Yard & Garden Line News Volume 3 Number 7                                                               May 15, 2001

Features this issue: Create a Colorful Scene With Flowering Annuals Some Common Sense Herbicide Guidelines Mosquito Control West Nile Virus 'Worms' Falling From Elm Trees More ‘Worms' In the Landscape The White Stuff Postemergence Herbicide Use in Lawn and Garden Editorial Notes

Create a Colorful Scene With Flowering Annuals
Deborah Brown, Extension Horticulturist

Cool color annuals. Photo credit: Deb Brown

This is an exciting time of year for flower lovers. Nurseries and garden centers are ablaze with color, ready to tempt even the most practical and parsimonious among us to buy more bedding plants than we had planned.

Though it seems obvious, color is an element of garden design that's often overlooked. When choosing garden plants we tend to focus on the beauty of individual flowers rather than the relationships between groups of flowers. And there's often a tendency towards sizzle rather than subtlety.

One of the nicest aspects of growing flowering annuals is that you can repeat really great combinations year after year, but you can also experiment easily with new plants and new colors any time you're dissatisfied the last summer's results.

Warm color annuals. Photo credit: Deb Brown

Color choices are a matter of personal taste. But there are some universal characteristics of color that you ought to take into consideration when selecting bedding plants. Visually, yellow, orange, and red are considered "hot" colors, while green, blue, and violet are considered "cool". Hot colors not only make you feel warmer, they appear to advance. Cool colors appear to recede; they "rest your eyes" and make you feel cooler.

If you have gardens at the very back of your yard, or you want your flowers to be seen from a distance by people driving past your house, choose lots of intense, sunny colors. They're dramatic, and they'll show up well. Scarlet petunias or zinnias, bright gold or yellow marigolds, and red-orange cosmos or Mexican sunflowers all stand out from quite a distance. So do neon rose-colored impatiens, geraniums and tuberous begonias.

Cool colors retreat. Photo credit: Deb Brown

Cool colored flowers are best viewed close up; they tend to disappear at a distance, particularly the darker shades. You can plant fascinating, nearly-black pansies, but you won't even notice them in the garden unless you're standing almost on top of them. Petunias, salvia, bachelors' buttons, Chinese forget-me-not, and impatiens are some of the many annuals available in soft shades of blue and lavender. They lend a cool feeling to the garden, and can be used to create an inviting, restful look on your deck or patio and in other parts of the yard where you'd like a visual oasis from summer's heat.

White or cream colored flowers are neutral, as is the silver foliage found in dusty miller. Take advantage of these colors to separate clashing combinations.

Some colors take on a life of their own at sunset. White flowers are particularly adept at reflecting what little light is available, including moonlight, as anyone who's grown moon flower will attest. `Blue Pearl' impatiens and pale lavender New Guinea hybrid impatiens seem to glow with inner light at dusk.

Except for plants you use as edging (dwarf marigolds, petunias, sweet alyssum) group bedding plants in clusters to form drifts of color. Save straight rows for corn and beans.

Some Common Sense Herbicide Guidelines
Deborah Brown, Extension Horticulturist

Spot spraying weeds. Photo credit: U of M Extension Svc.

Everyone -- not just the gardeners among us -- is becoming more aware of the need to use pesticides responsibly, to protect our own health and that of the environment. Here are some guidelines for using post-emergent weed-killers carefully and efficiently:

* Target weedy areas in your lawn rather than spraying the entire yard. Spot treat individual weeds whenever possible. If there are only a few scattered here and there, try digging them out after a rain, or soak the area first with your sprinkler. Even thistles pop out relatively easily when the soil is soft and moist.

* Choose ready-to-use formulations if you don't need much herbicide. If you buy a concentrate, dilute it exactly as the label instructs, no stronger. This is definitely not a case where more is better.

* Whenever possible, use a hand-held sprayer rather than a hose end device. It's too easy to become distracted and aim a hose in the wrong direction, allowing spray to hit non-target plants. Hose end sprayers are also less accurate in the delivery of the right concentration of spray.

* Hold your sprayer (or hose) close to the ground to avoid accidental drift onto other plants. Weed-killers can't discriminate desirable from undesirable plants, and there are lots of vulnerable tender young leaves and buds this time of year.

* Wet the surface of weed leaves with herbicide; never soak it into the soil.

* Spray only when wind is calm, temperatures range from the low 60's to low 80's, and no rain is expected for 48 hours. Spring and fall are prime times for using herbicide, not during summer's heat or when grass is moisture-stressed.

* Early morning is probably the best time to use herbicides, provided plants aren't covered with dew (which would dilute the herbicide.) It's usually least windy early in the day.

* Concentrate on growing thick, dense grass. Improving the health and vigor of your lawn will go a long ways towards keeping weeds at a tolerable level and reducing herbicide use.

Mosquito Control
Jeff Hahn, Assistant Extension Entomologist

Mosquito. Photo credit: Jeff Hahn

Every year we deal with mosquitoes in Minnesota. There has been concern that mosquito numbers could be substantially higher this season because of river flooding in many areas of the state. The good news is that these flooded areas should not increase mosquito numbers much.

Spring mosquito species, such as Aedes stimulans , are usually not numerous enough to cause much problems. Also their breeding sites are not typically found in areas that have been flooded. The primary summer species, Aedes vexans, requires warmer water temperatures and does not emerge until late May or early June. By then, most of the flooded areas should have receded, reducing potential larval habitat. While flooding will have little impact on mosquito numbers, rainfall is much more important influence on their relative populations. The more rain we receive, the more mosquitoes will be produced. If we experience a dry year (remember 1988), we will see fewer mosquitoes.

Regardless of how abundant mosquitoes are, their control is very challenging. To have any chance at being successful, a control program is best done on a large scale (e.g. the Metropolitan Mosquito Control District treats mosquitoes in the seven county area around Minneapolis and St. Paul). The best method to control mosquitoes is to treat the larvae. They breed in standing, shallow pools of water (of which there is great abundance of in Minnesota). Larvae are treated with Bacillus thuringiensis var. israliensis (B.t.i). or methoprene. Homeowners can buy B.t.i., but because they are treating just small areas, they are very unlikely to get good results. Spraying adult mosquitoes is not very effective or practical. At best, it should be only considered for special events or emergency spray programs of disease-infected mosquitoes.

So what can a person do? There is no guaranteed method to completely avoid mosquitoes. You can try the following these guidelines. Keep in mind that you can follow these suggestions and still have a problem with mosquitoes.

Potential breeding site. Photo credit: Sid Jarvis

Cut weeds and tall grassy areas near your home to help reduce mosquitoes harborage areas. Leave yard lights off when possible to avoid attracting them unnecessarily. You can also try less attractive lights like sodium lights as flourescent or incandescent lights are more attractive to mosquitoes. Make sure that window and door screens fit properly. Repair or replace any screens with holes or tears. Remove any containers that may hold water (e.g. old tires). If they can not be removed, then drain them. If this is not possible, then apply a small amount of vegetable oil on the water's surface (this will suffocate any larvae in the water). Keep gutters cleaned so water doesn't accumulate.

Mosquitoes are most active early in the morning and at dusk. Try to avoid those times when possible. If you find yourself out when mosquitoes will be a problem, protect yourself by wearing long-sleeved shirts and long pants. Use a repellent. DEET (N,N-diethyl-meta-toluamide) is the most effective. Apply DEET to clothes or skin but only enough to lightly cover the desired areas. Do not overapply repellents! Do not treat children with a product containing more than 15% DEET. Always read product information thoroughly before using.

West Nile Virus
Jeff Hahn, Assistant Extension Entomologist

Culex mosquito laying  eggs. Photo credit: CDC

[Note: the information in this story was obtained from The Centers for Disease Control and Prevention (CDC) website at http://www.cdc.gov/ncidod/dvbid/westnile/index.htm and the New York City Department of Health, http://www.ci.nyc.ny.us/html/doh/html/cd/cd/cdwnv.html]

In a related story, there has been much concern about a mosquito-transmitted disease, West Nile Virus which was found recently in New York. This virus can cause encephalitis (inflammation of the brain) or meningitis (inflammation of the brain and spinal cord). The virus was first isolated in the West Nile region of Uganda in 1937. New York experience an outbreak in 1999. There were 62 cases of disease, including 7 deaths. In 2000, there were 17 cases (through September), including 1 death. Although not found in Minnesota at this time, it is believed that this virus could be introduced here.

Most people infected with West Nile virus show no symptoms or may experience mild illness such as fever, headache, and body aches before recovering. Some people also develop a mild rash or swollen lymph glands. At its most serious, it can cause permanent neurological damage and can be fatal. Encephalitis symptoms include rapid onset of severe headache, high fever, stiff neck, confusion, coma, muscle weakness or possibly death.

The disease is transmitted to people by the bite of an infected mosquito. In the United States, several species of mosquitoes, especially those in the genus Culex, are known to vector this disease. There are six species of Culex in Minnesota. Uninfected mosquitoes can acquire it by biting an infested host. When that infected mosquito bites another animal, it can transmit the virus to it. Fortunately in New York, only a very small percentage of mosquitoes are infected with the virus.

In New York, the primary reservoir of the disease is birds. Seventy species of birds have tested positive for West Nile virus with most of the specimens being American crows. Birds infected with this virus can die or become ill. There is no evidence that a person can get West Nile virus from handling live or dead infected birds. However, to err on the side of safety, people living in areas where West Nile virus is reported should wear gloves when handling dead birds.

There have also been reports of West Nile virus infection in bats, chipmunks, raccoons, skunks, squirrels, and domestic rabbits. West Nile virus does not appear to cause extensive illness in dogs or cats. A serosurvey in New York City of dogs and cats in the 1999 epidemic area showed that they can also become in infected but a low rate. There have also been cases of West Nile virus disease in horses, resulting in several deaths.

In New York, they are combating this disease by developing a comprehensive plan of treating and reducing larval breeding sites as well as testing adult mosquitoes and birds for the presence of the disease organism. They also offer advise to residents on personal protection. At this point, residents in Minnesota are not at risk and do not need to take any special steps to protect themselves beyond normal mosquito protection (see previous article). However, it is important to aware and informed of this disease if it should ever find its way to Minnesota.

'Worms' falling from elm trees
Jeff Hahn, Assistant Extension Entomologist

Large numbers of very small, reddish 'worms' have been found under some elms in early May. These insects are immature fly larvae known as gall midges. These gall midges attacks developing samuras (winged seeds) in early spring. Later in spring, the mature larvae drop to the ground to pupate.

These midges do not injure elms and control is not needed. They can be a nuisance when large numbers fall onto driveways, sidewalks, and other areas under elms. The only necessary control is to just sweep them away. They are a very short-lived problem and are a curiosity more than anything else.

More ‘Worms' in the Landscape
Jeff Hahn, Assistant Extension Entomologist

Leaf beetle larva Photo credit: Janna Beckerman

There have been several samples of worm-like insects found on weeds, turf and just generally around the yard. These insects are leaf beetle larvae (unfortunately, a species has not been determined). Except for chewing on some weeds, there has been no apparent injury on any important plants.

Apparently, these insects overwinter as larvae. In the spring, after feeding for a short time, they search for a place to pupate. As long as they are not feeding on anything valued, no control is necessary for these insects. They should be considered a nuisance and just ignored until they go away on their own.

Get the low down on this month's insect pests at Insects http://www.extension.umn.edu/projects/yardandgarden/EntWeb/Ent.htm

The White Stuff
Janna Beckerman, Ph.D, Extension Plant Pathologist

Powdery mildew on turf. Photo credit: Chad Behrendt

No, we're not talking snow! Instead, we are talking about powdery mildew of turf, which is making its presence known throughout the area. This year, our cool, wet spring favored the growth and proliferation of powdery mildew. Powdery mildew is a common disease when susceptible varieties of grass are subjected to extended periods of low-light, poor air circulation and cool conditions. The overcast, wet weather we are having favors the development of powdery mildew and allows it to spread over large areas of the home lawn.

Powdery mildew is one of the simpler diseases to diagnose. The key feature is the sign of the disease: Fine, white powder that is the fungus, covers the leaf surface. The spots of this fungus grow rapidly together and cover the entire leaf. The leaf appears covered in powder or flour. Older leaves appear more infected than younger leaves. These older leaves will eventually turn yellow and die. When the leaf dies, so does the fungus. The pathogen, Erysiphe graminis, is called an obligate parasite. That means it can only get its nutrients from a live host. By killing the host plant, the fungus, in essence, commits suicide. However, prior to this occurring, the fungus will produce overwintering sexual structures called "cleistothecia." These "kooshball"-looking like structures contain the spores inside, and protect them from our harsh winter climate.

Although the sexual spore inside the cleistothecia starts the infection process, the primary inoculum source is the conidia, another type of spore that gives the powdery appearance to the infected leaves. Infection happens rapidly, and new conidia are produced within a week to continue the infection cycle. Spore development is favored with when temperatures are 60-75 degrees F. Although the spores are short lived, they germinate and infect over a broad range of conditions and temperatures, but favors shady sites, with poor air circulation. Nitrogen fertilizers, particularly heavy applications, have been implicated in increasing disease severity.

The best way to control powdery mildew is to use shade tolerant grass cultivars, or resistant cultivars. Improved tall fescue varieties should be considered for shaded areas since they have minimal problems with mildews. Additionally, consider using mildew-tolerant cultivars such as 'Rugby', 'Glade', 'Galaxy', 'A-34', 'Sydsport', and 'Baron'. These cultivars are not completely resistant, so mix two or more in plantings. Pruning or selective placement of shrubs to increase light penetration to the turf also helps in reducing this disease. Grass should be mowed high in areas that are susceptible to powdery mildew, watered to only avoid drought and fertilized to promote healthy, but not overly vigorous growth.

Test your diagnostic savvy monthly with Disease Watch at: http://www.extension.umn.edu/projects/yardandgarden/PlantPathWeb/Plpa.htm
Postemergence Herbicide Use in Lawn and Garden
Roger Becker, Extension Weed Scientist

Creeping Charlie and dandelions. Photo credit: Beth Jarvis

Postemergence herbicides that are called systemic translocate, which means they move within plants to kill underground root and dormant buds at the crown. Contact herbicides burn the sprayed leaves but do not move to the roots so they do not control underground parts of perennial weeds. Contact herbicides are used to control emerged vegetation in driveways, patios, sidewalks, but have little long-term control of perennial weeds. To use either systemic/translocated or contact herbicides effectively, some basic understanding of how postemergence herbicides work in needed.

The key decision points for postemergence herbicide use in lawn and garden are:
- the type of plant to be controlled
     - is it perennial or an annual?

- the site to be treated
     -what are sensitive plants or organisms in the area?
     - what are the environmental issues if any such as:
          - shallow water tables
          - nontarget plants down-slope where herbicides could wash down the hill and damage plants
          - potential for vapor or spray drift to nontarget plants in the area

- characteristics of the herbicide to be used
     - is it systemic or a contact herbicide?
          - if systemic, does it translocate well or poorly?
     - is it volatile?
     - is persistent or does it degrade rapidly
     - is it highly water soluble or does it adsorb to soil (leaching issues, feeder root pickup)

Characteristics of Postemergence Herbicides Commonly Used in Lawn and Garden by Mode of Action.

A. Growth regulating mode of action herbicides

1. Phenoxy acetic acid herbicides
Active ingredients: 2,4-D, dichlorprop (2,4-DP), MCPA, mecoprop (MCPP)

Product names: Weed B Gone Weed Killer, TriMec, others

Low to moderate volatility with esters, negligible volatility with amine formulations. Are soluble and weakly adsorbed, but are short lived. Low risk of movement to feeder roots. Translocate reasonable well and can be absorbed through bark. Weak on plantain, smartweeds, and creeping charlie. Moderate to good activity on trees and shrubs. Little to no carryover in gardens and flowerbeds. Will not harm established grasses.

2. Benzoic acid herbicides
Active ingredient: dicamba

Product names: Banvel, TriMec, others

Volatile so vapor drift is an issue. Are soluble, weakly adsorbed, and moderate persistence so can damage plants by leaching to feeder roots (the potential for this is highly rate dependant). Translocates well and can be absorbed through bark. Generally added to phenoxy herbicides at low rates to improve control of clover, chickweeds, plantain, etc. High activity on some trees and shrubs. Will carryover if used in gardens or flowerbeds. Potential to move downslope to nontarget plants in heavy rains after application. Will not harm established grasses.

Violets. Photo credit: Beth Jarvis

3. Pyridine acid herbicides
Active ingredients: picloram, triclopyr, clopyralid
Product names: Weed B Gone Chickweed, Clover & Oxalis Killer, Weed B Gone Poison Ivy, Poison Oak, and Brush Killer, Tordon RTU, Confront (commercial applicators), others

Negligible volatility. Very soluble, persistent and weakly adsorbed to soil and organic matter. Risk of movement to feeder roots if used at excessive rates. Translocate very well and can be absorbed through bark. Excellent on tough perennials. Moderate to excellent activity on trees and shrubs for picloram and triclopyr products. High risk of carryover if accidentally applied to gardens and flowerbeds. Potential to move downslope to nontarget plants if heavy rains occur shortly after application, but is generally not an issue if small, isolated areas are treated. Will not harm established grasses.

B. Amino acid synthesis inhibitor mode of action herbicides

1. Amino acid derivative
Active ingredient: glyphosate
Product names: Roundup and others

Negligible volatility. Is very soluble, moderate persistence but extremely tightly bound to soil or organic matter, therefore no risk of movement to feeder roots. Translocate very well but is not absorbed through mature bark unless petroleum oils or crop oil concentrates are added. Nonselective, will control most grasses and broadleaf weeds but rates and timing for control will vary by species. Good activity on trees and shrubs. Will not carryover in gardens and flowerbeds. Dandelions are relative tolerant to glyphosate.

C. Ammonium assimilation inhibitor mode of action herbicides

1. Amino acid derivative
Active ingredient:glufosinate
Product names: Finale

Negligible volatility, is very soluble, short to moderate persistence but is bound to soil or organic matter. Little uptake by roots, therefore no risk of feeder root damage. Little translocation so only controls foliage that is sprayed. Does not absorbed through mature bark. Nonselective, will control most grasses and broadleaf weeds but rates and timing for control will vary by species. Because does not translocate, treated perennial plants will often regrow from the base. Poor activity on trees and shrubs. Will not carryover in gardens and flowerbeds. Often used to control emerged vegetation in driveways, patios, sidewalks.

D. Unknown/unclassified mode of action herbicides

1. Fatty Acid Derivatives
Active ingredient: potassium salts of fatty acids, others
Products names: Safer, others

Negligible volatility, not very soluble, short persistence, moderate absorption to soil or organic matter. Little uptake by roots, therefore no risk of feeder root damage. Translocate very poorly so only controls foliage that is sprayed. Because this herbicide does not translocate, treated perennial plants will often regrow from the base. Could be absorbed through mature bark but likely little impact on cambium layer cells. Nonselective, will control most grasses and broadleaf weeds but rates and timing for control will vary. Poor activity on trees and shrubs. Will not carryover in gardens and flowerbeds. Often used to control emerged vegetation in driveways, patios, sidewalks.

2. Inorganic arsonates
Active ingredient: MSMA (monosodium methanearsonate)
Products names: Crabgrass Killer, MSMA, Weed B Gone Crabgrass Killer, others

Negligible volatility, very soluble, degrades slowly to inorganic arsenic, relatively strong absorption to soil or organic matter. Little uptake by roots, therefore no risk of feeder root damage but is readily absorbed and translocated through the shoots. Nonselective, will control most grasses and broadleaf weeds but rates and timing for control will vary. Because does not translocate, treated perennial plants will often regrow from the base. Poor activity on trees and shrubs. Will carryover in gardens and flowerbeds, but is used at trace levels that do not cause injury. Mainly used to control crabgrass postemergence in established turf. Will cause temporary injury but has little control of many broadleaf plants and perennial grasses at the rates.

Plant response to the systemic (translocated) herbicides.

Phenoxys, dicamba, glyphosate, and the pyridine herbicides are absorbed by the leaves and other above ground parts of the plant. Roots can absorb these herbicides if the herbicide is sprayed on the soil and leaches to the roots before degrading. Phenoxys generally degrade before leaching and glyphosate can not leach so these two result in little injury through feeder root uptake, conversely they do not control woody species through soil applications.

Dicamba, and the pyridine (picloram and triclopyr) can move to roots. Low rates that are used for turf uses generally do not result in lasting damage to woody species through feeder root uptake, but these product are used for brush control at higher rates so be careful around desirable woody plants. All of these products rapidly translocate (are absorbed by leaves and stems, then move to roots of plants) causing susceptible plants to die. These herbicides are absorbed most readily by plants.

Annual weeds are easiest to kill when they are young; many perennial weeds are easiest to kill while they are seedlings. After perennials are established, it is often best to spray difficult to control species well after flowering in late summer or fall. This is the time when sugars translocate from shoots to the roots and the herbicide move with the sugars. The typical exception in turf is common dandelion which can be treated any time, in part because dandelions flower very early in the season.

Glyphosate is relatively nonselective and controls deep-rooted perennial weeds as well as annual and biennial species. It is effective on grasses, sedges, and broadleaf weeds. Glyphosate should be applied before desirable plants emerge or as a directed spray to avoid contact with desirable plants. Glyphosate can be used as a directed spray at the base of woody plants if the bark is brown. Glyphosate can penetrate green bark (young trees usually < 3 years in age) and injury may occur. Glyphosate is relatively slow acting so visible effects normally do not occur on annual species for 4 to 10 days and on perennial species for 7 to 18 days. Control of woody plants is best if glyphosate is applied in late summer.

Clover--once cultivated, now cursed. Photo credit: Sid Jarvis

Tillage, pulling, or mowing of perennial plants treated with systemic herbicides should be delayed for at least 3 days after treatment to allow time for herbicide translocation to underground roots. Rainfall or irrigation shortly after application will decrease the control achieved with these herbicides. Rainfast intervals range from 1 to 6 hours for most products. Regardless, wait till the next day to irrigate, and do not apply herbicides if rain is imminent. Conversely, any weed is difficult to control if under drought stress, so do not apply herbicides when plants are under moisture stress.

Post emergence weed control for lawn and garden generally means dandelion control in lawns. Fall is an excellent time to control the more difficult to control broadleaf weeds in lawns such as clovers, plantain, and creeping charlie. The most common weed in lawns, common dandelion can be controlled with phenoxy herbicides like 2,4-D in the spring or fall, and escapes can be spot sprayed with phenoxy herbicides throughout the season. Fall weed control was discussed in the Yard and Garden September 1, 2000 issue, Fall Control of Perennial Weeds. Environmental aspects to consider were discussed in the Yard and Garden April 15, 2001 issue article on Pre-emergence Weed Control.

Applying Postemergence Herbicides

Postemergence herbicide applications can result in more nontarget plant damage compared to soil applied herbicides because of the simple fact that in general, postemergence herbicides translocate well and the foliage is out on nearby plants when applications are made. Avoid damage to desirable plants by applying herbicides carefully. Some ornamental plants are extremely sensitive to some herbicides and are severely injured or killed by small traces of herbicides from spray drift or vapors. Some of the most sensitive plants to phenoxy herbicides include grapes, tomatoes, cucumbers, roses, Bradford pear, redbud, and dogwood. When using herbicides near sensitive plants, observe all label precautions regarding vapor and spray drift. Do not apply herbicides for any use that is not listed on the label. Avoid spraying on windy days and always use low pressure and a sprayer that does not create a lot of fine, misting droplets that are carried easily in the wind. Do not apply ester formulations of herbicides or volatile herbicides like dicamba when the air temperature is above 85 to 90 F. Clean your spray equipment immediately after use. To avoid injury to other desirable plants, the best bet is to use a separate sprayer for postemergence herbicides.

Amines vs. Esters

Phenoxy and pyridine herbicides usually are formulated for use as amine salts or esters. Amine salt formulations are water soluble; when added to water they form clear solutions. The various phenoxy herbicide esters are formulated as emulsifiable concentrates. These concentrates form milk-white emulsions when mixed with water. Amine salt formulations have little volatility and present less risk of injury to nearby susceptible plants than do ester formulations. Amine formulations usually are preferred for controlling weeds in lawns to avoid vapor drift. Vapors from ester formulations can damage susceptible plants growing near the area where they are used. High temperatures increase the risk from vapors. Low-volatile esters vaporize more slowly than high-volatile esters but also can present a risk, especially at temperatures above 90 F. High-volatile esters are more likely to cause injury to susceptible plants in adjoining areas and probably should not be used in most situations. Ester formulations of phenoxy herbicides generally are more effective, pound for pound, than amine salt formulations. Esters are more effective than amines for killing weeds that are growing slowly because of dry weather, and they usually are best for treating weeds in areas of low humidity. Since they are formulated in oils, esters remain in a moist condition on foliage longer and penetrate the waxy cuticle of leaves better than amines. Because they are oily, esters are less likely than salts to be washed off foliage if rain falls soon after they are applied.

Cleaning Spray Equipment

Clean your spray equipment immediately after use. Some plants can be damaged or killed by traces of postemergence herbicides that are left in the sprayer after cleaning. It usually is wise to have separate spray equipment for herbicides and insecticides and fungicides. If it is necessary to use a herbicide sprayer for insecticides and fungicides, use all precautions available. It is best to spray the rinsate on the site where you are using the material if at all possible. There, it will degrade and not cause undesirable side effects. Common detergents or ammonia are recommended to clear spray and measuring equipment. Follow the label directions for the product you are using.

Editorial Notes

Artwork: Otso Kallinen

Here are our newest cartoon plants to join Daisy with that bug and Daisy and her geranium friend. You'll be seeing the terrified tree and (bored?) iris in upcoming advertising and on the web. We've been fortunate to be able to secure the cartooning talent of several students from the By Design, a student design studio serving the U. As noted, the two at left, plus the daisy with a computer, used on the Ask A Master Gardener, a gardening question input page, were created by Otso Kallinen. Adam Turman created the earlier daisies when he was at By Design sveral years ago.

In June, we'll have a report on the treated lumber study conducted by U soil scientists. We'll also hear from Forestry folk on options and alternatives to treated lumber.

We've rescheduled the cabbage and cancer piece for June 15th. Mary Meyer fill us in on the latest in ornamental grasses a bit later on. Bob Mugaas has agreed to comment on fertilizers, whether organic or synthetic is truly superior plus other thoughts he may have on the subject. Look for this in August.

I rely on your comments and questions for ideas for future articles. Please, keep the story ideas coming! We really try to be responsive to your needs.

Please feel free to cut and paste any of the articles for use in your own newsletters. All we ask is that you give our authors credit.

Back issues Yard & Garden Line News are on the Yard & Garden Line home page at www.extension.umn.edu/yardandgarden/. Our home page has clickable links to most of the components of the Yard & Garden Line, such as Bell Museum of Natural History, INFO U and the Soil Testing Lab.

Deb Brown answers gardening questions on Minnesota Public Radio's (MPR) "Midmorning" program on the first Thursday of every month at 10 a.m. Katherine Lanpher hosts the program that is broadcast on KNOW 91.1 FM, and available state-wide on the MPR news radio stations.

If you have gardening questions, please call the Yard & Garden Line at (612) 624-4771.

If you would like to receive an e-mail reminder when the next issue of the Yard & Garden Line News is posted to the web, just send an e-mail to: listserv@lists.umn.edu (note: the second E in listserve is omitted), leave the subject line blank, then in the body of the message, type: sub yglnewslist
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Happy gardening!

Beth Jarvis
Yard & Garden Line Project Coordinator


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