Polk County Conservation

Tree and Plant Questions

  • Do you have any good referrals for tree care? I have a paper birch that seems to be having some problems. The limbs are turning brown and is dying from the top down. Wondering about insects or diseases? This tree is over 12 years old and is nice and large (would hate to lose it!) Thanks!

    I would first recommend talking with a certified arborist. Pick someone from the list found on the Iowa Forestry Extension site. They will come to your property and make a diagnosis, but will not fix the problem. The good part about their service is they give you an unbiased opinion because they aren't selling anything. A certified arborist will most likely charge you for coming to your property though.

    You could certainly contact any of the tree care service companies in the phone book, but they may try to sell you services you don't need and may not accurately diagnose the problem. The other option is to take a leaf sample and photos of the tree to the Polk County Extension office and they will pass it along to someone in extension that can answer your question. Good luck!

  • When trimming a maple tree this spring, do I need to cover the cut with anything to keep out bugs or disease?

    If you can wait, delay pruning maple trees until late spring or early summer. There is a lot of sap moving through the tree and it is very difficult to prune without tearing the bark during spring. You will also notice a lot of sap "bleeding" from the wound. In general avoid pruning between the time of bud swelling (which they already are) and the leaves fully emerging. Once the leaves are fully emerged, go ahead and prune maple trees. You don't need to cover the wound with anything to keep out bugs or diseases. Extensive pruning should be done in winter when maple trees are dormant.

  • What is that pretty light blue flower found along roadsides?

    What you’re seeing is probably chicory, Cichorium intybus. This perennial plant has stiff, wiry stems with few leaves and can grow from two to four feet tall. The flower heads are windmill like, attached directly to the stem, and usually about 1+ inch wide. This spindly pale blue flowering plant blooms from June through September. Chicory was introduced to North America from Europe and is now a common roadside flower found throughout most of the continent. Chicory has many uses but is most well known for its association with coffee. The roots of chicory can be roasted, ground, and used as a coffee additive. This coffee additive is very popular in the south, particularly New Orleans.

  • Why are trees pruned and why is winter the best time to prune?

    Trees are pruned to preserve their health and appearance and to prevent damage to human life and property. Health reasons for pruning include the removal of rubbing and/or crossing branches, to decrease the chance of self-wounding, and removing insect and diseased affected branches to prevent decay from spreading. Safety pruning includes pruning branches that may impede vehicular (when you are sitting on your riding mower) or pedestrian traffic and removing branches that interfere with lines of sight for automobiles, bicycles and pedestrian traffic.

    Pruning should be done when it is cold for several reasons. It is easier to make pruning decisions without leaves obscuring the branches. Diseases are less prevalent at this time and fresh wounds are only exposed for a short time before the sealing process begins to occur. Oaks and elms are particularly susceptible to diseases and dormant pruning greatly reduces the possibility of infection.

    Unless absolutely necessary for safety reasons, do not prune while the leaves are expanding until they are fully mature. Energy reserves are limited at this time leaving little for defensive activities like wound sealing and compartmentalization. Also avoid pruning during the leaf color season in the fall when fungi are sporulating and absorbing roots are forming.

  • Why are fall colors more brilliant in some years compared to other years?

    Fall colors vary from year to year based on weather conditions. Warm, cloudy and rainy fall weather will cause the leaves to have less red color. Well distributed rainfall during the summer and fall will favor a good fall color display. Trees under drought stress will many times drop their leaves without showing much color. Temperature also has an effect. An extreme cold snap will kill the leaves before allowing them to change to their fall display. Heavy rains or high winds will also cause the leaves to drop early.

    It’s hard to predict when fall colors will peak, but in general the northern half of Iowa has prime colors during the last week in September to the second week in October. The southern half of the state has prime fall colors during the second to the fourth weeks in October. Learn more about fall colors on the Iowa DNR site.

  • My son came home from school today talking about prairies and mentioned his class was going to visit a prairie on a field trip. What exactly is a prairie and what might he expect to see?

    A prairie is a habitat dominated by native grasses and flowers with fertile soil and few trees. There are approximately 72 types of grasses that grow in Iowa’s prairies and some of them will be taller than your son. Prairie grasses help with erosion control of the soil and provide food and cover for wildlife. Your son might also see wildlife like red-winged blackbirds, dickcissels, snakes, and insects. Prior to the 20th century, 85% of Iowa was covered by the tall grass prairie. Today, less than 1/10th of 1% of the native prairie remains. These native prairie remnants are found along railroad right of ways, roadsides, and parks. Polk County Conservation has planted and restored thousands of acres of native prairie and wetlands at Chichaqua Bottoms Greenbelt. Check our Calendar for our Prairie Festival. The Amazing Prairie Festival will feature a prairie maze to challenge your navigation and problem solving skills. There will also be other activities, educational information, and food.

  • There are huge white mushrooms popping up in my yard that I’ve never seen before. What are they and will they hurt my lawn?

    With the recent rains many types of mushrooms are popping up in our yards. Most likely the huge white mushrooms are a type of fairy ring mushroom called Chlorophyllum. These mushrooms have caps that can reach up to 12 inches across. Chlorophyllum is common in the summer and fall in lawns and other grassy areas. They are nature’s recyclers and will not harm your lawn. Mushrooms help break down and decompose dead plant material. This mushroom is poisonous and should be avoided. You should always use extreme caution before collecting and consuming any mushroom. Many types of edible mushrooms look very similar to poisonous ones. A great guide to help you identify mushrooms in Iowa is a publication titled "Mushrooms and Other Related Fungi". This publication is available at your local county extension office.

  • On a recent camping trip to Wisconsin I hauled firewood into my camp site as I have done every year for the past six years. This year I was told this was illegal because on an insect called the Emerald Ash Borer. What exactly is the Emerald Ash Borer?

    The Emerald Ash Borer (EAB) is a beetle from Asia. This non-native pest poses an enormous threat to our urban and rural forests. EAB differs from most native borers in that it will attack healthy trees while most native borers attack stressed and declining trees. It is so aggressive that ash trees may die within two or three years after they become infested with the beetle. If it is not contained and eradicated, the impact of Emerald Ash Borer beetle attacks on ash in North America will be similar to that of the devastation from two fungal diseases, Chestnut Blight and Dutch Elm Disease, which destroyed woodland and urban forests in the 20th century.

    The borer has been found in Michigan, Ohio, Indiana and recently Illinois in the United States and also in Windsor Ontario. One way the borer has spread is by transportation of firewood. As a camper you can do your part to limit the spread by using local sources of firewood, not taking firewood out of quarantined areas and if you do bring firewood into a quarantined area do not leave it−burn it.

    For more information about EAB visit the following web sites:



  • The lower leaves on my white oak tree seem to be turning brown and wilting. Is this oak wilt?

    Based upon your description, I doubt you are seeing oak wilt but rather another fungal disease called anthracnose. Anthracnose is a common foliage disease of many of our indigenous shade trees. The disease commonly affects sycamore, maple, ash, linden, bur and white oak. The disease is particularly prevalent on white oaks this year. Anthracnose usually occurs on the lower portion of the tree while oak wilt usually starts in the upper portion of the tree. Another main difference is the timing of the diseases. Anthracnose is commonly associated with cool, wet springs and exhibits leaf symptoms in spring, conversely oak wilt exhibits symptoms in the summer months. Anthracnose damage does not have a long lasting impact on tree health. Many of the trees in our parks are producing a second flush of foliage which will help in the recovery process. By the end of the summer, these trees will look "normal".

  • I started a compost pile a couple of years ago and something’s wrong because the pile doesn’t seem to be composting down. I throw my kitchen scraps and yard waste into the pile. Do you have any suggestions?

    I’ve had a similar problem with one of my compost piles. All organic material will break down eventually. The speed at which it breaks down depends on: the carbon to nitrogen ratio of the material, amount of surface area exposed, aeration or oxygen in the pile, moisture, temperatures reached in the pile, and outside temperatures.

    First I would evaluate the material in the compost pile. Too much of any one material will slow down the composting process. The bulk of organic matter should be 30 parts carbon to 1 part nitrogen. Leaves are a good source of carbon and fresh grass, manure, and blood meal are good sources of nitrogen. In general it’s good to keep a mix of green and brown material. Secondly, keep your compost aerated. The contents need to be mixed up so the pile gets oxygen and can break down effectively. A good resource to check out online is compostguide.com. Good luck!

  • We moved into a new house this winter and there aren’t any trees on our lot. I’d like to plant a few trees in my yard this spring, but don’t know where to start. Do you have any tips to help me choose which trees to plant?

    I’m glad you are giving this some thought. Choosing the right tree can affect the surrounding area for years to come. Proper planting choices save time, money and later disappointments. One of the first things you need to do is evaluate the site where the tree or trees will be planted. You’ll need to consider exposure to light, wind and salt. How close are buildings, signs, and other trees? Underground considerations include soil pH, drainage, water table, rooting space restrictions, and underground utilities. To locate underground utilities, homeowners are required by law to contact Iowa One Call (1-800-292-8989) at least 48 hours prior to digging. Knowing these things will help you pick out a tree that will thrive in its planted location.

    More information can be obtained from a number of resources such as Polk County Conservation, Iowa State University, Iowa State Extension, Iowa Department of Natural Resources-Forestry Division or you can contact your local Certified Nursery Professional.

  • Why do oak trees produce a lot of acorns one year and hardly any in other years? I have tons of acorns to rake up under my bur oak trees this fall.

    When a tree produces a huge crop of nuts, it is called a "mast" year and this year is a mast year for bur oak and white oak trees. However the acorn crop for pin oak, swamp white oak, and red oak is poor. There aren’t any good predictors as to why acorn production varies from year to year or from species to species. On average, most oaks produce a good crop of acorns every three to four years. Environmental factors can influence a tree’s ability to produce acorns. For example in warm wet years, trees have more resources to produce a large crop. While in cold, dry years, not many acorns are produced. Late frosts in the spring can also affect the acorn productivity. If an oak tree produces a good crop of acorns one year, it is likely that the following year will not yield as many. Acorns are an important source of food for deer, squirrels, turkeys, and other wildlife.

  • I saw the most unusual fungus on a tree. It was bright orange, fleshy and was almost glowing in the woods. What was it?

    It sounds like sulfur shelf or "hen of the woods". This edible fungus is quite tasty when fried and has a taste and texture similar to chicken. It is best eaten when it is still young and tender. You should only eat fungus if you are 100% positive of the identification. People react differently to edible fungi so you should eat only small amounts. Sulfur shelf is a bracket fungus that grows on living or dead trees but most commonly on oak trees. It grows into fleshy, knobby clusters with shell or feather-like curves. The largest ever found weighed 100 pounds.

  • I have a pin oak tree in my yard with low-hanging branches making it difficult for me to mow. Would now be a good time to prune this tree?

    I can sympathize with your situation because I have the same problems with a couple of trees in my yard. Many trees, especially those that bear fruit, have a tendency to have low-hanging branches during the summer months. This is usually a result of additional weight caused by fruiting and is common on walnut, apple and crabapple trees, to name a few. Other trees such as pin oak, river birch and willow have a natural weeping habit, which contribute to the mowing problem.

    Although many trees can tolerate minor pruning during the summer months to alleviate the mowing problem, oaks should not be pruned at this time. Oaks that are pruned during the summer months have a higher risk of infection by the oak wilt fungus. Members of the red oak group (red, black and pin) oak are rapidly killed by this disease, while members of the white oak group (bur, white and swamp white) oak die back more slowly.

    I recommend pruning your oaks during the dormant season. If wounding your oaks during the summer months is necessary, wounds should be protected by a wound treatment compound (shellac) or paint (white latex). Under no circumstances should asphalt based creosote paint be used to treat wounds.

    Another solution which would provide a better growing environment for your pin oak tree would be to apply mulch out to the edge of the branches. Mulching is a cost-effective method to reduce landscape maintenance costs and keep plants healthy. Mulching helps to conserve moisture because as much as 10-25% of the soil moisture can be lost through evaporation. Mulches help with soil aeration by reducing the soil compaction that occurs when raindrops hit the soil. They also reduce water runoff and soil erosion. Mulches help maintain a more uniform soil temperature (warmer in the winter and cooler in the summer) and promote the growth of soil microorganisms and earth worms when using organic mulches.

  • When and where should I start looking for morel mushrooms?

    Morel mushrooms appear in spring and it varies from year to year. Generally black morels appear first followed by gray and yellow morels.

    There are many theories on where to find morels. But one thing is pretty clear and that is morels associate with trees. Morels can be found under just about any tree given the right conditions. However, some trees are more likely to have morels growing around them than others including dead or dying American elm, white ash, and old apple trees. Remember not to trespass on private land when you are out mushroom hunting this spring. Polk County Conservation Board offers an informational program on Morels in April or May at the Jester Park Lodge. Check our Calendar for date and time.

  • I was camping last weekend at Jester Park and took a hike through the woods. A couple of days later, an itchy rash and blisters showed up on my leg. I’ve hiked in the woods numerous times and have never gotten a rash before. Is this caused by poison ivy or poison oak?

    Poison oak does not grow in Iowa, so undoubtedly you were exposed to poison ivy. Poison ivy and poison oak both produce a poisonous, oily irritant called urushiol (oo-roo-she-all) on the plant’s stem, roots, branches and leaves. Sometimes it takes numerous exposures to the oil before you finally react and become allergic to it. This oil can also remain on clothing, tools, and animal fur for up to a year or longer unless you clean them. You can still get a rash from this oil! Once exposed to the oil, it usually takes 1-3 days before a rash will appear. If the blisters break and ooze, the fluid does not contain the oil that causes the rash in the first place. There are several products on the market to help prevent and relieve symptoms of poison ivy. I’ve had good success with a product called, Tecnu, which helps remove the oil from your skin after being exposed to poison ivy. For more information about poison ivy, visit poisonivy.aesir.com.

  • I took a hike through Thomas Mitchell Park the other day and noticed lots of wildflowers blooming in the woods. Is it illegal to pick them?

    Yes, it is illegal to pick wildflowers in state and county parks. By picking wildflowers you are destroying a natural resource in the park. Plus flowers are the reproductive parts of the plant and by removing them they can no longer propagate seeds. You can collect fruits, nuts, berries, and mushrooms as long as you don’t destroy the parent plant and you don’t plan on selling them. Anything else, including wildflowers, is off limits.

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Administration Office
12130 NW 128th St
Granger, IA 50109

P: (515) 323-5300
F: (515) 323-5354

Monday – Friday, 8:00 a.m. – 4:30 p.m.

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