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Gardening Answers Knowledgebase

Search Results for: Insect pests | Search the catalog for: Insect pests

Plant Answer Line Question

Keywords: Fungal diseases of plants, Insect pests, Lonicera

I noticed my honeysuckle, which is intertwined to look like a topiary bush with the greens and flower all bunched up at the top, to have yellowing of the leaves and drop off. Why are the leaves yellowing? It smells lovely and is green on the outside, but if you look under the canopy you can see many yellow leaves. Is it a disease? Should I use a fungicide?


There are a few possibilities. It might be a kind of leaf blight, as described by Iowa State University Extension.

Leaf blight is a fungal problem, but the control methods described above are not nontoxic, so you may want to look for a safer fungicide (example here), and also try to prevent the ideal conditions for fungus. Avoid wetting the leaves of the plant, and make sure there is good air circulation around the plant (by siting it properly, and by pruning to keep the plant's shape open).

Yellowed leaves could also be caused by scale, which is an insect. Do you see small bumps on the leaves and stems? If so, here are recommendations from The Organic Gardener's Handbook of Natural Insect and Disease Control edited by Barbara Ellis (Rodale, 1996):

"Minor infestations can be controlled by scraping the insects off the plant with your fingernail, and by pruning out the most infested parts of the plant. You can also use a soft brush and soapy water to scrub scales off the stems, or you can apply dormant oil to the trunk and stems of the plant just before growth begins next spring, and use superior oil during the growing season."

Because I'm not certain which type of problem your honeysuckle may have, you should bring a sample to a Master Gardener Clinic.

Date 2017-05-24
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Plant Answer Line Question

Keywords: Schlumbergera, Rubus, Indoor gardening, Insect pests, Fertilizers

I have whiteflies on my orchid Christmas Cactus. How can I get rid of them? I also would like to know if grass clippings are good to fertilize raspberries.


Christmas cactus, or Schlumbergera bridgesii, does occasionally have problems with insects. Whitefly nymphs and adults cause damage by sucking plant juices, and their feeding can weaken a plant. They also secrete a sticky substance called honeydew, which may then harbor sooty mold. For indoor plants affected by this insect, you might try gently washing the leaves. Rodale's Encyclopedia of Indoor Gardening, edited by Anne Halpin (1980) says that adults are easy to wipe up when it is colder indoors, and the young are usually on the undersides of leaves and may be wiped off with a sponge. Many whiteflies are now resistant to insecticides, and so it is best to start with plain water or soap and water. The book Indoor Gardening the Organic Way by Julie Bawden-Davis (Taylor, 2006) lists sticky traps, insecticidal soap, alcohol spray, oils, and pyrethrin as potential controls. There are products containing Neem oil which could help, if plain water or soapy water don't control the problem.
Clemson University Extension has some helpful information on general care of this plant.

As for using grass clippings as fertilizer, as long as the grass was not treated with weed-and-feed or other pesticides, it should be a good source of nutrients. Also, avoid using grass which has already gone to seed. Mulch It! by Stu Campbell (Storey Books, 2001) advises not to spread the clippings too thickly, and to let them dry out a bit before using. Here is a link to Virginia Cooperative Extension's page on recycling grass clippings.

Taylor's Guide to Fruits and Berries edited by Roger Holmes (Taylor, 1996) says that "reasonably good soil enriched with an inch or two of good compost or a moderate dose of balanced fertilizer each year should provide sufficient nutrients for your plants to thrive. Berry lovers sometimes provide regular doses of foliar fertilizers to give their plants a boost. Absorbed by the leaves in liquid form, seaweed, fish emulsion, and similar organic materials in balanced formulations provide a broad spectrum of nutrients."

Date 2017-08-08
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Plant Answer Line Question

Keywords: Vaccinium, Berries--Diseases and pests, Rubus, Fragaria, Insect pests, Prunus, Fruit--Diseases and pests, Berries

Could you tell me more about a new type of fruit fly that is supposedly infesting fruit here in the Pacific Northwest? Which fruit are affected?


The fruit fly is called the Spotted Wing Drosophila. It is known to affect strawberry, raspberry, blueberry, plum, peach, cherry, and grape. Oregon State University has created an information clearinghouse about this pest. Here is their information for home fruit growers. Washington State University has also devoted several web pages to this fly. Here is their Integrated Pest Management information, excerpted below (SWD stands for Spotted Wing Drosophila):
"Monitor for SWD using traps. [...] These vinegar traps are for monitoring purposes only and will not provide control of SWD. Remember, chemical control is not necessary if SWD is not present.
Composting fruit will likely not be effective at destroying maggots and pupae.
Remove infested and fallen fruit. Destroy or dispose of infested fruit in a sealed container.
Management recommendations are currently being developed for this pest. For the time being, good sanitation practices should be used."

Whatcom County Extension has clear, basic information for home gardeners as well. Since this insect is a relatively recent invader in the Northwest, information is constantly being adjusted and research is ongoing.

Date 2017-08-15
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Plant Answer Line Question

Keywords: Invasive species, Ailanthus altissima, Paulownia tomentosa, Insect pests

I've been hearing lately that there's a new invasive insect called brown marmorated stink bug.

What plants does it damage, and how can I prevent or control the damage?


Yes, the brown marmorated stink bug is a recent arrival in the Pacific Northwest. Washington State University Extension has a Pest Watch fact sheet that provides details on its life cycle, contrast with similar-looking bugs in our area, and potential damage the bug causes. "BMSB," as it is called, is well-known on the East Coast for damaging agricultural/edible crops and ornamental plants, as well as seeking refuge inside houses during cold weather (they don't harm people, but they do emit offensive odors).

The website "Stop Brown Marmorated Stink Bug" is the main information clearinghouse on controlling this pest.It includes a list of host plants (two of the most attractive to BMSB are invasives themselves: Ailanthus altissima or Tree of Heaven, and Paulownia tomentosa or Empress Tree). Washington State University is involved in research on natural predators and control methods for this invader (as well as another recent one, Spotted Wing Drosophila). Most chemical interventions attempted so far have had limited efficacy. Research into organic controls is ongoing.

For now, get to know what the bug looks like, and if you think you see one in your garden or home, report it as a citizen-scientist using the form on the website of Stinkbug-Info.org or contact your local WSU Extension office.

So far, the only officially reported sightings in Washington State have been in Clark and Skamania counties.

Date 2017-04-22
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May 31 2018 13:14:08