Indoor Plant Pest & Disease Tips

​General Tips:

1. Buy clean plants—thoroughly look over plants before you bring them home,
   
2. Place them in "quarantine" for a couple weeks before introducing them to your other plants,
   
3. Decide your threshold of tolerance and patience; sometimes pest problems are more hassle than the plant is worth,
   
4.  Scout your plants often!

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Interested in something a little more challenging?  Try:  African Violet, Succulents and Cacti, Weeping Fig, Croton, Orchids
Crotons  need bright light to keep their colorful leaves.   

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Scale & Mealy Bugs They come in various colors and can be armored, soft, or woolly. Piercing-sucking insects that create honeydew and make things sticky.  Populations quickly increase and control is difficult.
Control of scale and mealybugs: 1) Light infestations can be addressed with a Q tip dipped in rubbing alcohol, 2) Attempt to scrape off insects? 3) Use insecticidal soaps…or something stronger, 4) Remove infected plant tissues, 5) Submerge the entire plant in water? 6) Throw the plant away

Note about homemade insecticidal soaps: "New and improved" and concentrated liquid detergents with "grease cutters" and other ingredients have a high potential for being phytotoxic to plants. Proceed with caution. It’s better to go with a product that has been specifically developed and is labeled for your plants. 

APHIDS: Just like your garden aphids, but may have a waxy coating.   They create honeydew, like scale and mealybugs.  Scout and catch them early! Control of aphids: 1) Remove plant parts with the worst infestations, 2) Hose down plants or wash them off, 3) Use insecticidal soaps

SPIDER MITES: Related to spiders, Suck plant juices and cause yellowing and browning of plant tissues, If populations are high, you will also see webbing. Control of spider mites: Attempt to increase humidity in the home, Periodically wash down houseplants with a strong spray of water; including the lower leaf surfaces, Use miticides labeled for use on indoor plants
 
FUNGUS GNATS: Small flies that infest soil, potting mix, and organic matter, A nuisance pest Larvae primarily feed on fungi and organic matter, but also chew roots, Do not damage mature plants, Can have a generation every 17 days when temperatures are right.  Controlling fungus gnats: Target the larval stage, Reduce moisture and organic matter let media dry down between waterings, Use yellow sticky traps to catch adults? Repot using pasteurized potting mix, Will kill flies and the algae and microorganisms they feed on, Place chunks of potato on the plant surface to attract larvae, Consider using nematodes, predatory mites, or Bti (Mosquito Bits, Gnatrol)
 
WHITE FLIES: Tiny, white, moth like insects, Female adults lay eggs on the undersides of the plant’s foliage and the nymphs feed on the foliage, The nymph and adult stages feed by inserting their short, needle like beaks into foliage and sucking out plant sap. Heavy often cause stunting or yellow of leaves, leaf drop, and a decline in plant health.
Management: 1) Prevention is the best management strategy, 2) Check newly purchased plants and plants brought indoors from the garden or patio in the fall, 3) Begin control measures at the first signs.4) One way to reduce the whitefly population on an infested plant is to wash the undersides of the leaves with a moist cloth or sponge, 5) Use yellow sticky traps, 6) Insecticides specifically labeled for use on houseplants can be used, 7) Discard heavily infested plants
 
SCALE: Sucking insects both soft shelled and armored, Soft shell will produce honeydew, Heavy infestations may cause leaf yellowing, stunting, and dieback
Management: Scrape off, if possible, Wash off or crush any visible scale insects, Treat with an insecticidal soap or horticultural oil labeled for houseplants, Can use systemic houseplant insecticides, Heavily infested plants should be discarded
 
FOLIAR Disease:
Bacterial and fungal leaf spots: Decrease stress, Remove infected leaves and plant parts: Powdery mildew: Increase circulation around the plant; lower humidity, Remove infected leaves; Viruses: No cure; destroy plant
 
GENERAL DEFOLIATION: Likely causes: Sudden change in temperature, Transplanting shock, Sudden change in light intensity, Over watering, Lack of light

BROWNING LEAF TIPS: Likely Causes: Improper watering (such as water being too cold), Exposure to cold drafts, Insect attacks, Excess fertilizer, Floride or Boron deficiency (allowing water to sit for day before watering can help reduce floride.)

ABNORMAL LEAF COLOR: Likely Causes: Over watering, Lack of fertilizer, Insect attacks, Improper light
SPOTTED LEAVES: Likely Causes: Over watering, Burning from direct sunlight, Disease
 
REPOTTING: tips on when a plant might need repotting:

1. Roots begin to grow through the drainage holes,
2. Roots appear on the soil surface,
3. Soil mass is filled with roots,
4. New leaves are smaller than normal,
5. The plant wilts between normal waterings,
6. The plant keeps tipping over due to height

Repotting is best accomplished when the plant is actively growing, typically in spring or early summer which encourages new growth:  1) Gently knock/tip the plant out of its container and look at the roots, 2) If the plant is root bound, cut and/or unwind any circling roots, 3) If there is a salt buildup (crusty white residue) on the media surface, remove it carefully by scraping away the top inch of media, 4) Replant into the new container using fresh potting mix, 5) Make sure the plant is re potted at the same depth it was grown in the old pot, 6) Leave a little room at the top of the pot to allow for easy watering, 7) Press the soil around the roots and water immediately

PRUNING: All houseplants (with the exception of palms and Norfolk Island pine) can be top pruned to encourage new lateral growth. The best time to prune is in Spring, when growth usually occurs.
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DUST CONTROL: Keep houseplants clean by carefully washing foliage. Washing leaves with water or cleaning with leaf polish is not recommended on plants with hairy leaves. Rinse plants off with room temperature water in a shower or sink. Use a soft, damp cloth to wipe foliage. Leaf polish products should be used sparingly and only on plants with firm foliage.

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Master Gardener Vicki Gee Treft writes about what she learned from a "HOUSEPLANTS" course presented by Katie Dunker from the Colorado State University Extension.  ​