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.

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Planning Your Garden

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*Reference to commercial products or trade names is made with the understanding that no discrimination is intended of those not mentioned and no endorsement by University of Nebraska–Lincoln Extension is implied for those mentioned.

In January the seed catalogs begin to arrive in the mail. Each of these catalogs is a promise that spring will come again. In all the cold, snowy weather, I like the excitement of planning my garden for this year. When you are planning your garden, keep in mind things like sunlight, location, and water availability. Planning is important for the vegetable garden as well as for flowers, trees, and shrubs.

Planning a Vegetable Garden

It is always hard not to get overwhelmed with all the fun, new plants available to us. But when planning your garden, look at the location available first. If you are planning for a vegetable garden, you need to have at least 5 hours of sunlight per day but 8-10 hours per day is ideal for vegetables, preferably more sunlight in the afternoon. If you don’t have the correct sunlight, look for shade loving plants. The garden should be in a location that is fairly level and has good soil for best growth of the plants. Be sure to plant your garden near a water source to ensure the plants get watered sufficiently through the growing season.

Also, be sure to have the proper spacing allowed for your garden plants. We tend to plant vegetable plants too close together because they are small when we plant them. Remember to space them according to the label directions. If plants are too close together it can lead to more disease and insect problems when they grow too large and overlap one another.

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Black Walnuts Photo courtesy of Paul Wray, Iowa State University, Bugwood.org

Black Walnut Trees

Another important aspect of your garden to keep in mind, would be to keep your garden at least 50 feet away from Black Walnut trees. Black Walnut trees produce juglone, which is a type of plant produced toxin that works as a weed barrier around the tree. Juglone will hinder growth and sometimes kill many different types of plants. Tomatoes are very susceptible to juglone. There are also a lot of other trees, shrubs, and perennials that are susceptible to the juglone. If you are planting near a black walnut tree, be sure to check if your plant choices are tolerant of the juglone. If you are unsure about a nearby tree, bring a sample of the tree to your local Extension Office for identification and they can help you determine which plants will do well planted near your black walnut tree.

Mulch

Mulch is a necessity for your garden. Whether it is a vegetable garden, a perennial bed, or trees or shrubs, mulch is vital to help keep weeds down and to retain moisture around plants. Mulch can be either wood chips, straw, grass clippings, or another form of organic mulch. Inorganic mulches are not the best option due to the fact that it is very hot around the roots of plants and does not retain moisture. Make sure that your mulch layer is not too deep, keep it around 2-3 inches deep and keep it uniform around the tree, avoid mulch volcanoes.

Plant Size

Make sure you always read the growing requirements and full size of the plant before planting it in your landscape. It is most economical to plant things that fit in the space in your landscape, rather than pruning or removing it later. Often times, trying to keep a plant in a space that is too small for it will lead to death and costly removal fees. So it is best to start with a plant that will grow no larger than the space available to have a long-lasting plant for that area of your landscape.

Have fun when searching through your garden catalogs and find something fun and interesting to try. The 2019 Pantone Color of the Year is Coral, try to use that in your garden this year. Check out the All-American Selections for new varieties that have been tested in real garden settings, many of them were tested in Omaha and Lincoln with help from Nebraska Extension.

Volunteer to Garden

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After the holiday season, winter gets long and exhausting. We can’t go outside to do any of our fun outdoor activities like gardening. This is the time of the year that the winter blues begin for many of us, and it’s understandable since we can’t garden. However, we can use this time indoors to educate ourselves in the best practices for gardening. One way to learn more about gardening in the winter and help the community during the growing season, would be to become a Master Gardener Volunteer.

The Nebraska Extension Master Gardener program is a horticulture related volunteer training program based in many counties throughout the state. It has been part of Nebraska Extension since 1976. Master Gardener volunteers are trained by UNL Extension faculty and staff and then they take that knowledge gained to volunteer in their community. They contribute time as volunteers working with their local Extension office to provide horticulture-related information to their community. Participants are required to complete 40 hours of training and 40 hours of volunteer service throughout the first two years of their involvement in the program. Master Gardener volunteers retain their certification through 10 hours of annual training and 20 hours of volunteering each year.

Each year the Master Gardener program is held throughout the state, including many locations in southeast Nebraska. The programs are held from 6:30-9:00pm on Tuesday nights at the Gage County Extension Office in Beatrice. This year the programs run from February 5-March 12. The schedule for the classes is as follows:

February 5- Introduction & ‘Do you know Plants?’– Nicole Stoner

February 12- Wildlife in the Landscape – Dennis Ferraro

February 19- Weather Ready Landscapes – Elizabeth Killinger

February 26- Secrets of Service for Master Gardeners – Terri James

March 5- Lawn Weeds & Pesticides – Nicole Stoner

March 12- Tree Hazard Awareness & EAB – Nicole Stoner

This class will also be provided in Wilber following the same schedule on Wednesday afternoons from 1-3:30pm. It will run from February 13-March 20 at the Saline County Extension Office. There are also many other opportunities and locations to take the Master Gardener Classes. Please contact Nicole if you are interested or if you would like to find another location for the classes.

The Master Gardener program is a great way to learn about gardening, help your community, and make good friends who share your love of gardening. For volunteer service, most of the Master Gardeners in the area participate in management of many of the gardens in your community. Look around the landscapes in public areas the next time you drive around town, there are signs to show many landscapes the Master Gardeners help to manage. They do a great job and really help keep our communities looking nice.

The cost of the Master Gardener program is $160 for the first year, which includes a book, t-shirt, and nametag. For returning Master Gardeners the cost is just $15. Please contact Nicole at the Gage County Extension office at 402-223-1384 to sign up for the program. The deadline for enrollment into the class is January 31, 2019.

Poinsettia

Poinsettia Blog

A common host gift we take to Holiday parties are Poinsettias. If you receive one for Christmas this year, do you know how to care for it? Poinsettias are a staple for the Christmas season, but they don’t have to be a short-lived gift that is thrown away at the beginning of the year.

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Red bracts and yellow flowers of a poinsettia

Typically, poinsettias are most commonly found in red, but the color range is expanding all the time. They can now be found in white, pink, green, or a marbled pink or marbled red. On an old-fashioned poinsettia, the red colored portion of the poinsettia is not actually the flower of the plant. The colored, leaf-like structures are actually bracts, which are modified leaves. The actual flower of a poinsettia is the yellow center of the colored bracts.

Poinsettias need to be cared for during transport and while in the home. When you first purchase a poinsettia, you need to protect it as you transport it. Wrap it in a plastic bag when you take it outside to protect the plant from the cold, windy outdoor conditions. This should be done when you leave the store, when you move it from your car to your home, and if you take it to another house as a gift. Once in its permanent location, remove the decorative foil wrapping from the pot of the plant. This foil can retain water for the plant, but in a bad way. It can make it so that the plant roots are constantly wet and root rot may occur.

The care of a poinsettia can be tricky as the plants tend to be particular. Water the plant when the soil becomes dry to the touch, but don’t wait until the plant wilts prior to watering again either. Place poinsettias where they receive indirect light for 6 hours a day. Keep the plant away from cold drafts and keep them from touching a window. This plant prefers temperatures of 60-70 degrees F during the day and 55 degrees F overnight. Do not fertilize poinsettias during the flowering period. Poinsettias can be fertilized monthly with a houseplant fertilizer during the rest of the growing season if you choose to keep it alive.

You can keep the poinsettia year round if you wish. After Christmas, care for the poinsettia as you would any other houseplant. Keep it evenly moist and in bright, indirect light. In February or March, cut back the plant to 4-6 inches in height. In May, repot into a larger container. It can be placed outdoors after the danger of frost has passed. In the fall, bring the poinsettia indoors before night temperatures drop below 55-60 degrees F.

To encourage poinsettia to bloom again, it takes a specific routine of light and darkness. Poinsettia flowering is induced by a photoperiods, like Christmas Cactus. It takes 12 hours of darkness per night to initiate flowering. Starting at the end of September, place the poinsettia in a closet or cover it with a black cloth to keep it in total darkness from 5pm until 8am the next morning. Even the lights in our homes can interfere with the flowering cycle of this plant, so it needs to be completely dark around the plant. Once the flowers begin to develop in mid-December, you do not need to continue the dark period. It will help, though, if you continue this until the bracts are fully expanded. Then, you can enjoy your poinsettia through the holiday season for years to come.

Firewood

Fireplace

Flickr image courtesy of Shay Sowden per CC license

This winter has been exceptionally cold and full of snow and wind. With cold winters, our heating bills go up. One way many people try to spend less heating bills is to use wood burning stoves and fireplaces to supplement the heat inside our homes through the winter months. However, if the firewood is stored incorrectly insect issues can develop inside our homes.

Firewood Storage

Firewood should only be brought into the home as it is needed, only a few pieces at a time. Many insects lay their eggs or pupate within trees prior to or just after they have been cut down for firewood, the insects may still be inside the wood when you bring it indoors. When the wood warms up in your home, the insects can emerge. These insects rarely cause an infestation in your home or cause damage to your furniture or home structure, but can be a nuisance when they get into your home.

Be careful of how you stack your wood outdoors as well, to avoid problems with termites. If you stack your wood directly on the ground outdoors up against your home, you may be providing a highway for the termites to move from the ground to your home. The best practice for stacking firewood would be to stack it on a rack made out of steel or another material other than wood. Also, don’t stack your wood so that it is up against your home, shed, garage, or other building that termites can move into.

Insects in Firewood

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Carpenter Ant Photo Courtesy of UNL Department of Entomology

Carpenter Ants are commonly found in decaying wood. They do not feed on wood, but they dig into decaying wood to form galleries for their nests. Carpenter Ants are the large black or red ants often found on trees with decay because they are making a nest within that tree. In a house, carpenter ants can do damage if you have a leak which has caused wood in your home to decay. They can be brought indoors with firewood that they were living in.

There are many wood-boring beetles that are also found in firewood. Longhorned beetles, flatheaded borers, and bark beetles are all found in trees and logs cut for firewood. Females of these beetles are actually attracted to dying, freshly cut, or recently killed trees to lay eggs on the wood. These beetles can emerge in your home, but don’t usually cause problems in the wood products found within your home.

One common structure-infesting pest, a powderpost beetle, can get into your home, but they only lay their eggs on bare, unfinished wood. Wood that has been varnished, painted, or sealed is safe unless exposed surfaces appear.

Using Wood Ash in the Garden

Another issue I see with fireplaces is in the garden. People use the wood ashes on their gardens because the old saying is that it is good for the soil. It is true that wood ashes can be used on the garden, however, if the ashes are applied too often or too heavily it can damage the soil or plants growing in it. Ashes will raise the pH in the garden, making it more alkaline. However, in Nebraska soils it is not necessary to raise our naturally high pH. Adding nutrients to make the soil pH too high can be harmful for plant growth. Most Nebraska soils have a pH of 6.5 or higher and Illinois Extension recommends avoiding using ashes in your garden with this pH level. It is best to first get a soil test to know where your levels and your pH are at before you add ashes, or any fertilizer, to your garden. If you could benefit from ashes, only apply a little to the garden and use the rest in your compost pile where the nutrients can be beneficial.

Make a Wreath from your Landscape

Happy Thanksgiving blog

Happy Thanksgiving! With the passing of Thanksgiving means the full wave of Christmas preparations. Many of us like to shop for our Christmas trees and put out all of our holiday decorations through our homes within the week of Thanksgiving. For Christmas trees and other holiday traditions, we often use artificial replicas of real plant material for our decorations. However, if you choose to use real trees and use real branches in your wreaths, the smell is a wonderful alternative to any artificial selection.

Wreaths are a great decoration for the Christmas season. Wreaths have been used for centuries to decorate for the holidays. According to North Carolina Extension, using evergreens in holiday celebrations comes from the middle ages when people viewed evergreen trees to be very special, representing life and growth to come. This can be especially important to us during long, cold winters.

Plant Selection for Wreaths

Plant material used for Christmas decorations can come from your own landscape. Many of our tree and shrub species make great wreaths, swags, and garland for use during the holiday season. White Pine has long, soft needles that can be used in these decorations, but it needs to be kept moist and needs to be layered to look full. Junipers are often used in decorations as well for good fragrance, but they can be messy. Firs have a great scent that can fill a room with a fragrance reminiscent of the holidays. They hold their short needles well and will tolerate indoor conditions. Spruces can be used as well, but be careful with these, the needles are short and sharp. It might be best to wear gloves when handling spruce to avoid injuring your hands. You can also add in accents from other plants such as berries from Ivy, unique leaves and berries from holly, and pinecones. Just stroll through your landscape and gather some materials from whatever is green and catches your eye.

Making your own Wreath

DSCN5798If you are making your own wreath from your landscape materials, walk around to find the best quality materials to use. Small amounts of pruning from your landscape for your wreath will not be harmful to your plants. Make sure you still make a good pruning cut and remove small branches back to a larger branch and do not leave a stump behind. Once back inside with your branch materials, cut them into 6-8 inch sections and overlap them along the frame as you wrap them with wire to hold them in place. If done correctly, the overlapping of plant material will cover up the wire as you build the wreath. Build your wreath as full or thin as you choose. When finished with the base of the wreath, you can add berries, other leaves, and pinecones that you find in your landscape as well.

Maintaining Freshness in your Wreath

Wreaths made from live material has a shelf life, they will not remain green and full of fragrance long term. Given good conditions, however, they should remain green and full of scent for the holiday season. If the wreath is kept indoors, it will only last for a week to 10 days. If the wreath is hung outdoors, it can remain fresh for 3-4 weeks. However, if hung on a front door in full sun behind a glass door, it will not last this long. It would be best to store the wreath in a cool, damp location where it is sheltered from the wind, rain, and sun but has good ventilation. A door on the north side of a building would be best. It will also help with longevity of your wreath if you spray the wreath with water often to maintain moisture to the plant materials. If a floral foam is used, it can be watered down every 2-3 days to ensure the plant material stays hydrated to last longer.

Protect Plants from Winter Problems

Now that November is here, we can begin to prepare our plants for the winter conditions. Some of those preparations are to get plants ready for cold weather and some are to protect them from wildlife.

My beautiful picture

Wildlife Damage

During the winter months we can see plant damage from deer, rabbits, and voles. Deer can chew off the ends of small twigs and bucks can rub their antlers on the trunk of smaller trees. Rabbits can also chew on smaller plants, sometimes chewing small plants off at ground level. Rabbits and voles can also gnaw on the thin bark of our young trees to feed on the green, inner bark areas. There is no cure once it happens, so it is best to protect our plants prior to damage.

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Rabbit Protection Fence, Photo from Lancaster County Extension

Exclusion is the best defense but is sometimes a difficult task. There are fences that can be utilized but they need to be at least 8 feet tall for deer damage. Rabbits can be managed with a fence that is 2 feet tall. Voles can be controlled by removing tall grass and weeds from around the trunk of trees and by avoiding mulch layers deeper than three inches around trees. Placing hardware cloth around tree trunks will also prevent vole feeding. The commercial spray repellants available for deer or rabbits are not very effective and would need to be reapplied often.

Winter Mulch

Winter mulch can be applied now, or within a few weeks when temperatures are consistently dropping down to the twenties each night. Winter mulch is the heavier layer of mulch we apply to herbaceous perennial plants and strawberries to keep them from having temperature fluxes throughout the winter. Any plant that may be prone to frost heaving, the plant being pushed up out of the soil by a constant freeze and thaw condition, or plants that were just planted this fall could also benefit from winter mulching. This mulch can be up to four inches deep, which is deeper than we usually advise but is needed for winter protection. It is better to use coarse wood chips or leaves for winter mulch rather than grass.

Winter Watering

Winter watering is essential in dry winter years. Winter desiccation commonly occurs on evergreen types of trees and shrubs. All trees are still transpiring, or losing water, throughout the winter months, evergreen trees are transpiring at a higher rate than deciduous trees. Winter desiccation occurs when the amount of water lost is greater than the amount of water the evergreen takes in throughout the winter months. The damage from winter desiccation is brown needles out on the ends of branches. However, the damage from winter desiccation will not usually show up in our trees until early spring, so they will stay green through the winter. Drought effects can damage deciduous trees as well. Especially newly planted deciduous trees. All of our trees may need to be watered throughout the winter months if natural precipitation or snow cover is absent.

Winter watering should occur during the day on days when the temperature is 40 degrees Fahrenheit or above and is only necessary 1-2 times per month until spring. It is a good idea to test for soil moisture with a long screwdriver or soil probe prior to watering to determine if watering is necessary. If the screwdriver goes into the soil easily up to 18 inches, watering is not necessary. However, if pushing the screwdriver into the soil is very difficult, watering would be necessary.

Trees turn color in fall

Fall tree color blog

Fall is a great time of the year. The trees start turning colors and everything looks so beautiful, even the green conifer trees. Evergreen trees should maintain their green color all of the time, right? This time of the year I get many calls on a natural process of evergreen trees called Natural Needle Drop.

Natural Needle Drop

Natural Needle Drop

White Pine with Natural Needle Drop

Evergreen trees turning yellow in the fall may not be a problem, in fact it may be completely natural. Evergreen trees do hold onto their needles, but eventually the older needles are shed from the tree in the fall. When this happens, those needles turn yellow before they fall from the tree. As long as the needles that turn yellow are all on the interior of the tree, there is no real concern. The older needles are the needles that are shed, which will be held on the interior of the tree, not on the ends of the branches.

Natural needle drop is very noticeable on white pine trees because they are naturally not a dense tree and they lose their needles every 2 years, making it quite common. Ponderosa pines lose their needles every 3 years, while Austrian pines lose their needles every 4 years. It is not as common to notice the needle drop on these trees due to the infrequency as well as the density of the tree. Spruce trees will also lose their needles, but much less often. Spruce trees will typically hold onto the majority of their needles for up to 10 years

Deciduous Conifers

It is important to know what you tree is supposed to do in the fall and winter months. We have a couple of trees that are classified as ‘Deciduous Conifers’ meaning that they are a conifer due to their needles and how they are arranged but are deciduous because they lose those needles annually. Two deciduous conifers are commonly found in Nebraska, the Larch and Baldcypress. These trees will lose all of their needles in the fall after first turning brown throughout the entire tree. If you don’t know what type of tree you have in your yard or are not familiar with the growth habit of these trees, you might think they died, when they are really just going through their normal lifecycle.

Fall Color for Deciduous Trees

20181023_152033Speaking of deciduous trees, this is the time of the year when our deciduous trees, those with leaves rather than needles, will change color and the leaves will fall from the tree. As the nights gets cooler and the days get shorter, the tree produces a membrane between the branches and the leaves which causes the leaves to be shed from the tree. Prior to leaf drop, this membrane also causes cessation of chlorophyll from the leaves for the year. At this time, the other pigments are allowed to show up in the leaves.

The brightest fall colors are produced when dry, sunny days are followed by cool, dry nights. The dry, sunny days are needed to break-down the chlorophyll in the leaves allowing the other pigments to be dominant in the leaves. The cool, dry nights are also necessary for fall color because trees need to avoid freezing temperatures which can injure or kill the leaves causing them to stop producing much sugar at all. The sugar content is what increases the amount of the anthocyanin, or red pigment.

Biting Insects

Shagbark hickory, flickr, Nicholas A. Tonelli

Now that Fall is officially here, the weather is starting to cool down and we can venture outdoors more. Activities such as Hiking, harvesting, hunting, football, and just enjoying the cooler weather on your patio in the evening are all pleasant outdoor activities this time of the year. However, when we venture outdoors, our plan is never to be the menu for all the pesky insects outdoors.

Mosquitoes

mosquitoMosquitoes are out in full force right now. After the rains we have seen over the past couple of weeks, their population has exploded. Mosquitoes can transmit many diseases, so it is best to protect yourself when you are outdoors. Use Insect repellent and wear long sleeves and long pants or permethrin-treated clothing when outdoors between dusk and dawn when mosquitoes are most prevalent.

As far as chemical control, Mosquito Dunks contain the active ingredient bacterium, Bacillus thurengiensis israelensis (Bti), which is toxic to mosquito larvae when consumed, but non-toxic to humans, pets, pollinators, fish, and other wildlife. They are sold in hardware stores, and will dissolve in standing water such as water troughs, fishponds, rain barrels, and birdbaths. They are effective immediately and can last for a month. For homeowners, it is not recommend to use foggers or adulticide treatments. These treatments are not effective for more than a couple of days and should only be used a few days ahead of a large outdoor get-together if absolutely necessary. At this point, it would be best to just wait for a frost to kill off the majority of our mosquitoes. Our average first frost date is the end of September to the beginning of October, so one should be here soon.

Minute Pirate Bugs

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Minute Pirate Bug

Minute pirate bugs are also a nuisance right now as well. Minute pirate bugs are the tiny, black insects that seem to fall out of the trees and bite us during the fall months. The bug, which is a true bug, is 1/8 inch in length black insect with white and black wings. The appearance of this bug is very similar to a chinch bug. The wings have an “X” on them which is typical for insects that are true bugs.

Minute pirate bugs are present throughout the summer but they are out in fields, woodlands, and gardens. During the summer they are feeding on other insects, making them a beneficial insect. But, in the fall, these insects move into the areas where people are more often outside and they begin to bite us. When they bite us, they insert their piercing-sucking mouthpart into our skin, which can be painful. Some people may react differently and swell up from the bite, but most people just have the initial pain with the bite. Minute Pirate bugs do NOT feed on blood, inject a venom or transmit diseases. Control is not practical for them as they will also die with our first frost. Insect repellents do not deter them, so it is best just to wear long pants and a long-sleeved shirt to reduce areas for them to bite us.

Ticks

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Lonestar tick life stages, Photo from Jim Kalisch and Wayne Kramer UNL Department of Entomology

Ticks are also still a problem this late into the season. Ticks are common in wooded areas or in tall grass. If outdoors in areas where ticks are commonly found, wear light-colored, long-sleeved shirts and long pants and closed toe shoes to reduce exposed areas where ticks can attach to your skin. Also, use insect repellents any time you are outdoors, the repellents with DEET have the highest efficacy. One tick I have seen recently is the immature form of the Lonestar Tick. This immature form is very tiny in size and would be easily missed by a quick visual inspection. This tick can spread diseases if left to feed on you long-term, so be sure to protect yourself prior to going outdoors and check yourself when you come indoors.

Battling Weeds in the Lawn

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September is a time for the lawn. In my last article, I discussed overseeding and fertilizing the lawn, but weed control is another key to a healthy lawn. Some weeds in the lawn are often tolerated, but when the weed population begins to outweigh the turf population, management should be incorporated.

The Battle with Weeds

Plants are considered weeds because they are adaptive, aggressive and opportunistic. Weeds come into a lawn that is thin or bare. They are often found on the edges of our lawn or places where the grass doesn’t grow as well. Eventually they will work their way into the rest of our lawn. So overseeding a lawn may be the answer to reducing the weed population.

Growing turfgrass in the shade is not always possible. Even the shade mixes are not made to grow in high shade. Dense shade is not the growing condition for turfgrass and it often leads to weeds. In some cases, trees may be pruned to improve the sunlight getting to the turf, but be careful not to ruin the shape or health of a tree or shrub  just to get more sunlight to the turf. If the shade is too dense, a good alternative might be a shade tolerant groundcover or apply mulch where grass won’t grow.

Crabgrass

Crabgrass has been found in high populations this year, even in locations where crabgrass preventer was used. The University of Nebraska-Lincoln Turf department says the weather is to blame. Crabgrass germinates when soil temperatures reach 57-64 degrees at a one-inch depth, with the highest germination when soil temperatures increase to 73 degrees. Crabgrass will continue to germinate through the summer until soil temperatures reach 95 degrees. With the unusual weather we had this spring and summer, the largest amount of crabgrass germinated later than normal when the concentration of our original spring crabgrass pre-emergence herbicide was declining. This is why we saw so much more crabgrass later this summer than we usually do.

To help prevent this problem with later emerging crabgrass in the future, switch to longer lasting chemicals, such as prodiamine. You can also look to a second application of crabgrass preventer in mid-June to stop the germination of the late flush of crabgrass. There are also post-emergent herbicides to use for crabgrass, but I don’t recommend them this late in the season. Remember, crabgrass you are seeing now will die when the first frost hits. Also, it is difficult to kill a large crabgrass plant with a post-emergent herbicide.

Broadleaf Weed Control

As for when to treat for broadleaf weeds that do come into our lawns, fall is the best time to control them. In fall, perennial weeds are moving carbohydrates from the leaves into the roots for winter storage to help get them going again next spring. If you spray them in the fall, the herbicide will also be moved into the roots which makes the herbicide more effective. Also, the weather is more suitable for herbicide use than in the spring when Dicamba and 2,4-D have a potential to drift to non-target plants. Fall is also a great time to apply herbicides to kill the winter annual weeds such as Henbit either with a pre-emergent herbicide such as prodiamine (Barricade) or dithiopyr (Dimension) or with a post emergent after the henbit has germinated.

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Henbit along a sidewalk edge

The best time to apply herbicides in the fall is mid-late September and again in mid-late October. The second application helps to get better control on perennial weeds that may have been missed or were not fully killed. The second application also helps to ensure that winter annuals have germinated to help get control of those with a post-emergent herbicide. Products containing 2,4-D, carfentrazone, sulfentrazone, quinclorac, or triclopyr are all good for controlling perennial weeds in the lawn. Use caution around trees, shrubs, and landscape beds as these products can damage broadleaf plants but they will not harm our turf.