Summer Stress to Plants

This year has been a little out of the ordinary, regarding weather. It was quite chilly for what seemed like a long time this spring. Then, when it did warm up a little, we kept having very cold overnight lows, some quite damaging to the plants that were growing. As I assumed, the summer would come on with a vengeance, which it did. Suddenly, it got very hot, windy, humid, and dry. This can be damaging to our plants for multiple reasons.

Watering

We need to make sure that we are watering all our plants in this heat. Even trees need a drink sometimes. The best way to water a tree is to let a hose trickle at the base of the tree or use a small sprinkler for up to an hour, depending on the size of the tree. Younger trees would only need to be watered for about 20-30 minutes. This should be done once a week with younger trees if we are not seeing natural precipitation.

Grasses may also be dealing with some heat stress. Visual cues can be used to determine water stress on lawns. On drought stressed lawns, you will notice that the wilted grass will turn blue-gray or grayish-green in color. You may also see that your footprints will remain visible in the lawn after walking on it. Turf with these signs should be watered that evening or the next morning. The best time to water a lawn is early in the morning, between 4am-10am. Even with automatic irrigation systems, the best way to water a lawn is to just turn it on when irrigation is necessary, not to set it and forget it. If running a pre-set irrigation system, 1-1.5 inches of water per week is adequate for home lawns. This can be applied over 3 applications per week at about ½ inch per watering.

We also need to remember to keep watering our gardens as well. Gardens should also receive about one to one and a half inches of water per week. If possible, irrigation should be provided through soaker hoses or drip irrigation, to avoid wetting foliage, sprinklers can be used as well. If you water with sprinklers, it can cause diseases problems due to wet leaves, especially in the cooler temperatures of night, so just be sure to water earlier in the day to allow dry time.

Herbicide use

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Herbicide injury on Tomato

Herbicide injury to many plants has started showing up. Herbicide drift can be done via the wind as well as through volatilization, which is when herbicides turn into a gas that moves to non-target plants. Volatilization occurs in warm, humid environments, or typically when temperatures are over 85 degrees and is common with 2,4-D and Dicamba products. Discontinue use of these products during the summer.

The signs of herbicide damage on plants include curling, cupping, and vein distortion of leaves. Certain plants are more susceptible to drift including tomatoes, redbuds, grapes, and oaks. If you do get herbicide damage to your tree or shrub, you cannot fix the damage that is already done, but most trees and shrubs will grow out of it. It is not advised to eat fruits or vegetables from plants that were hit by herbicide drift, due to the variables regarding the herbicide, there is no way to know when or if they will be safe for consumption.

Heat stress

Wilting is occurring lately on many of our plants as well. It was difficult on our plants to move quickly from a cool spring to very hot, windy conditions this summer. When you notice wilting on your plants, water them as stated previously. When plants are wilting due to heat or drought stress, they will often look much better or completely recovered in the mornings and be wilted later in the day.

Arbor Day, Plant for Diversity

As an arborist, trees are my favorite plants. And there is a holiday to celebrate my beloved trees, Arbor Day. Arbor Day is celebrated on the last Friday of April every year in Nebraska. This year that falls on April 24th. This holiday is not the same throughout the United States, it is moved around for other states to be in the best planting time for the year for each state that celebrates it.

Diversity

Deciding what tree to plant is very important and sometimes difficult. Diversity is key when choosing your tree. The general rule is to plant no more than 10% of a tree species, no more than 20% of a tree genus, and no more than 30% of a tree family in a respective urban area.

Diversity has not always been used as widely as today, and we have learned from that. In the early 1900’s American Chestnut trees were wiped out by Chestnut blight. We replaced many of those trees with American Elm trees which were then destroyed by Dutch Elm disease in the 1960’s. Those were then replaced with Ash trees which are now being demolished by Emerald Ash Borer. Also, in the early 2000’s we lost a majority of our windbreaks to Pine Wilt disease.

Diversity of our tree species helps reduce the problems from widespread disease and insect outbreaks. Look around at what types of trees you have and what types of trees your neighbors have before deciding on a new tree, try to avoid over-planting the same few trees throughout the neighborhood. Plus, diversity of trees is more aesthetically pleasing because of the different leaf and bark textures, different bloom times, and overall differences in trees.

Using understory trees

There are many trees that make a great understory trees and can be planted in the shade and protection of larger trees. Those trees would include things like redbud, pawpaw, and some of our dogwoods including flowering or Kousa dogwood. These trees prefer to have part shade so under a larger tree is a great spot for them. This can help mimic nature and help the overall growth of both the understory tree and larger tree.

Care of Trees

Keep newly planted trees well-watered. Always water newly planted trees, shrubs, or any other plant immediately after planting. Trees should be watered every 10-14 days throughout the growing season and even some during the winter on warmer days. Each watering should give the tree 1-2 inches of water. The best way to determine if a tree needs to be watered is to insert a soil probe or 12-inch-long screwdriver into the ground around the tree. If it goes in easily there is no need to water, if it is difficult at any point then water is necessary for the tree.

A mulch ring should be established and maintained around every tree. Mulch helps to keep the roots cool in the summer and regulated to a uniform temperature through the winter. Mulch will also help keep weeds down and reduce competition of water and nutrients from turf and other plants. Mulch also reduces damage to the trunk of trees from lawn mowers and trimmers. Finally, organic mulch is a way to hold moisture for use later by the tree. Mulch rings should be only 2-3 inches deep and in a circle around the tree at least 2-3 feet out. Organic mulches are a better choice than inorganic mulches. This mulch will need to be renewed every year to maintain an effective layer because it will break down over the growing season which will improve the soil.

Do’s and Don’t of Late Winter Pruning

February and March have inconsistent weather patterns. It can make it hard to stay indoors on days in the late winter when the temperatures reach near or above the mid-50s. When we can go outside we feel we can do yard work, but don’t get too excited in your landscape too early in the year.

Pruning Trees

We have always pruned deciduous trees in the late winter, however new research shows the optimum time to prune is really in the late spring to early summer. We now recommend tree pruning in May to June. The reason for this change is that through research they have determined that this is the time when tree cells are most active during the season and it promotes the quickest sealing of the pruning wounds.

When we prune in the winter months, the pruning wound will sit open and exposed to disease and insect infestation until the wound can be sealed up. If you do the pruning during the most active time for the plant, the wound will seal up very quickly, greatly reducing the damage to the tree overall.

However, we may not always have a choice on the pruning time. If you are hiring an arborist to do the work, they may only be able to fit it into their schedule earlier in the season. Also, if you have damage from a storm, you would want to do corrective pruning as soon as possible. Also, remember that oaks are best pruned during the winter months to avoid potential infection from oak wilt. Oaks should be pruned in December, January, or February.

Pruning Shrubs

You also want to be careful pruning shrubs in the late winter. If it is a spring blooming shrub, the blooms are already present on the shrub for this spring. Pruning now could reduce the bloom or eliminate it all together, depending on how you prune. For a rule of thumb, if it is a spring blooming shrub, prune it within a few weeks after it blooms in the spring. If the shrub blooms in the summer, prune it in the late winter. So you can prune summer blooming shrubs this time of year. Examples of shrubs to prune in late February or March include spirea, potentilla, and smokebush. Examples of shrubs to wait to prune until after they have bloomed this spring include lilac, forsythia, weigela, mock orange, and viburnums.

Pruning Fruit Trees

Late February through March is a great time to prune fruit trees. Fruit trees need to be pruned to maintain good structure and air flow to allow for best production. They are best pruned during the dormant season, in late February through March. Peaches and apricots should be the last trees pruned in late spring, just before growth begins, to avoid winter injury. Peaches and apricots are less winter hardy and therefore more susceptible to damage from early pruning. Apples, plums, cherries, and pears can be pruned a little sooner than peaches and apricots, but still none should be done before January to avoid damage from winter injury.

Fruit trees are often neglected leading to overgrowth. It is important to remember that no tree or shrub should have more than 1/3 of the plant removed in one growing season. If it is a neglected fruit tree, it may take a few years to get the structure back to the desired shape.

The information for this article came from the HortUpdate from Nebraska Extension. Sign up online for this monthly newsletter for green industry professionals at hortupdate.unl.edu

Fallen Leaves

The fall is a great time of the year. The trees turn such beautiful fall colors and then those leaves fall to the ground. Tree leaves are fun to play in as a kid, everyone loves the crunch sound under your feet as you walk over fallen leaves. However, leaves shouldn’t be just left on top of our grass like when they fall from the tree. This can be damaging to our lawns and to surface water. So, it is best to utilize them or remove them.

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Why Rake

Leaves should be removed from the turf in the fall. If left on the turf over the winter months they can smother the grass. They can also cause snow mold to develop over the winter. Raking the leaves will allow the turf to dry out on warm days with no snow cover to reduce the chance of getting snow mold.

Leaves can be a pollutant to surface water if left on the ground. Leaves left on the ground can be washed away into storm drains and other surface water locations. Fallen leaves release phosphorus and nitrogen when they decompose. If that decomposition occurs in the water, an overload of nutrients can contribute to impaired water ecology, such as excess algal growth (From Kelly Feehan, Extension Educator in Platte County Extension).

Other alternatives to raking leaves

Raking leaves can be quite a bit of work. As I drive around town, I notice some landscapes that contain quite a few trees, which as an Arborist, I love. However, in those landscapes it would take a long time to rake all of those leaves. And it really doesn’t matter when you rake up your leaves, it seems as soon as you are finished more leaves have found their way to your lawn. An easier way to do this would be to mow the leaves.

According to the UNL Turfgrass Department, mulch mowing can be easier than raking and it returns complex organic matter and nutrients to the soil. Some research also shows that mulch mowing can help control weeds. The weed control is sporadic, but it can be possible. So, this is a very beneficial alternative to raking the leaves. Mowing over the area at a higher deck height two or three times can help break down the leaves and incorporate them back into the turf for added nutrition for the lawn. Just as grass clippings don’t add to a thatch layer in the lawn, mowing over leaves and leaving them on the lawn will not add to any thatch layer in your turf.

Another use for the fallen leaves in your landscape would be to utilize them as a mulch in your gardens. You can bag them up and use them next spring or add them to your compost pile for the addition of carbon that is needed in any compost pile. Or you can rake them up and around your plants and trees for added winter protection. Be careful when you choose which leaves to use as mulch or additions to your compost pile. Leaves that were diseased this year, or had one of the many leaf spot diseases we saw this year, should not be used as mulch or in the compost pile. The compost pile will not get hot enough to kill the pathogens on those leaves and if left as a mulch around the tree, this could just reintroduce the disease to the tree next spring again. For those diseased leaves, it is best to just rake them and destroy them.

Putting the Garden to Bed

Now that fall has arrived and we have hit some very cold temperatures at night, it is time to clean up our gardens for the winter. Some things should be done this fall, but some can be left until spring. Here are a few things to do now to put your gardens to bed. 

Fall Pruning

Annual flowers can be cleaned up in fall because they die with a freeze. Perennials are best left standing until spring but some can be cleaned up now. It is nice to leave the plants over the winter for added interest and to provide food to birds. Plants such as roses and butterfly bushes that have hollow stems should be left standing and not pruned back until next spring. Precipitation can get into the hollow stems and freeze and thaw through the winter, which could crack the plant crown and lead to death. Leaving plants standing through winter will protect plants with hollow stems or with moderate hardiness to our zone. If you do chose to leave your perennial plants over the winter, be sure to wait until we are past our last spring frost before removing the plant material next spring, even if the plants green up underneath. The plant material does act as insulation and if removed too soon the plant will be more exposed to late winterkill. If removing plant material this fall, wait until it turns brown and replenish mulch to protect it over the winter. Mulch can be added up to 4-6 inches over the winter months, reduce back to 2-3 inches deep during the growing season.

People often think about pruning trees in fall. However, this isn’t the best time of the year to prune them. The optimum time for tree pruning is April, May, or June because at this time the tree can seal up the wound quickly while it is actively growing. If your tree needs to be pruned this fall, wait until the leaves have fallen from the tree to allow the tree to go completely dormant before pruning. If you are pruning an oak tree, the dormant period is the best time for pruning to avoid damage from oak wilt. Pruning evergreen shrubs is best done after they are fully dormant to avoid damage from winter injury. As for flowering shrubs, if it blooms in the spring, prune it after it blooms. If the shrub blooms in the summer, bloom in the late winter such as in February and March. 

Garden Cleanup

Now that our vegetable plants have died due to cold weather, it is time to clean up the garden. If any of your plants had disease or insect issues this summer, it is best to remove those plants and destroy them, don’t compost them. This will reduce the chance of seeing the problem again next year. Also, removing the plants from the garden at the end of the season will remove the overwintering site for insects found in the garden. Cleaning tomato cages and fences upon removal will also help remove the disease spores from the garden for next year.

After removing the plants, you may want to till your garden. If you plan to add fresh manure to your garden, that should be added in the fall rather than in the spring. So you can till your garden, add manure, and till it again to incorporate the manure into your garden soil for reduced compaction and improved organic matter content. If you till in the fall, add a layer of mulch to the garden to keep the soil from blowing off site during the winter. Grass clippings from a lawn that wasn’t treated with herbicides this year make a great mulch for the winter. You can till that back into the soil next spring before planting again.

Apples

Fall is a great time of the year. It can be bittersweet, though, because it often signals the end of our growing season. The good thing is that this is also the time of the year to go pick apples.

Harvest

Each different variety of apple differs for their harvest time. To determine the harvest time for the apple, knowing the variety will help you. In fall, a common question from gardeners with a favorite apple or pear tree is for identification of the cultivar from the color and shape of the fruit. This almost impossible to do, in fact, it’s really only realistic to give a general idea of possible cultivars. So, if you don’t know the variety, you can look at the color, flavor, and texture of the apple.

To know a mature apple, look at the “ground color”, which is the color of an apple’s skin disregarding any areas of red. For red-fruited cultivars, observe the portion of the apple that faces the interior of the tree. When the ground color turns from leaf green to yellowish green or creamy yellow, the apples are ready to harvest. In yellow cultivars the ground color will become a golden color when they are ready to harvest. You can also taste one to ensure that it is the correct sweetness and make sure it is firm and not overripe and soft. Overripe apples will detach from the tree more easily than those that are at the correct stage of ripeness. If the apple is too ripe, it will break down in storage more quickly than those that are at the peak of their maturity.

Storage

For storage it is best to pick apples when they are still hard but mature. Place the apples in a box or crate with a smooth lining so that staples don’t puncture or injure the apple. They can be stored in boxes or crates lined with plastic or foil to retain humidity around the apples. They should be stored in the fridge or other location where they are kept at temperatures around 32 degrees Fahrenheit, an apple stored too warm will ripen faster.

Remove bruised and large apples that will break down more quickly than the rest of the apples. Apples produce ethylene gas, even after they are removed from the tree, which speeds up the ripening process in fruits, including apples that are stored together. A damaged apple will produce more ethylene than other apples. Damaged and large apples should be eaten or processed first and not stored like the other apples.

Tree Selection

Fall is also a great time to plant a tree. If you are reading this article thinking you should plant an apple tree so you can start to have your own apples to harvest, there are some great choices. One thing to remember when choosing an apple tree for your landscape is to get a variety that is resistant to cedar-apple rust and apple scab. These 2 diseases are very problematic for apple trees in Nebraska and require spraying multiple times throughout the growing season to combat. There are also some varieties that are resistant to fire blight which can also be very damaging to your apple crop and would be a good trait to look for in your future apple trees.

Some good apple tree choices include Liberty, Enterprise, and Freedom which all have good disease resistance for the most common diseases. Enterprise is self-unfruitful and therefore does require a pollinator tree be planted nearby when planting Enterprise. Honeycrisp is a delicious apple that many people want to plant. However, it is susceptible to cedar-apple rust and powdery mildew so you would need to spray for those diseases. It is moderately resistant to apple scab and resistant to fire blight. Honeycrisp is also only moderately strong for tree growth, so it could break more in storms.

*The information on Harvest and Storage came from Sarah Browning, Nebraska Extension Educator in Lancaster County.

Weather & Plants

 

The environment impacts our plants in many ways. We are always happy to see the shift in weather to help the heating and air conditioning costs of our homes. Plants are also very happy when the weather changes to a more comfortable temperature. Extremes for moisture and temperature can be very damaging to our plants on both ends of the spectrum. This year we have seen a wide range of these problems which are negatively impacting our plants. To say we have a “normal” growing environment or weather pattern in Nebraska is almost unheard of and this year was unlike any we have seen recently.

Floods

2015-06-04 18.32.28Typically we are excited to see rain throughout the season. However, when the rain doesn’t seem to end, like this spring and even again now, this can harm our plants. There is such a thing as overwatering plants. Plant roots need to breathe too, if they don’t have the oxygen they need they can start to develop root or crown rot that can kill the plant.

Besides problems with root growth and development, many fungal diseases have been popping up on our trees this summer. There are many leaf spots on our trees such as maples, oaks, pears, and crabapples as well as on our vegetable crops such as tomatoes, cucumbers, and others. The cool, rainy environment this spring led to the infection which is showing up now. Spraying so late in the season won’t really help. The best thing for these plants is to just keep them healthy through the season and then use sanitation in the fall to reduce the diseases next year. Destroy fallen leaves at the end of the season by raking them up and throwing them into the garbage and remove annual plants from the garden. Don’t compost infected plant parts because the spores may not be killed in a compost pile. Leaves left at the base of the plant or vegetable plants left in the garden will make a good location for the disease spores to overwinter and move back into the plant next spring.

Heat

Hot temperatures can be problematic for our plants, especially when that heat comes on fast after such a long, cool spring and winter. We have had problems with leaf scorch showing up on plants when we had that swing of temperatures into the 100’s with high humidity. This extreme heat is damaging to our plants, but especially this year when they were accustomed to cooler temperatures with more than enough water available to them. Scorch is still apparent on trees even though temperatures have cooled back off. For the survival and health of our plants through extreme heat, keep a 2-3 inch layer of mulch around the plants and keep them well watered when rains end in the summer.

Excessive cold

Excessive cold temperatures that we saw this winter can also harm our plants. The good thing for Southeast Nebraska was that we had snow cover most of the winter this year. If we had seen that much wind and cold temperatures without snow insulating the roots and crowns of our plants, we would have seen a lot more dieback.

Some of our plants did still have problems from the cold and some had problems from the high salt buildup around our plants from all the snow. Evergreen plants still transpire through the winter months. Desiccation happens when the moisture released from plants through transpiration exceeds moisture taken in through the roots. White pines see desiccation quite often in the winter months on the north side from the strong winter winds we see in Nebraska. This desiccation becomes even worse on plants that are in an area where snow with deicing salts are piled up each time we scoop snow.

There isn’t much to be done to fix trees now that desiccation has set in. For this coming winter, it would help to water the trees once a month on a warm day in the winter. You can also apply anti-desiccant products once every six weeks beginning after plants have completely hardened off, usually in late November. Continue applications through mid to late February. Avoid covering plants so heavily they become sticky with needles glued together. Have warm, soapy water nearby and clean out the sprayer immediately or equipment may be ruined by the product.

Moisture Problems for Trees and Other Landscape Plants

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The excess rain this year is a change from many years where we are already worried about drought stress on our landscapes. However, excess moisture is causing problems in our landscapes this year from fungal diseases as well as nutrient deficiencies.

Chlorosis

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Photo of Chlorosis by Amy Cogswell

Chlorosis is a condition that occurs to many tree species with symptoms of the leaves or needles developing an abnormally light green or yellow color. Chlorosis is typically caused by a deficiency of iron in the plant tissues. With iron chlorosis, the leaves will be lime green in color while the veins of the leaves remain darker green. Chlorosis can also be caused by over-watering, over-fertilization, and damage to roots among other things. This year, with the high levels of moisture we have seen this spring and summer have led to a lot of chlorosis in trees like birches, maples and oaks.

Chlorosis happens commonly in southeast Nebraska soils because of our high pH levels. The pH in an alkaline or clay soil is higher and that high pH will tie up the iron making it unavailable to trees. Iron is sufficient in the soil but it is not available to the tree. In overwatered or compacted soils, the roots have low oxygen levels that can affect the ability of the roots to pick up iron and other micronutrients. The excessive rains this year have caused more chlorosis than other years because the roots are lacking oxygen and can’t pick up the nutrients they need. 

Anthracnose

Anthracnose is a fungal disease that affects the leaves of many ornamental trees. It is seen primarily on sycamores and maples but can be seen on many trees including oaks, ash, and walnut. It causes irregularly shaped brown areas on the leaves. The affected portions of the leaf will follow the veins and will eventually cause death of the leaf and stem tissue. This disease is primarily an aesthetic issue, it will not kill the tree, at least not in only one year of infection. Because of this, Fungicides are rarely recommended.

Anthracnose is more common under cool, wet conditions, which is why we are seeing it this year. The fungi is host specific, so if anthracnose affects your ash tree, that fungi will not spread to the maple tree. However, if the conditions are favorable for anthracnose on one host, it is likely that it will be found in multiple hosts.

There is an anthracnose found in cucumbers and other cucurbit or vine crops in the garden as welll. If your cucumbers have anthracnose on some leaves, pinch those leaves off and destroy them, don’t compost them and don’t leave them around your plants. Fungicides are not usually cost effective for home gardeners, but mancozeb or other copper fungicides can be used to minimize damage to plants if desired. Be sure to read and follow all instructions on the product label.

Septoria Leaf Spot

Septoria leaf spot is a problem showing up this year on our perennial plants including mums, coneflowers, coreopsis, blanket flower, lambs ear, and many more. This is another fungal disease showing up with all of the rain this year. With septoria, purplish to brown colored spots will develop on the leaves, sometimes completely covering the leaves. It tends to start on the older foliage of the plant, but if overhead irrigation or excessive rain events continue, it can continue to spread through the plant. If you see Septoria leaf spot in your garden, remove infected plant parts. Fungicides such as copper can be used for Septoria leaf spot as well if desired.

Septoria leaf spot can also be found in tomato plants. It will appear on the leaves as small spots with a whitish center and dark colored border. Eventually the spots can coalesce into larger spots and destroy entire leaves. It can lead to defoliation and in severe cases even death of the plants. As you see Septoria leaf spot on your tomato plants, remove the foliage. Copper fungicides can also be used but should be used at first sign of the disease to reduce the spread. Also, avoid overhead irrigation to reduce spores splashing and spreading the disease; water only at the base of the plants.

 

Flood Recovery

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Photo of breached Levee in 2019 Flooding along the Missouri River, Photo by John Wilson, Nebraska Extension Educator

Many parts of Nebraska have faced flooding issues recently that have done a great deal of damage to homes and properties. Flooding has also caused damage to our landscapes and garden spaces.

Trees in the floods

Floods can do a lot of damage to our trees, depending on the length of time the trees were under water. According to the University of Wisconsin Extension, most plants can tolerate a few days of flooding during the growing season. Now that flood waters have or are receding take time to look at your tree and assess the damage.

When assessing the damage to your tree, make sure the roots remain at the same level in the soil and remove debris from around the tree roots. Hire an arborist to remove broken branches and check the stability of any leaning tree. If the tree is now leaning toward a building or other damaging location, have the tree removed. Do not fertilize your trees for at least a year to avoid further damage or disruption to re-establishing roots.

Garden space in the floods

Vegetable Gardens would be a concern due to food safety reasons. Floodwaters are not clean and they can carry bacteria and other harmful debris and pollutants with them as they move across the land. Fortunately, the floods came through before our gardens were planted, but there is still a concern with the soils and what crops we will plant. Spring garden crops and crops with edible parts coming into contact with previously flooded soils would be the most concerning.

According to John Porter, Urban Ag Program Coordinator for Nebraska Extension:

The recommendation depends on whether or not the crop comes in contact with the soil.  For crops that do not have direct contact with the soil, such as tomatoes, peppers, beans, etc. the waiting period between flooding and harvest should be at least 90 days. For crops that do have direct contact with the soil, such as lettuce and leafy greens, squash/pumpkins, and root crops such as potatoes and carrots the waiting period should be at least 120 days.  If the crops that don’t typically make contact with the soil are allowed to make contact, like tomatoes that aren’t staked, the 120 day recommendation should be followed.

Food safety concerns wouldn’t be present to gardens that were not affected by the floods. We can still plant our gardens into the soil during the 90 or 120 day waiting period, but any mature harvest should be discarded until after that waiting period for food safety. This means that we should opt out of spring gardening in areas where the floods impacted our vegetable garden spaces. Most of our summer crops would be fine, but you may want to use a trellis for cucumbers and use container gardening for things like zucchini to be on the safe side.

Turf in the floods

Lawns are resilient in flooded areas. It is best to stay off of wet lawns to avoid compacting the soil. Wait until it has dried out before mowing, driving equipment over, walking excessively over, and cleaning up the debris that may be on the lawn. Turfgrass can survive 4-6 days submerged, according to Missouri Extension. Most of our localized flooding receded quickly, so the lawn should survive. Also, because the flooding happened during the dormant period for the turf, the injury will be less than if it occurred during the warmer growing season. In areas that are still under water, when the floods do recede soil work, clean-up, and overseeding will be necessary. We may also see an increase in lawn diseases this summer due to the high amounts of rain and floodwater that affected them this spring. View this Turf iNfo on Turf Recovery after Historic Flooding for more information.

For more Flood Resources, visit: flood.unl.edu

 

Landscaping Around a Tree

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This photo shows a good example of landscaping under a tree. Notice the wide, thin mulch rings.

The winter is a great time to start thinking about spring gardens. One of the gardens you might think about for improvement or development is around trees. There are things you can do around trees to help improve the overall look of your landscape, but be careful, some things may be harmful.

Exposed Tree Roots

Exposed tree roots are often a problem in landscapes. Some trees will pop their roots up and out of the ground which makes it difficult to mow around and can be a trip hazard. Unfortunately, there is not a good fix for this problem. If you were to cut the root to remove it from above the ground, you would severely injure the tree and possibly kill it, depending on the size of the root. Adding more soil around the root to try to cover it up is also a bad idea. Adding more soil to the existing grade of a tree can suffocate the roots and kill the tree.

Raised Beds around Trees

One idea many people want to use around their trees is to add a raised bed around an existing tree. Adding the soil necessary to make a raised bed around a tree can kill the tree. If the tree is correctly planted into an established raised bed after the raise in soil grade is complete, that would be fine. However, adding this bed around an existing tree will severely damage the tree and could lead to tree death. Trees are slow to react to these things, so your tree may live just fine for 5-10 years, but then the damage will begin to show up as the canopy starts to thin or die.

Turf under Trees

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Thin turf under a tree, photo from John Fech, Nebraska Extension Educator

Another issue around trees that many people ask about would be thin turf growth or constantly bare soils under a tree. Turf is a sun plant and it will not grow well in shade. There are shade mixes in the market, but those are designed for light shade. Underneath a full grown, healthy tree is often too much shade for the turf to grow in.

A better option instead of thin turf for underneath the tree would be to just mulch the area. Mulch helps to keep the weeds down, retains moisture, keeps the roots cool, and keeps the lawn mower and weed trimmer back away from the tree trunk to reduce the incidence of damage from this machinery. Keep the mulch at a flat layer of 2-3 inches deep and don’t create a volcano of mulch around the tree. The mulch ring should be at least a 3 foot diameter around the tree, but it can be as wide as the dripline.

You can mimic mother nature and provide a nice growing environment for your tree by utilizing mulch and shade plants under the tree. You can plant shade plants into the area around your tree as long as you don’t add soil to put them in. In nature, trees grow great on their own with little input from humans. A big part of that is the growing conditions they are placed in. Trees in nature grow with leaf litter and smaller plants growing all around them. The leaf litter acts as a mulch and the shade plants thrive in the shade of the large trees.