Care and How-To Articles - Problems and Pests

Splitting on tree caused by normal growth and development

Shedding, peeling, or splitting bark on trees in the landscape can be a concerning sight. 

Understanding what is causing the bark loss is an important first step to preventing further damage in the future.

When light is insufficient leaves of succulents like Echeveria will often lay flat and develop a pale color

Succulents have relatively few pest and disease issues.  Scout plants frequently to catch problems early and treat them before they become severe.

Over Watering  |  Under Watering  |  Root Rot  |  Insufficient Light  |  Sun Damage  |  Mealybugs  |  Dead Lower Leaves  |  More Information

The true fruit on a potato

Gardeners are occasionally surprised to find small, round, green, tomato-like fruit on their potato plants. These fruit are not the result of cross-pollination with tomatoes. They are the true fruit of the potato plant. The edible tubers are enlarged, underground stems. 

The true fruit on a potato
Potato fruits are a novelty and of no value to the home gardener.

Summer is often the time of year Phytophthora root rot starts showing up in rhododendron and azalea plantings. The fungus is favored under extremely wet conditions and in heavy, poorly drained soils. The wet spring may have aggravated the condition more this year.

Phytophthora root rot of rhododendrons is caused by several species of Phytophthora. The pathogens, primarily P. connamoni, P. citriocola and P. cactorum, are soilborne and invade roots under wet conditions. Most cultivars of rhododendrons are highly susceptible to attack by Phytophthora.

Buttonbush with bee

Many trees and shrubs thrive in Iowa's fertile, well-drained soils. Most trees and shrubs, however, don't like wet soils. Fortunately, some plants tolerate wet soils better than others.

When selecting trees and shrubs for the home landscape, gardeners should select plants suitable for the site. Wet sites can be a challenge. However, the trees and shrubs listed below will perform well in wet soils.

Hay Scented Fern (Dennstaedtia punctilobula)

When selecting perennials, choosing plants that are suitable for the site is important. Garden sites can vary tremendously. Some areas are hot and dry. Others are wet. Wet sites can be challenging, but they also provide gardening opportunities. The following perennials perform well in moist to wet soils.

Fernleaf yarrow (Achillea filipendulina)

In addition to providing color in the garden, perennials can be used as solutions to problem spots in the home landscape. Many landscapes have hot, dry sites that are difficult for many perennials. Drought-tolerant perennials are the perfect solution for these dry sites. Below is a list of some perennials that, once established in the garden, will tolerate or even thrive in dry conditions.

Fernleaf Yarrow

Fernleaf yarrow (Achillea filipendulina)
Fernleaf yarrow (Achillea filipendulina)

Marigold (Tagetes)

Most annual flowers require consistent moisture throughout the growing season for adequate growth and bloom. However, there are a few annuals that perform well in dry weather. When other annuals suffer from a lack of moisture, these annuals will flower profusely without a significant rise in the water bill.

All of these drought-tolerant annuals will require water initially to establish a good root system. Once established, however, they require little watering. All perform best in full sun with well-drained soils.

Don't let dry weather stop you from having flowers in your garden. These annuals will tolerate the heat and drought better than we will.


When selecting annuals, perennials, shrubs, and trees, choose plants that are adapted to the growing conditions at the planting site. Most landscape plants prefer moist, well-drained soils in full sun. However, there are plants that will tolerate more difficult sites.

Lists of annuals, perennials, shrubs, and trees that tolerate dry soils, wet soils, and partial shade are provided below.

Perennials for Wet Soil Conditions

Many plants grown in the home landscape require consistent moisture throughout the growing season without staying too wet. However, there are a few annuals, perennials, shrubs, and trees that perform well in wet soil conditions.  This includes low-lying areas, water edges, or soils with poor drainage. Many of these plants will also tolerate periodic flooding.  

Perennials for Dry Conditions

Many plants grown in the home landscape require consistent moisture throughout the growing season.   However, there are a few annuals, perennials, shrubs, and trees that perform well in dry weather or dry soil conditions. All of these drought-tolerant plants will require water initially to establish a good root system. Once established, however, they require little watering and will make it through the driest of years with little damage.

Vine crops (cucumber, muskmelon, watermelon, and squash) are some of the most popular vegetables in the home garden.  While vine crops are easy to grow, home gardeners are occasionally disappointed in crop yields.  Poor fruiting of vine crops may be due to the plant's flowering habit, poor pollination, or blossom-end rot. 

birds nest fungus

Wood chips and shredded bark are commonly applied to landscape areas to control weeds and conserve soil moisture.  Wood chips and shredded bark are organic matter.  The decaying organic matter provides an ideal environment for some strange-looking fungi or fungal-like organisms when weather conditions are favorable.  Fungi that occasionally grow in landscape mulches in Iowa include stinkhorns, slime molds, and bird’s nest fungi. 

Japanese Beetle on Rose

Roses have a number of potential problems that can make them more difficult to grow.  Planting them in a good garden location and selecting a winter-hardy and naturally disease-resistant cultivar is the best way to avoid many problems.

Japanese Beetle on Rose
Japanese beetles are common insect pests on roses.

Learn more about the potential disease, insect, and animal pests, as well as the environmental conditions that can negatively affect roses and how to manage them below.

crown dieback

Several factors cause branch dieback on trees. Correctly diagnosing the problem(s) is the first step in managing an unhealthy tree. Below are some common causes of branch dieback on trees in the landscape.  Use this guide to evaluate your tree and determine the likely cause of the branch dieback.

Established tree with girdling roots

Stem girdling roots happen when a tree’s own roots either completely encircle the trunk or grow tangential to the trunk on one or more sides, causing stem compression and damaging important vascular connections (xylem and phloem). Learn more about how to address this all too common issue with trees in the landscape.

Honey bee swarm. Photo by Jessica Edler.

Honey Bee Swarms are Common But Not Dangerous

Swarming is a natural process in the life of a honey bee colony.   Swarming occurs when a large group of honey bees leaves an established colony and flies off to establish a new colony, essentially creating two from one.  Swarming is a natural method of propagation that occurs in response to crowding within the colony. Swarming usually occurs in late spring and early summer and begins in the warmer hours of the day.

Double Balloon flower (Platycodon grandiflorus)

With the arrival of spring, herbaceous perennials have popped up throughout the landscape!  However, as you tour the garden in early spring you may notice that certain perennials are noticeably absent.  Don’t worry.  Several perennials are tardy every year. These perennials require several weeks of warm soils and air temperatures before they begin to grow in spring.  Sometimes they do not emerge from the soil until June! 

Overall, lilacs are easy to care for and problem-free shrubs.  Occasionally, problems arise like failure to bloom, flowers opening out of season, powdery mildew, and other disease or insect issues.  

More information about common lilac problems and how to manage them is presented below.

Raised beds By daryakomarova

Crop rotation is an important and beneficial factor when planning a vegetable garden. Problems with diseases, insect pests, and soil fertility can increase when the same crop is planted in the same area in successive years. With careful planning and consideration, crop rotation can reduce issues with diseases and pests and balance the soil's nutrients. Learn how to best rotate your vegetable crops at home.

concolor fir

The Colorado spruce does not do well in the less-than-ideal growing conditions of Iowa's hot, humid summers.  Here are alternatives to consider.

Peony with powdery mildew

Peonies are easy-to-grow, long-lived, and reliable performers in the garden.  But they occasionally have issues.  The most common issues with peonies, such as failure to bloom, powdery mildew, and flopping over, are listed below.

Picture of a cell phone taking a picture of a plant

Your smartphones can be wonderful tools, and several apps on our phones can help with plant identification. These apps are best utilized to aid in identification rather than as a tool to definitively identify the plant. Learn more about how to best utilize these convenient tools for plant identification. 

tulips with deer damage

While easy to grow, tulips do occasionally develop problems.  Early emerging foliage, browsing from deer and rabbits, and bulb rot are a few common ones.  Below are potential problems encountered when growing tulips in the landscape and how to manage them.

Ant Mound on Sidewalk

There are many species of ants that occur in lawns or along and under sidewalks. Most ants are beneficial and do not require control. However, ants may become a nuisance by constructing mounds or small hills in the lawn, landscape, prairie planting, pasture, CRP field, roadside, or on the sidewalk or patio, or by invading the home in search of food.

When Kentucky bluegrass and other cool-season grasses begin to green-up in spring, some home gardeners are dismayed to see brown spots in the lawn. In some cases, the brown spots are dead patch.

Trees are valuable additions to the home landscape.  When problems arise with the health of a tree, it can be difficult to determine what is causing the issue.

Used plant containers

Reusing plastic, clay, and other containers is a great way to save money and reduce the amount of plastic waste that goes into landfill.  Plastic containers cannot be recycled in traditional single-stream home recycling programs and, unfortunately, programs to collect and recycle plastic pots are not common.

Proper cleaning and disinfecting of pots requires just a minimum amount of effort, yet can mean the difference between the success or failure of containerized plants, plus it allows you to reuse containers and reduce plastic waste. Follow the steps below to clean and disinfect used containers.

Blueberries Photo by Andris Tkachenko AdobeStock

Iowa soils are very diverse and so are the chemical characteristics that make up these soils.  Soil pH is one property that can vary widely across the state both naturally and due to how we manage the field or garden.  It is also one of the most cost effective and easy to manage soil properties that can be modified to improve plant health and crop production.

Learn about how to decrease and increase your soil pH below.

healthy oak leaves

Oak trees are valuable assets in the home landscape.  Occasionally oak trees need to be pruned for health, safety, and appearance reasons.  Pruning oaks makes them more valuable to infection from the fungus that causes oak wilt. By pruning oaks properly, you can reduce that risk and keep trees healthy.

poison ivy

Poison ivy (Toxicodendron radicans) is a native vine common to woodland areas but found frequently growing in gardens and along fence lines.  This vine causes an allergic reaction (dermatitis) in most people when their skin comes in contact with urushiol produced by the plant and present in all parts of the plant including leaves, stems, and roots on both living and dead plant material. 

Control of this weedy vine requires special consideration.  When working around this plant, gardeners should wear long sleeves and pants with waterproof gloves to protect the skin from the urushiol oil. 

Perennial grassy weeds die back to ground level in the fall but send up new growth from the same root system in the spring.  These weed species have long thin leaves with parallel veins.  They are often in the Poaceae (grass) family or a closely related family and are botanically classified as monocots.  Perennial weeds reproduce by seeds or may spread by creeping above or below ground stems or by spreading root systems. Examples of perennial grassy weeds include quackgrass, nimblewill, orchard grass, and in certain cases bermudagrass and zoysiagrass.

Keeping ahead of weeds and controlling them when they are small is essential for good weed management. This requires persistence throughout the entire growing season to remove weeds as they emerge. 


Perennial broadleaf weeds die back to ground level in fall but send up new growth in spring.  These weed species have leaves that are wider and often have a major vein running down the center of the leaf with secondary veins branching off of it.  They are typically botanically classified as eudicots (dicots).  Perennial weeds reproduce by seeds or may spread by creeping above or below ground stems or by spreading root systems. Examples of perennial broadleaf weeds include dandelion, thistle, pokeweed, plantain, violet, and creeping Charlie.


Annual weeds grow rapidly, flower, set seed and die in a single season. New annual weeds, such as crabgrass, velvetleaf, purslane, knotweed, lambsquarter and foxtail, germinate from seeds each year. Before they die, most annual weeds produce large quantities of seeds. If annual weeds are controlled every year before producing seeds, they will eventually become less of a problem as the seed population gradually decreases. 

Annual weeds like crabgrass (Digitaria sanguinalis​​​​​) grow from seed each year.

Flame weeding is the use of intense heat, usually produced by a propane torch or other fuel-burning device, to kill weeds.  This organic option for weeding causes the water and sap inside the plant cell to boil and expand rupturing the cell walls and causing the plant to wilt and die.  

Flame Weeding is Not Setting Plants on Fire!

The goal is not to ignite the weeds on fire.  Instead, plants are subjected to a brief, intense heat that causes the cell walls to burst.  Immediately after exposure plants will turn a dull green and wilt slightly.  Over the next several hours to days weeds will wilt completely and die.  

Managing weeds in the vegetable garden is important for growing healthy and productive plants.  There are several methods that can be used to manage weeds and in most cases using several methods together will produce the best results.  All of these methods can be considered "organic" except those that utilize herbicides.  

A variety of indoor plants

Due to improved construction methods, buildings are better sealed to maximize energy efficiency. Yet, these "sealed" buildings often trap gases from synthetic materials that can pollute the indoor air. These air pollutants can cause problems for inhabitants especially during the winter when people are forced to spend a great deal of time indoors.

ice covered twig

Heavy amounts of snow and ice on the branches of trees and shrubs can cause considerable damage. Improper removal of ice and snow can increase the amount of damage to trees and shrubs. Learn about how to manage ice and heavy snow on trees and shrubs.

Salt and Sand Deicing Material on Patio

Snow and ice are headaches for motorists and pedestrians. To prevent accidents on slippery surfaces, deicing compounds are used by highway departments, businesses, and homeowners to melt ice and snow on roadways, parking lots, sidewalks, and driveways. While deicing materials improve travel conditions, they can damage automobiles, concrete surfaces, and landscape plants. 

Learn about the important considerations that must be taken for using deicing materials in your landscape.

Rabbit feeding injury to crabapple tree

Deer, rabbits, mice, voles, and other animals can cause a lot of damage on trees and shrubs over the winter months.  Prevention is key to managing these garden pests.  By taking steps in the fall, you can prevent damage from occurring over the winter.

Common Morel, Morchella americana

Identifying mushrooms can be challenging when compared to identifying trees, birds, or butterflies. Challenges of identification stem from the lack of information collected in the field or lack of distinguishing features on the mushrooms collected. Fungi guides often rely on details that may be easily overlooked in the field or require microscope observations.  But don’t let these challenges stop you from trying to identify that mushroom.

Raccoon Damage to Lawn

In late summer and fall, skunks and raccoons can cause damage to lawns as they search for earthworms, soil-dwelling insects, and insect larvae, such as white grubs.  They dig up the lawn leaving behind large patches of loose turf, eat the grubs, worms, or other insects and leave behind a torn-up mess.  The damage can be extensive and often happens overnight as both skunks and raccoons are active and feed at night. 

Hail damage on young apple fruit. Picture credit: Jose Gonzales-Acuna

While there are many environmental factors that can damage apple trees as well as the apple fruit, hail damage is one that can be very frustrating. Below are answers to questions that come up quite frequently regarding hail damage on apples.

Boxwood (Buxus sempervirens) is a dark green evergreen native to southern Europe and northern Africa. It usually grows to a height of three to four feet in Iowa's climate and is popular for borders and hedges because of its dense, dark green foliage. Boxwood requires fertile, well-drained soils and prefers wind protection if grown on an exposed site.

Winter can be tough on boxwoods in Iowa. Over the winter, boxwood may see extensive damage or even die. Sometimes, entire hedges will succumb. Exceptionally low temperatures are to blame in most cases. Boxwoods are marginally hardy in Iowa and can suffer from foliar burn and twig kill in severe winters in exposed locations. Leaves turn brown and twigs die back. 

Newly planted trees can eventually add great color and valuable cover to any landscape. But winter’s harsh conditions can hamper, delay or completely derail their development. There are several things you can do to help these new additions to the landscape survive and thrive in colder temperatures.

Water Newly Planted Trees Until the Ground Freezes

The roots of trees continue to grow until the ground freezes in winter. If the weather is dry, continue to water newly planted trees until the soil freezes. Small trees usually require watering for one or two growing seasons. It may be necessary to periodically water large trees for three or four years.

A newly planted maple tree showing signs of drought stress

When a summer heat wave arrives, it can be stressful for the plants and gardeners alike.  The plants of your landscape will require a little more TLC to make it through periods of extreme heat.  Below are a few tips to protect your lawn, garden, and landscape when temperatures soar.

red apples on the apple tree

Growing high-quality apples in the home garden is possible but requires significant inputs. Apples have several serious disease and insect pests that can significantly lower the quantity and quality of the apple harvest in the fall. Managing these disease and insect pests is important, and many of the most effective management steps occur in spring, well before the apples form and ripen.

Hosta with Deer Damage

Damage caused by deer browsing on garden plants can be a problem in rural and suburban areas in Iowa. The amount of damage depends upon seasonal factors, weather conditions, availability of alternative foods, and plant palatability. Prevention of deer browsing is difficult.  

Browse these lists of plants that are less likely to browsed by deer.

Rabbits can cause extensive damage to flowers and vegetables in the home garden. Fortunately, some plants are usually ignored by browsing rabbits. No plant is guaranteed to not be browsed on by rabbits, but they tend to avoid plants with strong aromas or dense hairy leaves.  The feeding habits of rabbits may vary due to fluctuations in the rabbit population, availability of alternate foods, and other factors.

The most effective way to prevent damage from rabbit browsing is to exclude them from the garden.  More information about rabbit management can be found at this website: Rabbits: Damage Management

Winter is a challenging time for trees and shrubs.  Animals, wet snow, drying winds, sunscald, and deicing salts can damage trees and shrubs in the home landscape.  Fortunately, steps can be taken to minimize damage to trees and shrubs in winter.