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Lilac Leaf Problem

There are at least 3 possible issues here. If the black will rub off on your finger, it is sooty mold which grows where tiny insects like aphids have been feeding. Suggest you wash the mold off with a light solution of soapy water and spray the plant with a pyrethrin or insecticidal soap to control the insects. If the black is in the leaf and spreading from the outside in, a fungus may be at work and we suggest you show a leaf to the horticulturist at your favorite garden center for an in person id and control suggestion. However, it is also possible that this leaf issue is the result of growing this shrub indoors in a dry environment or in a soil that is too rich in organic matter for this plant. If this last might be an issue, add lime when you repot.

By | 2017-09-11T15:49:20-07:00 March 13th, 2016|Shrubs|0 Comments
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Arborvitae Dieback

From this shot, it looks like the plant is a pyramidalis arborvitae (Thuja occidentalis 'Fastigiata'). Check the trunk at the soil line to make sure it's not injured or damaged.

Occasionally pests such as spider mites are an issue - you can check for them by placing a white sheet of copy paper under a branch and shaking the branch slightly. If present, the spider mites will fall onto the paper and should be easily spotted. Look for other signs, such as webs for spiders, tunneling on the stems and leaves, leaf miners and wet sticky sap that might be a sign of aphids. If you discover a pest, your local garden center or nursery can help you determine effective solutions. (Never spray without knowing what your pest is, because that, too can cause browning!)

By | 2016-03-13T09:28:09-07:00 March 13th, 2016|Shrubs|0 Comments
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Camellia Petal Blight

If it's the flower you're asking about, it's got camellia blight, a fungus that is soil-borne. During winter and spring rains, moisture splashes the soil and moves the fungus from the soil to the branches and foliage and then to the buds and opening flower petals. When and if the buds open, the petals decay and are brown and mushy. If infected buds, flowers, and leaves are left on the ground, the cycle will continue and destroy your plant’s flower production. So pick up the fallen camellia debris and dispose in the trash. Also apply a 2-3 inch layer of mulch around the plant, leaving a 2- inch diameter around the base of the plant clear to help break the cycle. And, once flowers are spent, camellias need an acid fertilizer such as Camellia/Azalea food or cottonseed meal. Camellias do best in partial shade or filtered light and regular water. Here's more: http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/DISEASES/campfbli.html

By | 2016-03-10T19:06:40-08:00 March 10th, 2016|Shrubs|0 Comments
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Rust Fungus On Rose

This appears to be a fungal disease called Rose Rust; its very common on roses. If you look at the underside of the affected leaves you'll see orange colored fungal structures (sometimes dark brown and black structures appear when the fungus is in the reproductive stage) - it does look like rust. This fungus is spread by water, so splashing water will move it upward thru the plant. It is also favored by shade and poor air circulation. You may need to consider a fungicide if its a very bad infection, but you can reduce the spread of the spores by removing the affected leaves (without defoliating the shrub), pick the fallen leaves up and dispose of them, prune for good air circulation around/within the shrub, and grow roses in full sun. Here's more info about Rusts and Roses: http://www.ipm.ucdavis.edu/PMG/GARDEN/PLANTS/DISEASES/rusts.html
http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7465.html

By | 2016-03-10T17:00:54-08:00 March 10th, 2016|Shrubs|0 Comments
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Plumeria

Plumerias do best in full sun, good draining soil, and moderate water during the growing season, with drier conditions during winter. Plants in general are not able to fend off diseases and pests when they are not provided their optimum environment. The spots suggest a possible fungal disease which would result from the plant not being able to have the optimum environment (full sun). The mottling of the leaves sounds like a fertilization issue. You will want to feed with a slow-release or organic fertilizer formulated for blooming plants during the growing season. As it get cooler, your plant is due to lose its leaves. In order to prevent the spread of any diseases or pests that might be present, you will want to collect and dispose of the fallen leaves. We have had some cool temps lately and Plumeria do not tolerate frost . You will want to provide protection as we go into the winter months.

By | 2016-03-10T09:46:08-08:00 March 10th, 2016|Shrubs|0 Comments
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Scale Insects On Camellia

Scale insects form raised bumps on leaves and stems as they stick their beaks in to suck the life out of plants. They are not uncommon on camellia, nor are aphids, mealybugs, and mites; they often coexist on stressed plants. As they feed, the leaves turn yellow, often develop spots, and fall off. There can be webs and sticky exudate that soon grows black sooty mold. Start gaining control by spraying the plants thoroughly, if temperatures permit, spray with a horticultural oil spray. These oils are highly refined and will not burn if used as directed on the label and should be used each winter on camellias. In hot weather, use a non-oil control product made for piercing and sucking insects. Spray the trunks and upper and lower leaf surfaces. This looks like a serious infestation so do consider also using a systemic insecticide to continue control this year. Keep fallen leaves raked up; water and fertilize as usual. The plants are tough; with your help, they'll shake off the insect issues.

By | 2016-03-10T06:15:13-08:00 March 10th, 2016|Shrubs|0 Comments
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Defoliated Lilac

Your lilac certainly doesn't look happy. While it's normal for them to lose their leaves for the winter, the remaining leaves on your plant look a bit wilted. And then there are all the bare branches. Too much water can cause wilting, as the roots drown. Roots need as much air as they do water. Lilacs only need about an inch of water per week.
Another possibility is unintended side effects from broad-leafed weed killers. Lilacs are broad-leafed plants, and the weed killer used on a lawn doesn't distinguish between lilacs and dandelions. Have you applied any turf weed killers near your lilac?
We suggest you prune out the dead stems at ground level. Then, in early spring, feed your lilac at about half strength with a high nitrogen fertilizer (fish emulsion is great). Most Colorado soils have plenty of potassium and phosphorus. Add a couple of inches of mulch around the base of the shrub, leaving a gap near the "trunk" so the stems don't rot. We hope that helps!

By | 2016-03-09T20:58:43-08:00 March 9th, 2016|Shrubs|1 Comment
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Viburnum Sargentii Onandaga

Your Viburnum looks very much like an 'Onandaga', an outstanding selection introduced by the U.S. National Arboretum in 1966 as a result of the work of Dr. Donald Egolf. Upright habit when young, then more rounded with age. A superior cultivar featuring both ornamental foliage and floral displays. Leaves emerge fine textured, velvety, and maroon, later turning green but retaining a moroon tinge. This makes a vivid contrast for the new foliage which continues to emerge maroon. Showy maroon buds open in May to pinwheel-type creamy-white flowers with a pink tinge and purple anthers. The inflorescence, when opened, has a dainty, airy appearance that we like to think of as having a Milky Way effect. Red fruit is sparse. Fall color is red. A must have plant as a specimen or in mass plantings. Zone 4

You viburnum may also be the maple leaf viburnum, Viburnum acerifolium. It's really hard to tell from the picture.

By | 2017-09-11T15:49:21-07:00 March 9th, 2016|Shrubs|0 Comments
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Powis Castle Artemisia

'Powis Castle' is a selection of this gray-leaved shrub that has finely divided leaves. An invaluable foliage plant, 'Powis Castle' is unique in carrying multi-branched stems of silver filigree foliage, which acts as a superb foil to medium-sized flowering perennials such as pinks or scabiosa. This plant's silvery, lacy foliage is an outstanding accent plant in the flower garden, it is an ideal complement to blue and purple flowering plants, and a useful buffer between flowering plants of non-compatible colors. Forms dense rounded mounds, and tolerates hot, humid weather better than most artemisias. Well-drained soil is essential for winter survival in colder climates. This artemisia benefits from periodic shearing to keep stems full and dense. Foliage stays on in the winter garden; cut back hard in early spring when new growth appears along the stems. Considered deer-resistant once mature.

By | 2016-03-09T11:01:08-08:00 March 9th, 2016|Shrubs|0 Comments
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Plumeria Problem

Please accept our apologies for the delay in responding! Plumerias (also known as Frangipani,) need well-draining soil, full or partial sun and regular water. Make sure drainage occurs from the bottom of the pot with each watering. Fertilize with an acid food such as cottonseed meal. From what we can see in this photo, there are a couple of possible causes of leaf death, including lack of sunlight (especially if it is indoors), improper soil moisture (watering), and/or spider mite damage. We recommend you move the plant into full sun but away from any walls or fences that can reflect/increase light intensity and heat, and use a magnifying lens to look for spider mites (although we think the problem is more the result of inadequate light and or irregular watering) on both the upper and lower surface of the leaves. We've included a link about spider mites and another about Plumeria from the Plumeria Society:
http://www.ipm.ucdavis.edu/QT/spidermitescard.html
http://www.plumeria.org/Tech_Info/Tech_info.htm

By | 2016-03-08T01:13:16-08:00 March 8th, 2016|Shrubs|2 Comments
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