Help with fungus like disease on ornamental plant (white powder on leaves)?

Question

I found a powdery like disease on my garden and I was wondering if someone is familiar with this. I live in South Florida where the weather is mostly warm and humid. And this is a photo of the actual disease on the plant.
http://i240.photobucket.com/albums/ff251/rayoscentellas/Fungus3.jpg
After a month is killing all this plant and also the new ones I planted. Any help greatly appreciated.

Thanks to all of you for the excellent answers. Very interesting information about plant disease. They all help me understand a lot better what's going on with my plants.

Answer 1

They are "woolly aphids". I don't see any fungal evidence on top of the leaves and if this were in fact powdery mildew it would be visible at this location. Woolly aphids secrete a fuzzy,waxy covering over there bodies to protect them from predators and the elements, this accounts the white puffy substance you see. If it were powdery mildew, the leaf surface would be somewhat smooth instead of the bumpyness that is shown in the pic. By them being on the stem as well as the "undersides" of the leaves, particularly along the main, central vein only further weighs on my professional opinion that they are in fact woolly aphids. There are many varieties that attack an abundance of different plants and shrubs, in fact, a new variety has been introduced to the southeastern part of the country which is called.. Asian woolly hackberry aphid (Shivaphis celti). It may be the Woolly apple aphid (Eriosoma lanigerum) as well. One of these may be your culprit. Regardless, it is one of the woolly aphid species.

Some of these species feed in groups and cause gall-like swellings on the bark or curled leaves, such as your picture depicts. Woolly aphids are hard to manage unless you use a "systemic" insecticide, like the one manufactured by Ortho called Ortho "Systemic Insect Killer". It contains 8% of the active ingredient.."Orthene" (acephate) which works very well in the control of woolly's and many other sap sucking insects and is available over-the-counter. A systemic will penetrate the plants cell structure and stay available for up to about 3 weeks. This means it will do the job if anything feeds on the plant for that length of time. After that you will need to apply another application, however, a second application may be warranted due to the woolly's toughness. O.S.I.K also works as a "contact" insecticide and will kill immediately on contact. However, these little buggers are tough with that waxy coating protecting them so you may have to get them when they feed on the plant, with the systemic action part of it. This product can be gotten at any leading garden center like Walmart, Home Depot, or Lowes. Hope this answers your question. Sorry for being so long winded, but some answers require a good explanation to get the point across and to give exacting information. Good luck.
http://www.extension.umn.edu/projects/yardandgarden/ygbriefs/e453woollyaphid.html
http://www.ortho.com/index.cfm/event/ProductGuide.product/documentId/72c90bb34e83ab40af12b25b1d77e798
http://www.scotts.com/media/media/pdf/productGuide/labels/Systemic%20Insect%20Killer.pdf

Added Info below taken from "Yard & Garden Brief".....

........ Woolly Alder Aphid: Also called the maple blight aphid, this species produces dense, white, woolly masses on the leaves and twigs of its primary host, silver maple, and secondary host, alder. The infested leaves may fold lengthwise and cover the aphids inside. This species overwinters as an egg or nymph on either host. The eggs hatch, and the nymphs become active when new leaves appear in the spring. Although not damaging to the tree, the white, waxy threads can be mistaken for a fungus, causing the homeowner to believe the tree is diseased.



**Billy Ray**

Answer 2

I have checked your photo quite closely, it could be that your plant has more than one plague.

What I can see under the leaves looks like what the other user has said, never the less what I see on the stems is not any powdery fungus, at least not to my eyesight.

Just check it out, see if under the leaves and/or on the stems it is sticky, also check well if what is on the stems looks like little cotton balls with a white & very small insect in them. If so then those are aphids, these insect do destroy plants and are very contagious to the nearby plants.

I am leaving two good sites for Aphids Management & another with photos of these plant insects, you may have to use different products if there is more than one plague.

Good luck.

Answer 3

You don't need the alcohol but mix 1 part water to 1 part dishwashing liquid in a large container like a 5 gal bucket. Turn the plant upside down in the bucket while holding the soil, dip the plant up and down about 10 times, let it set for about 5 min then take it outside or in the bathtub and rinse it off. You could also do it by hand leaf by leaf wiping both top side and underside. It sounds to me as if it has mealy bugs, they will definitely kill it if not taken care of. Be sure to let the soil dry good before watering this type of plant, these plants don't like alot of water and keeping any plant to moist only attracts critters. Good Luck.

Answer 4

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Answer 5

try spraying the plant with rubbing acohol, I find that works to get rid of many plant pests, spray once a day for a week and see if problem clears up

Answer 6

This is a copy and paste of a very informative portion of a website: http://ohioline.osu.edu/hyg-fact/3000/3047.html
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Powdery Mildews on Ornamental Plants
HYG-3047-96
Stephen Nameth
Jim Chatfield

Almost all landscapes have plants that become diseased with one of the powdery mildew fungi. Although the fungi that cause powdery mildew are usually different on different plants, all of the powdery mildew diseases are similar in appearance. In most cases, prompt recognition and control actions can prevent severe damage to plants from powdery mildew diseases.
Symptoms

Powdery mildews, as the name implies, often appear as a superficial white or gray powdery growth of fungus over the surface of leaves, stems, flowers, or fruit of affected plants. These patches may enlarge until they cover the entire leaf on one or both sides. Young foliage and shoots may be particularly susceptible. Leaf curling and twisting may be noted before the fungus is noticed. Severe powdery mildew infection will result in yellowed leaves, dried and brown leaves, and disfigured shoots and flowers. Although it usually is not a fatal disease, powdery mildew may hasten plant defoliation and fall dormancy, and the infected plant may become extremely unsightly. On roses, uncontrolled powdery mildew will prevent normal flowering on highly susceptible cultivars.

Powdery Mildew on begonia leaves Powdery mildew on lilac leaf
Hosts

Powdery mildew fungi infect almost all ornamental plants. They are commonly seen only on those plants more naturally susceptible to the disease. Susceptible woody plants include some deciduous azaleas, buckeye, catalpa, cherry, a few of the flowering crabapples, dogwood, English oaks, euonymus, honeysuckle, horse chestnut, lilac, privet, roses, serviceberry, silver maple, sycamore, tulip tree, some viburnums, walnut, willow and wintercreeper. Powdery mildews are also common on certain herbaceous plants, such as chrysanthemums, dahlias, delphiniums, kalanchoes, phlox, Reiger begonias, snapdragons and zinnias. Remember that each species of powdery mildew has a very limited host range. Infection of one plant type does not necessarily mean that others are threatened. For example, the fungus that causes powdery mildew on lilac does not spread to roses and vice versa.

P.M. on Dogwood leaves P.M. on Euphorbia sp. P.M. on gerba azalea leaves maple leaf
Environment Favoring Powdery Mildews

Most powdery mildew fungi produce airborne spores and infect plants when temperatures are moderate (60 to 80 degrees F) and will not be present during the hottest days of the summer. Unlike most other fungi that infect plants, powdery mildew fungi do not require free water on the plant surface in order to germinate and infect. Some powdery mildew fungi, especially those on rose, apple, and cherry are favored by high humidities. Overcrowding and shading will keep plants cool and promote higher humidity. These conditions are highly conducive to powdery mildew development.
Control of Powdery Mildews

Before using fungicides you should attempt to limit powdery mildews by other means. The following cultural practices should be beneficial for controlling powdery mildews.

* Purchase only top-quality, disease-free plants of resistant cultivars and species from a reputable nursery, greenhouse or garden center. Horticulturists in the green industry and Extension offices should be consulted concerning the availability and performance of resistant varieties.

* Prune out diseased terminals of woody plants, such as rose and crabapple, during the normal pruning period. All dead wood should be removed and destroyed (preferably by burning). Rake up and destroy all dead leaves that might harbor the fungus.

* Maintain plants in a high vigor.

o Plant properly in well-prepared and well-drained soil where the plants will obtain all-day sun (or a minimum of 6 hours of sunlight daily).

o Space plants for good air circulation. DO NOT plant highly susceptible plants--such as phlox, rose, and zinnia--in damp, shady locations.

o Do not handle or work among the plants when the foliage is wet.

o Water thoroughly at weekly intervals during periods of drought. The soil should be moist 8 to 12 inches deep. Avoid overhead watering and sprinkling the foliage, especially in late afternoon or evening. Use a soil soaker hose or root feeder so the foliage is not wetted.

Chemical Control of Powdery Mildews

In many cases, powdery mildew diseases do little damage to overall plant health, and yearly infections can be ignored if unsightliness is not a major concern. For example, lilacs can have powdery mildew each year, with little or no apparent effect on plant health. On some plants, powdery mildews can result in significant damage. Thus, fungicides must be used to achieve acceptable control. For best results with fungicides, spray programs must begin as soon as mildews are detected. Spray on a regular schedule, more often during cool, damp weather. Use a good spreader-sticker with the fungicides. Be sure and cover both surfaces of all leaves with the spray. Fungicides generally recommended for powdery mildew control include: Triadimefon (Bayleton, Strike); Triforine (Funginex), Thiophanate-methyl (Cleary's 3336, Domain) and Propiconazole (Banner).