Pest News for Week of Aprill 28th

ORNAMENTALS AND TURF

From: Steve Frank, Extension Entomologist

Rose Sawflies

I found these sawflies on knockout roses this week in Georgia. I also found some on my roses in Raleigh that were slightly smaller. They are probably the curled rose sawfly, Allantus cinctus, but I am waiting on a positive identification. In any case you can look for damage to leaves by these and other sawflies. Small larvae typically skeletonize the leaves. Larger larvae consume entire leaves. Scout for this damage and also for feces which are a sure sign of something feeding on your plants. If infestations are large a contact insecticides such as a pyrethroid or acephate can be applied. Conserve is also labeled for sawflies. Small infestations in home landscapes could be managed with horticultural oil or insecticidal soap.

Tiny rose sawfly larva on knockout rose leaf. Photo: S. D. Frank.

Azalea Lace Bugs

Azalea lace bugs (Stephanitis pyrioides) are one of the most damaging pests of evergreen azaleas. They overwinter as eggs in azalea leaves and begin hatching in Spring. This is actually late compared to some other years, but I found the very first ones yesterday. I found them near HVAC units that blow hot air behind our administration building. This is my monitoring spot for azalea lace bugs because they always hatch here first. In addition the high temperature always leads to greater abundance and damage, too. This is a great example of how high temperature increases advances pestphenology and increases development rate leading to more generations per year.

Azaleas planted next to HVAC equipment that blow hot air. The azaleas always get lace bugs first and worst. Photo: S. D. Frank.

Control is best targeted early in the season when nymphs are present for two reasons. First, nymphs are easier to kill than adults and if you kill nymphs before they mature and lay eggs you have a better chance of clearing up the infestation. Second, the longer azalea lace bugs are on your plant the more damage they do. On evergreen azaleas this damage sticks around for a long time so plants may be permanently damaged. So scout your azaleas and get those lace bugs cleared up before damage occurs. 

Photo: S. D. Frank.

Juniper Scale Crawlers are Active

Juniper scale, Carulaspis juniper, attacks some of the most commonly used plants in ornamental landscapes including all Juniper species, but also cypress species and false cypress. There is one generation per year in which females fill up their armored cover with eggs in spring from which crawlers hatch and look for new feeding sites. Infestations can lead to foliage that becomes yellow or brown and generally less lustrous than normal. Large infestations can cause the tips of branches to die and the plant to become sparsely foliated. Isolated infestations can be pruned off of plants. Natural enemies will often keep scale below damaging thresholds. However, in environments where natural enemies are not abundant control may be necessary. Horticultural oil will smother crawlers. Other chemicals such as dinotefuran (Safari), acetamiprid (TriStar), and pyroproxifen (Distance) and others can be used to manage infestations. More information on armored scale management can be found at:http://www.ces.ncsu.edu/depts/ent/notes/O&T/shrubs/note157/note157.html.

Heavy infestation of juniper scale on Leyland cypress. Adult females are white and round with a yellow center and resemble a fried egg. Photo: S. D. Frank.

For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.

Pest News for Week of April 21st

ORNAMENTALS AND TURF

From: Steve Frank, Extension Entomologist

Oak Eriococcin Scale Active

Oak eriococcin, Acanthococcus quercus, is not very well known. Not much research has gone into understanding its biology or control. It is in the family Eriococcidae which includes several felt scales including azalea bark scale. This scale is quite common around Raleigh and is very apparent this time of year. As the name implies its primary hosts are oak trees. I find it primarily on willow oaks along streets. The oaks on Hillsborough Street by North Carolina State University campus are literally covered head to toe. The scale produces cottony white egg masses that are often in the crotches of twigs. Very little efficacy data is available, but there are reports that imidacloprid and other treatments for soft scale work for these as well. Even horticultural oil may be an effective treatment this time of year right after egg hatch. Visit website: http://www.ces.ncsu.edu/depts/ent/notes/O&T/shrubs/note156/note156.html.

Boxwood Leaf Miners Emerging

Boxwood leafminer adults emerged this week. Look for small orange flies hovering around boxwoods and for pupal casings sticking out of leaves. This indicates adults recently emerged. The maggots pupate in the leaf blister. As the adult emerges the pupal case gets caught on the leaf. This holds the leaf in place so the adult can wriggle out. Boxwoods can be treated with a pyrethroid to prevent flies from landing on the bush to lay eggs, but watch out for mite outbreaks. Imidacloprid will kill maggots within the leaves, but it is best to apply after flowering to protect pollinators. 

From: Mike Munster, Ornamental Pathologist, Plant Disease and Insect Clinic

Pseudomonas syringae Blight and Dieback

As March was going out like a lamb, a nursery submitted four container-grown shrubs to the Plant Disease and Insect Clinic: three rose cultivars and a lilac. Very young shoots on these plants were withering and dying. At least in the case of the lilac – and possibly with the roses, too – the new flush of growth had been hit by freezes. While you’d expect the tender shoots to be blasted by the cold, in this case the woody stems were also dying. Bacterial streaming was seen in much of the stem tissue. We did not see fire blight on rose or lilac, so what was happening? It turned out to be the bacterium Pseudomonas syringae. One of the roses also had Botrytis canker, common canker, and downy mildew.

Although Pseudomonas syringae is named after lilac (Syringa), it is capable of causing cankers and dieback in a wide variety of plants. Besides lilac, we have found it on the following woody ornamentals: cherry-laurel, flowering quince, Indian hawthorn, Yoshino cherry and multiple varieties of roses. In addition, we have recovered it from leaf spots of hydrangea and Japanese holly. Bacterial canker caused by Ps. syringae can be a serious problem in peach orchards and with woody ornamentals, we almost always sees it in nursery situations. One exception came in last year on the twig of a weeping willow from a home landscape. As the weather warms up and cankers become inactive, this disease becomes more difficult to detect. According to the PDIC's records, almost every case of Pseudomonas bacterial canker on woody ornamentals since 2008 was diagnosed between February and May. The bacterium is still present on and within plants during the summer, but the disease process temporarily shuts down.

[http://4.bp.blogspot.com/-6LjJk6ibB1E/U01mLDhWdlI/AAAAAAAAAUU/3ZMU6YmeJg8/s1600/18385_Rose_2014.JPG]

[http://3.bp.blogspot.com/-uAfrF0TXORU/U01nCKLWrmI/AAAAAAAAAUc/jmYAKFR13G0/s1600/18388_Syringa_2014B.JPG]

Note: We occasionally find Ps. syringae causing leaf spots on ornamentals in the greenhouse, and there are variants – called pathovars – that cause certain very specific problems such as bacterial speck of tomato and angular leaf spot of cucurbits.

[http://2.bp.blogspot.com/-cp5HQMNrTiI/U01o1fG-YkI/AAAAAAAAAUo/4GUtRu0Ie9Q/s1600/18387_Rose_2014C.JPG]

Like many bacteria, Pseudomonas syringae is able to live and multiply on plant surfaces. This is known as its epiphytic (“on the plant”) phase. In the recent case, the bacteria were almost surely present before the spring flush occurred, and so were able to strike quickly. These bacteria enter plants following injury, in particular frost damage. What’s more, the bacterial cells actually promote freeze damage through a process known as ice nucleation. As if this trick were not enough, Pseudomonas syringae even produces a toxin that damages plant cells.

The most important way to minimize damage to woody plants from Pseudomonas syringae is to limit the stressors that predispose plants to infection. Stress factors include pruning injury and frost injury. Bacterial canker of stone fruits caused by Pseudomonas syringae can be reduced by pruning in the early summer, instead of the fall or winter. Sanitize shears or knives frequently and avoid working the plants when wet. Keep tabs on substrate pH. Do not over fertilize plants, especially when they need to harden off for the winter. Protect plants during cold snaps. Don't allow plants to undergo stress from too much or too little water. Keep foliage and stems as dry as possible by changing irrigation methods or reducing overhead irrigation, which favors and spreads the bacteria. If you have already had this problem, Ps. syringae is probably present as epiphytic populations on the surfaces of much of your nursery stock and even the surrounding weeds. There are few chemical options that hold any promise, at least not enough to make a recommendation.

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Recommendations for the use of chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by North Carolina State University, North Carolina A&T State University or North Carolina Cooperative Extension nor discrimination against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact an agent of North Carolina Cooperative Extension.

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Employment and program opportunities are offered to all people regardless of race, color, national origin, sex, age or disability. North Carolina State University, North Carolina A&T State University, U.S. Department of Agriculture, and local governments cooperating.

For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.

Pest News Alert week of April 14th

Our first pest alert of the season is now out!  Please read carefully and begin to scout now.  While we may be 1-2 weeks out from the folk in Raleigh a lot will depend on the weather over the next few days.  

ORNAMENTALS AND TURF

From: Steve Frank, Extension Entomologist

Ambrosia Beetles

Ambrosia beetle activity has been sporadic this year due to the cool spring, but now we are catching quite a few beetles. I have also had confirmation of ambrosia beetles active in the foothills. 

Ambrosia beetle management starts with reducing plant stress. In particular we have found that trees with too much water are preferentially attacked. It is easy to overwater this time of year when transpiration and evaporation are low. The next step is preventive applications of permethrin. Apply permethrin to tree trunks and try to avoid spraying the canopy. Our research shows that spraying tree canopies results in spider mite outbreaks later in the year (see the article listed:http://ecoipm.files.wordpress.com/2012/02/franksadof2011reprint.pdf). 

Cankerworms Hatching

I found the first cankerworms of the year a couple days ago. Cankerworms were very abundant last spring and we predict the same this year. Cankerworms eggs were laid over the winter and just started hatching in Raleigh last week. You can see the tiny caterpillars if you shake branches or just watch for them dangling below trees. They feed on many hardwood tree species, but willow oaks seem to be damaged most heavily. We have written a lot on the biology and management of these critters. See a recent article in American Nurseryman

(http://ecoipm.files.wordpress.com/2013/03/an_feb13_planthealth.pdf). You can find information and links to other articles on our dedicated Cankerworm Project webpage (http://ecoipm.com/research/cankerworm-project-home/cankerworm-project/). The important thing to remember is that they only feed for 4 to 6 weeks and only have one generation per year. By the time they get big and start defoliating trees they are about to quit and pupate in the soil until fall. The best management tactic is tree banding in the fall when adults are active. This time of year there is not much to do especially for large trees.

Eastern Tent Caterpillars

Eastern tent caterpillars hatched in the past couple weeks and have already established big nests. The easiest way to deal with tent caterpillars is to prune out the nests. Eastern tent caterpillars make nests in the crotch of trees. (Fall webworms make nests at the end of branches.) So if you can’t remove the nest, you can poke it with a pole pruner. This destroys the nest so many caterpillars fall to the ground and others get eaten by birds. Opening the nest also lets parasitoids in to kill the caterpillars. For severe infestations there are some insecticide options. Products containing Bacillus thuringiensis (Bt) are effective against caterpillars. Other active ingredients labeled for caterpillar control include spinosad, Beauveria bassiana, acetamiprid, acephate, azadirachtin, and bifenthrin. Keep in mind that these caterpillars spend most of their time in a water-proof nest so contacting them is difficult. This limits the efficacy of many insecticide applications.

      

Extension Resources Online

We have many extension resources such as factsheets, articles, pest news, and presentations consolidated as links on my website http://ecoipm.com/. In addition, you can visit the site to read my blog or twitter feeds. You can also sign up to follow my pest alert Twitter feed @OrnaPests and my general ecology and IPM twitter feed @ecoIPM via Twitter or by clicking the ‘Follow’ buttons on my website. @Ornapests provides short timely alerts when new pests become active in the field accompanied by pictures and links to management information. I recently posted “pdf” files of articles I have written for industry magazines and a new free book on the management of tree pests in nurseries and landscapes (http://ecoipm.com/extension/extension-resources/).

From: Matt Bertone, Extension Entomologist

A. destructor

Armored scales (Diaspididae - http://bugguide.net/node/view/43499) are one of the most common insect pests of ornamentals. More like diseases than insects, these sedentary bugs (literally – they are in the Order Hemiptera - http://bugguide.net/node/view/63) sit and suck the sweet fluids of plants, all the while taking energy from their host and replicating as big sacs of eggs. Their babies, called "crawlers", infest new areas and settle in for the long haul of motherhood (or the short, but free, life of a winged male - http://bugguide.net/node/view/15888/bgimage).

Over the past month or so we received two samples of different plants that had an interesting armored scale infestation. The first was poet's laurel (https://www.google.com/search?q=poet%27s+laurel&espv=210&es_sm=122&source=lnms&tbm=isch&sa=X&ei=QnA9U6P-L--nsASqx4HADg&ved=0CAYQ_AUoATgK&biw=1920&bih=965#q=danae+racemosa&tbm=isch) (Danae racemosa), that looked as if it was a variegated variety from the amount of chlorosis associated with the scales.

Looking under the microscope, I noticed two types of armored scales. The first, and less common, were some typical brown, oyster-shaped fern scales (http://www.insectimages.org/browse/subthumb.cfm?sub=8350) (Pinnaspis aspidistrae). However, the most noticeable scale was one I did not recognize. It had a very thin, translucent test that resembled delicate wax paper with a bright yellow scale underneath.

When lifted off, the scales underneath looked like this.

The scale certainly had the rounded shape characteristic of most members of the subfamily Aspidiotinae (as opposed to the elongate shape of most Diaspidinae, such as the previously mentioned fern scale), but what was it? Well, I have to confess that our friend and former clinic member Dave Stephan took a peek during a visit and thought it looked like the genus Aspidiotus. Luckily, he said that because the scale book I most often reference first, Scale Insects of Northeastern North America (http://www.bioquip.com/search/DispProduct.asp?pid=3836) by Michael Kosztarab, does not cover this genus which is primarily Southern in distribution. So I referenced another great resource Ferris's Atlas of the Scale Insects of North America. Lo and behold, Dave Stephan was right – the scale keyed out to the genus Aspidiotus and further to the species A. destructor, the coconut scale (http://scalenet.info/validname/Aspidiotus/destructor/).

Luckily, I had identified that sample, because the same day there was an image of aucuba (http://en.wikipedia.org/wiki/Aucuba_japonica) (Aucuba japonica) that was submitted with a potential scale infestation. Although I was not able to ID the species from the pictures, when the sample came in I recognized the similarities with A. destructor.

After clearing some specimens, I was able to definitively ID them as the same scale. Was this a coincidence? Probably, but who knows whether these scales are becoming more abundant. Our clinic records show that A. destructor was only submitted and identified four times in the 14 years prior to these two samples. Does that mean that we will be seeing more of this scale? I am not ready to conclude that, but if more are submitted this year we may have to investigate what's going on.

           

Aspidiotus destructor was described by Signoret in 1869 and goes by several common names including bourbon scale and transparent scale (I am assuming based on the thin test). The scale appears to be Southeast Asian/Pacific in origin, but has been spread throughout the world. Although mainly a pest of coconut and banana, it is extremely polyphagous being found on over 60 families of plants. The genus is characterized by the following traits that can be seen in the title image (Ferris, 1938).

* absence of paraphyses or intersegmental scleroses

* three pairs of lobes with no indication of a fourth pair

* plates long, flat and fringed (two between median lobes, two between median and second lobes, three between second and third lobes, and a variable number beyond third lobe)

* characteristic sclerotization on dorsum of pygidium

The scale can cause significant economic damage at high densities (which can be common), stunting plants and eventually killing them if enough of the leaves become unable to undergo photosynthesis. Treatments can include chemical control

(http://www.ces.ncsu.edu/depts/ent/notes/O&T/shrubs/note157/note157.html), but there is also a diversity of natural enemies known to attack the species including various fungi, ladybugs, thrips, mites and several parasitoid wasps, most of which are in the family Aphelinidae (http://bugguide.net/node/view/13407). In fact, after clearing the scales from the aucuba, I noticed some sinister-looking aliens inside a few of the scales that are certainly wasp larvae and likely a species of Aphelinidae (below "A").

I don't know whether or not the wasps are able to keep these scales in check alone, but there were at least a few being eaten by these tiny larvae. Every bit helps I guess!

References:

Ferris, G.F. 1938. Atlas of the scale insects of North America. Series 2. Stanford University Press, Palo Alto, California.

Signoret, V. 1869. [Essay on the gall forming insects (Homoptera – Coccidae) – 3rd Part.] Essai sur les cochenilles ou gallinsectes (Homoptères – Coccides), 3e partie. Annales de la Societe entomologique de France (serie 4) 9: 97-104.

For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.