Yard & Garden Line News Volume 2 Number 1                                                              January 1, 2000

Features this issue: Bag Apples for Spray-Free Apple Maggot Control Growing Tropical Ferns Indoors Making an Accurate Plant Disease Diagnosis, Part 1 Phomopsis Blight of Junipers and White Cedar Insect Damage to Clothes Editorial Notes

Bag Apples for Spray-Free Apple Maggot Control
Larry Zilliox, Extension Educator-Horticulture, Douglas Co.

Irene Seppanen, MG, bags apples.

Damaged apple.

Bagged apple.

Paper was no match for wind and rain.

"Saran Wrap" had its problems.

Water collected in bags.

Apples shaded completely in commercial bags.

Apples grown in plastic bags. All Photos: Larry Zilliox

Plant researchers around the world cover various parts of plants to protect them from insects, diseases, or to prevent pollination. Paper bags are the most common means of providing protection.

Some Asian countries use the same concept to raise high quality fruit. South Koreans place a paper bag over apples, peaches, pears and grapes to produce blemish-free fruit. Japanese do the same and are able to obtain a premium price of three dollars per apple for this high quality product. Washington state apple growers capitalized on this process and bag approximately 15 million apples a year for export to these Asian markets.

Several Douglas County Master Gardeners and I decided to try covering apples with commonly available bags to protect them from the apple maggot.

Why apple maggot?
The apple maggot is one of the most destructive pests of apples grown in Minnesotan's backyards. Each year this insect emerges around the first of July continues until September. This long season is a frustration for many homeowners who find the weekly spraying a real inconvenience.

Ten days after emergence the female adults start laying eggs under the skin of the apple. These eggs hatch in five to ten days and become maggots that feed and tunnel through the flesh of the fruit. The larvae live three to four weeks in the apple and usually finish their development once the apple falls to the ground. At that point the maggots mature and burrow out of the apple into the soil where they remain until the following summer.

Sanitation is the key to reducing the number of apple maggots in the area. Picking up and properly disposing of fallen apples prevents the apple maggot from burrowing into the ground. However, many backyard orchardists have no control over their neighbors' apples or abandoned apple trees.

Bagging
We used two commercial orchards and five home backyards for our research sites. All apples were bagged between June 1 and June 18. The apples were approximately the size of a quarter and could be distinguished from the ones that would be aborted.

We set up five treatments to evaluate the effect of bags or other covering in controlling apple maggot problems. The treatments were: plastic bags, brown paper bags, commercial paper bags (gray bags, specifically used for bagging fruit in orchards), plastic film ("Saran Wrap"), and zipper closure plastic bags plus the control of no treatment.

In the orchards, we used plastic bags, brown paper bags, commercial paper bags and the control. Twenty apples were used in each treatment except for commercial paper bags in which only six apples were bagged.

The bags were attached with twist ties or masking tape. Paper bags were a real challenge due to the amount of paper that had to be secured around the stems. Five percent of the apples were knocked off in the process of bagging. At the second commercial orchard we resorted to stapling the bags closed. This worked much better and improved the efficiency of applying the bags.

In the orchards, plastic bags stayed on the fruit much better than the commercial or brown paper bags. Several days after we placed the paper bags over the apples, a strong wind tore many of the commercial and brown bags off. Only 24% of the brown and 28% of the commercial bags remained on at the one orchard. The surface area was just too large and the wind whipped the bags around resulting in their falling off prematurely. The brown bags also tore and fell apart after rain. Because there was no evidence of apple maggot in the orchard we were unable to determine if it deterred the apple maggot.

In the home backyards, we used plastic bags, "Saran Wrap": and zipper closure bags. We bagged five apples per tree and identified five control apples per tree.

We stapled the plastic bags closed. The "Saran Wrap" was difficult to use because we needed to leave enough room for the growing fruit, but also be able securely cover the apple.

The most efficient method was stapling the zipper closure plastic bags. Our experience was we could apply 30 plus bags per hour. We stapled the bag one third of the way across the zipper, slipped the plastic bag over the apple, then zipped it closed. The apple stem, aligned with the staple on one side, was then secured in place by another staple on the other side. Bagging in this manner can be done very quickly and by one individual without knocking off many apples.

Both types of plastic bags and the "Saran Wrap" remained on the tree throughout the summer. We had bag retention as high as 100% on many trees. Where it was less it was due to the apple dropping off the tree. This may be an issue with certain varieties. It is something to test for next year.

During the summer, heavy apple maggot infestation occurred in several of the backyards and some varieties were so damaged that there wasn't an edible apple on the tree. However, the bagged apples on those trees did not show any signs of apple maggot damage. No infestation was observed in the two commercial orchards. All sites indicated that they did not use any apple maggot control sprays.

Summer rain water collected in our plastic bags. We decided to clip both corners of the bags so that the water would drain out. This worked very effectively and resolved the problem. Several bags were left unclipped and a half a cup of water accumulated in the bag. This did not seem to affect the apple even at full maturity. However, we advise draining off the water as the excess weight did bend the branches down.

Conclusion
Preliminary results from the first year testing of this concept look very positive. The apples protected in either type of plastic bags colored up properly, had excellent flavor and size and best of all, there was no apple maggot damage when compared to the controls. The bags also appeared to prevent disease symptoms on the fruit.

We envision home orchardists stepping into their backyard on a late spring morning to survey their still-healthy apple crop. Using ordinary household plastic bags, they could bag 30 to 40 apples in an hour to protect them from insects and possibly diseases the rest of the season. Once they bagged the anticipated number of apples needed, they could forget the rest of the apples on the trees.

This demonstration project is worth repeating again next year. It needs to be modified slightly to look for other potential problems. Individuals who have a maggot problem and would like to participate are encouraged to contact me, Larry Zilliox, at the Douglas County Extension Office at 320-762-3890 or e-mail:lzilliox@extension.umn.edu. I am looking for a number of different varieties and sites from around the state.

Growing Tropical Ferns Indoors
Deborah Brown, Extension Horticulturist

Boston fern. Photo credit: Deb Brown

Despite good results growing most houseplants, success with ferns eluded me for many years, even though they multiplied like weeds in my shady garden outdoors. Repeated failures led me to believe they were just too finicky to bother with indoors. Every few years I would plunk my money down for a healthy, robust new fern, only to see it go downhill before reaching its first birthday.

It wasn't until I moved from my inner city home which was surrounded by tall elms and bur oaks, to a new townhouse with unobstructed west windows that I saw the light -- literally and figuratively -- and my luck with ferns turned around. It seems they just never got quite the amount of light they needed before I moved.

How can that be? Everybody knows that ferns do best in shady locations, right? Well, it depends......

Most ferns thrive in filtered light or shady sites outdoors, but the tropical ferns we use as houseplants are poor candidates for low light locations. Golden pothos (Epipremnum aureum), heart-leaf philodendron(Philodendron scandens oxycardium), snake plant (Sansevieria trifasciata),and Chinese evergreen (Aglaonema commutatum) are much better for north windows and other poorly lit places in our homes.

Most tropical ferns actually grow best indoors in "medium" light, such as an east-facing window or a few feet from a west or south-facing window. During our short days from November through February, ferns can be placed directly in a sunny west or south window with no ill effects. But as days lengthen and sunlight becomes more intense, you run the risk of burning delicate foliage in such bright places, unless the light in those windows is filtered by large trees nearby -- or sheer curtains.

Without adequate light, no fern will prosper indoors, but there's more to growing ferns than providing enough light.

Moisture
You'll find that new ferns come with care tags suggesting they need to be kept evenly moist. That means the soil should never be allowed to get very dry; it doesn't mean it should always stay wet.

It's important to water ferns thoroughly each and every time you water. Don't just dribble a little water on top of the soil from time to time. Use room temperature or lukewarm water -- not processed through a softener-- if at all possible.

Water until excess moisture begins to drip through the container's drain holes, then spill out whatever remains in the tray or saucer after a few minutes. Wait to water again until the soil surface feels dry to the touch. It's a mistake to water before that; soggy soil encourages root rots.

Soil
Ferns are usually potted in highly organic soil that's porous, yet moisture-retentive. When it's time to transplant them into larger containers, choose potting soil that contains a large percentage of peat moss.

Air Circulation
Place ferns far enough from walls and other plants to insure good air circulation. Ferns look particularly handsome displayed on pedestals Odin wicker ferneries. They're also commonly grown in hanging baskets, but you must be careful not to hang them too near the ceiling. Because temperatures are higher there and air is dryer, the tips of a fern's fronds are more likely to turn brown and die.

Humidity
Ferns are known for their high humidity needs. Some people still mist their ferns to increase humidity, but it's really not very effective. Unfortunately, misting also increases the likelihood of foliar leaf spot diseases. It's better to rely on room humidifiers. Because it's difficult to improve humidity significantly indoors, it's usually better to concentrate on proper watering to eliminate moisture stress.

Nutrients
Typically ferns have modest fertilizer needs; they can be damaged more easily than most houseplants if you overdo it. Over-fertilizing will result in browning and drying that begins at the tips, then works its way back into the rest of the fronds. A lack of nutrients results in foliage that pales and loses its vibrant green color.

Fish emulsion seems to work well on ferns, though other fertilizers formulated specially for houseplants are fine, too, provided they're mixed at half the label-suggested strength and applied sparingly. Fertilize only when the plants are actively putting on new growth.

Easy-to-Grow Favorites:

Dallas fern. Photo credit: Deb Brown

* Boston fern, Nephrolepis exaltata 'Bostoniensis' is an old-fashioned fern with long, arching fronds. A dozen or more named "sports" or mutations of the original Boston fern have all but taken its place by now. Many boast foliage that's more ruffly or finely divided than the original. Dallas ferns are particularly notable for their compact stature and their ability to survive at lower light levels than Boston ferns endmost of their descendants.

* Rabbit's foot fern, sometimes called Squirrel's foot fern, Davallia fejeensis, is known for its tan "furry" rhizomes that grow down over the pot like little legs. Short, lacy green fronds sprout from these rhizomes, creating wonderful contrasts in color and texture. Because of its growth habit, this fern must be suspending in some type of hanging apparatus.

* Mother fern, Asplenium bulbiferum, is aptly named for the little plantlets that form on its large, feathery fronds. To propagate Mother ferns, all you need do is pluck off the little "babies," plant them in moist, peaty potting soil, then enclose the container in a plastic bag. Keep them in bright, indirect light until they root. (Direct sunlight would overheat them while they're still bagged.)

* It might be difficult to find a Holly fern, Cyrtomium falcatum, but it's well worth the added effort. Unlike more delicate-appearing ferns, the stiff fronds on this plant are rather coarse and leathery, with an attractive, deep glossy green surface. And unlike most indoor ferns, this plant does best when temperatures are on the cool side and you allow this soil to dry between waterings.

* Asparagus ferns such as the Sprenger fern (sometimes sold in spring as"sprengeri"), Myers fern, and Plumosa fern are not really ferns at all. Named for their fern-like, feathery foliage, they're actually close relatives of the asparagus we eat, and as such, grow best in bright sunlight. Commonly kept outdoors in summer, they often suffer from inadequate light in winter, elongating and dropping many of their tiny leaf-like structures.

* Two to avoid unless you're looking for a real challenge: Maidenhair fern, Adiantum species, and Staghorn fern, Platycerium bifurcatum. Each has specialized growing requirements, including high humidity levels more typical of greenhouses. Native woodland ferns are also poor choices for indoor growth; they've evolved to conform to climatic conditions and have a "built in" dormant period each winter.

Test your diagnostic savvy monthly with Disease Watch at: http://www.extension.umn.edu/projects/yardandgarden/Plpa.htm
Making an Accurate Plant Disease Diagnosis, Part 1
Chad Behrendt, Extension Plant Pathologist

Host plant: zinnia, symptoms: leaf spots. Photo credit: Beth Jarvis

Diagnosing plant diseases is a difficult task that requires patience and determination. There is rarely one simple answer to a problem. As a result, you must learn to become a good detective. The key to being a good detective is to ask a lot of pertinent questions, listen to the answers, and keep looking. Although this may seem like common knowledge, it is not. Most people, when trying to make a diagnosis, stop asking questions and begin guessing. At this point, the hope of identifying the problem is grim. You must keep asking questions.

In this article I hope to provide you, the diagnostician, with a simple outline for making diagnoses including the pertinent questions required to make an accurate diagnosis. In the February issue of Yard and Garden News, we will discuss how to interpret answers provided to the pertinent questions, along with a few examples.

Two more things before getting started: 1) I am going to assume that you, the reader, have some background knowledge in plant pathology and related theories. 2) Understanding that there will always be exceptions is also a necessity for becoming a good diagnostician.

Steps to making an accurate diagnosis.

1. The first question you need to ask is "What is the host plant?"

• This is an important question to ask since different plant diseases occur on different host plants.
• Knowing the species and/or variety can also help when making a diagnosis.

2. The second thing you need to do is identify the problem. Although this seems extremely easy, it may be the hardest step in the process. Especially, if you have to work over the phone. The following questions will help identify what is wrong with the host plant and define the symptoms being expressed. These are some of the most important questions!

Pine with only older needles affected. Photo credit: Beth Jarvis

• What portion of the plant is affected? (These answers could include: branches or leaves, top or bottom of the plant, north side or south side of the plant, etc.)
• What symptoms are present? (These answers could include: yellowing, browning, spotting, curling, death of the leaves, etc.)
• When did the plant become infected?
• Are the symptoms progressing and if so, how fast?
• What is the pattern of the disease? (These answers could include: randomly throughout the plant or uniformly along one side or the top, etc.)

3. The third set of questions should help provide a history of the plant’s previous conditions. These questions can be grouped into two general categories.

A. Cultural Background

• What crops have been previously planted in this site?
• When was the plant or crop planted?
• How was it planted?
• Was the plant properly watered, fertilized, and mulched?
• Were any chemicals applied near the plant? If so what kind and where?
• What is the soil like?

B. Environmental Background

• Where is the plant located? (These answers could include: along a roadway, next to the house, on the south side of a hill, etc.)
• What are the patterns of the disease? (These answers could include: uniformly throughout the environment, randomly on scattered plants, localized in a central area and spreading outward, etc.)
• Has there been any physical damage from construction, animals, storms, etc.?
• What was the weather like prior to the expression of symptoms?
• Are any other plants of the same or different species affected?

Hostas. All plants uniformly affected.

Celosia. Not all plants uniformly affected. Photo credit: Beth Jarvis

4. The next step in making a diagnosis to begin the process of elimination.

• This is the step where you begin to use the information you received from the previous questions to eliminate unlikely problems.
• As you begin to eliminate the unlikely problems, you need to focus on the remaining possibilities.
• As you focus on the remaining possibilities, you need to develop a new set of questions that will help eliminate the remaining possibilities. This can be a difficult step, often requiring experience.

Example: Biotic (living) agents like fungi typically cause random patterns of damage to occur on the plant and throughout the environment. Abiotic (non-living) agents like frost injury typically cause uniform patterns to occur on the plant and throughout the environment. Therefore, a problem that is occurring randomly throughout the environment is usually biotic in nature (eliminating abiotic), and a problem that is occurring uniformly throughout the environment is usually abiotic in nature (eliminating biotic). Again, there are always exceptions.

5. Finally, when making a difficult diagnosis do not hesitate to seek help. There are a variety of reference materials and qualified professionals available to help. These qualified professionals may include county extension educators, city foresters, private consultants, or University extension faculty.

Through practice and experience you will soon develop an extensive background of knowledge, which helps identify the key questions and what the answer means. I like to think of diagnosing plant diseases as a large jigsaw puzzle. Each question you ask and each problem you eliminate provides one more piece to the puzzle. Sometimes we need almost every piece before we can see the image, and sometimes just a few key pieces will paint the picture. Good luck in your future diagnoses!

Phomopsis Blight of Junipers and White Cedar
Chad Behrendt, Extension Plant Pathologist

Tip dieback. Photo credit: U of M Extension Service

Phomopsis blight is a fungal disease caused by the fungus Phomopsis juniperovora. This disease can cause shoot blights, twig cankers, and dieback on cedars, junipers, and other gymnosperms. Phomopsis blight is generally considered a minimal threat to native stands of cedar or junipers. However, phomopsis blight can be a great concern in the nursery and landscape industries, causing death of nursery seedlings and landscape plantings. Phomopsis blight can also reduce the survival rate of newly planted junipers and cedar. Although a wide variety of junipers, cedar, and other gymnosperms are affected by the fungus phomopsis, their susceptibility varies greatly.

Phomopsis blight typically causes death of the newly emerging shoots, by penetrating young immature leaves. After the fungus has entered the plant it progresses to the xylem tissue, where it girdles the young shoot, causing death. The fungus is then able to continue colonizing the stem, resulting in the formation of a canker. Rarely, does the fungus cause cankers in stems larger than 1 cm in diameter. A very similar disease, caused by the fungus Kabatina juniperi, also frequently occurs on junipers and cedar. In contrast to phomopsis, kabatina typically kills one year old or older stems, and is unable to infect healthy foliage.

Upon initial infection of the young leaves, a small yellow spot may develop, but this symptom usually goes unnoticed. The bright, deep green color of healthy young shoots quickly fades to a pale green, as the fungus continues to colonize healthy tissue. Eventually shoots turn reddish-brown. Close examination of infected shoots, may reveal a small gray band near the base of the reddish-brown tissue. This gray band marks the initial point of infection. It is also the section of the plant where the fungus is most likely to produce spores.

Spores are produced during wet periods throughout the growing season, and infection can occur at any time when young succulent foliage is present. Spores, commonly called conidia, are produced in reproductive structures called pycnidia. These structures initially develop beneath the outer layers of tissue, but later emerge and protrude through the leaf tissue. These structures can be observed under close examination with a hand lens. It is during wet periods that these structures form and release spores, which are rain splashed and wind blown to nearby plants.

The fungus survives the winter on previously infected material, and is able to persist as a saprophyte, non-pathogen, for two years. Most infections occur in the spring as the new growth emerges and surviving pycnidia produce spores. Due to the ability of the fungus to survive as a saprophyte for two years it is extremely important to practice good sanitation. Prune and remove all infected shoots during the dormant season and properly dispose of them. If disease is severe, infected shoots can be pruned during periods of dry weather. Remove severely infected plants and destroy. If phomopsis blight continues to be a problem, a fungicide such as Mancozeb or Cleary’s 3336 can be applied in spring to protect the new growth from infection.

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

Insect Damage to Clothes
Jeffrey Hahn, Assistant Extension Entomologist

Webbing clothes moth. Photo credit: U of M Entomology Dept.

Clothes moths and carpet beetles can potentially damage clothes and fabric derived from animals, such as wool, fur, feathers and hair. However, the incidence of them attacking clothes or other fabrics in homes is uncommon. Infestations are more likely when susceptible materials are left undisturbed for an extended period of time. Materials that are soiled are also more commonly attacked.

When insects infest clothes, they usually create irregular-shaped holes. Insects are often found on and/or near the damaged material. Only the immature larvae actually feed on fabric from animal products (adult clothes moths do not feed and adult carpet beetles feed on pollen). Clothes moth larvae are small, whitish caterpillars that usually construct a case or tube. Clothes moths are typically found under collars and cuffs and other hidden areas. Carpet beetle larvae are worm-like, dark, and hairy; molted skins (empty shells) may also be apparent.

Finding small moths in a home does not usually indicate clothes moths are present. In nearly all cases, small moths are Indianmeal moths, a type of insect that feeds on dried food products such as pasta and flour. These pantry insects do not feed on any clothes or fabric made from animal products.

In a lot of cases, clothes with holes have not been damaged by insects. This is especially true if damage occurs in cotton or synthetic materials, such as rayon, or nylon, fabric that clothes moths and carpet beetles do not eat. If you suspect insects, search carefully in the areas where the material was stored for evidence of them. However, if you do not find any, then it is much more likely that the holes developed because the fabric was accidentally hooked or snagged or from wear and tear.

Editorial Notes

Mega-Tom tomatoes. Photo credit: Beth Jarvis

Why, oh why do calendars show snow and ice scenes during the winter months?? Those of us in the snowbelt can (usually) just look out the window.

Rather than thinking snow, I'm thinking tomatoes, homegrown tomatoes. Those at left are Mega-Tom, raised by Twin Cities tomato enthusiast Romaine Breault. Click on the thumbnail to enlarge the picture and you can see the bird mesh he uses to support developing plant and fruit.

Once holiday trappings are stashed away, those of us who garden are free to start seriously perusing the catalogs that begin to trickle in around Thanksgiving. Of course, now there are all the choice available on the Internet, as well.

To help you make plant choices, in February, Erica Davis, Hennepin Co. Extension Educator, will discuss the new blueberry releases and selecting cultivars. In a subsequent issue, Doug Foulk, Ramsey Co. Extension Educator, who has been researching organic/low-input apple growing, will share some of his findings. Topics should include disease resistant apples and a bit about apple rootstocks. Christian Thill has promised a piece on potatoes this spring, as well. In an upcoming issue, Mary Blickenderfer, shoreline vegetation and landscaping specialist, will be sharing some ideas on landscaping around ponds.

I'm always looking for article ideas and have received some intriguing story suggestions. So, don't be shy!! Your story suggestions are most welcome!

Yard & Garden Line News is on its winter publication schedule. We will publish only on the first the month from now until April. Then, we'll resume twice monthly issues, on the first and 15th of the month.

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 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.

MPR news radio stations.

For plant and insect questions, visit http://www.extension.umn.edu/askmg. Thousands of questions have been answered, so try the search option in the black bar at the top left of the board for the fastest answer.

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 or to unsubscribe, enter: unsub yglnewslist



Happy gardening!

Beth Jarvis
Yard & Garden Line Project Coordinator

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