Rust on Native Azaleas in Nursery

This week, Rust disease was identified on native deciduous azaleas and smooth hydrangea in a nursery in western North Carolina. Most guidebooks list it as either Rust, hemlock-blueberry rust (Pucciniastrum vaccinii) or hemlock-hydrangea rust (Pucciniastrum hydrangeae). Apparently it affects hemlock needles in early spring and summer, then the infected needles inoculate both wild hydrangea (Hydrangea arborescens)(photo) and panicle hydrangea (Hydrangea paniculata) during the summer (Sinclair et al 1987). Because Rhododendron are in the Ericaceae family along with blueberry, these plants also seem to be infected. Additionally, blueberry grown as an ornamental in nurseries has been a "hot" trend lately, which could contribute to the renewed presence. On native deciduous rhododendron, for example, R. canescens (piedmont azalea), R. periclymenoides (pinxterbloom azalea), R. runifolum (Plumleaf azalea), R. viscosum (Swamp azalea), and R. calendulaceum (flame azalea), symptoms resemble these photos. Symptoms of leaf rust first appear in mid-summer as circular yellow flecks about an 1/8 inch in diameter on the upper leaf surface.

The fungus can be found forming spores in rust-colored pustules on the undersides of the leaf below the yellow flecking (photo below).

The orange-colored spores in the pustules are disseminated by air currents to other azalea leaves. If the leaf remains wet overnight, new infections (pustules) can form repeating the cycle throughout the remainder of the summer and fall. When conditions are favorable for severe disease development with numerous pustules early in the summer, extensive defoliation of infected leaves can occur. In mild climates, the fungus may over winter as spores in pustules of fallen leaves. So removing leaves from deciduous azalea blocks or plantings in the spring can help reduce the severity of disease later in the season. However, the fungus also can be re-introduced to azaleas in the nursery/landscape each year from nearby hemlocks (Tsuga canadensis) that serve as a second (alternate) host of the fungus. Normally, fungicides are not needed to control leaf rust (Benson and Creswell). It is possible to let the foliage die back and fall off this year without control, especially if plants are not going to be sold until spring 2010. In a study conducted by Jones, Bir and Benson in 1981, Plantvax 75W (oxycaboxin; Class: Carboxamide), Mancozeb 80W (Manganese ethylenebis; Class: carbamate), and Ferbam 76W (Ferbam; Class: carbamate) provided the best control for rust on the hybrids mentioned above when applied from mid-August through September according to label recommendations. Heritage (Azoxystrobin; Class: QOI-strobilurins), is only labeled for Puccinia sp. of rusts and not Puccinastrum spp. of rusts. Please read the labels of all fungicides applied and always wear personal protective equipment required on the label.

For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.

New Products for Ornamental Greenhouse, Nursery, and Landscape Pests

New Products for Ornamental Greenhouse, Nursery, and Landscape Pests

From: Steve Frank, Extension Entomologist, NCSU

A new product Kontos is available to manage most sucking pests in greenhouses. It is also labeled for use in nurseries. Kontos from OHP is effective against whiteflies, aphids, mealybugs, thrips, and other insects. Kontos has a unique mode of action (IRAC group 23) that makes it an important tool in resistance management programs. This could be particularly important as a product to rotate with Conserve (spinosad) to kill thrips. It is also soft on beneficial organisms. More information on Kontos can be found at:Kontos.

In ornamental landscapes we now have Acelepryn by Dupont. This unique chemical has a very low vertebrate toxicity. So low in fact that it does not require a signal word on the label. It is effective on many landscape pests and can be used as a foliar spray or drench to provide translaminar and systemic plant protection. Acelepryn also is soft on beneficial organisms compared to older products. More information about Acelepryn can be found at Acelepryn.




For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.

Weekly Word on Weeds

Weekly Word on Weeds, from Dr. Joe Neal, NCSU Department of Horticulture

Want an overview of weed control in container nurseries?
Here is a link to video of one of my presentations at the SE Greenhouse conference on weed management in container nurseries. BASF corporation taped the presentation and posted it on their web site. I just saw it today. Here is the link:

Joe Neal Video


Editor's footnote: Dr. Joe Neal's daughter Marie, desperately needs a liver transplant. If you wish to help out go to Marie Neal and check out the procedure to make a contribution.




For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.

Notable Blogs

Blogs are one way to find information and keep up to date in this new electronic age. Below are five blogs to consider subscribing to if you have already. The last in the list is primarily for your customer- the home gardener but well worth visiting and sharing with those clients.
Alternatives and Organics
Open Register
Making Cents
Project Green Industry
WNC Vegetable News
Master Your Garden

If you are not blogging or using one of the other Social networking tools such as Facebook or Twitter, you may want to consider doing so. These tools are not just for the techni-geek but are becoming popular marketing tools.

We can discuss offering a class on getting started- possibly on-line!


For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.

Speaking of Gardening

Speaking of Gardening Symposium

Explore great plants at this year's Speaking of Gardening symposium. Two days of garden lectures by six highly regarded designers, research specialists and nurserymen will provide participants with great new ideas and inspiration.

Symposium topics include private and public garden design, new plants from NCSU plant research program, designing with grasses, new perennials from Jelitto and the Human Flower Project.

For more information visit this link on the NC Arboretum's website:

Speaking of Gardening


For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.

Western Flower Thrips

Western Flower Thrips in Greenhouses- from Dr. Stephen Franks, NCSU Dept of Entomology

Thrips are a constant problem for growers. Not just this particular week, but all the time. Western flower thrips, Frankliniella occidentalis, is the most important and damaging thrips of greenhouses and has been called the most damaging greenhouse pest in the world. This is true of greenhouse-grown food and ornamental crops. Nearly all floriculture crops are susceptible to thrips damage. Western flower thrips reproduce rapidly and are difficult to manage because they live in the cracks and crevices of flower heads and foliage. Thus they are difficult to contact with insecticides. Western flower thrips also develop insecticide resistance rapidly so it is important to emphasize chemical rotation and to have a resistance management plan. Sanitation is also very important in managing thrips. Because they can feed and reproduce on hundreds of plant species, weeds in and around a greenhouse will provide a constant supply of thrips even if the crop is sprayed. Western flower thrips pupate in soil, so clean up spilled potting soil and other debris to deny them this vital part of their lifecycle. More information and chemical recommendations can be found in the newly-revised Ornamentals and Turf Insect Note No. 72 at Western Flower Thrips

For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.

Weekly Word on Weeds

New Weekly Word on Weeds from Dr. Joe Neal

Lontrel Update – Field Nursery Uses Allowed

Lontrel herbicide (active ingredient: clopyralid) has been labeled for controlling legume and aster weeds in turf and landscape settings for several years. Some of the susceptible weeds include clovers, sicklepod, hemp sesbania, vetch, eclipta, groundsel, horseweed, dogfennel, and thistles. It is generally safe when used as a directed spray around most established woody ornamentals but treatments near plants in the legume family, such as red bud, should be avoided.

The Lontrel label was recently amended to allow for use in nurseries; but, only in FIELD nurseries. Lontrel is very active in low concentrations on susceptible species. So, when using Lontrel, read and follow the instructions and precautions on the label. Some important precautions include:
Do not contaminate irrigation ditches or water used for irrigation

Do not use in greenhouses

Do not make broadcast applications to ornamental plantings; however, spot and directed applications are permissible

Do not allow sprays of this product to contact exposed suckers or roots of susceptible trees or shrubs as injury may occur

Do not collect treated grass clippings for mulch or compost

Do not apply to container grown ornamentals.

What does this mean to nursery crop growers?

Lontrel is another “tool” that field producers may use to control legume and aster weeds. It may be particularly useful in fields with a history of sicklepod, hemp sesbania or glyphosate-tolerant horseweed. Use it as a directed spray around woody crops only. But keep it off of actively growing foliage. I’ve seen significant injury on many broadleaf crops from directed sprays that contacted low hanging limbs (picture field grown hollies here). And, do not use Lontrel around red bud trees; plants can be damaged from root uptake of the herbicide.

Of course, read the label before you use Lontrel. This is a very good herbicide but a little bit of spray drift can cause significant damage to susceptible crops.



For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.

Herbicide Carryover in Hay, Manure, Compost

Herbicide Carryover in Hay, Manure,
Compost, and Grass Clippings.

Home gardeners and landscapers may feel they are doing the right thing, organically, when applying manure or compost to their gardens but- knowing something about the herbicides applied to the hay that the animals that produced the manure, ate can impact your choice of using the compost. The same goes for grass clippings of other plant debris that may end up in the compost. The attached article below describes the results being seen by many farmers and gardeners alike:
Herbicide Carryover in Hay, Manure, Compost, and Grass Clippings

Check your compost sources before using them!




For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.

The Blue Ridge Community College landscape class designed a plan for the Hospice Elisabeth House. They would like to install it this fall in the landscape construction class. I was hoping you could help me through your blog by posting this along with a materials list in hopes that some nurseries will have things they would be willing to donate.

Here's their wish list:
Thuja occidentalis – 2
Liriope muscari – 100 1 gal.
Erica carnea – 18
Nandina domestica ‘Nana Purpurea’ or ‘Firepower’ – 9
Perovskia atriplicifolia – 1
Fothergilla gardenia ‘Mt. Airy’ – 5
Hydrangea anomala subsp. petiolaris – 3
Echinacea purpurea – may have enough
Chamaecyparis pisifera ‘Filifera Aurea’ – 6
Delosperma cooperi – 61 1 gal.
Ilex cornuta ‘Dwarf Burfordii’ – 14
Crytomium fortunei - 13
Potentilla tridentata – 575 1 gal. or in flats
Heuchera sanguinea – may have enough
Pansy/Impatiens – 2 flats
Hemerocallis ‘Stella De’Oro’ – 26 1 gal.
Clematis x jackmanii – 2

Other items:
Shredded mulch
Bird baths
Bird feeders
Shepherd’s hooks for feeders
Fertilizer
Organic matter – compost, peat moss, etc. to amend soil
Trellis

If you have any of these items that you would care to donate to the Elisabeth House project please let Carolyn know. Her number is: (828) 694-1840 or you may contact her by e.mail at cm_evans@blueridge.edu .


For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.

Maple Mites

Maple Mites
From Dr. Stephen Franks:


Mid-summer damage to maples is often attributed to the twospotted spider mite. However, I visited several nurseries this week and found the culprit was actually the maple mite, Oligonychus aceris. This mite feeds on maples and causes severe damage to maple leaves in midsummer. Leaves are yellow and stippled and mite debris is evident on the underside of leaves. Growers report more damage on “Autumn Blaze” than other maple varieties. However it is common on October Glory and most commonly grown varieties. Management recommendations are the same as for the twospotted spider mite discussed in previous articles in the June 5, 2009 and June 26, 2009 North Carolina Pest News. However, to my knowledge no efficacy tests have been conducted on this particular species. Remember that any damage done to the leaves will remain for the rest of the season and will not be corrected by treatments, nor will the debris wash off from treatments or irrigation. Therefore, be sure to determine if live mites are present before repeating a treatment bases on damage or debris.



For additional information, see Ornamentals and Turf Insect Note No. 25 on twospotted spider mites at Twospotted Spider Mite

For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.