Common diseases of annual and perennial plants include damping-off, root and stem rots, leaf spots and blights, rusts, powdery mildew, downy mildew, vascular wilts, and virus and nematode diseases. Insect pests include aphids, plant bugs, leafhoppers, spittlebugs, mealybugs, scales, thrips, whiteflies, mites, caterpillars, beetles, wasps, leafminers, and borers. For additional information on nonpesticidal alternatives to managing pests in annual and perennial flowers in the home garden, see Chapters 2 and 8 in Part I: Cultural Methods, of Pest Management Around the Home.

To keep the plants healthy and attractive, you should be able to diagnose common insect and disease problems and formulate an appropriate treatment plan. This plan should include cultural control measures such as proper site preparation; diversified plantings; sanitation during and after the growing season; disease-free transplants and seed; crop rotation; and scouting (checking for pests and disease symptoms). Remember to use the least toxic measures to manage pest problems. In some cases, pests such as aphids and spider mites can be washed off with a strong stream of water.

For all plant diseases, practice plant sanitation. When plants are not wet, carefully remove and destroy or discard affected plant parts or portions thereof. In autumn, rake and remove all garden debris. Avoid wetting foliage if possible. Water early in the day so aboveground plant parts will dry as quickly as possible. Avoid crowding plants; space plants apart to allow air circulation; prune or thin plants or plantings.

Table 9 covers many of the common insect pests and diseases of annual and perennial plants found in the home garden. Roses and vines (such as clematis) are discussed with other woody ornamental plants in Chapter 10 – Tree and Shrub Pest Management. It is a good idea to test a product first on a small portion of the plant or planting to see if it causes any adverse effects on the plant(s). Varieties or cultivars may differ in their reaction to pesticide products. For toxicity information, see Table 3 in Chapter 3 and Tables 4b and 4c in Chapter 4.

* Plant Sanitation: Carefully remove and destroy or discard affected plant parts, at a time when plant parts are not wet. In autumn, rake and remove all garden debris. Avoid wetting foliage. Water early in the day so aboveground plant parts will dry quickly. Avoid crowding plants; space plants apart to allow air circulation; prune or thin plants or plantings.

** Imidacloprid: Products containing imidacloprid are not registered for use in certain New York City and Long Island counties (Kings, Queens, Nassau, and Suffolk). Most formulations of imidacloprid once available to homeowners are now classified as restricted-use (for professional application only) in New York State. Check product status and label prior to purchase.

Table 9. Annual and perennial pest management Also see Chapter 8 in Part I: Cultural Methods, of Pest Management Around the Home.
Plant		Pest	Some Pest Management Options
Ageratum		Spider mites	Wash off with a strong stream of water. If necessary, apply: acephate, insecticidal soap (potassium salts of fatty acids), lambda-cyhalothrin, Mite-X (plant extracts), or neem oil.
		Whitefly	Apply as necessary: acephate, cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), lambda-cyhalothrin, neem oil, or permethrin. Spray two or more times at five-day intervals. Good coverage of leaf undersides is important for control. Repeat spraying only if necessary.
Chrysanthemum		Fungal leaf spot	Practice plant sanitation.* (see note). Apply if needed: Bacillus subtilis, chlorothalonil, copper ammonium carbonate, neem oil, potassium bicarbonate, or sulfur.
		Powdery mildew	Practice plant sanitation* (see note). Apply if needed: Bacillus subtilis, copper ammonium carbonate, neem oil, potassium bicarbonate, or sulfur.
		Rust	Practice plant sanitation* (see note). Apply if needed: Bacillus subtilis, myclobutanil, neem oil, potassium bicarbonate, or sulfur.
		Viral diseases	Remove affected plants and destroy. Management of insect vectors (such as aphids or thrips) may not be completely effective, especially if weeds or other nearby plants harbor the virus.
		Aphids	Wash off with a strong stream of water. If necessary apply: acephate, cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), lambda-cyhalothrin, malathion, Mite-X (plant extracts), neem oil, permethrin, or pyrethrins plus PPB.
		Beetles	Handpick and discard beetles. If necessary, apply carbaryl or cyfluthrin.
		Borers	Cut and bury large-stemmed weeds nearby that may serve as alternate hosts and sources of infestation. No pesticides are available for borers.
		Caterpillars	Handpick and remove caterpillars. If necessary, use Bt (Bacillus thuringiensis ssp. kurstaki), carbaryl, cyfluthrin, lambda-cyhalothrin, neem oil, permethrin, pyrethrins plus PPB, or spinosad.
		Plant bugs (including four-lined plant bug)	Apply as necessary: carbaryl, imidacloprid**, insecticidal soap (potassium salts of fatty acids), or lambda-cyhalothrin.
		Spittlebugs	Apply as necessary: carbaryl, cyfluthrin, lambda-cyhalothrin, neem oil, or pyrethrins plus PPB.
Cockscomb (Celosia)		Fungal leaf spot	Practice plant sanitation* (see note). If needed, apply neem oil or sulfur.
		Spider mites	Wash off with a strong stream of water. If necessary apply: insecticidal soap (potassium salts of fatty acids), or Mite-X (plant extracts).
Columbine (Aquilegia)		Fungal leaf spot	Practice plant sanitation* (see note). Apply if needed: Bacillus subtilis, neem oil, or sulfur.
		Aphids	Wash off with a strong stream of water. If necessary, apply: cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), or neem oil.
		Leafminer	Handpick and destroy mined leaves. If necessary, use lambda-cyhalothrin or spinosad. Spray three times at weekly intervals, beginning when leaves are about half-grown.
		Sawfly (larvae)	Remove by hand. If needed, use carbaryl, imidacloprid**, insecticidal soap (potassium salts of fatty acids), or spinosad.
Dahlia		Botrytis blight (Gray mold)	Practice plant sanitation* (see note). After periods of wet weather, apply Bacillus subtilis, copper ammonium carbonate, or neem oil.
		Powdery mildew	Practice plant sanitation* (see note). Apply Bacillus subtilis, copper ammonium carbonate, myclobutanil, neem oil, or sulfur.
		Viral diseases	Remove affected plants and destroy. Management of vectors (such as aphids or thrips, depending on the disease) may not be effective, especially if weeds or other nearby plants harbor the virus.
		Aphids	Wash off with a strong stream of water. If necessary, apply: acephate, cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), neem oil, or pyrethrins plus PPB.
		Beetles	Handpick and discard beetles. If needed, spray when beetles first appear. Use acephate, carbaryl, cyfluthrin, imidacloprid**, pyrethrins plus PPB, or spinosad. Repeat as per label directions only if necessary.
		Leafhoppers	Spray when first leaf damage is noticed and thereafter as necessary. Use cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), neem oil, or pyrethrins plus PPB.
		Spider mites	Wash off with strong stream of water. Apply if necessary: acephate, insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), or pyrethrins plus PPB. Good coverage of leaf undersides is important for control. Repeat spraying may be necessary.
		Thrips	If needed, spray when flowers begin to open. Use acephate, carbaryl, cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), neem oil, pyrethrins plus PPB, or spinosad.
Daylily (Hemerocallis)		Fungal leaf spot	Practice plant sanitation* (see note). Apply if needed: Bacillus subtilis, neem oil, or potassium bicarbonate.
		Rust	Apply if needed: Bacillus subtilis, neem oil, potassium bicarbonate, or sulfur. Once infections are present, application may be required on a regular basis to prevent new infections. Sprays made early in the infection process have been more effective than those applied when disease incidence is severe.
		Thrips	If needed, use cyfluthrin, insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), neem oil, or spinosad. Spray two to three times at five- to seven-day intervals, beginning just after buds form.
Delphinium		See Larkspur.
Forget-me-not (Myosotis)		Aphids	Wash off with a strong stream of water. If necessary, apply: cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), or neem oil.
		Flea beetles	Handpick (brush off into a container of soapy water) and remove. If needed, use carbaryl, neem oil, or spinosad.
Geranium Botrytis blight on a geranium flower cluster and leaf		Botrytis blight	Practice plant sanitation* (see note). After periods of wet weather, apply Bacillus subtilis, chlorothalonil, copper ammonium carbonate, neem oil, or potassium bicarbonate.
		Aphids	Wash off with a strong stream of water. If necessary, apply: acephate, cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), neem oil, or pyrethrins plus PPB.
		Caterpillars	Handpick where possible. If needed, use acephate, Bt (Bacillus thuringiensis ssp. kurstaki), carbaryl, cyfluthrin, neem oil, or spinosad.
Gladiolus		Thrips	If needed, use acephate, cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), lambda-cyhalothrin, Mite-X (plant extracts), neem oil, permethrin, pyrethrins plus PPB, or spinosad. Some products are only effective on thrips exposed on the plant leaf or flower surfaces, not hidden in buds or crevices.
Hollyhock (Malva)		Rust	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis, chlorothalonil, myclobutanil, neem oil, or sulfur.
		Beetles	Handpick and discard beetles. If needed, use carbaryl, cyfluthrin, imidacloprid**, or spinosad.
		Leafhopper	If needed, use carbaryl, cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), or neem oil.
		Mites	Wash off with strong stream of water. If needed, use insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), or neem oil. Good coverage of leaf undersides is important for control. Repeat spraying may be necessary.
Impatiens		Alternaria leaf spot	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis, or neem oil.
		Rhizoctonia web blight	Practice plant sanitation* (see note). Apply azoxystrobin if needed.
		Aphids	Wash off with a strong stream of water. If necessary, apply: cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), or neem oil (check label; product may damage blossoms).
		Spider mites	Wash off with strong stream of water. If needed, use insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), or neem oil. Good coverage of leaf undersides is important for control. Repeat spraying may be necessary.
Iris Didymellina leaf spot		Didymellina leaf spot	Practice plant sanitation* (see note). Apply chlorothalonil, neem oil, or potassium bicarbonate.
		Aphids	Wash off with a strong stream of water. If necessary, apply: cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), or neem oil.
		Iris Borer	Clean up all plant debris in late fall. Borers deposit eggs on old leaves and stems in late-summer to early fall. Parasitic nematodes (Steinernema carpocapsae) can be applied as a drench treatment around the base of each iris (covering an area of 1 square foot) in the spring when soil temperature is above 50°F. It is best to apply on an overcast day.
Larkspur (Delphinium)		Powdery mildew	Practice plant sanitation* (see note). Apply Bacillus subtilis, copper ammonium carbonate, myclobutanil, neem oil, potassium bicarbonate, propiconazole, or sulfur.
		Aphids	Wash off with a strong stream of water. If necessary, apply: acephate, cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), or pyrethrins plus PPB.
		Borers	Cut and bury large-stemmed weeds nearby that may serve as alternate hosts and sources of infestation. No pesticides are available.
		Spider mites	Wash off with strong stream of water. If needed, use insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), or neem oil. Good coverage of leaf undersides is important for control. Repeat spraying may be necessary.
Lily (Lilium)		Botrytis blight (Gray mold)	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis, chlorothalonil, copper ammonium carbonate, or neem oil.
		Aphids	Wash off with a strong stream of water. If necessary, apply: cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), or neem oil.
		Lily leaf beetle	Handpick and discard beetles. If needed, use neem, cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), or spinosad.
Lupine (Lupinus)		Powdery mildew	Practice plant sanitation* (see note). Apply Bacillus subtilis, neem oil, or sulfur, according to product label directions.
		Aphids	Wash off with a strong stream of water. If necessary, apply: cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), or neem oil.
		Whitefly	Apply as necessary: cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), or neem oil. Good coverage of leaf undersides is important for control. Repeat spraying may be necessary.
Marigold (Calendula)		Botrytis blight (Gray mold)	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis, chlorothalonil, copper ammonium carbonate, neem oil, or potassium bicarbonate.
		Spider mites	Wash off with a strong stream of water. Apply if necessary: insecticidal soap (potassium salts of fatty acids), lambda-cyhalothrin, or Mite-X (plant extracts). Good coverage of leaf undersides is important for control. Repeat spraying may be necessary.
Nasturtium		Fungal leaf spot	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis, copper ammonium carbonate, or neem oil.
		Aphids	Wash off with a strong stream of water. If necessary, apply: cyfluthrin, imidacloprid**, or neem oil.
		Spider mites	Wash off with a strong stream of water. If necessary, apply neem oil. Good coverage of leaf undersides is important for control. Repeat spraying may be necessary.
		Tarnished plant bug	If needed, apply carbaryl, or imidacloprid**.
Pachysandra	Volutella blight		Practice plant sanitation* (see note). When new leaf growth starts, spray with chlorothalonil, following label directions.

		Euonymus scale See Chapter 10 – Tree and Shrub Pest Management for Growing Degree Day (GDD) information.	Signs and symptoms include yellow spots on leaves, and gray-white scurfy material on stems. Where possible, prune out scale-infested branches. Horticultural oil may be used as a dormant spray in mid-April to early May (35–120 GDD). In early to mid-June (533–820 GDD); and again in mid-July (1150–1388 GDD), use horticultural oil, imidacloprid**, insecticidal soap, malathion, or neem oil.
Pansy (Viola)		Anthracnose (Colletotrichum)	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis, chlorothalonil, copper ammonium carbonate, neem oil, or potassium bicarbonate.
		Downy mildew	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis (for suppression), copper ammonium carbonate, neem oil, or potassium bicarbonate.
		Fungal leaf spot	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis, chlorothalonil, copper ammonium carbonate, neem oil, potassium bicarbonate, or sulfur.
		Aphids	Wash off with a strong stream of water. If necessary, apply: cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), lambda-cyhalothrin, Mite-X (plant extracts), neem oil, or permethrin.
		Mealybug	Spray in spring or as necessary, using cyfluthrin, insecticidal soap (potassium salts of fatty acids), lambda-cyhalothrin, neem oil, or permethrin. Discard badly infested plants.
		Spider mites	Wash off with a strong stream of water. Apply if necessary: insecticidal soap (potassium salts of fatty acids), lambda-cyhalothrin, Mite-X (plant extracts), or neem oil. Good coverage of leaf undersides is important for control. Frequent spraying may be necessary.
Peony (Paeonia)		Botrytis blight (Gray mold)	Practice plant sanitation* (see note). Spray with Bacillus subtilis, copper ammonium carbonate, or neem oil. Begin sprays as new growth emerges in the spring.
		Redspot; Leaf blotch (Cladosporium paeoniae)	Early in the growing season, spray with copper ammonium carbonate if needed.
		Japanese beetle and Rose chafer Japanese beetle	Handpick and discard beetles. If necessary, spray when insects are first seen, and repeat weekly, if needed, using carbaryl, cyfluthrin, or imidacloprid**.
		Thrips	Use cyfluthrin, insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), neem oil, or spinosad.
Petunia		Botrytis blight (Gray mold)	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis, chlorothalonil, or neem oil. Chlorothalonil may discolor blossoms.
		Viral diseases	Remove affected plants and destroy. Management of vectors (aphids, leafhoppers, or thrips, depending on the disease) may not be effective, especially if weeds or other nearby plants harbor the virus.
Phlox		Fungal leaf spot	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis, chlorothalonil, copper ammonium carbonate, myclobutanil, neem oil, potassium bicarbonate, or sulfur.
		Powdery mildew	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis, chlorothalonil, copper ammonium carbonate, myclobutanil, neem oil, potassium bicarbonate, propiconazole, or sulfur.
		Plant bugs	If needed, apply carbaryl, imidacloprid**, or insecticidal soap (potassium salts of fatty acids).
		Spider mites	Wash off with strong stream of water. Apply, if necessary: insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), or neem oil. Good coverage of leaf undersides is important for control. Repeat spraying may be necessary.
Poppy (Papaver)		Aphids	Wash off with a strong stream of water. If necessary, apply: cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), or neem oil.
		Leafhoppers	Spray at five-day intervals or when needed. Use carbaryl, cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), or neem oil.
Rose (Rosa)		See Chapter 10, Tree and Shrub Pest Management.
Shasta daisy (Leucanthemum)		Fungal leaf spot	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis, chlorothalonil, neem oil, or sulfur.
		Aphids	Wash off with a strong stream of water. If necessary, apply: cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), Mite-X (plant extracts), or neem oil.
		Beetles	Handpick and discard beetles. If needed, use cyfluthrin, imidacloprid**, or spinosad.
Snapdragon (Antirrhinum)		Anthracnose (Colletotrichum)	Practice plant sanitation* (see note). If disease becomes severe, usually beginning in July, apply Bacillus subtilis, copper ammonium carbonate, neem oil, or potassium bicarbonate.
		Powdery mildew	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis, copper ammonium carbonate, myclobutanil, neem oil, potassium bicarbonate, or sulfur.
		Rust	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis, myclobutanil, neem oil, potassium bicarbonate, propiconazole, or sulfur.
		Aphids	Wash off with a strong stream of water. If necessary, apply: cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), lambda-cyhalothrin, Mite-X (plant extracts), neem oil, or permethrin.
		Beetles	Handpick and discard beetles. If needed, use carbaryl, cyfluthrin, imidacloprid**, lambda-cyhalothrin, permethrin, or spinosad.
		Spider mites	Wash off with strong stream of water. If needed, use insecticidal soap (potassium salts of fatty acids), lambda-cyhalothrin, or Mite-X (plant extracts). Good coverage of leaf undersides is important for control. Repeat spraying may be necessary.
Stock (Malcolmia)		Fungal leaf spot	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis, copper ammonium carbonate, neem oil, or sulfur.
Sweet alyssum (Lobularia)		Rhizoctonia root and stem rot	Practice plant sanitation* (see note). Apply azoxystrobin if needed.
		Leafhoppers	Apply as necessary: carbaryl, cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), or neem oil.
		Whitefly	Apply as necessary: cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), or neem oil. Good coverage of leaf undersides is important for control. Repeat spraying may be necessary.
Sweet pea (Lathyrus)		Fungal leaf spot	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis, copper ammonium carbonate, neem oil, or sulfur.
		Aphids	Wash off with a strong stream of water. If necessary, apply: cyfluthrin, imidacloprid**, or neem oil.
		Leafminer	Apply as necessary: imidacloprid**, or neem oil. Repeat spraying may be necessary.
		Seedcorn maggot	Use insecticide-treated seed. Wear gloves when planting.
Tulip (Tulipa)		Botrytis blight (tulip fire)	Practice plant sanitation* (see note). If needed, apply Bacillus subtilis, chlorothalonil, copper ammonium carbonate, or neem oil.
Verbena		Aphids	Wash off with a strong stream of water. If necessary, apply: cyfluthrin, imidacloprid**, insecticidal soap (potassium salts of fatty acids), neem oil, or permethrin.
		Leafminer	Spray at the first sign of mines, with carbaryl, imidacloprid**, neem oil, or permethrin.
		Plant bugs	If needed, apply carbaryl, imidacloprid**, or insecticidal soap (potassium salts of fatty acids).
		Spider mites	Wash off with strong stream of water. If needed, use insecticidal soap (potassium salts of fatty acids), or neem oil. Good coverage of leaf undersides is important for control. Repeat spraying may be necessary.
Zinnia		Alternaria leaf spot	Practice plant sanitation* (see note). If disease becomes severe, apply Bacillus subtilis, chlorothalonil, neem oil, or potassium bicarbonate. Repeat only if needed following label directions.
		Powdery mildew	Practice plant sanitation* (see note). Apply Bacillus subtilis, chlorothalonil, copper ammonium carbonate, neem oil, potassium bicarbonate, propiconazole, or sulfur, according to label directions.
		Viral diseases	Remove affected plants and destroy. Management of vectors (aphids, leafhoppers, or thrips, depending on the disease) may not be effective, especially if weeds or other nearby plants harbor the virus.
		Japanese beetle	Handpick and discard beetles. If needed, use carbaryl, cyfluthrin, imidacloprid**, lambda-cyhalothrin, or permethrin.
		Spider mites	Wash off with strong stream of water. Spray only if needed, using acephate, horticultural oil, insecticidal soap, lambda-cyhalothrin, or Mite-X (plant extracts). Good coverage of leaf undersides is important for control. Repeat spraying may be necessary.

Pest Management Guidelines A Cornell Cooperative Extension Publication	New York Pest Management Guidelines
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