Zebra Mussels, Don’t Let Them Muscle Their Way Onto Your Acreage
By Bobbi Holm, UNL Extension Educator
Have you heard that zebra mussels were discovered last fall in Zorinsky Lake in Omaha? Not muscles of striped, four-legged animals that work out a lot, but mussels as in aquatic animals with hinged shells, like clams. Finding them in Zorinsky is big news because they are not native to Nebraska, or even to the United States, and they are an invasive species. A non-native species is one that has been introduced into an area by humans. (Hello Nebraska, meet the zebra mussel.) And when an introduced species causes big problems for the native animals or plants, it is considered invasive.
Sometimes, due to a lack of natural controls such as disease or competitors, a non-native species can easily become established in a new area. Once established, it can out compete and displace the native species, disrupting and degrading the environment. That’s an invasive species. And the zebra mussel is definitely invasive.
The zebra mussel is native to the Black, Caspian, and Azov Seas in Eastern Europe and Western Asia. It was probably brought to the Great Lakes in the ballast water of a cargo ship. When the ballast was emptied, the mussel was released also. It was first discovered in North America in 1988 in Lake St. Clair which connects Lakes Erie and Huron. By 1990, the zebra mussel was in all the Great Lakes. They have since been found in a number of lakes and river systems in about 30 states.
These are small animals, less than 2 inches long. The D-shaped shells of adults are yellow to brown and often striped in a dark and light pattern, hence the name zebra mussels. But they can also have mostly dark or light shells. The underside of the shell is very flat. Zebra mussels have a special organ, the byssus, which they use to attach themselves to things. The byssus produces threads which protrude between the two halves of the shell and attach to hard surfaces with a strong glue. Zebra mussels are usually found attached to objects or each other by these threads. They are the only freshwater mussel that can firmly attach itself to solid objects like submerged rocks, dock pilings, boat hulls, and water intake pipes.
Zebra mussels are filter feeders, meaning they suck in water, filter out the tiny plants and algae, and spit the water out again. They are really good at filter feeding, an adult can filter about a liter of water a day. They are also really good at breeding. A female can produce up to one million eggs during a spawning season. Zebra mussel larvae are microscopic and free-floating. They will drift in the water for three to four weeks. As they develop, the juveniles search for something to attach to. They prefer hard or rocky surfaces, but will attach to plants if necessary. They will also settle on other zebra mussels and on native mussels.
Why are zebra mussels a problem? They lack natural control mechanisms here in the U.S., such as an effective predator, and their populations can increase quickly. Plus, they are very easy to spread from place to place. The larvae can be present in bait buckets or live wells and released when this water is emptied. As they mature, they can attach to boats and be transported from place to place. Even if a mussel infested boat is taken out of the water, the mussels could survive. When it’s cool and humid, adult zebra mussels can live for several days out of water.
Adult zebra mussels are well known for their ability to clog water pipes. They attach and grow inside the pipes in such numbers that they severely restrict water flow. They have also sunk navigational buoys because so many mussels grew on the underwater surface. Fishing gear left in water for long periods can be ruined and boating can be affected due to the drag created by attached mussels. Zebra mussels can damage dock and pier supports. These mussels can cover any hard object in the water, including native mussels, eventually killing them. Zebra mussels are believed to be responsible for drastic reductions in native mussels.
Katie Decker, Nebraska Invasive Species Project
Because they are such efficient filter feeders, they remove substantial amounts of algae from the water. This decreases the food available for the tiny aquatic animals and could impact the entire food chain, including the fish population. When there are large numbers of zebra mussels, they make the water more clear because they remove so much of the algae. While this may not seem to be a problem, it can increase the depth of light penetration into the water and cause a proliferation of rooted aquatic plants which couldn’t grow before due to lack of light.
Interestingly, zebra mussels do not eat blue green algae. What we call blue green algae is really a type of bacteria that captures energy from sunlight through photosynthesis, much like plants. These are the “algae” that can result in pea soup-like, scummy water. They can also produce toxins that are harmful to humans, pets, and wildlife. So, no, zebra mussels can’t solve problems caused by blue green algae.
Getting rid of zebra mussels is very difficult and expensive, so the best defense is to prevent their spread. To avoid spreading zebra mussels, boaters and others who enjoy water recreation should remember to CLEAN, DRAIN, DRY their equipment when removing it from the water. This includes boats, trailers, jet skies, waders, anything that comes in contact with the water. CLEAN off any plants, animals, or mud that you see. On land, DRAIN live wells, bait buckets, bilges, and any other compartments that hold water. If possible, allow equipment to DRY for at least five days before using it in a different body of water. Alternatively, you can pressure wash equipment with hot (140°F or hotter) water. Freezing temperatures will also kill the mussels, as will chlorine bleach and full strength vinegar.
Even if zebra mussels are not known to exist in your water, make CLEAN, DRAIN, DRY your standard practice. Infestations can go undetected and there are other aquatic invasive species - animals, plants, insects, and diseases - that you can prevent the spread of by practicing CLEAN, DRAIN, DRY.
Do spread the word on zebra mussels. Visit the Nebraska Invasive Species Project website for more information on zebra mussels and other invasive species found in Nebraska.
April showers? April flowers? This month, we have information on a 4-H Club dedicated to helping others, the Nebraska Statewide Arboretum, selecting pruning tools, and renovating your lawn.
Safety for You and Your Livestock
By Steve Tonn, UNL Extension Educator
One of the benefits of living on an acreage is having room for livestock. Although considered domestic animals, working with livestock carries with it an inherent risk of danger. National data shows livestock, machinery and falls are the dominant sources of occupational injury on farms. In fact, studies show that up to one-third of injuries on the farm are associated with livestock.
Safety becomes an important issue when handling livestock. Livestock safety applies to both the animal and the animal handler. It involves much more than simply “being careful” around livestock. In fact, many livestock accidents are not directly related to the animals themselves but are caused by improper use of equipment and poorly-maintained or poorly-built facilities.
People tend to give animals human qualities and forget that animals quickly revert to primal reflex reactions when they are threatened or under stress. Animals will fiercely defend their food, shelter, territory, and young. When frightened or in pain, animals may react in ways that threaten their and our health and safety. While livestock fatalities are not nearly as frequent as deaths involving tractors or machinery, animals are involved in more total accidents and with more work related accidents. Typical animal caused injuries to the handler range from cuts and sprains from falls, to broken bones and whole body injuries from being kicked, pushed, shoved, or run over by an animal.
Livestock handlers must be fully aware of the different ways livestock and humans react to certain situations. Handlers must remain in control of potentially dangerous situations and avoid actions which make them vulnerable to injury. The more predictable our actions, the less likely we are to injure livestock or be injured. The better we understand livestock, the less risk of animals harming us or themselves.
Observing animals to determine their temperament can alert the handler to possible danger. These signs include raised or pinned ears, raised tail or hair on the back, bared teeth, pawing the ground, and snorting. Male animals are always dangerous. Males of some breeds are more aggressive than others, but protective females, especially new mothers, can be just as dangerous. Often injuries occur from animals that do not openly exhibit aggression or fear. This reaction may be triggered by excitement caused, for example, by a person walking nearby. Typical injuries from this type of situation are usually a result of being kicked, bitten, stepped on, or squeezed between the animal and a solid structure as the animal tries to flee.
Treat livestock with respect. Always know where you are and where the animal is in relation to you when you are working with livestock. Never overlook warning signs exhibited by animals being handled.
An ounce of patience when handling livestock will be worth a pound of good working relationship when farm animals are concerned. Take time to understand how animals respond to various situations. This understanding should reduce the potential for accidents.
Source: Introduction to Livestock Safety, Auburn University
Managing Skunk Odor
By Stephen VanTassel, UNL Wildlife Project Coordinator
It's that wonderful time of the year, when skunks will be having their young. When young skunks arrive the smell arrives too, because juveniles are significantly more "trigger happy" than their mom. Fortunately, there are some effective methods to manage skunk odor, both at specific locations like your dog who hasn't quite learned his lesson, and when the odor pervades your home.
Put down the tomato juice, and learn what really works by reviewing Removing Skunk Odor, Internet Center for Wildlife Damage Management.
Alfred Viola, Northeastern University, Bugwood.org
Proper Mulch Use & Precautions
By Kelly Feehan, UNL Extension Educator
Mulch is a good thing to place around plants in gardens and landscapes. The list of benefits mulch provides is long and includes water conservation, cooler soil temperature, tree protection from lawn mowers and grass trimmers, and reduced soil compaction.
As with any good thing, too much may cause problems. There are also pros and cons to different types of mulches. The right mulch needs to be selected and applied correctly to be effective and not create problems.
Grass clippings can make good mulch, especially for vegetable and annual flower gardens. They are readily available, free, and using them as mulch recycles this prolific yard waste. Keep in mind it’s also a good practice to simply recycle clippings by leaving them on the lawn.
As mulch, grass clipping use requires some precautions. Allow clippings to dry before placing them around plants. Green grass clippings are high in water and nitrogen and readily ferment. The heat and ammonia released in fermentation can injure or kill plants.
After a lawn is sprayed with herbicide, wait until after three mowings before using the clippings as mulch. Because of their fine texture, grass clippings tend to mat down and impede water and air movement into and out of soil so only use about a one to two inch layer of grass mulch.
Wood chips are good mulch because their coarse texture allows for sufficient water and oygen movement into and out of soil. As organic mulch, they decompose over time to add organic matter to improve soils. This also means they need to be replenished from time to time.
There are a few precautions with wood mulch. It is wise not to use wood mulch near the homes foundation. Although it is not believed wood mulch draws termites, if there are already termites in the area they may find and feed on the mulch which brings them closer to the home. Keep wood mulch a few feet away from the foundation.
Fresh wood chips, and grass clippings from weedy lawns, may contain weed or tree seeds. Bagged wood chips are usually weed free as heat created in the bag during shipping and storage can become high enough to kill most weed seeds.
Other organic mulches to use include shredded leaves, pine needles and corn cobs. Sawdust is best avoided since it breaks down slowly, drawing nitrogen away from plants. It also cakes and repels water and reduces soil oxygen. If used, sawdust should be aged one year and applied no more than one inch deep.
Of the inorganic mulches, rocks or gravel tend to increase temperatures around plants creating stress and unseasonable warming in early spring that can lead to frost damage. Light colored rocks are reflective and can warm buildings in summer, increasing the cost of air conditioning and creating glare. It can also be dangerous if lawn mowers pick up and throw the rocks.
Crumb rubber is made from recycled car tires. It is typically used in commercial turf areas with high traffic, such as sports turfs and playgrounds, to reduce soil compaction and improve wear tolerance.
Crumb rubber use as a landscape mulch around plants is not recommended. It increases soil temperature which can increase plant stress. It is difficult to remove if needed and once in place, it is permanent as it will not decompose.
Again, the benefits of mulch are many and the use of mulch is highly encouraged in landscapes and gardens. Weigh the pros and cons of the different types of mulch before deciding which is best for your landscape. Do not apply too deep of a mulch layer; and keep mulch away from the stems of plants.
Source: Mulches for the Home Landscape G1257 (Revised April 2005)
By John Fech, UNL Extension Educator
Cole Crops? What's a cole? I'm not too sure, but the word cole helps me remember the basic growing conditions of this groups of veggies. Cole crops perform the best if they develop in cool weather (cold, cool, cole - get it?) Anyway, it's best to plant seeds or transplants in early April, so that they can develop and be ready for harvest before the heat of summer starts acting on them.
The cole crops include broccoli, cauliflower, brussel sprouts, cabbage, and kale. As they are growing, they all look similar and have a similar scent. The thick waxy leaves and thick stems are characteristic of this group of veggies.
Kohlrabi- Image from John Fech, UNL Extension Educator
Help out your cole crops, by keeping the soil as cool as possible. This will discourage bolting or early maturation of the edible portions of plant. Apply mulch once the soil begins warming up. In most cases, applying mulch in late April or early May would be harmful to veggie plants. While this is true for squash and tomatoes, it is helpful for the cole crops. The idea is to keep the cole crops cool and heat up the warm season veggies.
Growing Cole Crops in Minnesota Home Gardens, University of Minnesota Extension
Can't Miss Plants
By John Fech, UNL Extension Educator
If you're struggling with the plant selection/choice process, consider these Can't Miss Plants. These plants will perform well in most landscapes in the Midwest.
Trees - Kentucky Coffeetree, Red Oak, Bald Cypress, Ginkgo, Yellowwood, Yellow Buckeye
Shrubs - Viburnums, most dogwoods, shrub roses, burning bush, smooth sumac, cotoneaster
Perennials - Coreopsis, prairie coneflower, yarrow, Russian sage, boltonia, gaillardia, daylily
Groundcovers - Sedum, broadmoor juniper, catmint, leadwort, dwarf Japanese fleeceflower
Trees - Tuliptree, pagoda dogwood, corneliancherry dogwood, amur corktree
Shrubs - fothergilla, grey dogwood, blue mist spirea, butterfly bush, St. Johnswort, clethra
Perennials - astilbe, coral bells, ferns, columbine, bergenia, veronica
Groundcovers - Vinca, wintercreeper, English ivy, ajuga, sweet woodruff, barrenwort
Trees - Redbud, serviceberry, hornbeam, witchhazel
Shrubs - Coralberry, snowberry, blue holly, boxwood, bottlebrush buckeye, alpine currant
Perennials - Hostas, bleeding heart, Japanese anemone, ligularia, bugloss
Groundcovers - Japanese spurge, goutweed, lamium, lily of the valley, lady’s mantle
Cool Season Salad Crops
By Vaughn Hammond, UNL Extension Educator
Spring has sprung and April is the perfect time to be getting ready to plant your cool season crops. Cool season crops are crops that grow best in the 60-65 degree F temperature range. These crops will tolerate a light to moderate frost and in some cases these frosts can change the taste for the better. Cool season crops can not tolerate summertime heat and even limited exposure to higher temperatures can affect the quality of the crop permanently. Cool season crops can be planted in the early spring as temperatures warm or later in the fall as temperatures begin to cool.
Cool season salad greens and other vegetables commonly used in salads such as radishes and carrots are a favorite of many gardeners who are anticipating the early, fresh from the garden salad. Following are some guidelines for planting lettuce, spinach, radishes and carrots.
Image by Sarah Browning, UNL Extension Educator
Lettuce does best in daytime temperatures ranging from 60 to 70 degrees F. Higher temperatures results in a bitter taste and ultimately bolting which is when the lettuce plant produces a seed stalk. Heat resistance varies among lettuce varieties and you can extend the time you grow lettuce by planting heat resistant varieties later in the spring planting season.
Three primary types of lettuce are planted in Nebraska. These are leaf, Cos-also known as romaine and butterhead. Leaf lettuce is one of the most widely planted salad greens. Most varieties of leaf lettuce are ready for harvest 45-50 days from planting while the romaine and butterhead types take a little longer maturing in 60 to 70 days.
Lettuces grow best in soils that are high in organic matter so the use of compost is highly recommended. Lettuce seed should be planted ¼ to ½ inches deep with 10 to 12 seeds planted per foot and thinned to 4 inches apart for leaf lettuce and 6 to 8 inches apart for butterhead and romaine types. Multiple plantings 10 to 12 days apart will result in a extended harvest period. Lettuce is very shallow rooted with the majority of the roots only being 1 ½ to 2 inches deep. The shallow roots are very susceptible to damage and care must be taken when weeding. Lettuce responds to frequent, light watering by producing thick succulent leaves with little bitterness.
Howard F. Schwartz, Colorado State University, Bugwood.org
Spinach is a quick growing crop and ready for harvest in 39 to 50 days from planting depending on the variety. Harvesting can be done in two different ways. The whole plant can be harvested removing every other plant to allow more room for development of the remaining plants.
The other harvest option is to harvest individual leaves throughout the planting as they reach 3 inches in length. Leaves allowed too grow larger than 3 inches long tend to be less tender than the smaller leaves. Two to 3 plantings at 10 day intervals will extend your harvest up to the point that it becomes too warm for quality production.
Every spring salad has to include radishes. Spring radishes develop quickly and depending on the variety can be ready for harvest in as little as 22 days. Plant radishes as soon as the soil can be worked in the spring. The soil should be worked to a depth of 6 to 8 inches. Plant radishes in rows ¼ to ½ inches deep and thin to 1 inch between plants as they develop. If planting in a bed, broadcast the seed evenly throughout the area to be planted and rake in. Thin to 2 inches apart in all directions. Radishes are best if harvested as soon as are large enough to eat. Delaying harvest will result in a hotter radish that will be prone to cracking. Even moisture, not allowing the soil to dry out will help reduce the hotness. Successive plantings every 10 days will insure a good supply of radishes throughout the spring.
Plant carrot seed ½ inches deep with 18-25 seeds per foot. As the roots develop gradually thin to 2 inches apart and then to 4 inches for the final spacing.
Carrot seed is slow to germinate taking 14 to 21 days. Keep the soil surface moist to avoid crusting that may hamper the emergence to the seedlings.
Image by Vaughn Hammond, UNL Extension Educator
Deep watering is important for root development as shallow irrigation does little to support growth. It is a common practice to mix carrot and radish seed at planting. The quick germinating radishes loosen the soil surface, aiding the emergence of the carrot seedling reducing the need for thinning.
It’s Time for Spring Planting of Trees & Shrubs
By Sarah Browning, UNL Extension Educator
As spring arrives, the planting season gets underway. When planting trees and shrubs, spring is the second best time of year; second only to fall, with it’s long period of moderate temperatures allowing more time for root development before the plant is tested by a hot Nebraska summer. Gardeners wanting to plant trees and shrubs this spring, have a window of time from approximately April 1st through June 30th when soil is workable and temperatures are favorable for new plant establishment. Avoid planting trees and shrubs in the middle of summer, July 1st though August 30th, when conditions are very hot and dry.
Bare Root Plants
Bare root plants, such as fruit trees, small fruits and roses, are normally planted earliest in the spring while they are still in a dormant state and before their buds begin to swell. Ideally bare root plants should be planted the same day they arrive, however, this is not always possible and your plants may need to be stored until planting conditions improve. Careful handling before planting occurs will determine success or failure. Bare root plants have had the soil washed or shaken from their roots after digging from the field. Because bare root plants lack a rooting media that supplies water to the plant, they must be stored in a dormant state with temperatures slightly above or below freezing, and high (95%) humidity levels. However, do not allow them to freeze.
When bare root plants are shipped from a nursery their roots are usually wrapped in damp sphagnum moss or newspaper. The plants are then placed in a plastic bag and packaged in a wax-coated or cardboard box. After receiving the plants, inspect them briefly to ensure they are healthy and undamaged, and that the packing material is still moist. Re-wet the packing material if necessary, and then store the plants in their packaged state, under cold temperatures until they can be planted. It is helpful to re-hydrate the plants by soaking them in a bucket of water for a couple hours right before planting, however, DO NOT store the plants with their roots in water overnight.
Container plants have a longer window of time when they can be successfully planted, from approximately late April through the end of June. Be careful with plants that have been protected in a greenhouse, when planting them outside before the last spring frost date. You may need to provide protection if heavy frost is predicted to avoid leaf damage. To minimize stress on the plants, try to plant on a calm or cloudy day, and keep the plants moist during the planting process.
With wood plants like trees and shrubs, it is best to plant them directly into the native soil, without adding any soil amendments. New roots will tend to stay within the area of amended soil instead of spreading out and providing good support for the tree, so eliminating soil amendments actually results in a more extensive root system.
When planting any tree or shrub, one of the most important considerations is making sure it is planted at the correct depth. Roots need oxygen from soil to properly grow. If a plant is planted too deep, the root system doesn't develop as well because it doesn't receive enough oxygen. As a result, the plant can be stunted, have low vigor, and be more susceptible to insects and diseases throughout it’s life.
Image from the Nebraska Statewide Arboretum
To determine the proper planting depth, find the first main root at the top of the root system and plant it just below the soil surface. If the plant is in a container, remove it from the container, then pull the soil away from the top of the rootball until the first root or the “root flare” is located. The root flare can be found on all trees at the base of the trunk where the trunk widens before differentiating into the root system. When planted properly, the tree’s root flare should be visible at the soil surface after planting.
When ready to plant, don't dig the hole any deeper or loosen the soil at the bottom of the planting hole any more than necessary. If the soil is too loose, it will settle after the plant has been in the ground for a while, causing the plant to sink. Dig a shallow, wide hole and loosened soil around the sides. Roughing up the edges of the hole will avoid “glazing” from the back of the shovel that can make it difficult for the root to penetrate through the soil as the tree begins to grow.
Remove any burlap, ropes, strapping materials, plastic containers, wire baskets, plant tags or any other type of labeling attached to the plant before putting the plant in the planting hole. Once the proper planting depth has been checked, backfill with soil, gently firming the soil around the base of the roots. When the hole is filled, apply water and soak the planting hole, allowing the water to eliminate any remaining air pockets. Finally, apply a two to three inch layer of organic mulch, such as wood chips.
Staking trees is not recommended unless the plant is in a very high wind location. Also, don't fertilize new trees and plants for the first two to three years after planting. The same goes for pruning and shaping; limit pruning to broken branches only during the first few years.
Visit the Nebraska Forest Service web site for suggestions on great plants for Nebraska landscapes. ReTree Nebraska’s “Eleven for 2011” lists 11 great plants that are well-adapted to Nebraska conditions and should be used more widely across the state. Also, for more information on good techniques for planting trees and shrubs, visit the Nebraska Statewide Arboretum website.