Re: this is from the ASK US page, so please send me a CC
- Hi Sheri, [original emailed to Sheri]I will try to shed some light on each problem and deal with solutions in general.Gall: There are two types of gall, fungal and insect.
LacebugsFungal Gall or Exobasidium Leaf and Flower Gall, Exobasidium vaccinii: Exobasidium vaccinii is a very common fungal disease in the spring during wet, humid, cooler weather on azaleas and occasionally on rhododendrons. Some of the native azaleas are more susceptible than hybrid rhododendrons. In April and May leaves and buds of infected plants develop distorted growth. The fungus invades expanding leaf and flower buds causing these tissues to swell and become fleshy, bladder-like galls. Initially, the galls are pale green to pinkish. Eventually, they become covered with a whitish mold-like growth. Fungal spores are produced within the white growth and are spread by water-splashing or wind to other expanding leaf or flower buds, or they adhere to newly formed buds, over-winter, and infect these buds the following spring. Older leaves and flowers are immune to infection. As the galls age, they turn brown and hard. The disease does not cause significant damage to affected plants. It just looks unsightly. If only a few plants are affected, pick and destroy galls.Insect Gall or Gall Midge, Clinodiplosis rhododendri: Clinodiplosis rhododendri usually over-winters in the soil as a prepupa. Pupation occurs in spring, with the adult midge emerging just as the hosts begin vegetative growth. There may be two additional generations yearly corresponding with flushes of rhododendron growth. Eggs are laid in clusters on the undersurfaces of leaves that are emerging from buds. Larval feeding causes a downward and inward rolling of leaf margins. Larvae mature in about seven days, drop to the ground, burrow in and make a cocoon.
Petal BlightRhododendron Lace Bugs, Stephanitis rhododendri, and Azalea Lace Bugs, Stephanitis pyrioides: Adults are about 1/8-inch long. The body is pale yellow. The lacy wings (very distinctive) are held flat over the back and are transparent with two dark spots present. The nymphs are black, spiny and smaller than the adults. The eggs over-winter partially embedded in leaf tissue. The eggs hatch in May. The nymphs mature into adults in June and lay eggs during late June and July. The second generation of nymphs appears in August. The over-wintering eggs will be laid when these nymphs become adults. adults and nymphs feed on the undersides of leaves by piercing the leaves with their mouthparts and sucking the plant juices. This causes a mottled, silvery or white discoloration, known as stippling, on top of the leaf where the chlorophyll has been removed. The undersides of leaves are covered with dark brown to black, sticky spots of excrement. Plant rhododendrons and azaleas in partial shade to maximize the activities of beneficial insects.
Powdery MildewPetal Blight, Ovulinia azaleae: This fungal disease, caused by Ovulinia azaleae, primarily affects the flowers of azaleas, but mountain laurel and rhododendron flowers can also be infected. Indian and Kurume azaleas are especially susceptible. The disease starts on the flower petals as tiny, irregularly-shaped spots, giving a "freckled" appearance. On colored flowers the spots are white, and on white flowers the spots are brown. The spots quickly enlarge and become soft and watery. Flowers rot and stick to the leaves. Infection is easily spread from flower to flower by wind, rain and insects. The fungus survives the winter in the soil. The most important things that you can do to control this disease in the home landscape are to pick and destroy infected flowers and avoid overhead watering. This fungus survives in the soil, so it is important to replace the ground litter with uncontaminated mulches. Rake and remove flower debris from beneath plants and, if possible, remove old flowers still attached to plants. Apply new mulch around the base of plants to serve as a barrier to new infection. On large azalea plantings, where it is not practical to remove infected flowers, make weekly fungicide applications beginning just before bloom and continue until the last buds open.
Some general hints to avoid problems. Keep the plants healthy. Struggling plants are the most disease prone. Remove diseased material and destroy it (or put it in the garbage). Prune your plants so they get more open ventillation. Plants that are pruned like a hedge are the most disease prone. Old branches should be removed and the plants should be open enough for air to circulate. Place in partial shade so they don't stay moist too long and still have enough shade so the predators of pests can survive. If you wish to use chemicals, check with your county agent to see what is permitted and recommended in your area.Powdery Mildew, Microsphaera azaleae: Powdery mildew causes azalea and rhododendron leaves to discolor and become coated with a white powdery fungal growth. Control of the disease is difficult, especially in certain weather conditions that favor the disease, i.e. when it is warm and humid. Plants that are young or are growing in the shade are often most susceptible.This information came from my website at: http://rhodyman.net/rhodyho.phpSteve Henning, Zone 6, Reading, PA USA==============================Good day,First let me thank you for reading my email! My azaleas seems to have more than one disease.This happened before and I replaced all the ones that were diseased (my pink coral bellsare unaffected) but all the diseases are back!They have gall, lacebugs, petal blight and often powdery mildew although that seems okayright now.How do I treat all of that? I have seen fungicide reccomended, neem oil, insecticidal soap,but I dont know what to do first.ANY help you can provide is greatly appreciated!Thank you again,Sheri Williamson
Thank you so much for writing with so much information on azaleas.
Are the plants you recommended a dwarf size, not getting larger than 3 feet in height, and good in the sun; as I want at least 3 plants planted in the sun, in front of a small garden. There are so many varieties that I’ve seen on the internet that it is difficult to decide.
Elaine -- thank you so much for responding to my email – unfortunately, I did not get it, and thankfully, Mr. Klump had included it in his email to me. If there were photos included, can you re-send them to me.
Another question to ask both of you - - after checking your website, found another website for Encore Azaleas for sun azaleas and dwarfed size. What can you tell me about these? What makes them different from the ones you mentioned and the Miss Curlicue?
18 January 2017
Your area is well known to me. What Elaine Sedlack has written to you is excellent advice.
As for some specific azaleas, there are many which ought to be available to you in your location. You have spoken of white azaleas. There are many which would work there for you. Here are a few:
Any of these should work very well for you. The first three are all straight white. I have Alaska in my garden here and it tends to spot bloom most of the year. My Fielder's White does, too. The Haru-no-hibiki is a bit different -- and very beautiful --having a center which is sometimes white, sometime pink. The border of it tends to be pinkish red, rather unusual.
As far as the actual white/pink combination is concerned, Picotee is a nice one, since the flower petals are all edged with a pink color. Another idea is Tickled Pink which, I think, belongs to the Rutherfordiana group of azaleas. It's a lovely pink color with white on the edges of the flowers. California Sunset is similar, but it is more of a salmon pink with white edges. I have one and it blooms profusely for me. However, it is in the Belgian Indica group, though I think it would probably get by in your climate. A different azalea would be the Albert-Elizabeth azalea. I have one of those which grows very well for me and it is part of the Belgian Indica azaleas, too. The flower tends to be white, but the petal edges are usually red or some people describe it as coral. In any case it can be quite spectacular, when it is blooming.
Now about planting azaleas. Some people feel that this can only be done at certain times of the year. Our experience here has been that azaleas can be planted whenever you wish to plant them. [That assumes, of course, that your soil is not frozen for two feet down!] Being on the coast here as you are up north, our chapter has learned for the last 45 to 50 years that a few things are necessary for continued success with plants of this family.
First, dig the hole in which you are going to put the azalea wide enough. If the root ball is six inches in diameter, then, make the hole probably sixteen to eighteen inches in diameter. If the root ball is only six inches deep, then, you only need to dig the hole maybe seven or eight inches deep. Width will be more important than depth generally.
Second, we've developed over the years a good mix for our plants, a mixture which remains basically acidic which is exactly what azaleas need. We use three things together: coarse peat moss, perlite and shredded redwood bark. When I say coarse peat moss, I mean the chunky kind, NOT the finely milled variety many nurseries try to sell you. You can probably get the shredded redwood bark where you are rather easily and there is more than one brand of it, Kellogg's and Sequoia being two of them. Anyhow, the three items can be mixed physically in equal parts, e.g. 1 - 1 - 1. Just "eyeball" it. It doesn't have to be perfect. If you have a big bucket for this, that would be the best.
Third, after you've mixed these three items together, then, fill the hole you've dug perhaps 2/3rds of the way with the mixture. Take your hose and turn the mixture in the hole into a soup: let it drain. [Drainage ought to be fairly quick.] Then, take the hose and blow as much of the dirt off the root ball as you can and set the plant down on top of the thoroughly wet mixture you have already soaked well. Use the big roots as anchors and be sure that the little hair roots are pulled out away from the center. If you break a few doing this, don't worry. [These are the roots which are going to grow and feed the plant. They will grow out horizontally, not vertically.]
Fourth, take more of your dry mixture and cover the roots up to about one inch below the crown of the azalea. Do not go higher, since you do not want to invite crown rot to attack the azalea later on. Take your hose again and soak the entire mixture. When you've done that, walk away. It is not necessary to dump plant food in at this time. Wait awhile to allow the plant to acclimate itself. Just water it reasonably or rejoice in the rain!
Fifth, we use a feeding schedule which we have found works very well in our part of the USA. Azaleas tend not to appreciate too much food. So I follow a feeding schedule of just three times annually: Easter, Fourth of July and Labor Day. That's so I don't forget. What do I use? I use cottonseed meal for a number of reasons. One, it's organic. Two, it is a slow release fertilizer which, three, doesn't burn the plants. There are many good chemical fertilizers, too, and I used to use one years ago. However, I've found this cheaper, more effective with fewer possible side effects on the plants. And along with the shredded redwood bark, it tends to help the soil over time. If you water the soil around your plants a little bit first, then, you can spread the cottonseed meal around the root zone easily and water it in gently. The soil seems to accept it better that way.
A couple of general observations about planting azaleas. Coir or chopped up coconut can be used instead of the shredded redwood bark or the coarse peat moss. They all work well. However, coarse peat moss seems to be more readily available at most nurseries out here and shredded redwood bark tends to last much longer than most other similar materials. Beside the tannic acid it has, there are other enzymes which tend to discourage unwanted bugs from coming around attacking the roots, especially phytophora which is almost always a fatal root rot. At least this has been our general experience over the last 45 years or so. Over time it tends to improve the soil surrounding the azaleas. [I've got a box of Snairol sitting in my garden room unused for the last 30 years!]
My last general observation is this: if your soil consists of a lot of clay, which is not uncommon along the coast, I would suggest you buy some gypsum to keep around [calcium sulfate]. This can be broadcast over your soil perhaps as heavily as an 1/8th to 1/4 inch. It won't hurt. Water it in gently and within a week, your soil will drain much faster. This is very important. Azaleas will take all the water they can get SO LONG AS it drains away from the root zone rapidly. Azalea roots will tolerate moisture, but they won't tolerate sitting in water. [They are not water lilies!] So drainage out here is a big factor. One other related point to this: if you get some strong winds coming in off the ocean without any rain associated with it, this will tend to dry out your soil. [The opposite is also true, i.e. dry offshore winds.] You do not want the soil around your plants to dry out in cold weather in any case. That will desiccate the plants. Keep in mind that a desiccated plant is a desecrated plant.
I hope this helps.
George E. Klump, President
Southern California Chapter, ARS/ASA
On 1/17/2017 9:45 AM, Elaine Sedlack esedlack@... [azaleas] wrote:
The cultivar 'Miss Curlicue' should do fine in full sun in your area with the maritime influence. It has sun tolerant species and Kurume azalea in both sides of its parentage.
Others may be able to recommend more plants to you. So far as a good white, I think your relatively cool climate will give you a lot of leeway. Just ask at a local nursery and see what they are offering, because they will not likely be selling ones that don't do well there.
Was going through your great website of azaleas - - - so many -- I am looking for an azalea plant for planting in the sun, growing only 3-5 feet, and a two-toned color.
I could not find which plants fit what I am looking for – can you tell me which plants fit what plants I wish to plant in the sun.
I liked the white/pink, Miss Curlicue – but did not have any information re my requirements for planting. I am also looking into a white azalea plant too -- and if you can recommend a plant for planting in the sun.
I live in San Mateo County, California – more on the coastal region.