ProHort Update - March 1, 2024

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Nebraska's drought status, 2/22/24 Map updated weekly.

1. Oystershell scaleInspect plants now for signs of infestation

Winter is a good time to check plants for oystershell scale. If found, make plans for management. Oystershell scale can be found on ash, maple, lilac, cotoneaster, dogwood, poplar, willow; fruits such as apple, pear, apricot, plum, raspberry, currant and grape; and many other hardwood trees and

There are over 8,000 species of scale insects, but oystershell scale is one of the most common in Nebraska landscapes.  It’s named for the look and shape of the female insect’s hard, protective shell, which resembles a tiny, 1/16-1/8 inch, elongated oystershell.

Description
Scale insects are easy to overlook since they're small and immobile most of their lives and do not resemble a typical insect. Newly hatched scale insects are called "crawlers", and they are mobile for only a short period.  They are pale in color and smaller than a pinhead in size. 

Within a few hours after hatching crawlers find a suitable location, usually on a shaded area of the tree. They insert their mouthparts into the plant, begin to suck sap and soon molt, losing their legs. From this point on, most scales are immobile for the rest of their lives. Within a week they are covered with a waxy scale covering that provides protection from most insecticides. At this point, they appear to be part of the bark to the untrained eye. Scale insects can build up to large infestations with branches dying before the insect is noticed.

Winged males emerge during summer.  Female insects lay eggs in fall, and then die; leaving their eggs to overwinter under the mother’s shell.  Old scale shells will stay attached to the plant’s branches for several years before falling off.

Some types have one generation per year and others have two generations. If the scale cover is gray or banded, the scale has one generation and this group hatches in late May. If the cover is brown, there are two generations per season. The first hatches in late May and the second hatches in late July or August. (Source: Iowa State Extension)

Control
To manage scale, timing of practices is important. Prune out and destroy heavily infested branches before eggs hatch. In March or April, before buds expand, spray twigs, branches and stems with horticultural oil to suffocate eggs and reduce hatching. Some plants may be sensitive to oil sprays. Check to make sure a plant is listed on the label before spraying.

Apply labeled insecticide sprays when scale insects are in the crawler stage. Insecticides labeled for control include horticultural oil, insecticidal soap, acephate, bifenthrin or malathion. Repeat application in 7 to 10 days or according to label direction. Repeat again at August egg hatch if needed.

Oystershell Scale, Iowa State University

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2. March 1st growing degree days (GGD)

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3. Pest updatePests to watch for based on Growing Degree Days (GDD)

For a more complete list, visit Michigan State University GGD of Landscape Insects or GGD of Conifer Insects.

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4. Impact of Mulches on Landscape Plants and the Environment - A ReviewCosts and benefits of landscape mulches as reported in scientific literature

Mulches provide aesthetic, economic and environmental benefits to urban landscapes. Mulching is especially useful in the establishmentof trees in landscapes that receive minimal care, such as restoration sites. In general, mulches improve soil health, creating healthypopulations of plants and associated animals. These biodiverse, stable landscapes are more resistant to stress, are more aestheticallypleasing, require fewer applications of pesticides and fertilizers, and are ultimately more sustainable than those without mulch cover.All mulches are not created equally, however, and this review compares the costs and benefits of landscape mulches as reported in thescientific literature. It also presents real and perceived problems associated with various landscape mulches.

Chalker-Scott, Linda. “Impact of Mulches on Landscape Plants and the Environment - a Review.” Journal of Environmental Horticulture, vol. 25, no. 4, 2007, pp. 239-249, https://doi.org/10.24266/0738-2898-25.4.239.

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5. Plant native Nebraska trees & shrubs - ServiceberryFruit production, pollinator & wildlife habitat

Whether for fruit production, pollinator and wildlife habitat, or beauty, serviceberry is an excellent addition to any landscape. Also known as Juneberry or shadbush, plants are named for the month when fruits ripen, with shadbush referring to the plants bloom time "when the shad (river herring) run".

Native Range
There are about twenty plant species within the serviceberry genus, Amelanchier, native to temperate regions in North America, Europe and China. The greatest variety within this genus is found in North America, where at least one species is native to every state within the United States except Hawaii. For example, Saskatoon serviceberry is native to the Great Plains from Manitoba and Saskatchewan to Nebraska. Allegheny serviceberry is native from Newfoundland to Georgia and Alabama, west to Michigan and Kansas.

Characteristics
Serviceberry has so many great characteristics, it's amazing that we don't find one it every yard. They produce clusters of small white flowers in spring, followed by blueberry-sized green fruits ripening in June to a dark purplish-black. In summer plants have clean, medium-green foliage, meaning they are not attacked by many leaf-feeding insects so their foliage stays nice-looking all summer. They also have a nice fall color, ranging from yellow to apricot-orange to deep dusty red. What's not to love?

Downy Serviceberry
As a small ornamental tree, it's hard to beat Downy serviceberry, Amelanchier arborea. It has alternate, oval-shaped leaves that are medium to dark green, and when young may be covered with small hairs on the undersides. It forms a large, multi-stemmed shrub or small tree and when unpruned reaches 15-25 feet in height. Downy serviceberry is hardy to zone 4 and should be grown in well-drained soil with full or partial sun. It blends in well at the edges of wooded areas, along ponds or stream banks, or in shrub borders.

Drooping spikes of white flowers are produced in spring and followed by a berry-like fruit. The fruit changes from green to red, finally ripening to purplish-black in June. The fruits are edible and sweet. However, birds love them too so if you plan to harvest, provide some protection! Flower nectar supports many species of native bees. The fruits are a preferred food source for many bird species and other wildlife.

The cultivars below grow well in Nebraska landscapes and are crosses between Downy and Allegheny serviceberry, A. laevis.

'Autumn Brilliance' – often grown as a multi-trunked tree or large shrub, height 15-20', brilliant red fall color
'Robin Hill' – upright oval form, height 20-30', yellow to red fall color
'Rainbow Pillar' – tight upright form, height 25', mottled yellow, orange and red fall color
'Standing Ovation' – upright oval form, height 10-20', orange-red fall color

Fruit Production
Saskatoon Serviceberry, A. alnifolia, is the best choice for fruit production. It grows as a multi-stemmed shrub usually reaching 3-10 feet in height depending on the cultivar grown. Plants are adaptable to Nebraska's harsh weather extremes and alkaline soil. But if possible, protect plants from harsh summer or winter winds and provide good moisture for best fruit production.

Fruits ripen in June or July. Prairie Indians mixed serviceberry fruits with buffalo meat and fat to make pemmican, their main winter food.

One good fruiting cultivar widely available locally is 'Regent'. It's a compact shrub, only 4-6' tall by 4-8' wide, with extra sweet fruit. It has nice fall color and plants don't sucker much from the base. Adding serviceberries to your landscape will provide spring flowers, fruits, and great fall color. And you'll create habitat for summer songbirds. Consider adding a serviceberry to your landscape this fall!

For More Information

• Downy Serviceberry, Nebraska Forest Service
• Serviceberry, University of Minnesota Extension
• Amelanchier, Lady Bird Johnson Wildflower Center 

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6. Poison ivy rashes still occur in winterUse caution with winter/spring garden cleanup

When dealing with poison ivy, care must be taken during winter - as well as during the growing season - to avoid contact and a rash. All parts of poison ivy, including stems and roots, contain and secrete the oil called urushiol. Contact with this oil is what affects the skin, causing the itchy rash. The oil is in the sap, which is present in stems and roots during winter, and in dead and dried poison ivy plants. Grubbing it out during winter can still lead to a reaction.

Never burn poison ivy plant debris. Burning any plant part, even grubbed out roots or dried stems and vines, can be hazardous. Oil in the smoke can cause a skin rash. Inhaling smoke from burning poison ivy can result in serious consequences. If cutting or digging out poison ivy, protect yourself, and know the oil is very persistent on any clothing or tools it contacts, even during winter. 

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7. Lime for landscape soilNot needed in Great Plains

When homeowners read garden magazines, books or on-line resources, adding lime to soil may be recommended. This is one recommendation we can usually ignore for lawns and gardens in the Great Plains. The addition of lime to soil increases pH, making soil more basic or alkali. In the Great Plains, landscape soils, which are not on old farm ground, most often have a high pH and do not need to be raised any higher with the addition of lime.

If a garden resource (magazine, book, video, TV show) is produced for other areas of the country, such as the east coast where soil pH tends to be acidic and lime is needed to raise soil pH, this information does not apply to Nebraska. As most plants prefer a slightly acid to neutral soil, the addition of lime to soils with a pH of 7 or higher should not be done. If a client asks about lime for amending soil, recommend they have a soil test completed before using a soil amendment to have a good assessment of current soil pH.

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8. Fruit tree spray schedulesResources for professionals and homeowners

It will soon be time for dormant oil applications on fruit trees. These applications are typically the start of a fruit tree spray schedule needed to manage insects and diseases. For homeowners who wish to grow fairly pest free fruit, the need for a spray schedule is best communicated to them when purchasing fruit trees. A "one- and-done" spray application is rarely sufficient.

Apples are a common fruit tree grown and these tend to have the most insect and disease issues. If this a concern of clients, or using pesticides is a concern, suggest growing pears or tart cherries instead. Both are hardy and have fewer pest issues.

For fruit tree spray schedules, below are two good resources to share with homeowners.

• Fruit Spray Schedules for the Homeowner, MU Extension - University of Missouri
• Midwest Fruit Pest Management Guide

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9. Insect survival and cold temperaturesInsects cope well with cold temperatures

Cold winter temperatures and heavy snow does not result in fewer garden and landscape insects during summer. Insects have evolved many coping mechanisms enabling them to tolerate winter conditions. One insect pest that could be affected by cold temperatures is bagworm, which overwinters as eggs in female bags attached to trees. If the air temperature falls to 1˚F for 24 hours, there is potential for up to 75% kill of eggs. However, some will survive and until trees are monitored in June and July for bagworm populations, it will be unknown if enough eggs were killed to prevent serious damage.

How Do Insects Survive Winter, Nebraska Extension - GRO Big Red

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10. Soil mounds or tunnels in lawnsSeveral possible culprits - Voles, moles, earthworms

Vole damage appeared as “runs” in turfgrass as our snow melted. Vole damage to lawns is superficial and lawns eventually repair themselves during spring growth. Voles create “runs” in turf by clipping grass close to the ground. Overseeding may be needed to speed recovery. Controlling voles to prevent turfgrass damage is not neccessary. However, valuable landscape trees should be protected in the fall with a ring of hardware cloth to exclude voles from gnawing and girdling tree trunks. Trapping can be done to reduce vole populations.

Controlling Vole Damage, Nebraska Extension

Moles do not hibernate in winter. Soil mounds with no exit holes appearing in lawns in winter are most likely due to mole activity. When temperatures warm, a mole or moles could go after earthworms leading to soil mounds.

Moles and Their Control, Nebraska Extension

Earthworms leave castings (small, hard mounds) on top of the soil in lawns, leading to rough surfaces. While the mounds are a nuisance and create some walking/mowing difficulty, earthworms are beneficial by increasing air and water movement in soil and helping with thatch decomposition. Large numbers can thin turfgrass. Core aerification, power raking and verticutting will break down some of the castings and reduce bumpiness. Use of a heavy roller is not recommended due to creation of soil compaction.

While no product has earthworms listed as a pest controlled on the label, several have negative effects on them.  Carbaryl (Sevin) has been demonstrated to last 1-3 weeks against them and the same is true for combination insecticides (pyrethroid + neonicotinoid). Early Bird fertilizer is also known to have an impact on earthworm populations.

Managing Earthworm Casts on Golf Courses, USGA Green Section Record

Diagnosing Holes in the Yard, Iowa State University

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13. Commercial/Non-commercial pesticide applicatorsObtaining a new license or updating an expired license

If you have a pesticide applicators license which expired in April 2024 or you need to get a new license, commercial/noncommercial applicators have several options to recertify or get a new license.

2024 Traditional Classroom Training
Commercial/non-commercial in-person training classes are held from January through April. Training schedules will be available soon at https://pested.unl.edu/. In-person trainings are a supplemental learning opportunity; they DO NOT replace pre-class studying of category manuals or flipcharts for test preparation. Study materials for all commercial categories must be purchased online https://pested.unl.edu/

Testing-only Options

• Closed-book exams are given by the Nebraska Department of Agriculture (NDA). Preregistration is not required an there is no cost. Visit the link below for a list of available test-only dates, times and locations - https://pested.unl.edu/.
• NDA computer-based testing is provided through the Pearson-Vue company. Click here for a list of testing sites, categories available, dates, and registration information. Cost $55 per exam. (For applicators with multiple categories on their license, each category is charged the full testing fee.)

Commercial/noncommercial applicators are professionals who apply restricted-use pesticides for hire or compensation. Anyone who applies pesticides to the property of another person, either restricted- or general-use products, for control of pests in lawns, landscapes, buildings or homes must also have a commercial pesticide applicators license. Public employees (those employed by a town, county, state) applying mosquito control pesticides whether restricted- or general-use, must also hold a commercial or noncommercial certification.

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14. Digital Diagnostic Network - Need help with diagnostics?Submit pictures and questions for diagnosis by Nebraska Extension experts

Do you or your clients have questions you need help answering? Maybe you are a lawn care person and they're asking about trees, shrubs, or flowers? While you can refer them to their local Extension office, another option is Digital Diagnostic Network. Homeowners, lawn care professionals, pest control operators and others are invited to submit questions and photos through this website or with the assistance from an Extension professional at any Nebraska Extension office. All offices are equipped with high-resolution digital image capturing technology. Whether the question is about a lawn weed, insects on a plant, diseases in a shrub border or other, an expert panel of Extension professionals will review and respond to the question. To get started, create an account so the question can be reviewed and responded to via email. For more information and to create an account, go to Digital Diagnostic Network.

Bugging Out With Your Camera Phone - Tips on how to get a good picture.

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Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by Nebraska Extension is implied. Use of commercial and trade names does not imply approval or constitue endorsement by Nebraskas Extension. Nor does it imply discrimination against other similar products.