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How to Get White Stuff Off Houseplants

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You may think that houseplants, being indoors, would be protected from diseases and insect pests. Unfortunately, that is not the case. Insect pests can hitch a ride indoors on other plants and pets, and some houseplants are even infected or infested when purchased. The white stuff on your houseplants is likely mealybugs or powdery mildew. The former may be confused for the latter, according to the University of Minnesota Extension website.

Identifying Mealybugs

When on a plant, mealybugs look somewhat like tiny pieces of cotton stuck to the plant. In fact, the pests secrete a cottony substance in which to lay their eggs. Mealybugs cluster along the undersides of leaves and where the leaves meet stems. These sap-sucking pests drain a plant of its juices. A few mealybugs here and there probably won’t severely affect the health of your plants, but enough of them can cause the plants’ leaves to turn yellow and drop off.

Getting Rid of Mealybugs

Chemical methods usually are not recommended for getting rid of insect pests, especially on houseplants. Light infestations of mealybugs can be removed by picking them off the plants. Kill them first, if you prefer, by dipping a cotton swab in rubbing alcohol and dabbing the swab on the mealybugs. Because rubbing alcohol may damage or discolor some plants’ leaves, test it on an inconspicuous portion of a plant’s leaf before you use it on another portion of the plant. If a plant is heavily infested with mealybugs and is very weak or damaged as a result, then simply throwing away the plant may be the best option.

Identifying Powdery Mildew

Powdery mildew is a fungal disease. It usually appears in winter on plant leaves and flowers. Signs of the disease first appear as small, white spots that quickly grow and merge. Entire leaves may be covered with the thin, white layer of fungus, which may be mistaken for dust. Unlike dust, however, simply wiping off the substance is not enough to help an affected plant.

Getting Rid of Powdery Mildew

As with insect pests, chemical controls are not recommended for use in getting rid of powdery mildew, especially on indoor plants. Move an infected plant away from nearby plants, and then remove infected parts of the solitary plant. As you clip off infected leaves and/or stems, dip your cutting tool into bleach to disinfect it. Taking that measure helps to prevent the fungus from spreading to other parts of the plant. If an infection is severe, the plant may need to be thrown away, according to the Purdue Plant and Pest Diagnostic Laboratory website.

How to Get White Stuff Off Houseplants. You may think that houseplants, being indoors, would be protected from diseases and insect pests. Unfortunately, that is not the case. Insect pests can hitch a ride indoors on other plants and pets, and some houseplants are even infected or infested when purchased. The white …

White Spots on the Leaves on Petunias

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Petunias (Petunia x hybrida) are ornamentals that grow as a tender perennial in U.S. Department of Agriculture plant hardiness zones 9 and 10, though they grow as an annual almost everywhere else. Although petunias are prized for their flowers, it is still troubling if spots develop on leaves, as this makes them unsightly and can indicate a potentially serious issue. Numerous pests and diseases may trouble petunias, but only a handful of these could cause white spots to develop on leaves.

Thrips

Western flower thrips (Frankliniella occidentalis) are pests of petunias and many other ornamentals, shrubs, trees and food crops. Adults of this species are tiny, slender and winged with bristle-like hairs at the abdominal tip. Body color varies. Western flower thrips feed on leaves, petals and terminals, where they prefer rapidly growing tissue and cause the appearance of tiny light scars, or stippling. This thrips also serves as a vector for diseases that impact petunias like impatiens necrotic spot virus and tomato spotted wilt virus. Knocking thrips off of plants with a strong blast of water, removing spent flowers, providing the petunia with adequate water and avoiding the use of excessive nitrogen fertilizer limit thrips presence and impact. Avoid broad-spectrum insecticides and, if chemical control is necessary, instead apply narrow-range insecticide or neem oil.

Spider Mites

Spider mites are common landscape pests that are most prevalent when conditions are hot and dusty. Mites, which appear to the naked eye as tiny moving dots, suck out cell contents from leaves, causing the development of tiny light dots on leaves. Heavy feeding can cause leaf yellowing and drop and the spider mites’ characteristic webbing may appear. Drought-stressed petunias are particularly vulnerable to this pest. Usually, natural predators control spider mites. Spraying the petunia with water knocks the spider mites off and reduces the amount of dust on the plant.

Powdery Mildew

Powdery mildew fungi cause the development of white, powdery growth on the foliage of petunia and many other plants. The powdery mildew organism prefers moderate temperatures between about 60 and 80 degrees Fahrenheit and shady conditions. You can control powdery mildew by planting the petunias in full sun, providing the plant with adequate air circulation and avoiding excessive fertilizer applications. Protectant fungicides offer control powdery mildew if applied before or soon after the disease appears.

Viruses

The tomato spotted wilt virus, which uses thrips as a vector, appears as necrotic leaf spots. Petunias infected by the impatiens necrotic spot virus develop indicative light-colored spots encircled by a purple ring. These and other viruses that impact petunias are best controlled by avoiding infected stock and limiting the presence of the thrips that transmit these pathogens.

Nutrient Deficiencies

Multiple nutrient deficiencies could lead to light-colored spots or similar foliage symptoms. An iron deficiency first appears as yellowing between leaf veins, while a severe problem results in young leaves turning completely white or light yellow. Where zinc is inadequate, leaves develop chlorosis, causing them to twist. This chlorosis turns into tan or white dead patches. When plants don’t get enough potassium, mature petunia leaves develop yellow-green patches between veins that become tan dead spots before the entire leaf withers. Proper application of a balanced or supplemental fertilizer and, if necessary, taking steps to alter the pH, usually addresses nutrient deficiencies.

White Spots on the Leaves on Petunias. Petunias (Petunia x hybrida) are ornamentals that grow as a tender perennial in U.S. Department of Agriculture plant hardiness zones 9 and 10, though they grow as an annual almost everywhere else. Although petunias are prized for their flowers, it is still troubling if spots …