white spots on leaves

Natural Remedy for White Fungus on Leaves

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All fungi thrive when the weather is on the mild, damp side, and white fungi are no exception. Whether the white fungus you see on the leaves of your plants is powdery mildew, white rust or downy mildew, it’s probably an infection you can manage or prevent with a combination of cultural controls and natural treatments. Always try natural pesticides before resorting to more-toxic synthetic types that can be dangerous to people, pets and the environment.

Types of White Fungi

One of the most common white fungi is powdery mildew, which is caused by a number of different organisms, depending on the host plant. High relative humidity promotes the development of the disease, which appears as white, powdery-looking blotches on leaves, stems and flowers. The spores require dry plant tissue, though, so blast infected plant foliage with strong bursts of water during early morning in time for it to completely evaporate by nightfall. In addition to hosing your infected plants down, modify their growing conditions as necessary and treat them with natural products that contain baking soda, horticultural oil, neem oil, sulfur or copper.

Spread via wind and water and affecting a wide range of vegetables and ornamentals, white rust first manifests as white or yellow spotting on the tops of leaves. On the undersides of leaves, it develops into small, spore-filled white blisters or pustules and eventually causes disfiguring galls on stems in addition to malformed leaves and flowers. If the infection only affects a few leaves, remove and destroy them; severe infections require removal and destruction of the entire plant. The most effective way to manage rust is prevention, including cultural controls and use of a sulfur-based fungicide.

With downy mildew, you may see yellow spotting on the tops of plant leaves, with fluffy white growths that morph into gray developing on the undersides. Infected plant parts may be deformed; badly infected leaves may drop. Young plants and new foliage are most susceptible to downy mildew, which affects a broad range of plants, but is typically only fatal to small, tender seedlings. To help prevent downy mildew, supplement good cultural controls with copper-based fungicides when necessary.

Before treating a plant for a fungal infection, remove diseased leaves and stems in addition to any plant debris and old mulch. Throw everything away in a sealed garbage bag or closed container.

Natural Remedies

Natural remedies are substances that occur in nature that may be less toxic than synthetic products. Natural doesn’t necessarily mean nontoxic, however, so use these remedies with care. Protect yourself when applying any type of fungicide by wearing heavy gloves, pants, a long-sleeved shirt, socks, closed-toe shoes and eye protection. Move houseplants outside before spraying them and spray in the late evening to avoid possible negative effects on pollinators.

  • Baking soda. There’s considerable evidence that the use of a baking soda–water solution as a fungicide is ineffective. It also has the potential to damage foliage and doesn’t stick to plants, running off stems and washing off in the rain, thus possibly causing sodium buildup in the soil, which can harm the roots of your plants. If you still want to try it, spray infected plants with a mixture of .25 ounce of baking soda to 1 gallon of water, which may stop the growth of some fungi, such as powdery mildew, but doesn’t kill them. When the soda washes off, the fungi resume growth. You can use this spray at any time of year, but use it sparingly.
  • Horticultural oil plus baking soda. Petroleum-based horticultural oils combined with baking soda effectively control some types of fungi. In a spray bottle, mix 3 tablespoons of horticultural oil and 1.5 tablespoons of baking soda in a gallon of water. When you see signs of powdery mildew, spray the mixture on the leaves and stems of the plant until they’re dripping wet. During summer, use no more frequently than every 14 days. Don’t use horticultural oils on open flowers or young shoots, if the plant is wet or rain is in the forecast, or if the temperature is over 90 F or below 32 F.
  • Neem oil. This plant-based horticultural oil is a natural fungicide derived from the seeds of the neem tree (Azadirachta indica, USDA zones 10 through 12). It’s biodegradable and generally isn’t harmful to humans, birds, pets and beneficial insects, although it may be toxic to fish. On a dry day with no wind, thoroughly drench plant leaves and stems with neem spray when symptoms of fungi, such as powdery mildew or rust, are present. As a preventive, spray plants every week to every two weeks when weather conditions that promote disease development are present. Spray plants every seven days to kill fungi, followed by biweekly applications to prevent recurrence.
  • Sulfur powder or spray. A natural product, sulfur works to keep powdery mildew, rusts and other fungal infections from spreading and is effective when used early in spring as a preventive. Apply a sulfur product exactly as directed on the package label and avoid using it when the temperature is over 85 F. Sulfur is nontoxic to bees, birds and fish and relatively nontoxic to people, although you should wear a respirator during application and avoid eye and skin exposure. Don’t use sulfur for at least a month after applying an oil spray.
  • Copper fungicides and soaps. Copper-based products are manufactured as wettable powders, dusts, liquid concentrates and ready-to-use formulations that are effective against powdery mildew, downy mildew and other fungal diseases. Read and carefully follow the manufacturer’s directions on the package label for dosages, dilution recommendations, timing and safety precautions. Copper-based products are considered to be safe for bees and relatively safe for birds, but toxic to people, pets, and fish and other aquatic organisms. Over time, copper can accumulate in the soil to levels that may damage the roots of your plants.

To help protect fish from pesticide exposure, read the product label to find how far from a body of water you may safely use the product and never apply it on a windy, rainy day.

Preventing Fungal Infections

Choose plants that are resistant to fungal diseases and provide them with suitable growing conditions to help minimize the risk of disease development or spreading. Space your plants to allow adequate air circulation and educate yourself on the needs of different types of plants, grouping plants with similar needs together. For example, place plants that need full sun where they receive sunlight for 6 to 8 hours a day and don’t put a plant that likes continually moist soil near one that likes the soil to dry out between waterings.

Water your plants in the morning to reduce humidity during the evening and avoid overhead watering. Help prevent the spread of fungal infections by pruning off infected leaves and stems, destroying badly infected plants, and removing old mulch, plant litter and weeds. Always sterilize the blades of your pruning shears by dipping them in rubbing alcohol before and after using them to reduce the risk of spreading diseases between plants and avoid overwatering or overfertilizing. Overwatering can promote root suffocation and rots, while overfertilizing may stimulate new foliage growth, rendering the plants more susceptible to fungal attack.

Contact your local county extension office for more information about how to choose and use the safest, most effective treatments for fungal infections in your garden.

Natural Remedy for White Fungus on Leaves. If you see a white, powdery fungus on the leaves of your plants, it is likely they have powdery mildew. Initial infections are smaller white spots on the leaves, but later in the season, the fungus can spread to cover entire leaves. The fungus infects only the surface cells …

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 …