The Garden Scoop Featuring weekly articles by Ryan Pankau, University of Illinois Horticulture Educator. Sun, 15 May 2005 13:02:08 -0500 Protecting Tomato Plants Tue, 18 Jun 2019 11:00:00 +0000 Nothing beats a homegrown tomato! Even when in season, the store bought varieties just cannot compare to a fully ripe tomato harvested at its peak from your own garden. So many gardeners across American choose tomato plants for their garden each year for this reason, making it the most planted garden crop in the US.

I receive a lot of questions about tomato care each growing season, with many focused on disease control later in the season as pathogens prevail on infected tomato plants. This year, get a step ahead of tomato problems with a plan to combat the most common issues central Illinois gardeners encounter each summer.

Perhaps the premier pest on tomato plants, the tomato hornworm, is nearing its debut for the 2019 growing season. These defoliating larva emerge from pupa in July after overwintering in the soil. They are native to North America with a large home range spanning sea to sea.

It is often very easy to identify the damage that ensues after they hatch. The little critters are big consumers of leaves, fruits and smaller stems on tomato plants leaving very noticeable damage in as little as a day. I have always had excellent control from timely hand removal of these caterpillars. It does take a watchful eye to notice damage promptly and remove the culprit. During daytime, these guys hang out in the shady lower portion of the plant, waiting for their favorite time to feed which is after dark. At night, they are easily found feeding in the tip-tops of plants. I make the rounds each evening to easily pluck them off the branch tips as opposed to a more difficult daytime search.

Early blight is a foliar disease caused by the fungal pathogen, Alternaria solani. It appears as yellow spots on lower leaves which enlarge into dark brown spots, eventually withering and killing infected leaves. The disease always originates on lower, older leaves and moves upward, creating a noticeable pattern. As the infection worsens, it is known to attack petioles, stems and fruits also. Alternaria solani overwinters in infected plant debris at or near the soil surface. During favorable spring conditions, the fungi produce spores that are spread by splashing rain drops or wind to infect leaves.

Since this pathogen moves from soil to leaves, a mulch barrier is one of the most effective control measures. In fact, I've had excellent control of this condition simply by mulching immediately after planting my tomatoes, offering no opportunity for rain drops to splash the fungi up onto leaves. Watering plants with drip irrigation can also help immensely.

Providing good air circulation from staking and some light pruning can limit its spread by reducing favorable conditions, such as wet leaves. Preventative fungicides (cholorothalonil or mancozeb) may also be used to limit infection and spread, although I have never had to use any, accomplishing adequate control from cultural measures such as mulching, staking and pruning.

Septoria leafspot is another fungal pathogen that infects leaf tissues. It is characterized by small black spots on leaves, with centers that later turn white and develop tiny black dots. This disease also begins on lower leaves, thriving in wet weather and spreading up the plant. It is transmitted from the soil, much like early blight, with control recommendations identical for each pathogen.

Both of these fungal diseases can also be addressed by keeping plants healthy to limit susceptibility. Good fertilization (but not over fertilization) is part of that strategy including a starter fertilizer at the time of planting, a side-dress application when fruits are about golf ball sized, followed by 2 more applications (spaced out 3-6weeks) throughout the growing season. Follow product instructions for the recommended rate for each application.

Blossom end rot is another very common problem on tomatoes that is not caused by a pathogen but rather it is a physiologic condition of tomato plants related to the soil environment, which limits calcium uptake. It is characterized by large dead spots on developing tomatoes, often becoming brown and leathery before secondary fungi move in to rot the fruit.

Developing tomatoes need a lot of calcium to support rapid growth. Although calcium is plentiful in the soil, it must be in dissolved in water for plant uptake. Greatly fluctuating soil moisture, with extreme swings from wet to dry, can disrupt calcium uptake which often leads to blossom end rot as fruits develop. A simple solution to this issue is also mulching, which will regulate extremes. Appropriate watering as needed from fruit formation to maturity will also limit extremes and maintain a more uniform soil moisture.

Some simple steps now, such as mulching, staking, and appropriate watering intervals combined with scouting for hornworms in the coming week, can really set up your tomato patch for success this season.

Ryan Pankau is Horticulture Extension Educator with University of Illinois Extension serving Champaign, Ford, Iroquois, and Vermilion Counties.

This article was originallypublished in the News Gazette on June 15, 2019

Boxwood Blight Wed, 22 May 2019 13:25:00 +0000 Boxwood shrubs are perhaps one of the most planted evergreen shrubs in landscapes around the Midwest. Although they are typically fairly hardy in our area, many suffer from winter injury. In addition, there are a number of other ailments for this shrub that gardeners should be aware of including a new and very serious threat called boxwood blight.

From the standpoint of functionality in the landscape, these little, green and slow growing shrubs are matched by few other evergreens. They are synonymous with hedges, but have a variety of other landscape uses where a backdrop of evergreen foliage is needed.

Although I most commonly think of littleleaf boxwood (Buxus microphylla) as the primary species utilized in Zone 5 and 6, its cousin the common boxwood (Buxus sempervirens) is also hearty in Illinois. Cultivars of both species abound, creating a boxwood for almost all occasions and extending their range into warmer regions as far as Zone 9 for some.

Both species are not native, with home ranges spanning several continents and littleleaf boxwood's center of distribution being a bit more tropical. I view both species of boxwood as purely ornamental plants, likely having little value to our native fauna. Foliage actually contains compounds toxic to most mammals, making these plants deer or rabbit "proof". However, I can certainly understand why many folks may want a deer-resistant hedge somewhere in their landscape.

Over the past few weeks, I have observed quite a bit of winter damage on boxwoods around central Illinois. In most cases, it is not serious and can be pruned out once things green up for the year. Yet, I always caution people to hold off pruning out the dead too soon in spring. Although the foliage may be entirely dead, the limb itself may be alive. Once the shrub comes out of dormancy and begins to grow, you may see a flush of new growth on what previously looked like a dead stem. However, by this point in the season, a stem that is still alive should be showing signs of life, such as developing green leaves or at least swollen buds.

This type of injury appears as dead or dying foliage, typically tan to light brown in color. It is often limited to the outer canopy of the shrub or one side that is more exposed. One great indicator of winter injury is the pattern. All dead foliage on the plant in spring is a result of desiccating winter weather and should not spread after the growing season begins. Conversely, injury or infection from pathogens will often times spread as spring progresses.

In the current issue of the University of Illinois Extension Home, Yard, and Garden Pest Newsletter, there is a great article on "Boxwood Blight Look-alikes." My extension colleges that authored this article do a great job reviewing a number of pests and disease that occur on boxwood and appear similar to boxwood blight.

Earlier this week, I had a conversation with Diane Plewa of the University of Illinois Plant Clinic, who co-authored the article. We both agreed that one take-away from the article was the fact that there are quite a few ailments on boxwood. Many times they may not be that serious, often corrected with pruning or other cultural practices, but odds are you will deal with some issue or another over the life of your boxwood plant.

Boxwood blight is a newer pathogen on this continent, first appearing here in 2011 after already causing several decades of damage in Europe. In Illinois it was first detected in 2016 and has only been identified eleven times since. Plewa's article points out a key difference between boxwood blight and other common insects and diseases: It causes extensive defoliation. The disease is caused by a fungus, beginning as leaf spots in the lower branches that move upward in the canopy. Infected leaves drop from the plant, unlike many other problems which result in dead leaves that remain on the stem.

Although scouting and early detection of this pathogen is very important, the infections to date in Illinois have primarily been associated with production areas, such as nurseries. Therefore, thoroughly inspect any new plant material for symptoms before planting. It is predominantly spread by human activity with less potential for spread within the landscape by wind or insects. Nonetheless, if you believe your existing plants have boxwood blight, please contact the University of Illinois Plant Clinic ( or 217-333-0519) for information on how to submit a sample.

The current issue of the Home, Yard, Garden and Pest Newsletter is always available at: The newsletter website features an archive of all past issues and an option to sign up for email notifications of each new issue.

Ryan Pankau is Horticulture Extension Educator with University of Illinois Extension serving Champaign, Ford, Iroquois, and Vermilion Counties.

This article was originally published in the News Gazette on May 18, 2019

Native Plants and Biodiversity Fri, 17 May 2019 09:00:00 +0000 A startling report on global biodiversity was release by the United Nations last week noting an alarming trend in worldwide species extinction. We, humans were pegged as the primary cause of an increase in extinction rates to the highest levels in human history. Specifically, around 25% of the species assessed are threatened, suggesting that one million of the eight million known species of plants and animals are at risk of extinction.

Biodiversity refers to the variety of life on earth. The great diversity of life on our planet maintains the life-support systems humans need for basic survival. Think about the air we breathe, the water we drink, the soil that supports plant growth… all those basic elements of our environment are dependent on biodiversity— the diversity of species we have on earth. As we lose biodiversity, our planet loses its ability to provide many of the things we all need to survive, as well as the spectrum of colors and sounds of life on Earth.

As a biologist and a gardener, this is a troublesome report to wrap my mind around. Our footprint has grown large enough on a global scale to imperil on 1/8 of animal and plant life on this planet. That alone is difficult to comprehend, but how does biodiversity relate to what I do as a gardener?

Simply put, the choice of plants we add to our gardens and landscapes can have an impact on biodiversity, with native plants providing the greatest benefit. Our native plant life supports native insect populations, which in turn support larger animals creating a "food web" of interconnected species.

Insects are an important transition point for energy within food webs. Since many of them consume plant material, they consume the energy plants harness from the sun, and turn it into protein that larger animals need. As insects consume, the vital energy our sun provides is transferred on to the animal kingdom and supports a diverse food web.

If native plants can begin to fill a larger proportion of our gardens, then all of our home landscapes can become valuable habitat to support native wildlife. Not only do we provide a home for our local flora but we support our fauna.

Earlier this week I had a conversation with Dr. Greg Spyreas, a plant biologist at the Illinois Natural History Survey. Dr. Spyreas' work focuses on conserving and restoring our native Midwestern flora and habitats. In our conversation, I asked Dr. Spyreas to shed some light on the current status of Illinois native plant diversity.

"Worldwide, there are more than 250,000 species of vascular plants," notes Spyreas. "In Illinois, we have greater than 2,500 species of native plants, over 300 of which are currently endangered."

This means that over 300 plant species are at serious risk of being eliminated from the state or even going globally extinct in the very near term.

These numbers help to illustrate a point that Dr. Spyreas made, related to how preserving native plant diversity in Illinois fits into the global picture.

"Illinois' 2,500 species of native plants represent about 1% of the global plant species numbers," says Spyreas.

Although one percent sounds small, it's actually a large number when you look at it from a global perspective. We have an opportunity to preserve 1% of the plant biodiversity on this planet right here in Illinois and that's and exciting number to me.

As gardeners, not only can we can do our part to preserve plant diversity by adding native plants to our landscape, we can help boost the diversity of native wildlife species due to the complex relationship between native flora and fauna.

Although the species of native plants suitable for gardening are not typically any of those that are endangered, many of which are far too sensitive to thrive in cultivation, there is a great number of natives that work wonderfully as landscape plants. So, we might not be preserving the most at risk species, but we are certainly boosting native plant diversity at a very local scale, such as within your own yard or neighborhood.

One major challenge to planting more natives is sourcing the plant material. The horticulture industry in general has not responded adequately to a growing demand for native plants. The industry's traditional plant selection relied on nonnative ornamental species. However, as more and more gardeners begin to understand the great need to preserve plant diversity and support native wildlife, our purchasing choices can start to drive industry trends. So, be sure to ask your local garden center where you can find the native plant section. You may actually be pleasantly surprised at the result, with consumer demand eventually helping species conservation.

Special thanks to Dr. Spyreas for the great conversation and his contributions to the content of this week's topic.

Ryan Pankau is Horticulture Extension Educator with University of Illinois Extension serving Champaign, Ford, Iroquois, and Vermilion Counties.

Originally published in the News Gazette on Saturday, May 11, 2019.

Winter Injury to Fruit Trees Fri, 10 May 2019 14:43:00 +0000 Winer injury is a common problem among fruit trees grown in our area and this year's up and down spring temperatures resulted in damage to flower buds across central Illinois. Cold weather in some years can bring damage to many ornamental tree species as well, impacting much anticipated spring blooms. In fact, injury from cold weather is likely the most important limiting factor in plant species distribution around the globe, which is why most gardeners pay careful attention to cold hardiness maps.

If you paid a visit to the University of Illinois Arboretum this spring to view cherry blossoms in the Sen Cherry Tree Alle, near the Japan House, then you witnessed the effect of winter injury. Sadly, the cherry blossoms were almost entirely absent this year. I was only able to find a few isolated flowers that survived some of our late winter or early spring cold. However, this is a bit of an odd year and the cherry blossoms should be back in full force next year. It really is awe-inspiring display that I encourage everyone to visit next spring. It's certainly on my "must see" list each spring!

Many of the other ornamental species in our area, such as magnolias, crabapples, redbuds and dogwoods were not affected by cold weather, hosting their typical spring display. Crabapples are probably in their peak display this week showing little sign of any impact from cold weather. Redbuds and dogwoods also had an excellent display, possibly already peaking for the year as of this week. Magnolia trees, which flower a bit earlier that the species mentioned above, did well this spring and have already peaked. However, some magnolias in rural or more exposed areas did show signs of injury as flowers emerged.

Peach trees in our area were hit pretty hard this year, with some local growers reporting a complete loss. I've observed similar effects in several backyard peach orchards as well, without a single flower present. However, many apples trees suffered less damage, with many looking unaffected. I have observed some with few or now flowers, so there was an impact, but it appears to be specific to certain varieties of apple or more exposed areas.

So, what is it that makes some species' flower buds more or less susceptible to the cold? We can find some explanation in the timing of their flowering each spring. Peach trees flower earlier than apples trees, indicating they come out of dormancy sooner than apples. As trees break dormancy, their susceptibility to damage from cold temperatures increases. So, the answer really lies in how and when individual tree species break dormancy each spring.

There is interesting data as to where the limits of susceptibly lies at various stages of spring development among fruit trees based on Extension Bulletins from Washington and Michigan State. For example, swollen peach buds, or buds that have just broken dormancy and began development, can be damaged if temperatures dip below 23⁰F, with 90% killed by the time temperatures drop to 0⁰F.

The emerging flower buds on apples can endure lower temperatures, down to around 16⁰F before damage begins and 90% are killed around 2⁰F. When combined with the fact that apples flower later in the season and break dormancy later, there is much less chance of 16⁰F weather later in the season, making apple crops much more dependable in our area.

Once flowers fully emerge and are considered in 'full bloom' cold susceptibly is a much closer range, although peach flowers able to handle slightly lower temps at this stage. In apple trees, a fully developed flower can be damaged if temperatures reach a low of just 29⁰F (90% killed at 25⁰F), whereas peach flowers can endure a low of 27⁰F (90% killed at 24⁰F).

The weather this spring during March and April has been interesting. In early March we had 4 days in row with lows in the single digits, whereas last March had none. In April we only saw a few overnight lows approach freezing, whereas last April had a dozen.

If you are one of the unlucky plant owners that has experienced no flowers this spring, don't lose heart. Every spring is different and hopefully next spring will cooperate with appropriately timed temperatures for tree flower development. To look at the positive side, trees that didn't flower won't have to support energy-intensive fruit development this year and can reallocate that energy to other life processes, such as disease resistance and shoot or root growth.

Ryan Pankau is Horticulture Extension Educator with University of Illinois Extension serving Champaign, Ford, Iroquois, and Vermilion Counties.

Originally published in the News Gazette on Saturday, May 4, 2019]]>
Spring Beauties: A True Sign of Spring Thu, 02 May 2019 13:10:00 +0000 Last week the spring beauties (Claytonia virginica) in Lodge Park, near Monticello, were absolutely stunning. These tiny, ornate wildflowers adorn the forested trails at Lodge and other woodlands throughout central Illinois providing us with a sure sign that spring has arrived each year.

Spring beauties are perennial wildflowers that emerge early in the year and produce tiny (1/3") flowers that may seem insignificant when viewed alone. However, when assembled into a carpet of whit spread across the forest understory, they are a wondrous sight, typically occur in abundance where conditions are right.

From afar, the flowers appear mostly white. Upon closer inspection, they actually have fine pink strips that can vary from a light pink to a very bright pink color, adding beautifully intricate detail for the close observer. On bright sunny days, the flowers open wide to invite in pollinating insect guests. During colder or cloudy days in spring, the flowers close up and gently drupe downward, awaiting the next warm and sunny period. Blooms occur in mid to late spring and last for about 1-2 months, making this wildflower easily observable this time of year when compared to some of their more quick-flowering cousins.

I have always considered this flower the true sign that spring is here. It's certainly not the earliest spring wildflower, with others such as snow trillium, blood root, harbinger of spring and even bluebells beating it to blooms most springs and always giving me some much needed, early encouragement that spring is around the corner. However, by the time the spring beauties come along, we have usually gained some of those warm sunny days, asserting spring's arrival.

To me, they really symbolize the start to the gardening season as well, providing that gentle reminder that our frost free date is just a matter of a week or two away. It's nice that they aren't the final alarm, since they emerge in mid to late April and the typical frost free date for most areas in central Illinois is around the first of May, but are more of celebratory reminder to 'get it gear'. As and added pleasantry, they last well past the frost free date, nicely launching another year's growing season.

They also symbolize the early activity of an awakening insect population each year. The warm days associated with this time of year bring out many pollinators. A quick perusal of scientific literature indicates activity from many species of bees and flies on spring beauties. Most are visiting them for nectar, although some literature notes pollen collecting bees in the mix. I counted about eleven species of native bees and five species of flies associated with these tiny flowers. There is also evidence of butterfly use as the season progresses, although less frequent.

Spring beauties are common throughout Illinois, occurring in every county, according to historical records. They prefer dappled sunlight in the early spring which makes them more prevalent in forested areas, although they can be found in some prairies and savannahs as well. This species is not quite as sensitive to disturbance as other wildflowers in Illinois, allowing it to persist well throughout the state over time when compared to some of the more sensitive species that have drastically declined in numbers since early settlement of Illinois. Perhaps their overall abundance, being observed with relative ease, is why they seem so noteworthy in my mind each spring?

Although most of us think of spring beauties as a woodland wildflower, they are well adept to semi-shaded lawns as well. The entrance to Lodge Park has a large open space of mowed grass, maintained for camping and other recreational activities, with a canopy of age-old, towering white oaks. Last Sunday, this area was a virtual blanket of white from all the spring beauties in bloom. My accolades to the staff at Piatt County Forest Preserve for delaying mowing in this area so their population of spring beauties can flourish each year.

Since I live less than a river-mile away from Lodge, along the Sangamon River, I am fortunately enough to have spring beauties pushing up through my lawn right now. I will certainly delay mowing to preserve our population of this symbolic flower. It may not be the rarest nor the earliest wildflower, but it has always fascinated me how this tiny, white flower can persist from woodland to lawn, attempting to stretch into our more human-dominated environments while asserting its enduring, yet still ephemeral reminder of spring.

A Closer Look at Rain Gardens Mon, 11 Mar 2019 14:36:00 +0000 Rain gardens are one way for homeowners to use garden design as means to mitigate storm runoff by capturing and detaining water before it leaves our properties. Although these carefully designed gardens function as tiny rainwater detection areas, you wouldn't know it unless they were inundated with storm water. When it's not raining, they are attractive gardens filled with pollinator habitat and native plants with beautiful blooms.

Earlier this winter I mentioned rain gardens in this column and many readers have expressed interest in learning more about them. I hope to take a closer look at rain gardens this week to answer folk's questions and give you a better idea about where a rain garden might fit into your landscape.

A rain garden is simply a slight depression on the landscape which detains water during storm events, allowing it to slowly infiltrate, or soak in, after the storm. It is filled with native plants which help with infiltration while creating a gorgeous garden space as well. They are constructed at strategic locations in our landscaping that receive storm water runoff from the slope of the surrounding area or the gutters and roofing system of our home.

One of the biggest keys to installing a well-functioning rain garden is identifying the proper location. The ideal location is somewhere in the landscape with a relatively small drainage area (< 5,000 sq. ft.) where there is already concern for how stormwater is discharged and the conditions are right for infiltration of water into the soil profile. Additionally, the garden needs to be placed at least 10 feet from building foundations, wells and septic systems. To protect adjacent shade trees, the garden itself should be located outside the dripline of nearby trees in full sun.

Although it seems tempting, an area where water already ponds is not a good rain garden site. The fact that water ponds there already indicates that conditions are not right for good infiltration of storm water. Perhaps the soil is compacted or other physical properties of soil in that area do not allow water to infiltrate well?

With some careful design, your rain garden can be placed "upstream" of an area where water ponds to intercept some, or all of the runoff prior to ponding. By intercepting the runoff, a rain garden allows time for the water to infiltrate the soil, becoming groundwater instead of surface water that must find someplace to go.

Rain gardens capture storm runoff with the use of small constructed berm on the downhill side of the garden. The garden area inside the berm is dug out until level and serves as a pooling area for incoming rainwater. The berm serves as a mini dam, holding back stormwater and giving it time to infiltrate. Although talk of berms and dams do make me think of a pond-type structure, rain gardens are different from ponds since they very ephemeral, drying up shortly after the rain concludes. The berm that is constructed is quite small, often only inches tall. Once the vegetation in the garden is mature, the berm is often nearly undetectable.

Deep-rooted, native prairie plants are the superstars of rain gardens. Not only do they provide beautiful native flowers and foliage, but their deep root systems aid in infiltration of the rain water. As a storm event begins to fill your rain garden, plant roots begin to absorb and use the water. In addition, all the channels that roots make throughout the soil are conduits for rainwater to enter and infiltrate. It is a well-known fact that roots and organic matter in the soil increase infiltration rates significantly.

If you are interested in learning more about rain gardens so you can design and install your own, the Wisconsin Department of Natural Resources has a very concise and useful manual for homeowners and landscapers. This guide contains details on how to calculate the drainage area contributing to your rain garden in order to properly size the berm and garden space. It also has great instructions for measurement, layout and installation the garden. There is a wonderful list of prairie plants that work well in rain gardens with details about the preferred soil type, light preference, height and flowering time of each plant. This guide can be downloaded online at:

Ryan Pankau is Horticulture Extension Educator with University of Illinois Extension serving Champaign, Ford, Iroquois, and Vermilion Counties. Originally published in the News Gazette on Saturday, March 9, 2019

Create a Holiday Wreath- Sign up for VCMG Dec 4, 2018 'Make and Take' Class Mon, 05 Nov 2018 08:25:00 +0000 'Creating a Holiday Wreath' featuring Master Gardener Mary Stonecipher

DANVILLE – The holidays are right around the corner and finding time to shop, bake, decorate and enjoy time with loved ones can be challenging. How about spending quality time with friends and family while you make a fresh, fragrant evergreen wreath! Do you have someone who is difficult to buy for? This year, surprise them with a handmade wreath. If they enjoy being crafty, sign them up for the class, and give them both the gift of a fresh wreath and a new decorating skill.

The Vermilion County Master Gardeners will again hold their seasonal "Make a Holiday Wreath" class on Tuesday, December 4. The class will start at 6 p.m. and take place at International Greenhouse Company at 70 Eastgate Drive in Danville. Master Gardeners Mary Stonecipher and Pat Sollars will teach how to create a beautiful wreath. A $15 fee includes a metal wreath ring, floral wire, pinecones and a variety of fresh evergreens. Bring ribbon and decorations to add your own personal style. Master Gardeners will be on hand to help make a bow from your ribbon. You will also need hand pruners to cut branches and garden gloves to protect your hands.

Fresh wreaths add natural beauty to our homes, look festive and fill the air with their wonderful fragrance. Register now, as this class fills up quickly and we are unable to take walk-ins. Your $15 fee reserves your seat. Attendees may pay with cash or check at the Vermilion County Extension Office (3164 North Vermilion, Danville, across from the Village Mall). Credit card payments may only be processed online through the University of Illinois Extension website at If you have questions, contact the Extension Office at (217) 442-8615. Proceeds from this class fund Master Gardener programs in Vermilion County.

University of Illinois Extension provides equal opportunities in programs and employment. If you need a reasonable accommodations to participate call (217) 442-8615.