Watch white peach scale – crawlers coming soon

White peach scale (Pseudaulacaspis pentagona) is an armored scale common on many landscape plants and fruit trees. It has a wide host range including over a hundred plant genera such as Buddleia, Camellia, Clematis, Cornus, Euonymus, Hydrangea, Ilex, Ligustrum, Prunus, and many others. The most common host of samples submitted to the PDIC here at NCSU is cherry laurel (Prunus laurocerasus). Cherry laurel is an exotic species which of course is installed in nearly every new landscape I see.

White peach scale females and males on cherry laurel. Photo: SDF

Like most armored scales white peach scales are sexually dimorphic. The females are waxy bumps on twigs but the males grow wings and look like an actual insect. The males emerge from ‘pupal cases’ (not technically pupae). Twigs become covered with the fluffy white pupal cases. This is the easiest time to see and diagnose white peach scale infestations.

Female white peach scale with cover removed surrounded by fluffy white male pupal cases. Photo: SDF

Of course the males come out to mate. Two weeks after the males emerge females will begin producing eggs and crawlers will start hatching. Scouting for the males, even though they do not feed, gives you a head start to plan your management approach.

White peach scales have 3 to 4 generations per year. Infestations are often concentrated on particular branches since scales do not move very far. Dense infestations can kill the individual twigs they are on. Minor infestations in landscapes should be monitored. You can probably inspect most cherry laurels and find some of these. That doesn’t mean you need to treat them; they can just hang out in low densities for years controlled by natural enemies. Plant stress and insecticide applications, like mosquito sprays, could increase the likelihood many armored scale species become problems.

March 7th, 2017|Categories: Landscape IPM|Tags: , |

Early spring flowers=Insecticide risk for bees

Barberry is very attractive to bees and is blooming early in Raleigh. Photo: SDF

Spring in Raleigh is almost a month ahead of usual (is usual a thing anymore?). This means we’ve had red maples flowering since mid-January. More importantly they have been visited by bees the whole time. Not just honeybees either. We have been trapping bees in red maples for the past month or so and found honeybees, bumblebees, and smaller Andrena spp.

Today I noticed hollies flowering along with redbuds, barberry, and azaleas. Surely boxwoods, nandinas, cherry laurels, and other species attractive to bees are not far behind (or is it ahead?). This time of year folks making preventive insecticide applications may not usually think about bees and whether plants are flowering. Many insecticide labels restrict applications when bees or flowers are present.

Hollies have small flowers that many people don’t notice but bees love them. Photo: SDF

Neonicotinoids, like imidacloprid, have been in the news but label restrictions to protect bees are common on most insecticides including other landscape and nursery favorites like bifenthrin and orthene. To be safe: read the labels, don’t make applications when bees or flowers are present, and delay systemic insecticide applications until after flowering. A recent HRI publication and new bulletin and article from Michigan State University could help.

March 1st, 2017|Categories: Landscape IPM, Pollinators|Tags: |

New Bee BMP Summary from HRI

Photo: SD Frank

The Horticultural Research Institute just released a pdf summarizing some BMPs for protecting pollinators from insecticides in greenhouse and nursery production and in landscapes. The crux of it is read the label and follow some basic IPM practices like using alternative management tactics. However, there is also good advice like do not drench ‘bee attractive’ plants with clothianidin, dinotefuran, imidacloprid, or thiamethoxam. And, avoid spraying plants with these products within 3 weeks of shipping. Find other information in a previous post highlighting resources from Michigan State and on the ecoipm Native Pollinator Site.

January 27th, 2017|Categories: Landscape IPM, Pollinators||

Highlights of the 20th Ornamental Workshop

Frank Hale and Andrew Loyd in costume (not mandatory btw) during the Wednesday night social. Photo: Suzanne Wainwright-Evans.

Frank Hale and Andrew Loyd in costume (not mandatory btw) during the Wednesday night social. Photo: Suzanne Wainwright-Evans.

Now over 40 years old, the Ornamental Workshop convened for three beautiful days in late October. One hundred and twenty-three university researchers, extension personnel and representatives from agrochemical companies, biological control companies, tree care companies, public gardens, and others all converged in Hendersonville, NC to geek-out on the pests and diseases of ornamental plants.

Engaged participants soaking up knowledge.

Engaged participants soaking up knowledge. Photo: Suzanne Wainwright-Evans.

Our keynote speakers, Adam Dale (University of Florida) and Steve Oak (USDA FS), started big with presentations about how climate change and urbanization affect insect and disease biology and management. For the next 3 days we had talks and workshops on everything from the latest research on exotic pests like emerald ash borer, crape myrtle bark scale, sudden oak death, and rose rosette, to new innovations in extension delivery. We covered nurseries, greenhouses, chemical control, biological control, new pests, old pests, you name it. We even had a workshop on macrophotography by Matt Bertone (NCSU). You can view the whole program to see what you missed.

Participants Cliff Sadof, Brian Kunkel, Gerald Adams, and Carlos Quesada 'networking' on a hike.

Participants Cliff Sadof, Brian Kunkel, Gerald Adams, and Carlos Quesada ‘networking’ on a hike. Photo: Suzanne Wainwright-Evans.

Of course we never work too hard at the Ornamental Workshop even though ‘work’ is in the name. Each night we gather for drinks and snacks for networking (there is that ‘work’ again) and catching up with friends. The highlight for some folks is Wednesday when we take the afternoon off for a mushroom foray and hiking. This naturally inspires some to attend the social Wednesday evening dressed as their favorite insect or disease. This without a costume can decorate a moonpie to honor their favorite pests.

Moonpie insects and diseases ready to be judged. Photo: Suzanne Wainwright-Evans

Moonpie insects and diseases ready to be judged. Photo: Suzanne Wainwright-Evans

I personally thank all the participants and sponsors for another great workshop. If you want to attend in 2018 watch the website, Facebook page, or join the listserv. If you know someone who should attend this meeting please pass along this post.

Morning at the Ornamental Workshop. Photo: SD Frank.

Morning at the Ornamental Workshop. Photo: SD Frank.

November 9th, 2016|Categories: Landscape IPM, Nursery IPM|Tags: |

Crape myrtle bark scale: New tree pest has arrived in NC

A couple years ago I began warning about a new pest that was spreading throughout crape myrtle country. Now, the crape myrtle bark scale has arrived. From the severity of the infestation it looks like it actually arrived many years ago but now it is “official.” This is bad news because crape myrtles are one of our most commonly planted trees in yards and along streets. Crape myrtles are typically almost maintenance free (unless you top them) but now they will require pest management to stay healthy and beautiful.

Crape myrtle bark scale. SD Frank

Crape myrtle bark scale. SD Frank

Female scales produce fluffy white filaments that cover their body. In spring they produce eggs beneath their body then die. Tiny crawlers hatch from the eggs, settle in their new spot, and begin producing white filaments. They have at least 2 overlapping generations. At low density, crape myrtle bark scale feeds in rough areas around branch collars but as the population increases all the bark may be covered. These scales are most often noticed because trees become covered in black sooty mold. At first many people assume this is from crape myrtle aphids so the scales may go undetected. If you notice unusually heavy honeydew and sooty mold on crape myrtles take a closer look at the bark.

Crape myrtle bark scale is a felt scale related to azalea bark scale and oak eriococcin scale. They feed on phloem like other “soft scales”, thus the honeydew. Even though there is not a lot of efficacy data available drench applications of neonicotinoids are typically effective against phloem feeders. However, since crape myrtles flower continually and attract a slew of pollinators be sure to read the labels for restrictions on using them. Insect growth regulators such as pyriproxyfen and buprofezin are effective for many other scales and may be a good option. Horticultural oil, especially the heavier dormant rate, can reduce scale abundance also.

Crape myrtle bark scale on a rough branch collar. SD Frank

Crape myrtle bark scale on a rough branch collar. SD Frank

There are many subdivisions and streets in North Carolina lined with crape myrtles. Inspect these trees to determine when they become infested. Also consider diversifying the tree planting of your neighborhood. Luckily this pest does not kill trees outright like some other exotic pests increasing tree diversity helps ensure all the trees are not infested or killed at once by a single pest.

August 8th, 2016|Categories: Landscape IPM|Tags: , |

Impervious surface cover is bad for trees. How much is too much?

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Gloomy scales on red maple. Photo: AG Dale

We have studied the effects of urban warming and other factors on tree pests and tree health for several years. The gist of it is impervious surfaces increase plant stress by warming the atmosphere and reducing water availability. Adam Dale and Elsa Youngsteadt studied the effects of impervious surface cover on red maples to determine how much is too much? In a new paper they answer this question to create an impervious surface threshold that planners and planters can use to determine if sites are suitable for red maples. Their analyses of impervious surface cover and red maple condition in Raleigh, NC indicate that red maple condition is most likely to be excellent or good if impervious surface cover is less that 32% within a 25m radius. At 33% to 66% impervious surface cover, trees were most likely to be in fair condition. Above 66% impervious surface cover, trees were mostly in poor condition.

 

Good to know but how do you measure impervious surface cover? Not many landscapers are going to pull up satelite images on their phones and bust out ArcGIS to measure the amount of impervious surface around a tree. Instead we came up with the Pace to Plant technique. With this technique anyone can acurrately measure impervious surface cover at 25 m radius just by pacing transects and counting the steps that fall on impervious surfaces.

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With an impervious surface threshold in hand hopefully landscape architects and other planners will not specify red maples on plans when impervious surface cover is high. Tree care professionals on the ground will also be able to assess if a planting site is suitable for red maples. Two small (even medium) steps for urban tree IPM.

May 17th, 2016|Categories: Landscape IPM, Urban Ecology|Tags: , , , |

Dates set for 2016 Ornamental Workshop on Diseases and Insects at Kanuga

Everyone’s favorite biennial workshop on insects and diseases of ornamentals is scheduled for October 24-27, 2016 at Kanuga Conference Center in Hendersonville, NC.

Workshop title and discipline-specific schedules are still TBD, but go ahead and bookmark the new workshop website, ecoipm.org/ornamental-workshop/, and stay tuned for updates as the time draws nearer.

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Spoils of a 2014 fungal foray. Photo: Annemarie Nagle

November 23rd, 2015|Categories: Landscape IPM|Tags: , |

Ambrosia beetle attacks on landscape trees

Frass toothpicks and sawdust collected in the crotch of a crape myrtle tree. Photo: SD Frank

Frass toothpicks and sawdust collected in the crotch of a crape myrtle tree. Photo: SD Frank

Granulate ambrosia beetles are primary pests of nurseries in spring. However, it seems like every year folks report ambrosia beetle attacks on landscape trees in late summer. It is usually not clear if these are granulate ambrosia beetles but there are dozens of related species that do similar looking damage. In this case I found a row of crape myrtles that all had dozens of holes and the tell-tale frass toothpicks. These four crape myrtles were planted between the sidewalk and street but so are many of the 17,000 crape myrtles in Raleigh. So why these four? Why not the dogwoods planted a few feet away? Dogwoods are very suseptible to ambrosia beetles. Who knows? In any case it is not clear what will happen to these trees. Generally trees attacked by ambrosia beetles die because 1) they are full of holes and 2) the ambrosia fungus interferes with vascular transport. I will watch these trees for the next year or two to find out. In general though this is not a reason to spray all the trees in a landscape. Ambrosia beetles target stressed trees and home in on them very specifically.

September 3rd, 2015|Categories: Landscape IPM|Tags: |

Happy moths, very sad squash

This is a guest post by Annemarie Nagle

I planted yellow crookneck squash this year as an afterthought, after coming across a half-full packet of seeds and pushing last year’s disappointing crop out of mind in a hopeful bout of springtime enthusiasm.

wilty_squash_smallBy June those babies had grown big, lush and beautiful, and friends stopping by remarked on how great the garden was looking. A couple of weeks later and now those giant squash plants are looking more like an embodiment of how I feel after working in the NC heat for a few hours: pretty wilty.

The nemesis at work in my garden is an insect that will be familiar to aspiring squash (and zucchini and pumpkin) growers from Canada to Argentina. Melittia cucurbitae, the squash vine borer, and its host plants in the genus Cucurbita are native to North and South America. In fact, along with maize and beans, squash were cultivated by the Native Americans as one of the ‘Three Sisters’ that provided the agricultural staples for many tribes.

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Wet, brownish frass volcanoes coming out of your squash vines are a sure sign there are borers inside. Photo: A.M. Nagle

M. cucurbitae adults are beautiful orange and black clearwing moths. They fly during the day (most moths are active at night) and are often mistaken for wasps when encountered in the garden. They lay their eggs along the base, stems, and leaves of squash plants, and the larvae burrow into the stem immediately upon hatching. They set up shop and feed for several weeks through the center of the stem, eventually cutting off water flow to the rest of the plant: thus, the wilting.

The fact that I grew yellow squash in my garden last year (and lost them to borers) didn’t do this year’s plants any favors either. The mature caterpillars, which at this point in the year look like chunky, inch-long grubs with amber heads, chew their way out of the stem and drop into the soil, where they will bury themselves a few inches deep and pupate. There are two generations per year in NC, so the first generation will re-emerge as adults in a few weeks to polish off whatever plants they didn’t get the first time (or any new ones you’ve been hopeful enough to plant). The second generation will overwinter in the soil as larvae or pupae encased in cocoons and will emerge come spring.

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Part of the vine removed to reveal the nearly full-grown caterpillar within. Photo: A.M. Nagle

If you are a more dedicated gardener than I am (I’m a plant pathologist, and better at killing plants than keeping them alive…), there are several measures you can take to protect your squash plants from borers. Lightly tilling the soil in late winter can expose the overwintering pupae to the elements. Also, be sure to destroy squash plants when they are done producing to prevent any borers inside from developing, and rotate locations or years for growing squash. For vining varieties such as pumpkins, which can grow new roots at each node, burying portions of the stem encourages the growth of extra roots that can help portions of the plant survive, even when other portions are eventually attacked.

Keep an eye on your squash for the first signs of borer attack: the presence of eggs, then pin holes and brownish, wet frass accumulating at the base. You can ‘deworm’ your vines by making lengthwise slits in the vine near these holes and killing the larvae inside with a knife or pin. Pile an inch or so of soil or compost around the cut to prevent the vine from drying out and encourage rooting.

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M. cucurbitae adult hanging around my cucumber vines. Photo: A.M. Nagle

Insecticide treatments can prevent hatching caterpillars from burrowing into the stem, but are ineffective if you miss this window, so careful monitoring of adult moth activity is important. Adults are attracted to yellow (think squash flowers) and you can monitor when they become active in your garden by placing out a yellow bowl filled with soapy water in late May. Also bear in mind that squash depend on beneficial insects—bees—for pollination, so insecticides should not be applied to flowering plants.

There are some Cucurbita varieties that seem to be less preferred by the borers, particularly those derived from C. moschata, including butternut squash and some types of pumpkin. I’m thinking perhaps a packet of butternut seeds should be waiting for me next year when planting fever hits.

August 12th, 2015|Categories: Landscape IPM, Natural History and Scientific Adventures|Tags: , , |

Emerald ash borers found attacking white fringe tree – fluke or phenomenon?

Emerald ash borer adult. David Cappaert, Michigan State University

Emerald ash borer adult. David Cappaert, Michigan State University

As reported by Entomology Today, Emerald ash borer, Agrilus planipennis, has recently been found to attack white fringetree, Chionanthus virginicus, in Ohio. This is the first non-ash host recorded for emerald ash borers since they were discovered in Michigan in 2002. In a recent paper published in Environmental Entomology, researchers Don Cipollini and Chad Rigsby at Wright State University inspected white fringetrees and Chinese fringetrees, Chionanthus retusus, at Spring Grove Cemetery and Arboretum in Ohio and The Morton Arboretum outside of Chicago. They found 32% of white fringetrees at one site and 43% at the other were infested with emerald ash borers. In some cases it was clear the trees had been infested for multiple years.

No Chinese fringetrees were infested with emerald ash borers. This make sense because emerald ash borers are indigenous to Northeast China so trees there have likely evolved resistance mechanisms. Chinese ash trees are also more resistant to emerald ash borers than North American ash species. The researchers confirmed this resistance by trying to rear emerald ash borer larvae on both fringetree species and a closely related tree, Devilwood (Osmanthus americanus). No larvae developed on the Chinese fringe trees. On white fringetrees larvae survived the 40 day experiment developing to 4th instar but were smaller than larvae reared on highly susceptible green ash. Few larvae survived on devilwood and those that did were small 2nd instars rather than 4th so this does not appear to be a good host.

White fringetree flowers. William M. Ciesla, Forest Health Management International, Bugwood.org

White fringetree flowers. William M. Ciesla, Forest Health Management International, Bugwood.org

White fringetree and Chinese fringetree are frequently planted along streets and in residential and commercial landscapes. Its popularity is increasing as an alternative to other white-flowering trees such as Callery pear. Along Raleigh streets there are 580 white fringetrees 60% of which have been planted in the last 5 years.

Host switching by emerald ash borer from ash to fringe tree is obviously bad news.  We need more research to determine what is driving this phenomenon.

Does emerald ash borer only switch to fringetree after all the ash trees are gone? Do beetle populations have to be at a certain level so competition drives them to try new hosts? Was there a genetic anomaly in these populations that allowed these beetles to succeed in fringetrees when other may have failed? These are all things we need to know before treating or removing white fringetrees from our yards and streets.

So far emerald ash borer is patchily distributed in North Carolina and we do not have as many ash trees on streets or in natural areas as the Midwest and northeast. If this host-switch is a function high emerald ash borer density then maybe we will never get there. Much more work needs to be done.

July 28th, 2015|Categories: Landscape IPM, Uncategorized|Tags: , |