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Pest Management Guidelines
A Cornell Cooperative Extension Publication

  
New York Pest Management Guidelines

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Houseplant Pest Management

6. Houseplant Pest Management

Contents

 

Pesticides

IPM Considerations

Fungus gnats

Further Reading

Table 6. Houseplant pesticide guidelines

African violet

Asparagus fern

Begonia

Citrus

Coleus

Croton

Dieffenbachia

Dracaena

False aralia

Ferns

Fuchsia

Gardenia

Geranium

Gloxinia

Grape ivy

Ivy (English)

Jade plant

Palms

Philodendron

Pittosporum

Podocarpus

Poinsettia

Roses(miniature)

Rubber plant

Schefflera

Weeping fig

 

 

Various methods are available for managing pests of houseplants. The pest, number of plants infested, size of the planting, and inclination of the owner will determine what methods are best. Some insects and spider mites may be able to be washed off plants with a strong stream of water. Predatory or parasitic insects may be effective in some plantings. Removal of individual insects with a cotton swab dipped in rubbing alcohol can also be effective for some scales and mealybugs. Table 6 lists some registered pesticides for houseplants (for toxicity information, see Table 3 in Chapter 3, and Tables 4b and 4c in Chapter 4).

 

Pesticides

Many of the pesticides available for use on houseplants are formulated in ready-to-use pressurized cans or as pump sprays. Make sure the product you choose is labeled for use indoors and on houseplants. Other formulations may cause plant injury (phytotoxicity) or plant death. All pesticides labeled for use on houseplants should be applied outdoors.

Plant spikes containing insecticides may also be available. Be sure to follow label directions carefully checking for the amount to use, how to water, storing unused spikes, precautionary statements, and hazards to humans. Wash hands thoroughly with soap and water after handling, or better yet, wear disposable gloves and discard after use.

 

IPM Considerations

For a general description of some common insects and diseases on houseplants and for information on nonpesticidal management of houseplant pests and diseases, see Chapter 5 in Part I: Cultural Methods, of Pest Management Around the Home.

Consider removing infected leaves or discarding infested plants rather than treating with a toxic substance. Most chemical pesticides are effective at protecting plants against disease but cannot “cure” existing infections. If houseplants need to be sprayed, remove them from the living space for treatment. If weather allows, take the plants out of doors or into a garage to make the application. Bring plants back indoors when dry.

Fungus gnats

FungusGnatCycleLabelled

 

Life cycle of a typical fungus gnat species, Bradysia corophila:

Adult gnats live approximately 7 days.

The female lays up to 150 eggs, which hatch in approximately 5 days.

Larvae grow for 10 to 14 days, and then pupate.

The pupal stage lasts approximately 3 to 4 days, before developing into an adult fungus gnat.

 

Fungus gnats are small flies that can sometimes be a problem indoors, especially if houseplants are kept constantly moist. Adult fungus gnats are attracted to damp locations where fungi are likely to flourish, such as houseplant potting mix. Larvae feed primarily on fungi, but occasionally attack roots of growing plants. Adult gnats may become nuisance pests. Avoid keeping potting mixes too wet and prevent accumulations of stagnant water in pot saucers or other containers. To check for the presence of fungus gnat larvae in potting mix, cut a small potato in half, place cut side down, and lightly press into mix. Leave for 3 to 4 days, then lift up and look for shiny white larvae with black heads. For adult monitoring and capture, yellow sticky cards can be used: place on rim of pot. Larvae may be controlled using B.t.i. (Bacillus thuringiensis var. israelensis), or beneficial nematodes (Steinernema feltiae).

Further Reading

Common Sense Pest Control Quarterly. Bio-Integral Resource Center newsletter. P.O. Box 7414, Berkeley, Calif. 94707.

Compendium of Flowering Potted Plant Diseases. Daughtrey, M. L., R. L. Wick, and J. L. Peterson. 1995. American Phytopathological Society, St. Paul, Minn. 90 pp.

Compendium of Ornamental Foliage Plant Diseases. Chase, A. R. 1987.American Phytopathological Society, St. Paul, Minn. 114 pp.

Diseases of Geraniums. Horst, R. K., and P. E. Nelson. 1985. Cornell Cooperative Extension Information Bulletin 201. Ithaca, NY. 33 pp.

The Healthy Indoor Plant Powell, C. C., and R. Rossetti. 1992. Rosewell Publishing, Box 2920, Columbus, Ohio 43216. 297 pp.

IPM Practitioner. Bio-Integral Resource Center newsletter. P.O. Box 7414, Berkeley, Calif. 94707.

 

Rose powdery mildew 1      Rose powdery mildew 2

Powdery mildew on rose. The white or pale gray coating on leaf surfaces, dusty or fuzzy in appearance, is typical of powdery mildew on many kinds of plants.

 

 


Table 6 Notes:

·         Consider removing infected leaves or discarding infested plants rather than treating with a toxic substance. Most chemical pesticides are effective at protecting plants against disease but cannot “cure” existing infections.

·         Check all pesticide labels carefully. Products may not be registered on all varieties or may not be tested on all rare or unusual varieties. If the host and pest are not listed on the label, do not use the pesticide.

·         If houseplants need to be sprayed, remove them from the living space for treatment. If weather allows, take the plants out of doors or into a garage to make the application. Bring plants back indoors when dry.

 

Table 6. Houseplant pesticide guidelines

Also see Chapter 5 in Part I: Cultural Methods, of Pest Management Around the Home.

Plant

Pest

Some Pest Management Options

African violet

Botrytis blight (gray mold)

Apply hydrophobic neem oil or copper soap (copper octanoate), one time, following cultural plant sanitation practices.

 

Powdery mildew

Apply hydrophobic neem oil or copper soap (copper octanoate), per label directions.

 

Cyclamen mites

No pesticides available. Discard infested plant. Isolate new plants for three to four months before placing in your collection.

 

Mealybug

Use insecticidal soap (potassium salts of fatty acids) or hydrophobic neem oil. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk.

 

Root mealybug

Apply insecticidal soap, using drench treatment as specified on label.

Asparagus fern

Aphids

aphid

Spray with insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, or horticultural oil. Some products should not be used on delicate ferns; test a small leaf first. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk.

Begonia

Bacterial leaf spot (Xanthomonas sp.)

Apply Bacillus subtilis per label directions.

 

Botrytis blight (gray mold)

Apply Bacillus subtilis, hydrophobic neem oil, or potassium bicarbonate.

 

Powdery mildew

Apply Bacillus subtilis, hydrophobic neem oil, or potassium bicarbonate.

 

Aphids

Treat with insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, Mite-X (plant extracts), or permethrin. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk.

 

Mealybug

Treat with insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, or permethrin. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk.

 

 

Whitefly

Treat with insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, or permethrin. Good coverage of leaf undersides is important for control. Repeat sprays may be needed. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk.

Citrus

Scale

Treat with insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, permethrin, or pyrethrins with insecticidal soap. Treat the crawler stage (the young insect that emerges from the egg and “crawls” to a feeding site).

 

Spider mites

Treat with insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, permethrin, or pyrethrins with insecticidal soap. Good coverage of leaf undersides is important for control. Repeat sprays may be needed.

 

Whitefly

Treat with insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, permethrin, or pyrethrins with insecticidal soap. Good coverage of leaf undersides is important for control. Repeat applications may be needed.

Coleus

Mealybug

Treat with insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, permethrin, or pyrethrins with insecticidal soap. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk.

 

Whitefly

Treat with insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, permethrin, or pyrethrins with insecticidal soap. Good coverage of leaf undersides is important for control. Repeat sprays may be needed. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk.

Croton

Mealybug

Treat with insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, or pyrethrins with insecticidal soap. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk.

Dieffenbachia

Spider mites

Treat with horticultural oil, insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, permethrin, or pyrethrins with insecticidal soap. Good coverage of leaf undersides is important for control. Repeat sprays may be needed.

Dracaena

Mealybug

Treat with horticultural oil, insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, permethrin, or pyrethrins with insecticidal soap. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk.

 

Spider mites

Treat with horticultural oil, insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, permethrin, or pyrethrins with insecticidal soap. Good coverage of leaf undersides is important for control. Repeat sprays may be needed.

False aralia

Scale

Treat with horticultural oil, insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, or pyrethrins with insecticidal soap. Apply when crawlers are active. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk.

 

Spider mites

Treat with horticultural oil, insecticidal soap (potassium salts of fatty acids), or hydrophobic neem oil. Good coverage of leaf undersides is important for control. Repeat sprays may be needed.

Ferns

Anthracnose

Apply potassium bicarbonate if needed, or hydrophobic neem oil as a preventative.

 

Scale

Treat with horticultural oil, hydrophobic neem oil, or insecticidal soap (potassium salts of fatty acids). Check all pesticide labels carefully. Products may not be registered on all varieties or may not be tested on all rare or unusual varieties. If host and pest are not listed on the label, do not use the pesticide. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk.

Fuchsia

Botrytis blight (gray mold)

Apply Bacillus subtilis if needed. If a product with hydrophobic neem oil is used, test a small area of foliage first.

 

Mealybug

Use insecticidal soap (potassium salts of fatty acids) or permethrin. Some product labels recommend testing on a small area first. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk.

 

Whitefly

Use insecticidal soap (potassium salts of fatty acids) or permethrin. Some product labels recommend testing on a small area first. Good coverage of leaf undersides is important for control. Repeat sprays may be needed. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk.

Gardenia

Fungal leaf spot

Apply Bacillus subtilis or hydrophobic neem oil if needed.

* Note: Some formulations containing insecticidal soap should not be used on gardenias. Some varieties have shown sensitivity to it. Read label directions carefully before using. 

Mealybug

Treat with insecticidal soap*, pyrethrins with insecticidal soap*, or hydrophobic neem oil. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk.

Scale

Treat with horticultural oil, insecticidal soap*, pyrethrins with insecticidal soap*, or hydrophobic neem oil. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk.

Spider mites

Treat with horticultural oil, insecticidal soap*, pyrethrins with insecticidal soap*, or hydrophobic neem oil. Good coverage of leaf undersides is important. Repeat sprays may be needed.

 

Whitefly

Treat with horticultural oil, insecticidal soap*, pyrethrins with insecticidal soap*, or hydrophobic neem oil. Good coverage of leaf undersides is important for control. Repeat applications may be needed. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk.

Geranium

Black leg

(Pythium spp.)

No products for homeowner use are available. Discard diseased plants and potting mix.

 

Botrytis blight (gray mold)

Apply Bacillus subtilis, hydrophobic neem oil, or potassium bicarbonate.

 

Caterpillars

caterpillar

To control caterpillars, remove by hand, or use hydrophobic neem oil.

 

Spider mites

Treat with insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, Mite-X (plant extracts), or pyrethrins with insecticidal soap. Good coverage of leaf undersides is important for control. Repeat sprays may be needed.

 

Whitefly

Treat with insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, or pyrethrins with insecticidal soap. Good coverage of leaf undersides is important for control. Repeat sprays may be needed. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk

Gloxinia

Aphids

Treat with insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, or pyrethrins with insecticidal soap. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk

 

Cyclamen mite

No pesticides available. Discard infested plant. Isolate new plants for three to four months before placing in your collection.

 

Mealybug

Treat with insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, or pyrethrins with insecticidal soap. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk

Grape ivy (Cissus)

Powdery mildew

Treat with Bacillus subtilis, hydrophobic neem oil, or copper soap (copper octanoate).

Ivy (English)

Fungal leaf spot

Treat with Bacillus subtilis, hydrophobic neem oil, copper soap (copper octanoate), or potassium bicarbonate.

 

Spider mites

Use insecticidal soap (potassium salts of fatty acids), hydrophobic neem oil, Mite-X (plant extracts), permethrin, or pyrethrins with insecticidal soap. Good coverage of leaf undersides is important for control. Repeat sprays may be needed.

Jade plant

(Crassula)

Powdery mildew

Apply Bacillus subtilis, or hydrophobic neem oil, according to label directions.

 

Mealybug

Use horticultural oil, hydrophobic neem oil, or insecticidal soap (potassium salts of fatty acids). Some product labels recommend testing on a small area first. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk

Palms

 

Mealybug

 

mealybug

Use insecticidal soap (potassium salts of fatty acids), pyrethrins with insecticidal soap, horticultural oil, hydrophobic neem oil, or permethrin. Check all pesticide labels carefully. Products may not be registered on all varieties or may not be tested on all rare or unusual varieties. If host and pest are not listed on the label, do not use the pesticide. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk

 

Spider mites

Use insecticidal soap (potassium salts of fatty acids), pyrethrins with insecticidal soap, horticultural oil, hydrophobic neem oil, or permethrin. Check all labels carefully. Products may not be registered or tested on all varieties. If host and pest are not listed on the label, do not use the pesticide. Good coverage of leaf undersides is important for control. Repeat sprays may be needed.

Philodendron

Scale

Use insecticidal soap (potassium salts of fatty acids), pyrethrins with insecticidal soap, horticultural oil, hydrophobic neem oil, or permethrin. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk

Pittosporum

Spider mites

Use insecticidal soap (potassium salts of fatty acids), pyrethrins with insecticidal soap, or hydrophobic neem oil.

Podocarpus

Spider mites

Use insecticidal soap (potassium salts of fatty acids), pyrethrins with insecticidal soap, or hydrophobic neem oil.

Poinsettia

Whitefly

Discard infested plant to avoid spread of whiteflies to other plants, or isolate and treat with insecticidal soap (potassium salts of fatty acids) or hydrophobic neem oil. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk

Roses (miniature)

Botrytis blight (gray mold)

Treat with Bacillus subtilis or hydrophobic neem oil.

 

Powdery mildew

Treat with Bacillus subtilis or hydrophobic neem oil.

 

Spider mites

Use insecticidal soap (potassium salts of fatty acids), pyrethrins with insecticidal soap, hydrophobic neem oil, Mite-X (plant extracts), or permethrin. Good coverage of leaf undersides is important for control. Repeat sprays may be needed.

Rubber plant

(Ficus)

Anthracnose

Treat with hydrophobic neem oil.

Mealybug

Use insecticidal soap (potassium salts of fatty acids), pyrethrins with insecticidal soap, or hydrophobic neem oil. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk

 

Scale

Treat crawler stage with insecticidal soap (potassium salts of fatty acids), pyrethrins with insecticidal soap, or hydrophobic neem oil. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk

Schefflera

Anthracnose

Treat with hydrophobic neem oil.

 

Scale

Treat crawler stage with insecticidal soap (potassium salts of fatty acids), pyrethrins with insecticidal soap, permethrin, or hydrophobic neem oil. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk

 

Spider mites

Treat with insecticidal soap (potassium salts of fatty acids), pyrethrins with insecticidal soap, permethrin, or hydrophobic neem oil.

Weeping fig

Phomopsis canker and dieback

No homeowner products are currently available. Prune out dead or dying branches.

 

Scale

Treat crawler stage with insecticidal soap (potassium salts of fatty acids), pyrethrins with insecticidal soap, or hydrophobic neem oil. Systemic imidacloprid for use in potted houseplants is available, but is not registered for home use in the New York counties of Kings, Queens, Nassau, or Suffolk

Table 6 Notes:

·         Consider removing infected leaves or discarding infested plants rather than treating with a toxic substance. Most chemical pesticides are effective at protecting plants against disease but cannot “cure” existing infections. 

·         Check all pesticide labels carefully. Products may not be registered on all varieties or may not be tested on all rare or unusual varieties. If the host and pest are not listed on the label, do not use the pesticide.

·         If houseplants need to be sprayed, remove them from the living space for treatment. If weather allows, take the plants out of doors or into a garage to make the application. Bring plants back indoors when dry.