at dusk. At first, they admire the lovely bucolic sight, gentle deer, twitching their tails, flicking their ears back and forth. But as the newcomers settle down and try their hand at gardening, they learn that the deer are not as cute as they once thought. Continue reading

Gardening Questions? Ask These Experts

cucumberSummer is here and by now your Victory garden is planted. Dreams of fresh red tomatoes and lush green cucumbers are dancing in your head. But wait, what are those green caterpillars? What are those brown spots? Answers to these gardening questions and more are available from your local Master Gardeners and county extension agents. Even during this pandemic, they are standing by to help you with your gardening issues. Best of all, this is a free service for the public. Continue reading

Herbs Attract and Support Beneficial Insects in the Garden

Small thyme flowers

The herbs in my garden live among the annuals, perennials, vegetables, and shrubs. I do not have a separate, formal herb garden.  Every new herb plant gets tucked in any space I can find. I harvest them to use them fresh in the kitchen and for floral arrangements. By summer, many of my herbs are blooming along with everything else but that’s okay, they still serve a purpose. Even if I didn’t get to harvest them, they are helping the rest of the garden by attracting and supporting beneficial insects. Continue reading

Got Deer? Try These Tactics in the Garden

deerNewcomers to this area will eventually see deer standing on the roadside or venturing out of the woods at dusk. At first, they admire the lovely bucolic sight, gentle deer, twitching their tails, flicking their ears back and forth. But as the newcomers settle down and try their hand at gardening, they learn that the deer are not as cute as they once thought. Continue reading

You Got Gardening Questions? Ask These Experts

cucumberSummer is here and by now your Victory garden is planted. Dreams of fresh red tomatoes and lush green cucumbers are dancing in your head. But wait, what are those green caterpillars? What are those brown spots? Answers to these gardening questions and more are available from your local Master Gardeners and county extension agents. Even during this pandemic, they are standing by to help you with your gardening issues. Best of all, this is a free service for the public. Continue reading

Time to Cut Those Bagworms!

Last night, during my evening walk I noticed an unusual number of bagworms on a few evergreens. Bagworms are common pests in the Washington DC metro area. What I saw weren’t the bagworms themselves (Thyridoptery x ephemeraeformis) but their “homes,” 2-inch long “bags” they have created from their spun silk and plant debris. These bags were hung like small, brown ornaments on relatively new plantings in someone’s front yard. Some of the needles were clearly brown and dead.  Interestingly, one bag was hanging from the neighbor’s chain link fence, creating a very visible view of the threads wrapped round the metal.

Bagworms are moths, native to North America. They can attack more than 120 different types of trees but we tend to see them on evergreens such as juniper, arborvitae, cedar, spruce, pine, and Leyland cypress.

In the beginning of the summer, the eggs hatch and the larvae move out of the bags. The tiny caterpillars, 2 millimeters long, eat foliage and/or move to other trees via their silk threads. When they settle on their host tree, they spin a small bag of silk and plant debris. As they grow, their bags become bigger with more material collected from the host plant. By August, they have matured and the bags are very visible. During August and September the male adult bagworms, i.e., moths, emerge and fly to find a female to mate. The females cannot fly, they are grub-like and never leave the bag. Mating occurs through the bag and after mating, the female lays 500 to 1,000 eggs within her pupal cast skin and dies. The eggs overwinter and hatch next year in May or June.

Bagworms can defoliate and kill trees, especially evergreens. Although they can attack deciduous trees, most are not defoliated enough to be killed. Bagworms can also kill twigs by winding their silk around the twigs too tightly.

note white silk thread wrapped tightly around chain link fence

Now is the time to look for the bags and remove them by cutting them off–not pulling–bagging and disposing. Do not put them in your compost bin. If they are on the perimeter they will be easy to find but don’t forget to move branches aside and look within the tree. It goes without saying that a tree that has a bag will be damaged repeatedly each year, weakening the tree and possibly killing it.

Another option is to spray the tree with Bacillus thuringiensis (Bt) in May or June when the caterpillars have hatched and are on the foliage. This is a type of bacteria that kills the worms but does not harm the tree. If the tree is too tall, call an arborist. Spraying them later in the season after they have created their bags will not work since the bags will protect them. Or replace the evergreens with more resistant plants. But go out there now and inspect your plants, you need to remove them before the males emerge!