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Hort Update for September 17, 2018

Hort Update for September 17, 2018, Nebraska Extension, http://communityenvironment.unl.edu/update09172018
Bumble flower beetle adult. Image by Joseph Berger, Bugwood.org.
Serious ConcernsMajor Symptom:
1. New Emerald Ash borer advancement Dodge and Lancaster Counties in Nebraska
Minor issuesMajor points:
2. Moles Activity becoming more easily seen as soils cool and moles move higher in the soil profile 
3. Twig girdler, twig pruner Two insects cause flagging of small twigs in a variety of trees
4. Weedy grass control Base control strategies on weed identification and life cycle
5. Annual broadleaf weed control Fall control not recommended
6. Artillary fungus Nuisance fungus found in moist wood chip mulch, causes tiny black spects on home siding
Timely TopicsMajor points:
7. Fall lawn seeding window closing August 15 to September 15 ideal time to seed/overseed cool season turfgrass
8. New recommendations for fall lawn fertilization Still time to make September application; use combination of slow/fast release nitrogen
9. Tiny biters - minute pirate bugs & hackberry lace bug Painful, itchy bites from tiny insects common in late summer
10. Bagworms - what to do now Insecticide applications useless now; insects have stopped feeding
11. Green June beetle larvae emerging Grand Island, Beatrice reporting large numbers of white grub larvae appearing in and around landscapes
12. Sap & bumble flower beetles Beetles feeding on damaged fruits & vegetables


1. New Emerald Ash Borer advancementDodge and Lancaster Counties in nebraska

Thursday August 22 the Nebraska Department of Agriculture (NDA) confirmed discovery of emerald ash borer (EAB) in Lancaster county. Adult beetles were caught in a monitoring trap set up northwest of Pioneer's Park. At the same time, NDA announced the discovery of trees in the Fremont, NE area with signs and symptoms of EAB infestation, although they have yet to find live insects in the trees. NDA's EAB detection map has been updated to include these new sites. 

The following counties are currently under NDA's EAB quarantine - Dodge, Washington, Douglas, Sarpy and Cass. The quarantine will be adjusted later this year after the adult beetle flight period is finished.

Quarantine Regulations and Treatments of Ash Wood Products, Nebraska Forest Service

The Nebraska Forest Service does not recommend treating trees until they are within 15 miles of a confirmed site. However, the new EAB finds puts most of Dodge, Lancaster and Saunders counties, and eastern portions of Seward county within the 15-mile treatment consideration zone.

The best time to treat trees for protection against EAB is April through early June. Fall treatments are not recommended. Research has shown fall applications, although discussed on some product labels, require double the amount of product to provide the same level of control as spring applications.

EAB does not kill trees quickly; it takes a few years of continued infestation before trees begin to decline. Often insects have been in a tree for 2-3 years before signs of decline are noticed and 1-2 more years before the tree dies completely. If treatment begins when 30% or less canopy dieback has occurred, an otherwise healthy vigorous tree can usually be expected to fully recover.

Considering the slow-moving nature of EAB, both in movement through the state and damage to individual trees, waiting until spring is the best choice.

The following Nebraska Forest Service publications are available to share with homeowners. Additional publications are available on the Nebraska Forest Service EAB website.

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4. Weedy grass controlBase control strategies on weed identification and life cycle

Perennial Grasses - Nimblewill, tall fescue, creeping bentgrass, quackgrass, orchardgrass, tumble windmillgrass, zoysiagrass

Base herbicide selection and timing of applications on grass physiology - cool season or warm season grass. Specific herbicide recommendations are available in Lawn Care Pro Series: Perennial Grassy Weed Control

Summer Annual Grasses - Crabgrass, foxtail, goosegrass

Fall control is a waste of chemical and time. Continue to mow and these plants will die off naturally in a few more weeks.

The best way to prevent summer annual grasses is with dense, healthy turf. Provide adequate fertilizer and use good turf management practices. Foxtails tend to establish in thin turf, and goosegrass is common in compacted soils. So again, implement necessary cultural practices when environmental conditions are appropriate to encourage healthy turf.

Preemergence herbicide applications beginning next spring will enhance the control of summer annual grasses. Foxtails and goosegrass germinate later than crabgrass, potentially making these grasses more difficult to control with a single application. Split-applications ensure a sufficient concentration of herbicide in soil to prevent the establishment of these grasses in mid to late summer.

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5. Annual broadleaf weed controlFall control not recommended

Herbicide application for the control of annual broadleaf weeds - such as black medic, carpetweed, knotweed, purslane, spurge - at this time of year is also a waste of chemical and time. These weeds will die naturally at the first hard frost, just like crabgrass and foxtail.

Target summer annual weeds with the preemergent herbicide application next spring to kill germinating seeds. Homeowners are recommended to apply the last week of April or first week of May; professionals may apply earlier based on the residual length of products being used. However, since weed seed continues to germinate all summer long a second application is necessary in mid-summer to provide continued weed control after the spring preemergent is gone. Timing of this application should also be base on the residual length of the product used at the first application.

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7. Fall lawn seeding window closingAugust 15 to September 15 ideal time to seed/overseed cool season turfgrass

The seeding window is rapidly closing or has closed depending on your location within Nebraska. It is still OK to sod, however. If sod is impractical, then consider a dormant seeding in November.

Dormant seeding involves seeding while the ground is not frozen, but cold enough that seed germination will not occur until after soils begin to warm in spring. Other than the time of year of dormant seeding, typically mid-December through Valentines Day or Spring Break, the actual process of preparing the area to be seeded is the same as for seeding at other times of the year. If seedbed preparation took place last fall, and soils are not frozen, dormant seeding can take place now. The risk of dormant seeding is warm winter and early spring temperatures may cause seed to germinate and then a subsequent cold period kills the seedlings. When using dormant seeding, monitor seeded areas in mid spring for the need to do additional overseeding.

Mid-Fall Turf Tips, Nebraska Extension Turf iNfo
Establishing Lawns from Sod, Nebraska Extension Turf iNfo
Establishing Lawns from Seed, Nebraska Extension Turf iNfo

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8. New recommendations for fall lawn fertilizationSTILL TIME TO MAKE SEPTEMBER APPLICATION; USE COMBINATION OF SLOW/FAST RELEASE N

On older lawns (10 to 15 or more years), the first fall application should be made very soon if it has not yet been done. A fertilizer with a slow release nitrogen source can be used.

On younger lawns, two fertilizer applications during fall are recommended; one in late August/ early September and one in mid-October.

For the first one, use a slow release nitrogen source. For the last one, use a fast release nitrogen source. Applications much past November 1 are less efficient because plant uptake is low. This causes nutrients to leach away during winter or linger in soil until spring; resulting in too early succulent growth.  A specific winterizer-type fertilizer is not needed, but have homeowners buy a fertilizer with their particular fertilizer spreader settings listed on the label.

Improving Turf in Fall, Nebraska Extension Turf iNfo
Fertilizing Home Lawns, Nebraska Extension Turf iNfo

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10. Bagworms - what to do now?insecticide applications useless now; insects have stopped feeding

Bagworm infestations were high this year. Insects are now mature adults and no longer feeding, meaning they are also not susceptible to control with insecticides. Contact insecticides will not reach them inside their bags. Systemic insecticides will not go through the bags to kill the adult female insects and eggs inside or move through plant tissues and kill them. 

Removing and destroying the bags is the best method for control from now until May 1st. As many as 500 to 1000 eggs can overwinter in one female bagworm's bag. Destroy insects and eggs inside the bags by crushing or immersing them in soapy water. If bags containing eggs are discarded on the ground, eggs may still hatch and larvae return to the tree next spring.

Next year, wait until after egg hatch to apply insecticide, approximately mid-to late- June. 

Bagworms, Nebraska Extension

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11. Green June beetle larvae emergingGrand Island, Beatrice reporting large numbers of white grub larvae appearing in and around landscapes

Green June beetle larvae are unusual in that they will emerge from the soil at night and crawl on the surface of the grass. Excessively wet soil may be causing some larvae to emerge from the soil and not return during the day. Control is not necessary - most grubs will become a meal for other insects or birds. Chemical control at this time of year is not very effective, expect at most 70-75% kill when applying Dylox or carbaryl. 

Green June Beetles- Lawns, University of Maryland Extension

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12. Sap & bumble flower beetlesfeeding on damaged fruits & vegetables

Sap beetles are small, dark brown beetles, sometimes with blurry spots.  They are first attracted to rotting, damaged, or diseased fruits, but can also attack healthy fruit.  The larvae will feed on fruit, causing it to rot, or to become unmarketable.  The adults can also spread disease, so the damage is two-fold.  Strawberries are a favorite of the sap beetle, but they can also be found on sweet corn and tomatoes.  Chemical control is difficult because they don't usually show up until fruit is ripened.  Removing wounded, rotting fruits is the first and best course of action in control.

Sap Beetles, Iowa State University Extension

Bumble bee beetles, also known as bumble flower beetles or brown fruit chafer, is a mottled yellow/brown beetle, with a thick layer of fine hairs on its thorax. Adults emerge in later summer and feed on rotting fruit, corn, sap, and other plant juices.  They sometimes cause damage to flowers and have been found feeding on overripe or damaged tomatoes in Platte County. Remove old damaged or rotting fruits to reduce population.  Handpick adults and drop into a bucket of soapy water.  Chemical control is not necessary.

Bumble Flower Beetle,  Michigan State University Extension

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