Landscape and nursery
§ Bulbs and other plants are down, but not out
§ Pruning frost-damaged plants
§ Mulch madness
§ Scouting for pests: Black vine weevil
§ New formulation of Kocide® 3000 available for 2007
Turfgrass
§ Scouting for weeds: Ground ivy (creeping Charlie)
Christmas trees and forestry
§ Pre-emergence herbicides for use in Christmas tree plantations
§ Is it winter damage or needlecast?
§ Balsam twig aphid – scout in the south now
§ Christmas trees and forestry insect update
§
Garlic mustard: Rapid invader of
Around the home
§ Globs of boxelder bugs
§ Winter cutworm mystery solved
§ Bee colonies collapsing and implications for gardeners and homeowners
Other news
§ Enviro-weather is getting bigger and better
§ Weather news: Winter blues
Recently after the snow melted, yellow daffodil flowers and tulip buds sticking up out of the snow and flattened plants caused commercial landscape managers and homeowners a lot of concern. While there may be some damage to open flowers and developing buds, I don’t think a lot of long term damage occurred. However, removing foliage too quickly puts next year’s flowers at risk.
The size, number and quality of the daughter bulbs, which
will flower next year, are entirely dependant upon the amount of light energy
trapped by this year’s foliage and transported to the developing daughter bulb.
Even flattened leaves, as long as they are firm and green, will trap light
energy so don’t remove them. If leaves are translucent or mushy, they should be
removed because they’ve started to rot, and the rot organisms can move into and
destroy the mother and daughter bulbs. You could apply chlorothalonil or
similar products, if only a few leaves are beginning to rot, however most
materials are not effective if most of the leaves are affected. In many
Flattened leaves may not be aesthetically pleasing, and they make planting annuals between the bulbs a royal pain, but they shouldn’t be removed unless you plan to replant bulbs in the fall.
Many plants broke bud and started to grow early this year due to the unusually warm temperatures in April and early May. These warm temperatures were followed by freezing temperatures that caused damage to newly emerged shoots. The damage ranged from foliar malformations and necrosis to shoot die-back. In the cases where shoot die-back occurred, pruning out the dead and damaged portions of the plant are recommended to maintain the health and vigor of the plant.
First, let’s have a quick review of proper pruning techniques for small shoots and branches. Since large branches are usually not lost to frosts, we will not review how to prune them. Young shoots and small branches that have not formed branch collars should be either pruned back to the branch from which they emerge or to a lateral bud below the area of damage. When pruning to a lateral bud, the pruning cut should be made flat across the branch and just above the bud. A flat cut allows faster healing since there is less surface area exposed from the cut. Since the lateral bud will form the new shoot, cutting just above it reduces the amount of shoot material that will not grow and will eventually die back to the lateral bud.
Proper pruning when plants are damaged by frosts can be affected by severity of the frost and the type of horticultural operation due to the type of frost damage. Frost damage can often kill cambial tissue but not lateral buds above the cambial damage. Severe enough damage to cambial tissue causes girdling of the limb, which may not show up for several weeks after the damage has occurred. What generally happens is that a lateral bud begins to grow after the apical bud has been killed by frost, the bud continues to grow on reserves in the shoot above the cambial damage but eventually dies because it is no longer being supplied water and nutrients from the root system. This often perplexes people later in the season when unexpected branch die-back occurs.
In smaller operations and when aesthetics are important, it may be best to prune out the initial damage and then follow up with another pruning if cambial damage has occurred and further die-back is exhibited. For large operations where aesthetics are not the primary concern, postponing pruning for a couple of weeks will allow determination of whether cambial damage has occurred and then one pruning can be done to remove the original damage and the hidden cambial damage. Of course, there are some plants where it is more critical to prune the dead wood out immediately because of pathogen susceptibility but pruning can be delayed on the majority of plants.
Every season it seems as if I get the same questions about mulch. What is the best kind to use? How much should I use? Which mulch will best out-compete weeds?
Certainly, as gardeners we have had our own experiences and
developed opinions on the subject. With some recent research done at
According to Dr. Bert Cregg, MSU professor of horticulture, new varieties of mulch material available from local landscape supply stores are always increasing. He groups these into two broad categories; organic and inorganic. Both types of mulch provide some benefit to plants in the landscape. However, organic mulch such as ground tree bark, pine needles and recycled pallets have distinct advantages, such as directly contributing nutrients and organic matter to the soil. Cregg says that additional considerations in choosing mulch are cost and appearance.
During a three-year organic mulch study at
Organic mulches work two different ways to suppress weeds, Cregg noted. When mulch is placed in a landscape bed at approximately a three-inch depth, annual and some perennial weeds may be simply smothered. Lightly re-mulching on an annual basis prevents newly deposited seeds from germinating. However, as with anything organic, compounds may seep out that by their very nature retard weed growth. To weed scientists, this is called allelopathy. Many plants have compounds in their tissues that are allelopathic to surrounding plants. This is commonly observed with black walnut. The plant’s strong production of the compound juglone, kills dozens of types of plants. To a lesser degree, as mulch products decompose they do much of the same thing.
Mulch available from most garden centers can be purchased in
bulk or in bags. A popular type of bagged mulch is ground cypress bark. Cregg
likes the warm, natural appearance of
Recycled pallets are also a popular source of mulch and readily available in a myriad of colors. In the study, this product showed good weed suppression and like the other organic mulches had good moisture conservation. Cregg is baffled by the public acceptance of the colored wood mulches. He said, “My personal belief is that in a few years we will look at this material like we do polyester leisure suits and say, what were we thinking?” The down side to the pallet material is that it readily moves off-site. Downpours, lawn mowers and foot traffic tend to kick it out of the bed and into a lawn.
My personal favorite is a by-product of the lumber industry, commonly sold as hardwood bark or shredded bark. This product performed well in the trial for weed suppression and moisture conservation. The down side of it may or may not be a disadvantage, because it tends to decompose more quickly. I find this a positive thing in our home landscape because plants are benefiting from the nutrients released from the mulch.
The best performer overall was ground red pine bark. In
Although no studies were performed using a product known as pine straw, Cregg said that his experience with this product has been very positive. The pine straw (needles from the long-leaf pine or southern pine) is a uniform and natural looking product. It is a by-product of forest management practices done in southern states that help reduce wild fires. The easy-to-handle pine needles literally knit together and stay in the landscape bed. They have excellent weed suppression and become a good source of nutrients in the landscape. At the current time, however, only a few garden centers are carrying it.
Cregg says that mulch should be applied in a “doughnut” shape in the drip zone of trees and shrubs not a “volcano.” Too often we see big piles of the stuff dumped at the base of the tree trunk. This practice becomes a detriment to the tree by encouraging surface roots in the mulch as well as rot organisms at the trunk. I often think we need some local “mulch police” to go around crusading for tree health!
One of the most important practices we can implement for
tree and shrub health in the landscape is to provide mulch. During the dry
summer months mulch helps cool the soil in the root zone and conserve moisture.
Mulch suppresses weeds, which will compete with plants for nutrients and water.
Organic mulches such as shredded bark, compost and pine needle provides a
naturally slow-release form of nitrogen for plants as it breaks down. Lastly,
used in the right amount, mulch can provide a layer of insulation, which
protects tree roots from early onset of freezing temperatures in winter and
keeps them cool and happy in the summer. Dr. Bert Cregg of
Note: For more resources and training from the Kent County MSU Extension office, contact 616-336-3265 or log on to www.stuckongardening.com.
Black vine weevil adults do not possess wings, so they cannot fly. The adults are active primarily at night and hide during the day in debris or under plant containers. Adults feed on a wide variety of herbaceous perennials. The larvae, which are located in the growing medium, are white and grub-like and feed on plant roots. (view image)
Management: Remove plant and growing medium debris from the area. Contact insecticides with residual activity can be applied to the foliage in the evening. Beneficial nematodes such as Heterorhabditis bacteriophora may be applied as a drench to individual containers. The nematodes attack and kill the larval stage.
Editor’s note: This information is from the new field guide A Pocket Guide for IPM Scouting in Herbaceous Perennials. For ordering information, call 517-353-6740 or visit: http://www.ipm.msu.edu/pdf/pocketGuidesLandsc07.pdf
DuPont Crop Protection has introduced a new formulation of Kocide 3000 for the 2007 season. This formulation has a finer, more consistent copper hydroxide grind than previous Kocide formulations and some competitive copper products. Kocide 3000 has more copper ions available to provide disease control at a lower rate. The environmental benefit is less metallic copper applied per acre.
Improvements made with Kocide® 3000 include:
§ More available copper ions per pound metallic copper.
§ Improved worker safety including signal word 'caution', no PPE eyewear required, no early entry eyewear required, and there is no 7 day eye flush container and oral warning.
§ Improved handling characteristics including quicker dispersion, cleaner screens, low foaming.
§ Lower use rates, 2/3x Kocide® 2000 use rate.
§ Kocide® 2000 and Kocide® 3000 each received the OMRI approval to use on organically grown crops.
Kocide products have been used very successfully against many bacteria and diseases on fruit and vegetables. This preventative copper fungicide has also demonstrated very good activity against Septoria and powdery mildew in wheat to protect early plant health.
Family. Lamiaceae (Mint) (view images)
Life cycle. Prostrate, creeping perennial.
Leaves. Opposite, kidney-shaped to rounded leaves are approximately 1 inch wide with scalloped margins, palmate veins and long leaf stalks. Damaged leaves emit a mintlike odor.
Stems. Prostrate, creeping stolons are square in cross-section and root at the nodes to form thick patches.
Flowers and fruit. Purplish blue, funnel-shaped flowers with two lips are found in clusters in the upper leaf axils. The upper lip has two lobes; the lower lip has three lobes. Fruit are small, brown, egg-shaped nutlets.
Reproduction. Creeping stems and seeds.
Control. Ground ivy is an aggressive, difficult-to-control weed in lawns. It often thrives in damp, shady areas of the lawn, but can tolerate full sunlight. Hand removal can be effective with small patches of ground ivy. The square stolons (aboveground stems) creep in the thatch layer of the turf. These stems can be carefully removed with success, but persistence and patience will be required.
Homeowners have several herbicide options that can be very effective for ground ivy control if applied at the correct time. Effective products include any of the “3-way” broadleaf herbicides for lawns, such as Weed-B-Gon Lawn Weed KillerÒ, TrimecÒ, Bayer Advanced Lawn Weed Killer for LawnsÒ, etc.. These 3-way products contain a mixture of dicamba, 2,4-D and MCPP/MCPA. For optimum control of ground ivy in the spring, two applications of a 3-way herbicide should be applied approximately 30 days apart beginning at flowering. A single application in the fall is usually the most consistent. Products that contain the active ingredient triclopyr, such as Weed-B-Gon Chickweed, Clover, and Oxalis Killer®, can sometimes be more effective than the three-way mixtures listed above. Remember, always read and follow labeled directions.
Controlling ground ivy with borax laundry detergent has been
successful for some homeowners. Borax contains the element boron and all plants
require relatively small amounts of this element. Ground ivy is more sensitive
to high concentrations of boron than the cool-season lawn grasses. Therefore,
ground ivy can be selectively controlled or suppressed in the lawn due to boron
toxicity. Note: MSU has not regularly tested the use of borax in
Editor’s note: This article’s identification information is from the new field guide An IPM Pocket Guide for Weed Identification in Nurseries and Landscapes. For ordering information, call 517-353-6740 or visit: http://www.ipm.msu.edu/pdf/pocketGuidesLandsc07.pdf
Pre-emergence herbicides are useful in Christmas tree production to prevent competition from undesirable weeds. Generally, these herbicides are applied prior to budbreak in conifers. A couple of new herbicides have recently been added to the list available for producers: Westar and SureGuard (flumioxazin). Westar (hexazinone plus sulfometuron) is a premixture of Velpar (hexazinone) and Oust (sulfometuron). Westar rates range from 6 to 12 oz/A. Use lower rates where soil texture is coarse. SureGuard also provides good to excellent control of most weed species. Rates for SureGuard are from 8 to 12 oz/A. Add 1 pt/A to 1 qt/A of Roundup Original to the SureGuard tank as emerged weeds are present at spraying.
Previous research has shown both herbicides provide nearly
season long control. Other products
include Princep (simazine) at 2 qts/A plus Aatrex (atrazine) at 1 qt/A. Use only in fields where incidence of
triazine resistance is not an issue.
Kerb 50W (pronamide) at 3 to 4 lb/A plus Princep at 2 qts/A is also a
good option. Finally, Princep at 2 to 4
qts/A plus
Growers have been calling or sending samples of browning needles on Douglas-fir. Several problems that we are finding are winter damage, Swiss and Rhabdocline needlecast. To tell the difference, look on the underside of the needles. With winter burn you have a drying of the needles that causes the tips or the whole needle to be brown but the stomata (tiny pore-like openings) will be white. If you are seeing two rows of fuzzy black fruiting bodies coming out of the stomata on green, yellow and brown needles, it probably is Swiss needlecast. Rhabdocline infected needles will appear as yellow to purple-brown splotches (mottling).
Of these two diseases, Rhabdocline is the more serious and
can cause serious disease on seed sources San Isabel, Lincoln and Coconino; the
seed source Shuswap is resistant to Rhabdocline needle cast. Left
unchecked, Rhabdocline needle cast can cause devastating amounts of casting if
not managed through genetic, horticultural and chemical programs. Rhabdocline
is more severe along
Balsam twig aphid eggs begin to hatch early in spring,
typically around late March to mid-April, depending on temperatures and
location within the state. Hatching is completed in one to two weeks. Studies
in
Target the stem mothers. When spraying is necessary, it is critical to apply insecticides at the proper time to prevent damage to current-year foliage. The ideal time to target your pesticide application is between 100 to 140 GDD50. It is very important to control the stem mothers before they produce the sexuparae. Typically at this point, buds are swelling, but have not yet broken and the stem mothers have hatched and are exposed at the ends of the shoots. The sexuparae typically feed inside the expanding bud and are well protected from insecticides.
Growers (particularly in the southern third of the lower peninsula) that had Fraser or balsam fir trees that were heavily damaged by this aphid last year, should be scouting now. A simple sampling device consisting of an embroidery hoop covered with black cloth can be used to effectively scout your trees. Hold the hoop in the middle part of the tree canopy and rap the shoots at least 3 times with a wooden dowel. You will be able to easily see the white to greenish stem mother if they are present. Scouting will help you determine when most of the stem mothers have hatched. Scout the trees damaged last year, as that's where you will be most likely to find aphids this year.
Keep in mind, however, that if aphid populations are not very high and you did not have heavy damage last year, you probably don't need to spray. There are many different kinds of predators that will be happy to feed on your aphids, all summer long.
We have seen an increase in damage caused by Zimmerman pine
shoot moth in Scotch, Austrian and white pine. With the warm days we
experienced in March, some growers in southern
Larvae of the white pine weevil kill the terminal leader and the top two to four years of growth on many varieties of spruce, as well as white and Scotch pine trees. If you had weevil damage last year and you need to control the weevils, you will have to do it early this spring. The adult weevils overwinter on the ground, protected and insulated by the litter (fallen needles). Once they warm up, the weevils move up to the tops of the trees in the late afternoon or early evening and feed on the terminal leader. Each time a female weevil makes a feeding wound on the terminal, she lays one to four eggs in the wound.
If you need to control white pine weevil, your one opportunity is early in the spring. Insecticide should be applied to the terminal leader once it begins to warm up - somewhere around 25-65 degree days base 50°F and continue. It's better to be a bit early than to be late with this application. Use a persistent product, because the adult weevils don't all warm up at the same rate. You could have weevil adults feeding on the terminals for three weeks or perhaps longer. If you can avoid spraying the rest of the tree, you will conserve beneficial species like predatory mites.
Growers in
Surprisingly, we could start to see the first eggs of spruce
spider mites begin to hatch (150 – 175 GDD50) in the lower third of the
Cooley's and Eastern spruce gall adelgids are the sap-feeding insects that cause galls to form on the shoots of Colorado blue spruce (Cooley's adelgid) and white spruce (Eastern adelgid). If you had lots of galls on your spruce trees last year, the best time to apply an insecticide is when the buds are swollen, and the buds have not broken. With both of these adelgids, the first adults become active at 25 to 120 GDD50. Scout your spruce fields, examining for adelgid activity at the base of the terminal buds for Cooley and the terminal and lateral buds with Eastern.
Garlic mustard is rapidly becoming one of
Garlic mustard is a biennial, completing its lifecycle in just two years. For the first year, garlic mustard is a diminutive, even attractive little plant with clusters of 3 to 4 rounded leaves with scalloped edges. It can easily be mistaken for a wild violet. These first-year plants remain green throughout the summer season and into the winter, making it easy to check for invasion throughout the year.
The second season, garlic mustard gets going and sends up a
flower stalk in early spring resulting in tiny white flower clusters. They
pollinate quickly and result in viable seeds within a few days after flowering.
Second year plants can reach 20-40 inches. Seeds mature and become viable in
July and August when the plant dies. At this time, unsuspecting gardeners and
wood lot owners may think the plant has gone away until the thousands of seeds
germinate and begin their aggressive march through the forest. In the past
three to four years, I have watched this striking scene progress across miles
of
One way humans contribute to the spread of garlic mustard is by digging and sharing their garden plants. Contaminated soil along with a coveted hosta or iris is a not-so-good gift for Aunt Millie. If you are participating in a plant exchange of some type, wash all the soil from the roots and share clean, bare root plants only.
Any control method selected must be repeated for several years until the residual seeds from previous year’s plants have germinated. With a watchful eye, smaller garlic mustard infestations can be controlled by rigorous hand pulling. Plants are usually shallow rooted and pull cleanly out of a forest soil. Once plants have started to flower, whole specimens should be removed and bagged, buried or burned (with permission). Composting blooming plants is not a good option as seeds often escape the compost heating process and may not be destroyed.
You can also cut the plants before the flower buds have opened, to avoid future seed production. In other states, mowing or cutting has not proven to be the best solution. Herbicides can be used in extreme cases; however, the forest floor is a very delicate ecosystem. Severe infestations can be controlled by spraying Glyphosate in October or early spring on the green plants. This will avoid killing non-target plant material such as native plants. As always, when choosing a pesticide to control a pest, read the label carefully and apply as directed.
If you see garlic mustard on the rise, one way you could help make a difference in your community is to organize a garlic mustard pull event. Many states have successfully kept this weed at bay in parks, zoos and neighborhoods because they have been pro-active in organizing events and making them fun. On a chilly April or May morning, sponsor coffee and donuts and provide folks with as much education as you can. For a free color, printable copy of this article, send your e-mail request to angelob@msu.edu.
Note: For more resources and training from the Kent County MSU Extension office, contact 616-336-3265 or log on to www.stuckongardening.com.
Our lab and county extension offices around the state were getting swamped with calls about boxelder bugs when we had that warm spell towards the end of March. Many people complained about big disgusting globs of these black and red bugs appearing on the outside of their homes. I have globs of them too, but I don’t find these fall invading insects nearly as obnoxious as Asian lady beetles, as they are much more polite house guests. They don’t stink, they don’t bite and they pretty much keep to themselves. Many of the ones that come into my house die in the light fixtures. Boxelder bugs are harmless: they do not bite; they do not eat fabrics, stored foods, wood or pets; and they will not lay eggs in the house and multiply there. (view image)
During the summer, boxelder bugs feed on the flowers and seed pods of female boxelder trees. Boxelder bugs invade our homes and other structures in the fall of the year looking for dry, protected sites (attics, wall cavities) in which to spend the winter. They can become quite numerous on the south side of homes where they congregate in the warm autumn sun. In homes invaded by boxelder bugs, it is very common and likely that one will continue to see them throughout the winter. Once they are inside, there is not much one can do to completely get rid of them.
The best long-term method of controlling boxelder bugs is to prevent their entry, and if possible, the removal of any nearby female boxelder trees. Sealing exterior cracks and holes with caulk can help reduce the number of bugs that find their way inside walls and attics. There is very little that can be done once the bugs are inside the walls. Even aggressive and costly insecticide applications may not be effective, because it is nearly impossible to treat every hidden area that may be harboring insects. A vacuum cleaner is a pretty effective method of removing the sluggish, slow moving bugs from the house. Spraying the outside walls of homes, especially the south and west facing walls, with insecticides in September can help reduce the number of these insects entering homes. Be sure the insecticide is registered for this use. The spray should be applied when the first boxelder bugs are noticed congregating on outside walls. Be sure to read and follow all the instructions and safety precautions found on the pesticide label before using any pesticide.
Over the past five or six years we have been getting samples
of a noctuid caterpillar that people found crawling about their snow covered
yards during the early winter months.
The caterpillar looked like one of the many species of cutworm we have
here in
The larva is greenish or brownish with two rows of black
dashes along the back. The species
overwinters as a larva and is known to feed on mild days throughout the
winter. This bug was first discovered in
North America in
If you have been listening to the radio or reading papers the last few weeks, chances are you have already heard about the alarming honey bee die-offs around the country. The phenomenon is officially named “colony collapse disorder” (CCD). This disorder has the media all excited because it is large in scale (25 states are affected), came in quick (colonies that were fine in August/September collapsed around October/November), and hit people hard (many beekeepers with hundreds to thousands of colonies are losing 50-90 percent of their colonies). The worst of all of these scenarios; we do not yet know what causes it.
The symptom seems to be that bees simply disappear, which is why peopled initially called it the disappearing disease (or fall dwindle disease). A colony with 40,000 bees in the fall, apparently healthy with lots of honey and pollen, suddenly has nothing or a handful of bees with a queen left. Very few dead bees are found inside the hive or near the entrance. Strangely, wax moths, small hive beetles are slow in moving into such newly abandoned colonies. Several possible causes come to mind. When tracheal mites (Acarapis woodi) first showed up in North American (circa 1983), we had bees disappearing also. The disappearing mostly happened during the over-wintering process – colonies had small clusters or no bees in the spring because bees with their trachea plugged with mites could not make it back to the colony after defecation flights or they simply flew out to die in the late fall.
A new species of nosema (Nosema
ceranae, so named because it was discovered first in the Asian honey bees, Apis cerana) also showed up in the
European bees (Apis mellifera, the
only species we have in North America and Europe) in
Another concern is all the chemicals we have been throwing into the bee colonies, which conceivably can weaken the immune system of honey bees or affect their learning and orientation. A few years ago, French beekeepers suspected that “mad bee disease,” where bees got confused and could not return home successfully, was related to the use of an insecticide called Gaucho.
Unfortunately, all these factors (tracheal mites, nosema
disease and pesticide use) have been all ruled out for being the cause of CCD. Scientists
from
While the number floating on the Internet has put the
colonies affected by CCD to be around 600,000 colonies nationally, which is
about a quarter of the total colonies in the country, gardeners and homeowners
in Michigan will not notice a big difference in honey bee presence on garden
and wild flowers. While
Editor’s note: Get more bee information from Dr. Huang’s web site at: http://bees.msu.edu/
More station coverage and new technology are enabling
Enviro-weather to provide more weather related services to
Implemented by Steve Marquie, Enviro-weather’s Technical
Systems Manager, cell IP technology enables Enviro-weather’s central computer
to communicate more efficiently with the remote weather stations. Most states
in the
Get your weather-based information with a click of a button by book marking your favorite page on Enviro-weather. For example, to get easy access to the turfgrass page, go to www.enviroweather.msu.edu, click on the station of your choice and click on turfgrass or Christmas trees/forestry. Now that you are on the Turfgrass page (Christmas trees/forestry page), click on “Bookmarks” on your browser toolbar and click bookmark this page. The next time you need weather related information you can click the bookmarks button and go directly to the Enviro-weather page designed for turfgrass or Christmas tree/forestry users.
Winter returned to the
There is some better news looking ahead. A gradual
moderating trend is expected, although mean temperatures will likely remain at
near to below normal levels into the upcoming week. This weekend, an area of
low pressure will move through sections of the
In the medium range time frame, forecast guidance suggests a
less active, west to east zonal jet stream pattern across the